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RKV 2

2.250  1.650 

Description

3 (60%) 3 votes

( this product is no longer available by dealers – only here in our shop )

:::   ultra high end dynamic headphone OTL tube amplifier   :::

you’ll have to look far before you find one better ….

  :: Audio Valve is celebrating the 26h anniversary of the RKV since 1982 ::

 

Tube amplifier for dynamic headphones – preamplifier and power amplifier at the same time

Up to now the RKV (tube amplifier for dynamic headphones), developped and admitted to our distribution in 1982, is by far the most successful tube amplifier in our product range.

Traditional Tube technology has been abandoned and replaced by completely unorthodox approaches to create a concept which is still unique in the amplifier fabrication. Also it has not been resigned latest semi-conductor technology and so a product occurred which reflects 40 years of electronics. The German patent office has secured this idea 1984 with the number DE 3200 51.

“Why headphone amplifiers” – so the Reader might ask. “Doesn’t my output at the receiver suffice?” The answer is simply No. Good, dynamic headphones have a high impedance. For high dynamic jumps, e.g. from CD-Players, they require much higher voltage levels than the supply voltage of transistor amplifiers, which would otherwise be a possibility. The same applies to Hi-Fi systems. So it was one requirement for the amplifier to bring high levels. Moreover it was important to achieve short-circuit strenght and excellent technical data, under the special note of tube sound. The existing concept possesses all this qualities.

By reason of the conformation to high terminating impedances the OTL principle has been appropriated. This concept is geared now to the classic example of the so-called transformerless power amplifier. With the help of semi-conductor technology it has proved to be a felicitous symbiosis of the last 40 years electro-physics.

Also all negative existing aspects of the tubes, like weathering and tolerance hum, had to be eliminated. The RKV-electronic manages this problems effortless. An Op-Amp in the signal path creates a servo circle that compensates all above mentioned negative characteristics of the tubes.

 

It is even able to stabilize the operating point automatically, regardless the weathering of the tube, so that even older tubes continue working without problems. This automatic control circuit has no influence on the quality of the sound, even at the abrasion of the parts.

When judging the sound especially the high dynamic of the amplifier and the typical tube sound are to mention.The bass is tight and enormous, the middles are aery and from a liveley transparency and the high range shows an excellent release combined with transparent space.

Other products on the market, which want to force their headphones to diabolic peaks by the use of smaller battery voltages or 40mWatt output power, just fail here. Cost-intensive headphones, for example by GRADO or AKG, require effort and just there the RKV is the only reasonable driver source.

Of course the amplifer comes with all this qualities as well in his function as a pre-amplifer for power amplifiers. In this case the output voltage of the RKV is decreased to his 15th part and laid on another pair of Cinch Sockets on the backside of the amplifier.

But there is even a third way of using the RKV. The performance of nearly 2*3 Watt is also adequate for driving loudspeakers. Therefore we use the so-called “Impedancer”, that reduces the output impedance of the RKV to the size of the loudspeakers impdedance. Basically high-class transmitters which scale down the output voltage. With loudspeakers starting from 93 dB you can receive an excellent musical result.

The RKV as an universal genius in this three category groups of Hi-Fi technology has no competitor that is nearly able to hold a candle to him in this prize class. For all the people who only consider two of this mentioned possibilities for their own use the RKV is already the only right decision.

 

Warranty and tube Note

On each board is the model name of the product and the name of the tubes is set. So if you are not sure which tube you need, please look at the circuit board and watch what is written there(PCL805 – or ECL85 (6F5P)
In mid-2015 has been changed from PCL805 on ECL85 that affects the models RKV all, Luminare and Solaris


The warranty is void if the top glass of the amplifier is taken within the warranty period. Also void the warranty, if other than that we offer tubes are used for the so-called “tube rolling”. To buynew tubes, please contact your dealer, he has recommended tubes on stock. Incidentally Tube Rolling is simply stupid in the models RKV, Luminare and Solaris. You can convince yourself byknocking on the tubes, they will not hear any knocking sounds in the headphones.

Technical explanations for RKV2 and LUMINARE  that show why this concept provides such good results

 

The following photo shows you a screenshot from the oscilloscope from a channel on RKV 2 – Model 2016 6F5P with attached Verto and 8 ohm load at the output. You see, this clearly represents the new model series more power at the output at your disposal, as the past has been the case.
The re-sizing of some components and small circuit corrections deliver today on RKV 2 in OTL mode at the beginning of Soft Clipping per channel 8 watts.The following photo shows you a screenshot from the oscilloscope from a channel on RKV 2 – Model 2016 6F5P with attached Verto at the output of the STAX socket. Due to the increased power of the RKV 2 the yield of STAX signal now arises voltage is at Verto following measures.

 

A ROYAL TREAT FOR YOUR EARS
AudioValve
RKV Mark II
1) Special patented circuitry, OTL amplifier, stable and long lifetime vacuum tube. 2) Opulent sound carrying the luster of nobility with broad sound field. 3) Base frequency with detailed characteristics and controllability, a demonstration of high performance. 4) Strong drive to present a realistic earphone power.SUGGESTIONS
1) For earphones with impedance lower than 100 Ohms, use the matching impedance provided by the original manufacturer. 2) For best sound effects, use high quality earphones. 3) This earphone amplifier brings out the most beautiful and comfortable sound without distortion. So please properly adjust the volume control to avoid too loud a volume that may damage your listening pleasure.On the RKV back panel, there are two sets of RCA terminals. Why two sets? This is because these two terminal sets are connected in parallel. When one terminal is used as the input, the other terminal can then be used for recording output or connected to the front amplifier. The panel has two earphone inlets. The manufacturer recommends that simultaneous use of two low impedance earphones is to be avoided.I have always had some doubts about the earphone amplifier: 20 years ago, there was no such thing as an earphone amplifier. Nor in a recording room I saw the sound man use such a device. Is it really necessary to buy an earphone amplifier and discard the traditional earphone equipment? AudioValve does think the earphone amplifier necessary or it would never be put into production. The modern audio signal source such as CD has wide dynamic range which is in fact the voltage range that drives the earphone. Earphone output from an ordinary amplifier cannot handle the wide range of voltage variation and hence fail to respond or give good performance.

USE OF SPECIAL TUBES

Targeting at the earphone amplifier, the AudioValve originator Helmut Becker set out his research. What would be the optimum voltage amplifier element? It is without doubt that the vacuum tube is the ultimate candidate. What is the limitation of a vacuum tube? We need to output sufficient current for a low resistance earphone. The first generation RKV was born in 1984. Then, the special PCL 805 pentode for TV use was employed.
Next, the RKV Mark II adopted the OTL full vacuum tube differential amplifier circuit without output transformer. For this special purpose, AudioValve filed the patent rights of the circuitry (No. DE 3200 517). Helmut Becker considers this as a breakthrough of the 40 year progress in audio technology. Using the Op Amp for power supply coupled with complete vacuum tube amplifier for the signal path provides optimal combination of the vacuum tube and transistor technology. The circuitry uses the DC servo Op Amp network for power supply which automatically adapts to the routing conditions. The manufacturer claims that this circuitry will function normally throughout the lifetime of the vacuum tubes.

A BASE FREQUENCY WITH EVERY DETAIL AND CONTROLLABILITY

We used to give advices on the earphone. Nonetheless, an earphone can never produce a heart-rending base energy like a large speaker. Testing an RKV Mark II on Sennheiser HD-580 (300 Ohm resistance) which I have used for years, I can feel the base frequency copiously reborn with every characteristic detail and controllability. The feeling becomes very close to the effect of a large speaker. Comparing to my Graham Slee Voyager, a portable earphone amplifier, I can instantly discern the superiority of RKV Mark II as I can feel a better listening. Where does this better listening come from? More characteristic details? I quickly switch between the two earphone amplifiers. I find not much difference in the characteristic details. But after long listening, I start to pick up the merit of RKV Mark II as its sound is broader, fuller, and more stable. There is the characteristic of thickness and relaxation that makes you feel very comfortable without any pressure. Also, the sound from the RKV Mark II possesses some warmth and luster of gold, yet without any antique tube noise. It is the warmth as well as the luster that brings out the quality of the string instrument. It provides more elasticity to the guitar sound.

VERY STRONG DRIVE POWER

If using Beyerdynamic DT 990 Pro (250 Ohms), the difference becomes more pronounced. For Graham Slee Voyager, the volume must be turned to the 9 o’clock position to have more amplification gain and yet the sound drive is still not full enough. If changed to RKV Mark II, the sound becomes fully open and the dynamic state and stability are of first class. This brings out the real value of the flagship earphone device. As to the two low resistance earphones of AKG K240 Studio (55 Ohms) and Grado SR60 (32 Ohms), the performance can perfectly meet the standard requirement. But in reference to the earphone amplifier, the difference is not so obvious. To match the AudioValve with low resistance earphone (under 100 Ohms), we recommend the use of impedance matching device with a panel switchable between 8~64 Ohms in four divisions. The panel also should be provided with a speaker output terminal so that it can drive high sensitivity speakers.
Indeed the RKV Mark II is quite expensive. However, according to my experience, a good earphone device can last for a long time and will never be outdated. Therefore, it is definitely a worthwhile and necessary investment. The RKV Mark II is absolutely the top choice of all the earphone devices. I believe that an audio fan should value their ear highly. Using the RKV Mark II is a royal class enjoyment.

Warranty and tube Note
:
On each board is the model name of the product and the name of the tubes is set. So if you are not sure which tube you need, please look at the circuit board and watch what is written there(PCL805  or ECL85 (6F5P)
In mid-2015 has been changed from PCL805 on ECL85 that affects the models RKV all, Luminare and Solaris
The warranty is void if the top glass of the amplifier is taken within the warranty periodAlso void the warrantyif other than that we offer tubes are used for the so-called “tube rolling”To buynew tubes, please contact your dealer, he has recommended tubes on stock. Incidentally Tube Rolling is simply stupid in the models RKVLuminare and SolarisYou can convince yourself byknocking on the tubesthey will not hear any knocking sounds in the headphones.

Technical explanations for RKV2 and LUMINARE  that show why this concept provides such good results


The picture below shows you the max. Output voltage before start soft clipping in OTL mode at 220 Ohm load per channel  at 43 Vrms are on each channel 8,3 watts

     


The following photo shows you a screenshot from the oscilloscope from a channel on RKV 2  Model 2016 6F5P with attached Verto and 8 ohm load at the output. You see, this clearly represents the new model series more power at the output at your disposal, as the past has been the case.
The re-sizing of some components and small circuit corrections deliver today on RKV 2 in OTL mode at the beginning of Soft Clipping per channel 8 watts.


The following photo shows you a screenshot from the oscilloscope from a channel on RKV 2  Model 2016 6F5P with attached Verto at the output of the STAX socket. Due to the increased power of the RKV 2 the yield of STAX signal now arises voltage is at Verto following measures. Its round about 1500 AVCpp

600 VAC ( 1500 VAC pp )

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Specs

tech. describtion:

  • OTL – transformer outless tube amplifier ( signal closed feedback loop in OTL concept )
  • double mono construction
  • Alps volume control ( or remote control as option )
  • output: 2 pcs. 6,3 mm stereo / XLR combi jack and 4 pin Sennheiser jack for headphones
  • input: 2 pairs of cinch and 1 pair XLR inputs
  • tubes: actual 4 x 6F5P (ECL85) earlier time: (PCL 85 or 18GV8  )
  • power output: each channel 8 watt on 220 ohms load per channel
  • bandwide: 15 – 100 000 hz
  • damping 3600
  • distortion 0,002 % at 1 Watt-200 Ohm load
  • max. output voltage 100V
  • sens. 0dBm
  • IC – OPA134 – AC/DC controlled – full autom. – controlled bias
  • class – a / minimum load 35 ohms
  • power consumption min. 60 watt
  • size 360*200*120 mm (d.w.h.)
  • weight 6kg
  • patent full automatic servo tube biasing ( 1982 H.Becker )

option: VERTO step up tranformer with auto bias voltage generator for STAX

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Awards

Hifi magazines

A ROYAL TREAT FOR YOUR EARS
AudioValveRKV Mark II , The Earphone Amplifier
Patented circuitry, full vacuum tube OTL differential amplifier, 6.3mm stereo earphone inlet2, vacuum tube PCL8054, output power per channel 3W, bandwidth 15~100KHz, damping factor 3600, distortion 0.002%, maximum output voltage 80V, size 360200120mm, weight 10kg.
FOCUS
1) Special patented circuitry, OTL amplifier, stable and long lifetime vacuum tube. 2) Opulent sound carrying the luster of nobility with broad sound field. 3) Base frequency with detailed characteristics and controllability, a demonstration of high performance. 4) Strong drive to present a realistic earphone power.
SUGGESTIONS
1) For earphones with impedance lower than 100 Ohms, use the matching impedance provided by the original manufacturer. 2) For best sound effects, use high quality earphones. 3) This earphone amplifier brings out the most beautiful and comfortable sound without distortion. So please properly adjust the volume control to avoid too loud a volume that may damage your listening pleasure.

On the RKV back panel, there are two sets of RCA terminals. Why two sets? This is because these two terminal sets are connected in parallel. When one terminal is used as the input, the other terminal can then be used for recording output or connected to the front amplifier. The panel has two earphone inlets. The manufacturer recommends that simultaneous use of two low impedance earphones is to be avoided.
I have always had some doubts about the earphone amplifier: 20 years ago, there was no such thing as an earphone amplifier. Nor in a recording room I saw the sound man use such a device. Is it really necessary to buy an earphone amplifier and discard the traditional earphone equipment? AudioValve does think the earphone amplifier necessary or it would never be put into production. The modern audio signal source such as CD has wide dynamic range which is in fact the voltage range that drives the earphone. Earphone output from an ordinary amplifier cannot handle the wide range of voltage variation and hence fail to respond or give good performance.
USE OF SPECIAL TUBES
Targeting at the earphone amplifier, the AudioValve originator Helmut Becker set out his research. What would be the optimum voltage amplifier element? It is without doubt that the vacuum tube is the ultimate candidate. What is the limitation of a vacuum tube? We need to output sufficient current for a low resistance earphone. The first generation RKV was born in 1984. Then, the special PCL 805 pentode for TV use was employed.
Next, the RKV Mark II adopted the OTL full vacuum tube differential amplifier circuit without output transformer. For this special purpose, AudioValve filed the patent rights of the circuitry (No. DE 3200 517). Helmut Becker considers this as a breakthrough of the 40 year progress in audio technology. Using the Op Amp for power supply coupled with complete vacuum tube amplifier for the signal path provides optimal combination of the vacuum tube and transistor technology. The circuitry uses the DC servo Op Amp network for power supply which automatically adapts to the routing conditions. The manufacturer claims that this circuitry will function normally throughout the lifetime of the vacuum tubes.
A BASE FREQUENCY WITH EVERY DETAIL AND CONTROLLABILITY
We used to give advices on the earphone. Nonetheless, an earphone can never produce a heart-rending base energy like a large speaker. Testing an RKV Mark II on Sennheiser HD-580 (300 Ohm resistance) which I have used for years, I can feel the base frequency copiously reborn with every characteristic detail and controllability. The feeling becomes very close to the effect of a large speaker. Comparing to my Graham Slee Voyager, a portable earphone amplifier, I can instantly discern the superiority of RKV Mark II as I can feel a better listening. Where does this better listening come from? More characteristic details? I quickly switch between the two earphone amplifiers. I find not much difference in the characteristic details. But after long listening, I start to pick up the merit of RKV Mark II as its sound is broader, fuller, and more stable. There is the characteristic of thickness and relaxation that makes you feel very comfortable without any pressure. Also, the sound from the RKV Mark II possesses some warmth and luster of gold, yet without any antique tube noise. It is the warmth as well as the luster that brings out the quality of the string instrument. It provides more elasticity to the guitar sound.
VERY STRONG DRIVE POWER
If using Beyerdynamic DT 990 Pro (250 Ohms), the difference becomes more pronounced. For Graham Slee Voyager, the volume must be turned to the 9 o’clock position to have more amplification gain and yet the sound drive is still not full enough. If changed to RKV Mark II, the sound becomes fully open and the dynamic state and stability are of first class. This brings out the real value of the flagship earphone device. As to the two low resistance earphones of AKG K240 Studio (55 Ohms) and Grado SR60 (32 Ohms), the performance can perfectly meet the standard requirement. But in reference to the earphone amplifier, the difference is not so obvious. To match the AudioValve with low resistance earphone (under 100 Ohms), we recommend the use of impedance matching device with a panel switchable between 8~64 Ohms in four divisions. The panel also should be provided with a speaker output terminal so that it can drive high sensitivity speakers.
Indeed the RKV Mark II is quite expensive. However, according to my experience, a good earphone device can last for a long time and will never be outdated. Therefore, it is definitely a worthwhile and necessary investment. The RKV Mark II is absolutely the top choice of all the earphone devices. I believe that an audio fan should value their ear highly. Using the RKV Mark II is a royal class enjoyment.

A ROYAL TREAT FOR YOUR EARS
AudioValveRKV Mark II , The Earphone Amplifier
Patented circuitry, full vacuum tube OTL differential amplifier, 6.3mm stereo earphone inlet2, vacuum tube PCL8054, output power per channel 3W, bandwidth 15~100KHz, damping factor 3600, distortion 0.002%, maximum output voltage 80V, size 360200120mm, weight 10kg. Imported by Dean Lih Audio Company Ltd. (03-2127378).
FOCUS
1) Special patented circuitry, OTL amplifier, stable and long lifetime vacuum tube. 2) Opulent sound carrying the luster of nobility with broad sound field. 3) Base frequency with detailed characteristics and controllability, a demonstration of high performance. 4) Strong drive to present a realistic earphone power.
SUGGESTIONS
1) For earphones with impedance lower than 100 Ohms, use the matching impedance provided by the original manufacturer. 2) For best sound effects, use high quality earphones. 3) This earphone amplifier brings out the most beautiful and comfortable sound without distortion. So please properly adjust the volume control to avoid too loud a volume that may damage your listening pleasure.

On the RKV back panel, there are two sets of RCA terminals. Why two sets? This is because these two terminal sets are connected in parallel. When one terminal is used as the input, the other terminal can then be used for recording output or connected to the front amplifier. The panel has two earphone inlets. The manufacturer recommends that simultaneous use of two low impedance earphones is to be avoided.
I have always had some doubts about the earphone amplifier: 20 years ago, there was no such thing as an earphone amplifier. Nor in a recording room I saw the sound man use such a device. Is it really necessary to buy an earphone amplifier and discard the traditional earphone equipment? AudioValve does think the earphone amplifier necessary or it would never be put into production. The modern audio signal source such as CD has wide dynamic range which is in fact the voltage range that drives the earphone. Earphone output from an ordinary amplifier cannot handle the wide range of voltage variation and hence fail to respond or give good performance.
USE OF SPECIAL TUBES
Targeting at the earphone amplifier, the AudioValve originator Helmut Becker set out his research. What would be the optimum voltage amplifier element? It is without doubt that the vacuum tube is the ultimate candidate. What is the limitation of a vacuum tube? We need to output sufficient current for a low resistance earphone. The first generation RKV was born in 1984. Then, the special PCL 805 pentode for TV use was employed.
Next, the RKV Mark II adopted the OTL full vacuum tube differential amplifier circuit without output transformer. For this special purpose, AudioValve filed the patent rights of the circuitry (No. DE 3200 517). Helmut Becker considers this as a breakthrough of the 40 year progress in audio technology. Using the Op Amp for power supply coupled with complete vacuum tube amplifier for the signal path provides optimal combination of the vacuum tube and transistor technology. The circuitry uses the DC servo Op Amp network for power supply which automatically adapts to the routing conditions. The manufacturer claims that this circuitry will function normally throughout the lifetime of the vacuum tubes.
A BASE FREQUENCY WITH EVERY DETAIL AND CONTROLLABILITY
We used to give advices on the earphone. Nonetheless, an earphone can never produce a heart-rending base energy like a large speaker. Testing an RKV Mark II on Sennheiser HD-580 (300 Ohm resistance) which I have used for years, I can feel the base frequency copiously reborn with every characteristic detail and controllability. The feeling becomes very close to the effect of a large speaker. Comparing to my Graham Slee Voyager, a portable earphone amplifier, I can instantly discern the superiority of RKV Mark II as I can feel a better listening. Where does this better listening come from? More characteristic details? I quickly switch between the two earphone amplifiers. I find not much difference in the characteristic details. But after long listening, I start to pick up the merit of RKV Mark II as its sound is broader, fuller, and more stable. There is the characteristic of thickness and relaxation that makes you feel very comfortable without any pressure. Also, the sound from the RKV Mark II possesses some warmth and luster of gold, yet without any antique tube noise. It is the warmth as well as the luster that brings out the quality of the string instrument. It provides more elasticity to the guitar sound.
VERY STRONG DRIVE POWER
If using Beyerdynamic DT 990 Pro (250 Ohms), the difference becomes more pronounced. For Graham Slee Voyager, the volume must be turned to the 9 o’clock position to have more amplification gain and yet the sound drive is still not full enough. If changed to RKV Mark II, the sound becomes fully open and the dynamic state and stability are of first class. This brings out the real value of the flagship earphone device. As to the two low resistance earphones of AKG K240 Studio (55 Ohms) and Grado SR60 (32 Ohms), the performance can perfectly meet the standard requirement. But in reference to the earphone amplifier, the difference is not so obvious. To match the AudioValve with low resistance earphone (under 100 Ohms), we recommend the use of impedance matching device with a panel switchable between 8~64 Ohms in four divisions. The panel also should be provided with a speaker output terminal so that it can drive high sensitivity speakers.
Indeed the RKV Mark II is quite expensive. However, according to my experience, a good earphone device can last for a long time and will never be outdated. Therefore, it is definitely a worthwhile and necessary investment. The RKV Mark II is absolutely the top choice of all the earphone devices. I believe that an audio fan should value their ear highly. Using the RKV Mark II is a royal class enjoyment.

AUDIO VALVE`S RKV Mark II in test
GREAT END-OF-THE-MILLENNIUM HEADPHONE AMP ROUNDUP
By Dan Schwartz
Here we have the very
sort of thing that drives me crazy.
Four tubed headphone amplifiers
(Holmes-Powell, Moth Audio,
AudioValve, EAR) and three solidstate
(Grado, Headroom, and
McCormack), and after a
respectable amount of listening, few
sound anything like the others.
What originally started out as four
became seven, should have been
eight, went through delays because
of problems with delivery, and some
last-minute auditioners entered the
chorus line.
Headphones offer a
distinct difference from conventional
listening, with both advantages and
disadvantages. The ability to enjoy
music when one?s family requires
quiet is balanced by the possibility
of enjoying music when you can get
the little bastards quiet enough to
not be heard through the ?phones.
A true High End headphone set-up
can also offer a kind of intimacy to
the source that speakers will never
match, by removing the room from
the listening equation. Even a
mediocre set-up can offer that
improvement, but it may not convey
the nuances that your high-quality
speakers might. The main
disadvantage to headphone listening
is displacement of the soundstage.
Instead of a three-dimensional
soundstage appearing in a window
in front of you, the soundfield is
reduced to a plane inside the head.
This has one virtue, though – with
many CDs, the sound can be quite
reasonable but produces a flattened
soundstage that is no fun.
Headphones render most sources
equal in this respect, and many
otherwise unenjoyable CDs
pleasant.Since I use headphones
every day in my studio, the finger of
fate pointed at me for this survey. I
do recording in a variety of ways:
sometimes as a session musician,
which can involve using headphones
as the only way of hearing yourself –
and can lead to pretty serious
skewing of your sound to tape,
if you adjust your tone to
what you?re hearing, which with the
most common studio ?phones
doesn?t resemble a bit what?s
actually being recorded. Sometimes
I am by default an engineer using
my own multi-track portable
recording set-up. Here I prefer to
have the best headphones available
when using an open microphone in
the same room with the equipment,
but over the years it has become a
little less critical in that one gets
familiar with one?s methods and
gear and learns to trust one?s work
and instincts. The choice of
headphones is frequently limited by
the necessity of using closed-ear
types to prevent bleed from the ?
phones into the mikes, but I find
that the best-sounding so far are
always open-eared.In the first
round of the reviewing process (my
first headphone amp review
appeared in 1993), I settled on the
Melos SHA-1 amp and the Grado
HP-1 ?phones, with the Sennheiser
580 ?phones as an alternative. But
time marches on–the Melos started
developing problems I couldn?t get
fixed, it was drilled wrong for proper
rack-mounting, and was unwieldy.
So I found the original Grado Labsbuilt
Grado Signature HPA-1
headphone amp as a reasonably
low-cost, ultra-portable
alternative.This time out, Scot
Markwell procured the new
Sennheiser 600s ?phones for me,
which I immediately purchased, and
the first amp to arrive came along
with a set of modified Grado RS-1 ?
phones, which I found
uncomfortable, and so wheedled a
proper set out of John Grado
(wheedling being the foremost of
the reviewer?s necessary skills).And
so here we have the review set-up –
these two sets of phones along with
the old HP-1s driven by the tapeouts
of the EAR G-88 with the
Immedia RPM-2/Immedia Arm/Lyra
Clavis DC for analog and the Theta
Data III/Genesis Digital Lens/Theta
Gen Va/96k DAC/Illuminati cable
set-up for CDs.
For comparison?s sake,
music was also heard through
BEL 1001 Mk IV or EAR 509 Mk II
amps and a custom set of d?
Appolito-configured dynamic
speakers built by Richard Marsh.
(Though if you really want to
irritate yourself, try referencing
between speakers and
headphones a lot. I saved it for
the clinches).
We spent months
waiting for the arrival of the
much-hyped Cary CAD-300SEI
tubed integrated/headphone
amp. After many zig-zags, it
became clear that we were not
going to get it. Life goes on. The
first amp to arrive was the
$4,500 Holmes-Powell DCT-1
single-ended model. I love this
thing and picked it as my one
Golden Ear award victim. Nothing
has happened between then and
now to shake out of its place as
pick of the litter (although the
appearance of a fourth tubed
amp, though a prototype and
unreviewable, lessened my regret
at losing the Holmes). The DCT-1
puts out 500mW at 30 ohms
using 6072A input and 6005
output tubes. Holmes-Powell
estimates a typical tube life of 5
to 10 years (and half that for
commercial use, whatever that
means). The thing will handle a
driver load of 25-600 ohms,
which means that, unlike the
other tube units, no special
accommodation need be made
for switching ?phones.At the time
of the Golden Ear deadline, I
wasn?t confident in my
assessment of the HolmesPowell?s
accuracy, only of its
romantic beauty. I now am more
confident that it?s not particularly
accurate – I simply don?t buy
that the 1987 off-the-shelf CD of
Abbey Road, which sounds so
mediocre compared to vinyl
elsewhere, truly sounds as good
as it does with this thing.
If this is right, then
everything else is not good
enough. But I?m just as
certain that the DCT-1 is the
most pleasurable (and
significantly most costly) of the
amps I reviewed. With either
set of ?phones, it?s capable of
enhancing the details of a
recording to a degree of
apparent intimacy that is both
an education and a sensual
delight. In only one instance
was this too much of a good
thing: the new CD of a 1971
Graham Nash/David Crosby
Los Angeles performance
entitled ?Another Stony
Evening? released by Grateful
Dead Records. I don?t want to
overstate the negative effects
of headphone listening with
this one, but it was recorded
straight from the board, and
live mikes are rarely very
good. In this case, they were
the industry-standard Shure
SM-57s that I avoid using in
recording. And none of the
amps reviewed could make up
for the fact that the intimacy of
the ear-to-driver relationship
was just too much on the
cheap mikes, including the
Holmes-Powell.
Of course, it?s just
that ear-to-driver relationship
that makes headphone
listening so pleasurable and
problematic. With a good setup,
nothing can match the
degree of detail you hear.
Likewise, nothing can
overwhelm the ear as fast –
the better the set-up, the
longer you can listen, but
fatigue can set in fast,
especially if you succumb to
the temptation to listen too
loud to get more of that
intimacy. One of the hallmarks
of a better set-up is a
lessening of that urge to turn it
up.
Around the same time
the big macher of amps arrived,
so did its reciprocal: the tiny,
inexpensive, wood-enclosed,
battery-only (2-x-9v) Grado
Labs amp. Pocket-sized, you
don?t expect big things out of it
— and you don?t get them. But
for $350, it will outperform your
basic single-chip tape-deck
headphone output driving
lower-impedance phones like
the 32-ohm RS-1s. Compared
to the larger and more
expensive units, the Grado
seems slightly coarse sonically,
but on its turf, it holds its
ground respectably. Only the
lack of AC-option really irritates
me about it ? one would like to
leave it on to be assured (at
least for reviewing purposes) of
having it perform at its best. I
went through one pair of 9-volts
just doing what I thought was a
decent warm-up ? and stopped.
The Grado seems like
a steal compared to the $1,333
solid-state Headroom Max. I
couldn?t find any justification
for this thing. It?s ugly and
sounds dark and closed-in. It
has a couple of circuits that
might justify it if you find they
work for you – they did zip for
me. One is a kind of cross-talkinducing
circuit that is supposed
to ameliorate the hard left-toright
imaging of typical
headphone performance, along
with a filter designed to
compensate for some losses
induced by that circuit. I could
hear them working away, but
found nothing valuable in them,
or indeed the entire device. I
recall a Headroom amp I
listened to in ?93 with a circuit
that was described as similar in
function that I found more
effective than that in the Max.
If you?re going to
throw $1,333 at the problem,
then save a few bucks and
listen to the tubed $1,190
Audiovalve RKV. Now, this
thing represents good value
for money and would probably
be the winner of this
sweepstakes if dollars spent
vs. performance gained were
the prime criterion. A dualmono
OTL design based on
PCL 805 or PCL 85 tubes, it
uses an IC-based auto-biasing
circuit. In its stand-alone
form, it?s meant to drive ?
phones with a load of 100-
2k/ohm. The company sent it
with a little optional
transformer box called the
Impedancer ($390), which
plugs into the main unit via a
quarter-inch plug and provides
additional outputs switchable
from 8 to 16 to 32 ohms,
perfect for driving the Grados.
It has a stated output of 3
watts, 400 ohms, and a
damping factor of 3500.
Visually, it?s a nice squarish
black and gold box that looks
like Audiovalve?s amplifiers,
smoky see-through on the
sides for that nice tubular
glow. A visitor suggested that
it looked like an old-fashioned
box camera. Sonically it?s a
bit more straightforward
sounding than the DCT-1, not
quite as lush and warm, not
quite the same sense of ?
enhancement.? But
respectable in every sense —
open and beautiful.Much the
same can be said sonically of
the Moth Audio s2A3, with one
important exception. It took
me a long time to understand
the difference between these
two amps.
If the HolmesPowell
is Hawaii, a sound off
by itself, the Moth and the
Audiovalve are the two
American coasts – of a
continental body, cohesively
in the same family, but not
identical. I spent days going
back and forth between
them, trying to qualify that
difference and realizing
gradually that I was coming
to prefer one. (It took the
appearance of a fourth tubed
contender to clarify the
difference – one that plunked
itself sonically squarely in
the center – say Lawrence,
Kansas.) That sonic
exception is the way in which
the Moth characterizes noise.
After a bit, I called the
designers to suggest they
come by to check into why it
was so noisy. Like any
designers, they were taken
aback. And this time, they
were right – unplugging the
input silenced it. Absolutely.
No noise whatsoever. So
what was bugging me? It
was the way in which the
unit treated recording hiss,
whether from LP or
CD.Accuracy is hard to judge
when, to use the Japanese
phrase I love, you?re playing
ball on running water. Three
sets of headphones, all
different. Seven amplifiers,
all different. How do you
judge accuracy? Objectively,
you don?t. You need to be
intimately familiar with all
aspects of the recording and
production chain and process
to get even close. Recording
starts with an imperfect
transducer, ends with an
imperfect transducer, and
what happens between is
audio, which is still
somewhat mysterious.
So you listen and
listen and bring all your
experience to making an
informed opinion. And it?s my
informed opinion that the Moth
Audio s2A3 exaggerates hiss;
and though that may be less
easily discernible in musical
information, this quality made
me feel easily fatigued. The
Crosby/Nash CD is a great
example, and the one I used to
finally chase this down. After a
while, the recording hiss
became distracting only with
the Moth. Moth sent over a
technician to check this out
and he heard it, plain as day,
and agreed. We tried some
measurement equipment he
had brought, with all four
tubed amps, and though the
frequency-sweep and squarewave
response tests showed us
some interesting things, we
could find nothing pointing to
this quality. This is not to say it
can?t be found, just that we
didn?t with that simple
equipment. I also found
myself, without fail, turning the
Moth up when I plugged into it
on A/B rounds of the various
amps – something I did with
none of the others. Something
about it made me want more ?
oomph.?
But let?s talk for a
moment about the Moth?s
appearance. This thing is
beautiful – a few thought it
prettier than the DCT-1 ?in a
mad-scientist sort of way,? as
one fan put it. Inside, it?s
functionally elegant, which I
learned because it?s
apparently persnickety about
its output impedance – you
have to undo 16 small Philips
screws to get at the guts,
though once you do, changing
the impedance is ingenious
and fun. But the designers
must assume you have one set
of ?phones and so don?t want
to change loads very often, or
they?d do something about
Second, the unit is
a prototype, which TAS does
not review. But it taught me
a lot. It?s the Kansas resident
that helped me understand
the differing ways in which
the Moth and the Audiovalve
treated noise and other
signals in the same audio
band. Most importantly, using
recordings I?ve done, on
which I am playing bass, and
also knowing de Paravicini?s
characteristic rendition of low
frequencies (his hand-wound
transformer design is
extremely wide bandwidth), I
was able to determine
something all three of the
other tubed amps had in
I use EAR equipment
in my home system and as the
primary components of my
recording chain, including the
tape recorder, and I am leaning
on de Paravacini to design
interfaces for high-bit and
sampling rate hard-disc
recorders for me.
I bring this up to
explain the final comparison
between the $350 Grado and
the $750 McCormack Micro
Integrated Drive. For many
recordings, I find these two so
near to identical sonically, I?m
unsure I heard a difference. But
the opening track on Martin
I want to digress
one final time on the subject
of accuracy and musicality in
recording, and I am going to
borrow a phrase from
elsewhere in the fine arts:
“Magic Realism.” (Think of
the books of Gabriel García
Márquez or the paintings of
Edward Hopper.) If one
thinks about some of the
great audiophile recordings,
such as the Layton or
Wilkinson albums, one
realizes that what is being
heard is not particularly
close to the sound of a real
orchestra in any literal sense
– i.e., the string tone may be
“simply gorgeous!” but is in
those 16 screws. I listened to
it mainly with the Sennheisers,
since that?s what the
designers themselves
recommend. I had them install
a dummy load on the speaker
outputs1
so I could pop my ?
phones in and out – another
convenience limitation, but
one that is addressable. The
chassis has two little windows
that show you the drive tubes
and a mirrored black finish on
top out of which protrude the
pair of 2A3 tubes, which are
finely bulbous. A true
audiophile delight, in need of
its own stand or your top shelf.
At $1,800, the fit and finish
are a bargain.
Okay ? now for the
mysterious fourth tubed amp.
I can?t review it for a variety
of reasons, yet I must discuss
it because in the end it proved
crucial to my determinations.
It?s a prototype EAR amplifier.
First, I do business
professionally with EAR
principal and designer, Tim de
Paravacini, and the sudden
arrival of this prototype may
well have been the result of
my telling him that I was in
the midst of reviewing tubed
headphone amplifiers.
common. It sounded like an
audible phase shift from the
mid-bass on down, as if the
bass were spread out around
the center of the soundstage,
rather than focused in it. My
guitar sounded rounded and
a little hollowed-out through
the DCT-1, the s2A3, and the
RKV – all pretty much alike,
which I may well have not
picked up on with no other
basis for comparison. In my
other reference – my speaker
system – I had to listen
through a room. But the
moment I heard the bass in
the EAR prototype, I knew I
was hearing the closest to
accuracy in that sonic region.
I was even able to
demonstrate this to Moth
Audio?s tech.The EAR
prototype gradually became
my reference point. I don?t
want to belabor the point of
accuracy, because to
determine what is accurate in
headphone listening is
beyond me – maybe beyond
anyone. But the EAR ?
signature,? if such a range of
products can be said to have
one, is one that fits well into
my listening biases.
Carthy?s brilliant ?Signs of
Life,? a solo vocal with
extremely close-miked steelstring-guitar
version of the
BeeGees ?New York Mining
Disaster, 1941,? finally proved
the break I needed. Trusting the
EAR bass as I do, I found the
Grado?s rendition of the bottom
end of Carthy?s guitar the more
convincing of the two, i.e., more
in line with the EAR than the
McCormack and giving a
somewhat greater sense of
solidity. For practicality and
appearance, I give the edge to
the McCormack. While it costs
more, I prefer its slightly larger
size (less likely to follow along
when you move with the ?
phones on) and you can plug it
into the wall. And on Telarc?s
Arvo Pårt CD and John
Gardiner?s Beethoven Ninth on
DG, I couldn?t hear a difference
between the two with
confidence. Indeed, especially
for the money, both acquitted
themselves quite well by
comparison to the more
expensive and exotic amps,
proving the old adage about
how much more you pay for
that final few percent of
refinement.
every sense much too filled
with detail and shimmer to
resemble what one really
hears in a hall. The
Neumann microphone
capsule is far too non-flat in
its response, near- or farfield,
to give you the real
thing. That much is sure.
But equally sure is that the
results nonetheless contain
pure musical magic. And
that is the best of audio.
One could create a scale of
0-100 and place recordings
anywhere along it, ascribing
a value from the 0 of reality
to the 100 of magic. I would
put my favorite recordings of
the Beatles somewhere near
100, and the more literal
recordings of Altarus’ Chris
Rice or the new solo piano
recording by Tim
deParavacini with his new MS
line microphone2
somewhere around 50. The
RCAs? Well, they’re pretty
high up and vary with
pressing.
Drawing a conclusion from all of this is not particularly
easy unless one places some restrictions on the choosing: If I
could, I would choose the EAR protoype above all other comers
for its sense of accuracy and the useful relative compactness of
its package, bearing in mind my somewhat neurotic quest for
accuracy where I believe none exists.But the EAR is out. So, for
pure visual and musical aesthetics, I still stand by the beautiful
to hear and see Holmes-Powell DCT-1. In the price vs.
performance race, the AudioValve RKV, at nearly one-fourth the
price of the Holmes is nearly all one might want. I am reluctant
to dismiss the gorgeous Moth s2A3 out of hand – I want to
suggest that should the reader find one available for the
listening, do it, and simply bear in mind my experience. Among
the solid-state contenders, I give the slight sonic edge to the
Grado (over the more ergonomic McCormack), which somewhat
compensates for the nuisance of its battery-only operation. It is
clearly the place to begin if one is just getting into this kind of
thing.
RKV Mark II headphone amplifier
as reviewed by Carlo Flores POSITIVE FEEDBACK ONLINE © 2004 – HOME
Let me tell you one of the reasons I like Dr. Jan Meier. After he read my review of his HA-2 headphone
amp, he told me that I favored tube sound (I do), and asked if I had heard the Audio Valve RKV Mark II. A
week or so later, PFO received one for review. I do not know of another instance in which one
manufacturer offered another’s product for review, although I should point out that Dr. Meier distributes
Audio Valve products in North America. Meier seems to care more about his customer’s needs than he
does about hyping his designs. I mention this because I consider the HA-2 the standard for
performance/price, against which I must measure the RKV.
Audio Valve’s RKV Mark II is an OTL tube amp that measures a little over 5 x 9 x 12 inches in size and
is priced at $1050 shipped. According to Audio Valve’s website (www.audiovalve), it was designed by
Helmut Becker to drive any load between 32 and 2000 ohms, but it could not quietly drive my 40-ohm
Grado HP-1 headphones without a transformer (an option packaged as the $180 Impedancer), so I
used my Sennheiser HD580s. Finding replacements for the RKV’s set of four Tungstram PCL805
tubes is said to be easy, although I believe that tube rollers will find limited options. The amp’s piano
black finish with gold trim is more garish than elegant—it would look sharp in Snoop’s crib, but a picky
girlfriend may give grief. Its paralleled pair of single-ended inputs means that it can act as a twosource
headphone amplifier or function between a source and preamp. An IEC receptacle and two
headphone jacks are included. The top lid is made of a transparent material and is secured with metal
thumbscrews, which allows easy access to tubes and fuses as well as amorous glances at its sexy red
PCBs.
There’s a lot I like about the amp. It was so good during the first month that I felt seduced. I think of
music reproduction as a three-part process—attack, body, and decay—and I give the RKV good
marks in each. It has an almost lush sound, full but not bloated. Even when paired with an averagesounding
digital source like my modified Sony CE-775, the amp contributed an analog-like reverb to
strings. It sounded noticeably fatter and sexier than the HA-2. For example, Pulp’s Intro—The Gift
Recordings has lots of crazy riffs that sound electric and awesome with most amps, the HA-2
included, but dominating with the RKV. For you audiophiles, Norah Jones sounded huge.
I can’t overstate that the RKV makes music sound damn good. It’s all about midrange, bass, and
decay, though I’m not saying that the high frequencies suffer, because they don’t. I am not talking
about impact or detail, but about finding the music. The word that comes quickest is “wet.” Notes
sound wet when played through the RKV. A groovy acoustic guitar, such as Jonathan Richman’s, has
adequate groove, which is an accomplishment for a system featuring the HD580s. I’m also talking
about the kind of soundstage that makes me forget I’m wearing headphones.
Magnifying this is bass performance that pushed the Sennheisers to their limit. I prefer a quick
midbass and a direct relationship between the lowering of frequency and a note’s thickness, and the
RKV gives me what I want. The Sonics’ foundation, Serge Gainsbourg’s pace, and Mos Def’s beats
just sounded right, and involved me as a listener. I’ve heard more expensive amps mess up the lower
notes. Unlike them, the RKV ‘s separation between bass notes is distinct, and while their impact is
somewhat weak, instruments have adequate weight. When the foundation of notes is this good, I find
myself turning into a bass head.
What did I lose to get that scale? A great amp gives up very little, if anything. HA-2 doesn’t even try to
sound big, preferring to achieve frequency balance, and it offers Dr. Meier’s cross-feed to recordings
that need consolation. The RKV ignores audiophile sensibilities, offering gray backgrounds and little
resolution at low levels. While the stage is very wide, placement within that stage is fuzzy at best. It’s
easy to focus on one instrument—to ride a stringed instrument or be caught in a piano—and get lost
when listening to the RKV. However, place that instrument in relation to the others, and things turn
messy. As with badly set up speakers, the image of each performer is soft and indistinct. People who
want scale in a small room with reflection problems know what I’m talking about—the nuance is gone.
Albums sound good, but hardly ever interesting. If you owned this amp, why would you invest in highquality
recordings when you cannot hear their full potential? This is a music lover’s amp, not an
audiophile’s.
I have not mentioned my reference headphone source, the Audio Note 2.1x CD player, because it
does not complement the RKV and the HD580. Instead, it yields an unbalanced but juicy sound,
appealing at times (Nick Cave’s piano in the song “Into My Arms”) and irritating at others (Nick Cave
and The Bad Seeds’ album Murder Ballads). Unlike the HA-2, which mates well with even the most
flavored sources, the RKV gets in the way. In the end, the RKV is a designer Band-Aid that will help a
system that needs to add flesh to notes. It probably would have been great with my old reference, an
Arcam Alpha 9, or other typically dry British sources. The RKV only disappears at moments,
depending upon song and instrument. As much as I like this amp, I believe it has too many flaws—its
inability to drive low-impedance headphones, its high noise floor, and its lack of balance—at $1195.
The HA-2 can be the foundation of a system. Find the headphone you want and it’ll drive it. Choose a
flavored or unflavored source and you’ll hear the characteristics the designer wants you to hear. It
costs almost half as much, and it comes with cross-feed. For me, this just isn’t a contest.

New fashion of headphones—new fascinating headphones of this month
Overall drive! Another classic of tube-transistor hybrid amplifier
By Lin Jialiang
In the global spectrum of acoustics, “Made in Germany” always symbolizes preciseness and extreme high standards while its sound aesthetics represents a style of order, balance, strength, powerful action, self-restraint expression, decisive attitude and heroic spirit. (To illustrate with a pianist, Wilhelm Backhaus will be the very representation.) Besides, there is a major feature shared by the traditional German acoustics due to the consonants in German, whether being voiced, voiceless or even double consonants, they will always be produced clearly with powerfully cadence, which has virtually shaped the majestic and powerful style of German acoustics as well as the detailed and clear end sounds.
All those features mentioned above can be found in the brass brands such as T+A and Burmester as well as small brands such as MBL and Audio Valve. Noticeably, the German Sound based on the nationality tends to be more evident at small German brands and this is because the brass brand acoustics will adjust to local tastes according to aesthetic standards of different areas during the process of globalization. While the small brands are free from such problems and can do better in upholding its own style, and therefore it is more common to hear sounds from ASR and Audio Valve with strong German flavor.
Acryl cover—good in promoting music performance
Audio Valve is owned by Helmut Becker, whom I neither know nor meet in person. And I even don’t know how he entered this industry of acoustics. However, based on limited information from the English world, with a particular and strict taste, he will do everything himself. He won’t stop midway unless he has developed the product to the best, or publish the key techniques unless he has obtained patent rights. You can search for Helmut Becker’s life story on the internet. Otherwise, you can catch a glimpse of his personal style from the Audio Valve products because “You are What You Create”.
With a distant view, people will tend to associate RKV MK2 with its sister product MBL due to the black framework and golden knobs, and also connect it with another small yet refined brand: ASR, because of its acryl cover, which is as thick as 1cm. As far as the overall view is concerned, RKV MK2 impresses people with its majestic and magnificent style peculiar to German.
However, why the acryl cover? According to the study of material and sound, the acryl plate is smooth, gentle, soft and flexible with good music performance. It can also filter tiny details and noise in acoustics. Metal materials, which increase details, linearity yet with a sharp and hard tone, and the acryl plate are mutually complementary. And the proportion of mixture will indicate the ability of sound tuning of each manufacturer. Since Helmut Becker, who is famous for his particular taste, applies the design of acryl cover, it will definitely show his tuning skills.
[Text to picture one:
It is easy to associate RKV MK2 with its MBL due to the black framework and golden knobs, and also connect it with another small yet refined brand: ASR, because of its acryl cover, which is as thick as 1cm. As far as the overall appearance is concerned, RKV MK2 impresses us with its majestic and magnificent style peculiar to German. ]
OTL double single-track vacuum-tube amplification and Automatic Bias Regulation (ABR)
As to the music performance, I will talk about it later as I share my personal view about RVK MK2. What we know for sure in the least is that, the manufacturer who applies the acryl cover must be very proud of its circuits subconsciously, and don’t worry about the plagiary problems (after all the product is protected by patent rights) and tests by experts. Therefore, what is special about the circuit design of RVK MK2? Its amplification circuit applies the structure of OTL zero-output transformer and double single-track vacuum-tube differential amplification. Designed in this way, basically, vacuum tubes take the full control of the output of amplifier. In other words, Helmut Becker is very confident of the performance of vacuum tubes. What kind of tubes does RKV MK2 apply? They are PCL 805 (18GV8) of Elektronska Industrija (EI), which used to be applied as the five-stage tube on TV set. Frankly speaking, except RKV MK2, I can’t remember of any amplifier manufacturer, which has ever applied this kind of tube for amplification. With these rare tubes, Helmut Becker shows qualities and specialities, which will be testified soon later.
I’d like to remind you of its signal amplification circuit, which connects the Operation amplifier as DC server with four Ei PCL 805 tubes, and many ICs and active/passive units placed nearby for the purpose of bias regulation, which comprises the special design of bias regulation for vacuum-tube amplifiers. And this famous patent of ABR (Automatic Bias Regulation) of Audio Valve will not only integrate qualities of transistors and tubes, supply a maximum output voltage of 80V, a high voltage output of 3 W (100-400?) for each track, and the standard impedance factor as high as 3600, which is enough to drive any kinds of headphones with various impedances and voltages (the manufacturer states that the headphones can range from 32 to 2000 on its website), but also automatically adjust the output power of each tube according to its working conditions so as to minimize their effects on the performance of RKV MK2. Then, even it becomes necessary to replace tubes, replacing one tube is enough for one time and the tube matching and complete replacements are not necessary. To sum up, ABR is definitely helpful with stabilizing the performance and extending the lifespan of tubes. By the way, the former version of RKV Mark II, the so-called second version, was designed in 1982 to celebrate the 25th anniversary of the brand.
Need warming up like good wine
In the formal test, I applied the USB DAC digital current Onix DAC25A as signal source, Furutech GT2 as leads, and windows 7 + Foobar2000 + WASAPI as playing software, and the control group consists of DA&T HA-1A and Kingrex HQ-1, and as to the headphones for reference, I have tried AKG K701, Sennheiser HD800, Grado RS-1 and Denon AH-D7000, with various test results, among which AKG K701 did the best on the whole because it didn’t change the original characteristics and brand features of headphone (I think this point is of special importance to the fundamentalists of headphones), and therefore, all the following opinion comes from the arrangement of RKV Mark II with K701.
[Text to picture
This equipment has two sets of RCA input jacks and no pre-amp switch, which make it convenient for the users to input two signal sources. ]
[Text to picture
The ABR (Automatic Bias Regulation) that makes the manufacturer feel proudest is also applied, which has made use of the tube-transistor hybrid circuit to the best. ]
Within half an hour after turning on, RKV Mark II played extremely comfortable music, soft and smooth in tone, with a strong flavor special to tube amplifiers; however, something was missing in its music quality, and that was like the wine, which had not been decanted and therefore tasted a little acerb, was short of sweet aftertaste. However, after half an hour of warming up, its performance was totally different. It activated its full potentials so that the weak point of being loose and short of power at bass frequencies was fully recovered, and the bass sound became more condensed, powerful, and flexible and clearer, which continued smoothly with clear arrangements, grain and rich scales. What’s more fascinating is that the musical cadence was taken fully under control when RKV Mark II was used to drive K701, which was quite difficult to see in tube-structured amplifiers.
Who can say no to such powerful and clear bass frequency quality? It was not only K701 that could make such fascinating chemical transformations; however, when RKV Mark II was connected with HD800, which performed unsatisfactorily at bass frequencies, or other headphones, the performances at bass frequencies were all improved. The differences just lied in how better for each headphone or, with the bass frequency being improved, whether it could harmoniously join in with tweeter frequencies. Obviously, with RKV Mark II as the drive, as far as musical qualities such as tone, density, speedy and resolution were concerned, the tweeter and bass frequencies of K701 joined in more closely and smoothly; while playing human voice, the midrange frequencies could improve the resonance within the singer’s chest and the eruption as well as the sturdy linearity (fleshliness), which made the music sound stronger, vivid and dynamic. In addition to the warm treble, it also could filter noise, embellish the music, and make necessary compression to avoid Peak break, and with all these together, human voice sounded more vivid, emotional and touching.
Both improvements of depth of bass frequencies and width of sound field
Warm, strong, clear, pure, soft, comfortable, pressureless, low base noise and high resolution were the key points I constantly wrote down when I listened to different headphones such as K701 that were driven by RKV Mark II, and only when K701 was connected with it, could I put down so many advantages (certainly with the most notes). Furthermore, as we known, K701, which lacks in base sound, is a kind of headphone with strong temperament, which will be lost as most amplifiers try to power it up; if the temperament of headphone is fully taken care of, it is usually unavoidable to limit the types of music that K701 can play. Back to RKV Mark II, it will not only bestow K701 with powerful momentum, but also reserve its original refined temperament. Sorry, I shall say it becomes better.
Finally, there were improved results as RKV Mark II was connected with various headphones, and it was because it extended the depth of the sound field and at the same time strengthened impression of being surrounded by sound. Take the arrangement with K701 as example, the open-designed K701 could not create such vast found field as that of HD800 and HD650, which could be described as open and natural (especially natural). Driven by RKV Mark II, the sound field, compared with the control group, became deeper and broader with clearer resolution as well as clearer arrangement and position. What’s more surprising was that the sound image was created right before one’s eyes instead of his head, and its sound field could cross over the upper limit of “180 Degree Line of Headphones”—Joan Baez’s Diamonds and Rust in the Bullring. Listening to this album, the cheer and applause of the audience on the back were also reproduced vividly making a live impression of “as one falls, another rises”. It could be found that this amplifier did quite well in reproducing details and vividness in open space.
Among the best
To sum up, although my personal idea is that the arrangement of RKV Mark II with K701 is the best, I believe that it is highly possible for fans of other headphones to love this vacuum-tube amplifier. After all, warm and mellow tone, strong linearity, rich flavor of analogy, touching impression, and excellent music quality are advantages many amplifiers can never have. As far as the acoustic quality is concerned, the vacuum-tube structure of RKV Mark II is almost immune to the influence of impedance of different headphones. With high voltage output, it can easily drive any headphones and reproduce the record’s dynamics. Furthermore, the performance of RKV Mark II in clarity, speed and resolution are among the top rank in the vacuum-tube amplifier spectrum. Its performances when arranged with various headphones are beyond the standard with the difference being: whether the headphone itself can withstand such powerful drive. Therefore, although I am not sure whether the fundamentalists of headphones will like the sound qualities of RKV Mark II, I am sure that RKV mark II is among the best amplifiers that I’ve listened to! (Dean Lin Audio Company Ltd.: 03-2127378)
[Text to picture
A patent right has been obtained for the special vacuum amplification circuit designed by Helmut Becker for RKV MK2. ]
Test results
Figure 1 is the FFT frequency spectrum graph of this equipment with 1 KHz sine wave signal, a load of 200? and an output of 10mW and it is clear that the second-harmonic generation is about 100pW, and the 60Hz harmonic is also 100pW with a THD+N reading as 0.015%; Figure 2 is the FFT frequency spectrum graph of this equipment with 1 KHz signal, a load of 200? and an output of 100mW and it is clear that the second-harmonic generation is about 100nW with a THD+N reading as 0.015%; Figure 3 is the frequency response of 1mW, 10mW, 100mW and 1W, and it’s clear that the high frequency can extend to 80 KHz (-3dB). Figure 4 is the coordinate graph of output to distortion, and it is clear that the signal harmonic begins to increase with an output above 50mW and the maximum power without cutting wave shape is 4.4W. (Guan Peiqing)

Un plaisir royal pour vos oreilles
AudioValve
RKV Mark II

FOYER
1) Connexion breveté speciale, amplificateur OTL, le tube de vide stable et de longue vie. 2) Le son opulent portant le brio de noblesse avec un Sound field large. 3) La fréquence de base, des caractéristiques détaillées et la contrôlabilité, une démonstration de haute performance. 4) Une forte poussée pour présenter une performance d`écouteurs réaliste.

SUGGESTIONS
1) Pour écouteurs avec une impédance inférieure à 100 ohms, utilisez l’adaptation d’impédance fournie par le fabricant original. 2) Pour obtenir les meilleurs effets sonores, utiliser des écouteurs de haute qualité. 3) Cet amplificateur casque fait ressortir le son le plus beau et confortable, sans distorsion. Alors s’il vous plaît régler correctement la commande de volume pour éviter un volume trop fort qui peut endommager votre plaisir d’écoute.

Sur le panneau arrière du RKV, il ya deux couples de terminals RCA. Pour quoi deux couples? Parce que cet deux terminals sont connectés en parallèle. Quand un terminal est utilisé comme l’entrée, l’autre peut ensuite être utilisé pour l’enregistrement de sortie ou connecté à l’amplificateur avant. Le panneau a deux entrées écouteurs. The manufacturer recommends that simultaneous use of two low impedance earphones is to be avoided. Le fabricant recommande que l’utilisation simultanée de deux écouteurs à basse impédance doit être évitée.

J’ai toujours eu des doutes sur l’amplificateur casque: Il ya 20 ans, il n’y avait pas une telle chose comme les écouteurs amplificateur. Ni dans une salle d’enregistrement, j’ai vu l`assistant de son que vous utiliser un tel dispositif. Est-il vraiment nécessaire d’acheter un ampli casque et jeter le matériel écouteurs traditionnels? AudioValve croire aux nécessaire d`amplificateur casque ou il ne lui serait jamais mise en production. La source de signal audio modernes comme le CD possède une large plage dynamique qui est en fait la gamme de tension qui anime l’écouteur. Sortie casque d’un amplificateur ordinaire ne peut pas traiter le large éventail de variation de tension et, partant, ne répondent pas ou donner de bonnes performances.

UTILISATION DES TUBES SPECIALE
L’amplificateur casque avoir pour but, l`origine d`AudioValve, Mr. Helmut Becker, a commencé sa recherche. Quel serait l’élément amplificateur de tension optimale? Il est sans doute que le tube à vide est le candidat final. Quelle est la limite d’un tube à vide? Nous avons besoin de courant de sortie suffisante pour un casque à faible résistance. La première génération RKV est né en 1984. Ensuite, la spéciale PCL 805 pentode pour utiliser la télévision a été employé.
Ensuite, le RKV Mark II a adopté l’ensemble du tube à vide OTL amplificateur différentiel circuit sans transformateur de sortie. Pour cette destination particulière, AudioValve à déposé les droits de brevet du circuit (n ° 3200 DE 517). Helmut Becker considérez cela comme une percée de l’état d’avancement 40 années dans la technologie audio. Utilisation de l`amplificateur OP pour l’alimentation couplé avec un amplificateur à tube à vide complet pour le trajet du signal offre une combinaison optimale du tube à vide et de la technologie des transistors. Le circuit utilise l`amp DC servo OP réseau pour l’alimentation s’adapte automatiquement aux conditions qui routage. Le fabricant affirme que ce circuit va fonctionner normalement pendant toute la durée des tubes à vide.

UNE FRÉQUENCE BASE DE TOUS DETAILS ET LA CONTRÔLABILITÉ   Nous avons utilisé pour donner des conseils sur l’écouteur. Néanmoins, un écouteur ne peut jamais produire une base de l’énergie déchirante comme un grand haut-parleur. Quand testé un RKV Mark II sur Sennheiser HD-580 (300 ohms de résistance) que j’ai utilisé pendant des années, je peux sentir la fréquence de base caractéristique copieusement renaît avec chaque détail et la contrôlabilité. Le sentiment devient très proche de l’effet d’un grand haut-parleur. En comparant à mon Graham Slee Voyager, un amplificateur de casque portable, je peux instantanément discerner la supériorité de RKV Mark II que je peux sentir une meilleure écoute. D’où cela vient d’une meilleure écoute? Plus de détails caractéristique? Je basculer rapidement entre les deux amplificateurs écouteurs. Je ne trouve pas beaucoup de différence dans les détails caractéristiques. Mais après longtemps d’écoute, je commence à chercher le mérite de RKV Mark II que le son est plus large, plus entière et plus stable. Il est la caractéristique de l’épaisseur et de détente qui vous fait vous sentir très à l’aise, sans aucune pression. Ainsi, le son du RKV Mark II possède un peu de chaleur et brio de l’or, mais sans aucun bruit tube antique. C’est la chaleur ainsi que le brio qui met en valeur la qualité de l’instrument à cordes. Il offre plus d’élasticité au son de guitare.

TRÈS FORTE PUISSANCE DE COMMANDE
Si vous utilisez Beyerdynamic DT 990 Pro (250 Ohms), la différence devient plus prononcée. Pour Graham Slee Voyager, le volume doit être tourné sur la position 9 heures pour avoir  le plus augmentation d’amplification et pourtant le lecteur son n’est toujours pas assez pleine. En cas de modification de RKV Mark II, le son devient entièrement ouverte et l’état dynamique et la stabilité sont de première classe. Cela porte la valeur réelle de l’appareil phare de l’écouteur. Quant aux deux écouteurs à la résistance bas AKG K240 Studio (55 ohms) et Grado SR60 (32 Ohms), les performances peuvent parfaitement répondre à l’exigence standard. Mais en référence à l’amplificateur de casque, la différence n`est pas si évident. Pour faire correspondre l`AudioValve aux écouteurs avec une faible résistance (moins de 100 ohms), nous recommandons l’utilisation du dispositif d’adaptation d’impédance avec un panneau commutable entre 8 ~ 64 Ohms en quatre divisions. Le panneau devrait donc être muni d’une terminale de sortie haut-parleur afin qu’il puisse piloter les parleurs à haute sensibilité.
En effet, le RKV Mark II est assez cher. Cependant, d’après mon expérience, un dispositif écouteur bon peut durer longtemps et ne sera jamais dépassée. Par conséquent, il est un investissement utile et nécessaire. Le RKV Mark II est absolument le meilleur choix de tous les dispositifs écouteur. Je crois que d’un adhérent d`audio devrait valeur son oreille hautement. Utilisation de la RKV Mark II est un plaisir classe royale.

RKV Mark II headphone amplifier
as reviewed by Carlo Flores
POSITIVE FEEDBACK ONLINE © 2004 – HOME
Let me tell you one of the reasons I like Dr. Jan Meier. After he read my review of his HA-2 headphone
amp, he told me that I favored tube sound (I do), and asked if I had heard the Audio Valve RKV Mark II.
A
week or so later,
PFO
received one for review. I do not know of another instance in which one
manufacturer offered another’s product for review, although I should point out that Dr. Meier distributes
Audio Valve products in North America. Meier seems to care more about his customer’s needs than he
does about hyping his designs. I mention this because I consider the HA-2 the standard for
performance/price, against which I must measure the RKV.
Audio Valve’s RKV Mark II is an OTL tube amp that measures a little over 5 x 9 x 12 inches in size and
is priced at $1050 shipped. According to Audio Valve’s website (
www.audiovalve
), it was designed by
Helmut Becker to drive any load between 32 and 2000 ohms, but it could not quietly drive my 40-ohm
Grado HP-1 headphones without a transformer (an option packaged as the $180 Impedancer), so I
used my Sennheiser HD580s. Finding replacements for the RKV’s set of four Tungstram PCL805
tubes is said to be easy, although I believe that tube rollers will find limited options. The amp’s piano
black finish with gold trim is more garish than elegant—it would look sharp in Snoop’s crib, but a picky
girlfriend may give grief. Its paralleled pair of single-ended inputs means that it can act as a two-
source headphone amplifier or function between a source and preamp. An IEC receptacle and two
headphone jacks are included. The top lid is made of a transparent material and is secured with metal
thumbscrews, which allows easy access to tubes and fuses as well as amorous glances at its sexy red
PCBs.
There’s a lot I like about the amp. It was so good during the first month that I felt seduced. I think of
music reproduction as a three-part process—attack, body, and decay—and I give the RKV good

marks in each. It has an almost lush sound, full but not bloated. Even when paired with an average-
sounding digital source like my modified Sony CE-775, the amp contributed an analog-like reverb to
strings. It sounded noticeably fatter and sexier than the HA-2. For example, Pulp’s
Intro—The Gift
Recordings
has lots of crazy riffs that sound electric and awesome with most amps, the HA-2
included, but dominating with the RKV. For you audiophiles, Norah Jones sounded huge.
I can’t overstate that the RKV makes music sound damn good. It’s all about midrange, bass, and
decay, though I’m not saying that the high frequencies suffer, because they don’t. I am not talking
about impact or detail, but about finding the music. The word that comes quickest is “wet.” Notes
sound wet when played through the RKV. A groovy acoustic guitar, such as Jonathan Richman’s, has
adequate groove, which is an accomplishment for a system featuring the HD580s. I’m also talking
about the kind of soundstage that makes me forget I’m wearing headphones.
Magnifying this is bass performance that pushed the Sennheisers to their limit. I prefer a quick
midbass and a direct relationship between the lowering of frequency and a note’s thickness, and the
RKV gives me what I want. The Sonics’ foundation, Serge Gainsbourg’s pace, and Mos Def’s beats
just sounded right, and involved me as a listener. I’ve heard more expensive amps mess up the lower
notes. Unlike them, the RKV ‘s separation between bass notes is distinct, and while their impact is
somewhat weak, instruments have adequate weight.
When the foundation of notes is this good, I find
myself turning into a bass head.
What did I lose to get that scale? A great amp gives up very little, if anything. HA-2 doesn’t even try to
sound big, preferring to achieve frequency balance, and it offers Dr. Meier’s cross-feed to recordings
that need consolation. The RKV ignores audiophile sensibilities, offering gray backgrounds and little
resolution at low levels. While the stage is very wide, placement within that stage is fuzzy at best. It’s
easy to focus on one instrument—to ride a stringed instrument or be caught in a piano—and get lost
when listening to the RKV. However, place that instrument in relation to the others, and things turn
messy. As with badly set up speakers, the image of each performer is soft and indistinct. People who
want scale in a small room with reflection problems know what I’m talking about—the nuance is gone.
Albums sound good, but hardly ever interesting. If you owned this amp, why would you invest in high-
quality recordings when you cannot hear their full potential? This is a music lover’s amp, not an
audiophile’s.
I have not mentioned my reference headphone source, the Audio Note 2.1x CD player, because it
does not complement the RKV and the HD580. Instead, it yields an unbalanced but juicy sound,
appealing at times (Nick Cave’s piano in the song “Into My Arms”) and irritating at others (Nick Cave
and The Bad Seeds’ album
Murder Ballads
). Unlike the HA-2, which mates well with even the most
flavored sources, the RKV gets in the way. In the end, the RKV is a designer Band-Aid that will help a
system that needs to add flesh to notes. It probably would have been great with my old reference, an
Arcam Alpha 9, or other typically dry British sources. The RKV only disappears at moments,
depending upon song and instrument. As much as I like this amp, I believe it has too many flaws—its
inability to drive low-impedance headphones, its high noise floor, and its lack of balance—at $1195.
The HA-2 can be the foundation of a system. Find the headphone you want and it’ll drive it. Choose a
flavored or unflavored source and you’ll hear the characteristics the designer wants you to hear. It
costs almost half as much, and it comes with cross-feed. For me, this just isn’t a contest.

After about a month and a half of listening to the RKV, I received an Impedancer for review (to the left
of the RKV above). The Impedancer is a passive device meant to match its load to its input. It is a
stand-alone product that will work with other headphone amps. It has a small footprint, and will fit
comfortably next to an RKV in a standard-width stand. The Impedancer’s rotary bypass control is a
gold knob that matches the RKV’s volume knob. On the front face are gold-plated speaker binding
posts, turning this into an integrated amplifier for high efficiency speakers, which I did not try. There
are also two headphone outputs on the front face. Most importantly, the Impedancer allows listeners to
use the RKV with the dynamic headphones that matter, including Joseph Grado’s HP-1000 series and
Sony’s R-10s.
The Impedancer and RKV together are quieter than the RKV alone. I found that I listened at my lowest
levels using the two together. Considering the price of cables nowadays, $180 makes the Impedancer
a no-brainer, even when using high-impedance headphones. Nevertheless, the Impedancer did not
drastically change my opinion of the RKV/HD580 combination. After listening to the RKV with my
Grado HP-1s, I realized that the soft-sounding Sennheisers, paired with the RKV, were more mush
than lush. While the HD580s’ and RKV’s flaws overlap, the HP-1s’ focus and leading line gave a
sense of balance. Side-to-side placement was better than adequate, and the RKV’s depth was in
proportion to the HP-1s’ somewhat shallow stage. On some recordings—Tom Waits’
Blue Valentine
,
Aimee Mann’s
Bachelor #2
, and Dylan’s
Time Out Of Mind
, to name a few—the combination yielded a
haunting and spatially interesting sound. Perhaps it was more pretty than natural, but I like that. The
HA-2, Headroom Max, or Sugden Headmaster amps don’t make me sink into a song quite like the
RKV can with certain recordings.
Everything that was good with the RKV stayed good with the Impedancer and the HP-1s, especially
bass. This was where the lowered noise floor of the Impedancer made an impact. My perception was
that the top was faster and the bottom thicker. Still, other amps can go lower, and I can only wonder
how this amp would sound with a completely black background. Again, the HP-1s complemented this
amplifier, and the combination rocked. Hell, I spent a day listening to The Sonics and The Zombies
because this system rocked so much. Not many amps feed my love for distortion and wicked midbass.
Yet I would not call this amp fast. It does better with sultry electronica (Tricky’s
Maxinquaye
) than with
trippy and fast electronica (Aphex Twin). Transient information doesn’t pop out of the black, as it does
on quieter components. Are excellent macrodynamics worth the loss of microdynamics? Is scale more
important than subtlety? The RKV will always sounds like the RKV. I listen to albums I know and things
sound different. Then I think about how good womens’ voices sound with this system, and I reach for a
Joni Mitchell album. I see why so many like the RKV.
The Impedancer is a required option, even if using it means only that so you can divorce yourself from
Sennheisers. That makes this a $1230 system.
The RKV is at least the equal of the Headroom Max,
though you will give up the Max’s pitch-black background and winning linearity. I’d take the RKV over
the Sugden Headmaster and many other amps, but I couldn’t have it as my primary amp, and I don’t
think of it as a reference unit. Flavor doesn’t matter unless the basics—again, black background,
linearity, and separation—are addressed. The RKV, even with the Impedancer, only gets two correct.

 



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2 reviews for RKV 2

  1. admin

    RKV MARK II

    Röhrenverstärker für dynamische Kopfhörer und Hochpegelanwendungen

    Der bisher in unserer Produktpalette mit Abstand erfolgreichste Röhrenverstärker, ist der 1984 entwickelte und in den Vertrieb aufgenommene RKV, was soviel heißt wie, RÖHRENVERSTÄRKER für DYNAMISCHE KOPFHÖRER . Traditionelle Röhrentechnik wurde hier über Bord geworfen und mit völlig unortodoxen Lösungswegen ein Konzept geschaffen, was bislang im Verstärkerbau einmalig geblieben ist. Aber auch auf modernste Halbleitertechnik wurde nicht verzichtet und so entstand ein Produkt, in welchem sich 40 Jahre Elektronik widerspiegeln. Das dt. Patentamt hat diese Idee 1984 unter der Nummer DE 3200 51 geschützt. Warum so könnte der Leser fragen – Kopfhörer verstärker ? Genügt da nicht mein Ausgang am Reseiver? Die Antwort lautet ganz einfach Nein. Gute dyn. Hörer benötigen für hohe Dynamiksprünge – wie sie z.B. von CD Playern kommen – aufgrung ihrer hohen Impedanz Spannungspegel, die weitaus höher sind als die Versorgungsspannung von Transistorgeräten. Dies gilt auch für HI-FI Anlagen. Hohe Pegel zu bringen war also eine Bedingung die der Verstärker erfüllen sollte. Darüber hinaus galt es Kurzschlußfestigkeit und ausgezeichnete techn. Daten zu erzielen unter der besonderen Note des Röhrenklanges. Alle diese Eigenschaften besitzt das vorliegende Konzept.

    Trotz Röhrenverstärker wollte man natürlich auf einen Übertrager verzichten. Wegen der Anpassung an hohe Abschlußimpedanzen bot sich das Konzept des OTL Prinzip`s an. Am klassischen Beispiel der sog. -eisenlosen Endstufe – orientiert sich nun dieses Konzept und wurde unter zuhilfenahme von Halbleitertechnik zu einer gelungenen Symbiose der Elektrophysik der letzten 40 Jahre. Auch alle negativen, die Röhre umgebenden Eigenschaften wie da waren Alterung- Toleranzen Brummen, um einige aufgezählt zu haben, galt es zu eliminieren. Die im RKV befindliche Elektronik kann dies mit Bravour. Mit Hilfe eines qualitativ hochwertigen Op-Amp im Signalweg konnte ein Servokreis geschaffen werden, der alle o.a. neg. Eigenschaften ausregelt. Das geht sogar soweit, das der Arbeitspunkt unabhangig von Röhrenalterung autom. stabilisiert wird, sodas auch altgediente Röhren gut den Dienst weiter versehen. Zusammenfassend kann gesagt werden, daß durch diesen autom. Regelkreis selbst bei Verschleiß der Teile, keine Qualitatseinbuße in der Musikalität in Kauf genommen werden muß. In der Beurteilung des Klanges ist besonders die hohe Dynamik des Verstärkers hervorzuheben und der eben für Röhrenverstärker charakteristische Klang. Die Basse kommen straff und gewaltig, die Mitten sind luftig und von einer sehr lebendigen Durchsichtigkeit, und im Hochtonbereich zeichnet eine sehr gute Auflösung verbunden mit transparenter Räumlichkeit. Diese Eigenschaften besitzt der Verstärker natürlich auch bei seiner Verwendung als Linearverstärker in anderem Einsatz. Im übrigen treibt der Verstarker Impedanzen zwischen 30 – 2000 Ohm, womit der Anschluß auch mehrerer Hörer, solange die Gesamtimpedanz nicht zu niedrig wird. möglich ist. (Lemgo 1982)

    Und hier der Test aus der STEROPLAY 1984

    Eine kleine deutsche Firma möchte mit einem Röhrenverstärker Kopfhörer zu Höchstleistungen anspornen.

    KIein, aber fein

    Test Kopfhörerverstärker

    Helmut Becker, 30, hatte eine großartige Idee. Er wollte etwas konstruieren, was nirgendwo zu kaufen war. Und dafür gab es einen guten Grund.

    stereoplay untersuchte im Test, ob der Dynamp der kleinen Firma Audio Valve in Lemgo das vom Konstrukteur versprochene Ziel erreicht. Immer dann nämlich, wenn er Lust hatte, seine HiFi-Anlage aufzudrehen, vermiesten ihm lauthals protestierende Nachbarn sein Klangerlebnis. Wenn er sich aber verärgert den Kopfhörer überstülpte, konnte er ebensowenig frohen Herzens genießen. Denn die Wiedergabe mit seinem 800-Mark-Verstärker konnte ihn nicht zufriedenstellen. Was lag also für den gelernten Elektronik-Techniker, der in der Medizingeräte-Technik tätig war, näher, als einen Kopfhörer-Verstärker zu bauen, der höchsten Qualitätsansprüchen gewachsen war?

    In der Tat ist die Idee nicht schlecht, denn mancher HiFi-Freund, der Aktivboxen besitzt, muß auf Kopfhörer-Wiedergabe verzichten, wenn sein Vorverstärker keinen entsprechenden Anschluß besitzt. Es gibt aber auch Musikliebhaber, die aus Platz- oder Kostengründen nur Mittel-Klasse-Lautsprecher besitzen und über Kopfhörer Musik hoher Güte hören wollen – die weitaus billigste Art, HiFi zu erleben. Becker ist Anhänger der guten alten Röhrentechnik. Er studierte sehr genau gewisse Vorteile dieses einstmals glorreichen Bauelements gegenüber den modernen Halbleitern, die heute in allen HiFi-Komponenten zu finden sind. Für sein spezielles Vorhaben boten sich zwei Eigenschaften besonders an: Elektronenröhren können an hochohmige Lasten vorteilhaft angepaßt werden, wie sie dynamische Kopfhörer mit ihren typischen 600 Ohm darstellen. Und für elektrostatische Hörer, die nach extrem hohen Spannungen von einigen tausend Volt verlangen, bieten die Röhren geradezu ideale Voraussetzungen für harmonsches Zusammenspiel.

    So ganz wollte der Erfinder aber auch nicht auf die heutige Halbleitertechnologie verzichten. Dort nämlich, wo

    die Röhren eher Nachteile besitzen – etwa in der Eingangsstufe oder bei Kontrollaufgaben für die Endstufenröhren -, setzte er folgerichtig Transistoren und integrierte Schaltkreise ein. Der Dynamp besteht also aus einem sinnvollen Gemisch von Halbleitern und Röhren (Hybid-Verstärker), wodurch sich Becker ein gewisses Optimum verspricht.

    Äußerlich demonstriert der Verstärker kaum sein komplexes Innenleben. Das simple, schwarze Lochbiech, das als Ab- deckung dient, erinnert eher an Billig-produkte als an ein Qualitätsgerät. Die goldeloxierte Frontplatte zeigt ebenfalls, daß Audio-Valve noch eine sehr junge Firma ist, die vom Marketing nicht allzuviel hält. Becker verzichtete bewußt auf teures Finish und steckte das Geld lieber in die Elektronik.

    Zum Hörtest steckte der Dynamp am ,,Line”-Ausgang des Referenz-Vorverstärkers Onkyo P-3090. Als Kopfhörer diente der dynamische DT 880 Studio von Beyer (Test stereoplay 5/1982), den die Tester abwechselnd am Onkyo und am Dynamp betrieben. Es waren nur wenige Hördurchgänge mit unterschiedlichem Musikprogramm notwendig, um festzustellen, daß es gravierenden Unterschiede gab. Der Audio Valve reproduzierte über Kopfhörer alles, was in den Rillen steckte, sauber und natürlich. Untadelig und volle Kraft brachte er dynamische Passagen oder auch getragene Stellen. Solostimmen wie komplexe Orchester kamen über die Kopfhörer in brillanter Darbietung ohne jede Verfärbung.

    Gerald 0. Dick

    Stereoplay 9/1982

  2. admin

    Confrontation of the SRM 727 007t2 and RKV-WEE on 009 and 007
    Good evening, I finally passed in the listening in the afternoon of 3 systems of development of foots the bill
    Stax SR 007 mk3 and
    SR 009
    at my disposal: amplis Stax SRM 727-II (mine); SRM 007t2 (that of Pierre)
    and combi RKV MK2 + WooAudio WEE; every ampli connected on good phase sector (what obliged me to
    invert the sense(direction) of the cordon sector between the WEE-RKV and the amplis Stax (having no same
    visible sense of it phase)
    . Results on the listening of a test CD (Stéphane Grappelli and
    Michel Petrucciani
    in the album Flamingo)
    Reserved CD because very well registered(recorded), but however quickly hard in the treble with a bad
    system; quickly lung and dislocated in the grave (followed by the double bass) with a bad system; brief,
    quickly unpleasant to listen to with a bad system 😉
    And the winner is.
    … The
    walkman
    MP3 of my wife:mdr:
    It is not true, because it is so small that I did not find him where he hides and thus I was not able to
    test him …
    And the winner(conqueror) is …
    To go to you quickly the knowledge 🙂
    I proceeded with method 😉
    At first listening of the range 4 of this test CD Flamingo with my 727 + 007 mk3: results : intimist sound
    stage (that is not extra wide); soft and inarticulate basses (not obvious to follow), but there is of the curvature
    ( a soft curvature); the violin and the
    piano
    are not unpleasant to hear, stamps are rather fine, but with a
    rather curious presentation of ” clearly – dark “.
    I am understandable: the top-medium is rather dark (set back), the low medium is rather carnal, but there is
    also a bright aura and a sparkling of the very clear acute extreme, being able on this recording, by its
    insistence(emphasis) for the acute percussions and harmonious acute of the violin, the tiring future.
    By listening to the same range 4 of this test CD Flamingo with my 007 mk3, but this time connected on him
    007t2 of Pierre, I found the a little better listening in the sense than 007t2 limit, in my ear, the sparkling of
    the acute extreme which I find with 007 mk3 + 727. Stamps are also more refined; the a little wider, more
    clean sound image. The basses of 007 mk3 + 007t2 are a little bit set back with regard to that of 007 mk3 +
    727, not very dynamic, but maybe be a little more articulated
    than those of 727 with 007 mk3. The listening
    of 007 mk3 with him 007t2 is globally more pleasant, less tiring in the acute extreme than with 727, a little
    more refined, but without being an outstanding leader in dynamism.
    Thus I have in the end a small preference of 007t2 + 007mk3 with regard to727 + 007mk3.
    Now let us cross tuned tothe range 4 of this test CD Flamingo with my 727 + 009. Then there, it is one any
    other listening: as said it my friend Jean-Marc, as 007 seems round, as 009 appears by clear and defined
    contrast; it is almost the day and at night :wink:. First of all, the sound stage of 009 is wider and
    detailed(retailed) that that of 007 (most open sound). The dynamics is much better, with low sandbanks,
    articulated, very readable, less intense than those of 007, but far clearer; the grave extreme is very present.
    The sound is more clear with stamps of the violin and the more realistic, hard-hitting
    piano
    for the piano, but
    regrettably a little bit hard for these instruments at high level of listening. The acute extreme is less present,
    less twinkling than with 007, what in the end is more restful and more natural more also. The sound is rather
    alive, dynamic, but a little bit hard, ” a little bit raw “.
    When is it now the listening of 009 with 007 t2 of Pierre? (Always with the same test CD)
    And well I am going to surprise you, it is not for me the best listening, and I prefer that of 727 with 009 (by listening to
    not too hardly). 007t2 differs from 727 by a little less presence in the grave, even if very clean(appropriate) with 009,
    but it is a little bit it’s a pity to listen to one 009 the presence of which in the grave is sometimes little ” just ” (especially
    by comparison with 007); also, he limits slightly the acute extreme (always with regard to 727), what is rather good for
    007 mk3, but a little bit it’s a pity with 009 which has him no problem in the acute extreme.
    Certainly stamps are
    more refined than those of 727 who in comparison make more “raw”, but is missing something in 007t2
    (with regard to 727), a stalk of life. Indeed, I find the listening of 007t2 very civilized, very sophisticated, but
    being strangely lacking life, as disinfected. It is “squeaky clean”, but “slightly too squeaky clean” for my
    taste. It is very clear for the listening of this CD Flamingo: with 727 + 009 we want to stamp with the rhythm
    of the musicians and to increase the volume of the sound, until be called in to order, because the sound of
    727 eventually becomes hard and the tone of the piano and the unpleasant violin at high level of listening;
    but the rhythm is there, the life is there
    .
    With him 007t2 we can increase more easily the sound, but that if disinfected rest (too squeaky clean, “not
    rather” “raw”(“gross”)).
    Damage.
    Well, I finished it with my comparative degree …
    Except that I forgot to speak to you about the listening of 007mk3 and about 009 with the combi
    RKV + WEE (with the good phase sector (inverted with regard to that of the amplis Stax) for the
    WEE)
    And well, it is necessary to speak to you about it 😉
    First of all, listen to of the range 4 of this test CD Flamingo with my RKV-WEE + 007 mk3: results :
    improved sound scene(stage) and …
    And the
    headphones
    007 mk3 becomes unrecognizable, transfigured in its dynamics by the RKV-WEE: and
    well that moves and 007 wakes up finally: powerful, robust, rhythmical, very readable basses: we stamp; we
    go up the sound, there is of the life, but we are called back by the acute extreme, always too present, which
    becomes getting tired for a too high level of listening. The neutrality is certainly not the key point with grave
    sound everything in acute curvature, this high a little bit set back medium and this extreme sparkling
    (however not unpleasant to listen to on the condition of not pushing too far the
    potentiometer
    of volume).
    The best rest to be told you for the end, the listening of 009 with the RKV-WEE: and well, as said it
    Jean-
    Marie
    , it could be completed, because gathering the best of each of the previous listening: the sound stage:
    she is strangely wide, of course with regard to(compared with) that of 007 mk3, but also with regard
    to(compared with) that 2 amplis Stax (727 and 007t2) with 009. There is of the life, the rhythm, it is without
    appeal with regard to the listening of 009 on him 007t2 who by contrast made disinfected, as too much
    civilized ; there is some strength and the power: the rhythm of the bass and the percussions urges you
    instinctively to go(take) up the sound, and the more one goes up the sound, the more it is good, and we still
    increase the potentiometer of volume of the RKV, without limit or almost.
    ( If it is the small voice which
    says to me, stops there, because it becomes unreasonable; we are not in a concert live, and you are
    quickly going to become deaf if I continue to go(take) up the sound like that. But in the hearing,
    none limits visible; more we increase the sound, better is the scale, the rhythm, the life …
    As for stamps, the RKV-WEE + 009 manages of the exploit to obtain the quality of the stamps of 007t2, but
    with the life in more (with a contrasted, dynamic, alive sound, being able to be rough (percussions at strong
    level of listening), but also of a very big sweetness and a subtlety, on different musical passages), and not a
    little bit flat and disinfected as that of 007t2.
    I thus let on you decide on the winner of this confrontation 😉 🙂
    Unless the
    walkman
    MP3 of my wife knocks down the situation …
    Eric

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