StereoTimes’ Most Wanted Component Award 2017 for Challenger 115
"Lately I’ve been exploring the tube realm, and the more I listen to tubes the more I like them. I must say, tubes do something to the music and I really enjoyed my time listening to the Audio Valve Challenger mono-block amplifiers. The amp had no problem driving the Conspiracy and the Lyra loudspeakers with great control and finesse. Hats off to Helmut Becker! I highly recommend the Audio Valve Challengers. It is fine German engineering that comes with sensible pricing in today’s high-end audio arena."
Already since 1984 AudioValve produces the amplifier series with the name CHALLENGER. This is also the proven PP concept, with the difference that the entire circuit is fully symmetrical, that is, it handles the negative and positive signal phase. If the end tubes are selected accordingly, e.g. from a 115-watt power amp with EL34, the Challenger 150 model, if you're equipped with 6550, or a pair of Challenger 180 - when you equip with KT120. The quiescent currents are found by the amplifier with the help of Autobias (ABR).
The magazine HIFI-VISION has already chosen this device series in a test in May 1992 for "absolute top class". These series also have our so-called automatic BIAS regulators, which precisely set the quiescent current of each individual end tube. You will be alerted to spent tubes via LED's and can exchange them easily without having to resort to selected tubes. So do not let costly tubes sell for your AudioValve amp because our amplifiers do not need selected ones to sound. The tiresome topic about the right choice of the end tubes is thus over forever.
The use of these devices is primarily dynamic speakers, but also in interaction with electrostatic speakers prove the Challenger their absolute class. With an additional stand-by switch on the front left of the device, the anode voltage can be switched off in longer pauses without completely switching off the device. The tubes remain safely warmed and can immediately max. reproduce musical qualities after switching on in the "Operate Mode". But the Challenger's are already fully operational after 10 minutes of commissioning anyway.
Back to the Challenger - on a total of 6 tailpipes per channel, the performance is distributed. No tailpipe is expected too much. Even if one weakens, you will hardly notice. A big advantage, if you think about what services other concepts force the tubes to achieve the same performance only with 2 tubes - that goes on the life - no question. In general, push - pull amplifiers with only two tubes with caution to enjoy. Especially with two tubes in conventional technique, the sound lives from the quality and the symmetry of the tubes - and as these become increasingly aging you will soon experience the changes of the sound - unfortunately.
Unless you purchased a screwdriver with your device and subject your device to constant bias adjustment. Even such devices are still currently being produced from the USA or China. Where is the meaning, or maybe you can not do it better ?? We have had our Biasregulator now since 1991 and offer him in the meantime as a module for third-party products, so that their owners do not have to invest all their belongings in tubes. Perhaps this essay sounds a bit provocative to you, but so far has been explained by the coverage of the "trade press" of this concern for our devices little exhaustive, I think the press understands the technology behind it and can therefore explain the effect also not.
So - whenever you enjoy a range of cheap KT 120s, hit them - you'll enjoy using them in Challenger. We also do not dispute that the quality of the tubes today has decreased compared to 30 years ago - it certainly causes many devices of the competition biggest problems, but when used in the right circuit environment - as in AudioValve - prepare the tubes today more Enjoy it ever. All you have to do is choose the right concept, and for that you can do that, not a technical introduction to tubes, so that you can make an assessment.
The input stage of the Challenger is realized with a so - called parallel - symmetric - cross - coupled preliminary stage after Zechendorff. It allows effortless processing of XLR and RCA input signals. The Challenger has a huge two-sided PCB with all components and are soldered by hand. This assures best contact points at the solder joints, as the tin goes up through each pad, thus providing an excellent bond. The solder rises in the hole of the soldering eyelet and thus soldered each component from above and below. Good and short cables to the underground in the amplifier located transformers ensure the best electrical connections, so even with the Challenger even a 10 Khz rectangle still looks like the original. Without overshoots or flanks - just as it should be.
Another special feature of these amplifiers are the power supplies. PP requires an anode power supply, but that's not all, we still need the screen grid voltages for the left and right banks (PTC overcurrent protected), three heating circuits, neg. Grid voltage, reference voltages for the ABR`S, plus / minus power supplies for the OP` s, an anodes driving voltage, and all these voltages are partly floating associated with the respective banks of the right and left rows of tubes of a printed circuit board - so you get only once an idea of the state of development of our devices are.
Musically, preference should be given to equipping with EL34 in the Challengers. These deliver nearly 130 watts and shine with a special midrange and treble range. If you prefer more bass, you may be better off with the KT 120. The bias is set via four-digit DIP switches located on the printed circuit board. With their help, the reference quiescent current for automatic adjustment in all tubes is used. The Challenger series have experienced various cosmetic updates over the past 30 years. From the concept, however, nothing has changed until now - why should it? We do not have to undergo a constant new model policy to remain interesting, we stand by what we do - 1984 to 2020.
Again and again I hear, "one does not know you Mr. Becker ...". That's not quite true. We deny 95% of our sales abroad and that, because we know and appreciate us. But also in Germany there are attentive hi - fi - friends who have not been influenced for a long time by "test winners" of the press, or "forums - prophets", but consistently and above all with expertise to form their own opinion. And these listeners always find contact with us too. What I am most pleased about is the fact that they are individualists, both at work and in private life - just like me - in the search for the best result. People with self-determined characters and special charisms. No one is like the other, everyone is special and yet - or that's why - we come together for the love of music. To know them all makes me proud - and they are not a few - thank you for your trust.
The CHALLENGER series of monoblocs are the foundation of the AudioValve range of amplifiers, which have been refined and perfected since first introduced in 1987. The CHALLENGER is unique in so many key areas. For example, it can use KT-88s, 6550s or EL-34s with equal ease as power tube. And depending on the tube used, its output can range from 110 wpc to as high as 180 wpc. This is made possible by our revolutionary and proprietary ABR circuitry, which monitors, biases and controls each tube independently in the most AudioValve power amplifers.
This feature allows the use of any of the mentioned tubes or, indeed, a combination of any of the three. This redefines in a truly innovative way the concept of "plug and play." It also makes tube replacement very economical, as there is no need for costly and exotic tubes which have to be matched in order to get the best sound from the amplifier. Another truly impressive detail . That is, the circuitry is totally balanced from input right to output terminals. All of this means the CHALLENGER can drive any speaker on the market, from conventional drivers to exotic electrostatics and ribbons, with complete ease.
The most recent affirmation of the beauty and prowess of this truly unique and great amplifier came in the November 1999 issue of The Absolute Sound, one of the most respected industry magazine in the world. AudioValve Challenger combine also excellente with electrostatic speakers. Already since 1984 we produce our series called “Challenger”. We are likewise using the proved PPP concept with only one difference: the complete circuitry is fully symmetric. By chosing the correct tubes and making some little detailed changes for example a 115 Watt power amplifier with EL34 turns to Challenger 140 at e.g. 6550 / KT 88 / KT120 mounting.
The magazine HIFI-VISION has already chosen this series for being one of the best in a test in may 1992. In the meantime the technology has not stood still here, too. By now also this series is equipped with our so-called BIAS-regulators which define each tubes standby current exactly. LED lamps inform you about used up tubes, so you can change them easily. You can therefore use ordinary stand-tubes, also in case of replacement. Don’t let yourself be talked into buying expensive tubes – our amplifiers don’t need selected tubes for making a good sound. The prefered using of these instrments in combination with conventional dynamic loudspeakers is also the using in connection with electrostatic loudspeakers. Particularly in this case this series shows his enormous advantages regarding the loudspeaker controlling. Without problems and with a high musical sense you can obtain a harmonically interplay between your components.
With an additional Stand-By-switcher on the front panel you can turn down the anode voltage in longer intervals without shutting the amplifer down. The tubes stay warm and can deliver the maximum of musical quality directly after switching-on. Let us try to describe you with simple words what are the advantages of this series with PPP principle. You all remember the conventional PP circuitries . Nearly unexceptional every manufacturer uses this concept because of its little effort – at the expense of the sound we think. In our PPP circuitries we work with a so-called Autotrafo. This means, in our circuitry the transmitter is not in the high-voltage bearing anode, but in the mass bearing cathode. When employing our final tubes we talk about the cathode follower, which means that the cathode voltage follows direclty control voltage at the tubes control grid. So we are not using the characteristics of the final tube dynamic. In fact we use the tubes only as power suppliers. Which tubes delivers the power is getting a subordinated question. In plain language this means, we are not regulated by the characteristics of the tubes in our circuitry. With a little imagination you will soon discover the invaluable benefit of this conception.
The vexed topic of chosing the correct tube is therewith done forever. But we go another step far. Lots of people hold the view that you should not use chinese KT88 tubes and that their use leads to different problems in many units. But not with the Challenger ! Thanks to our Bias-Regulator , which injects each tubes closed current fully automated, the use of the above mentioned KT88s is no longer a problem but rather turns into a great pleasure, because this tube has got a lot of power reserves. So if you ever get the chance of buying economically prized KT88`s, don’t miss it – you will take much pleasure in those tubes. We don’t deny that the quality of tubes has decreased. compared to the quality of tubes 30 years ago And of course there are many units which have big trouble with this fact, but with adequate operation in the correct circuitry surrounding this tube will pleasure you now more than ever before. You just have to chose the right conecpt and therefore our little introduction in the topic of tubes for making a decision easier for you.
the graphic show you: 10 kHz square wave signal by 8 ohm load
But now back to the Challenger – the effort is divided on 6 final tubes on each canal. No tube is overstrained. Even if one decreases, you will hardly notice. A big advantage if you think of how other conecepts constrain their tubes to to achieve the same effort with only 2 tubes – this has got negative effects on the duration of life, that’s beyond question. Generally push-pull-amplifiers with only 2 tubes have to be taken with a pinch of salt. Especially at 2 tubes in conventional technology the sound depends on the quality of the tubes – and because of their continuous aging process you can discover the change in the sound soon. Unless you have also bought a screw-driver and subject your amplifier to a permanent Bias justage. Products like this are still produced today, coming from the USA. We, however, own our Bias-Regulator already since 1991 and offer it meanwhile as a module for machines from other manufacturers as well, in order that they don’t have to invest all their goods and chattels in tubes. Maybe this essay sounds a bit provocative. But all former tries of the specialized press to illustrate our units adequately have been a miserable failure.
The input stage of the Challenger is realized with with a so-called parallel-symmetrical-cross linked pre-stage. It allows the converting of also XLR-signals without problems. It has to be pointed out that the volume does not change , what is usually the case. The Challenger owns a big bilateral printed board with all components and get soldered in our spate bath. This guarantees best contact points at the soldering joints, as the tin rises up through every annular ring and creates an excellent connection like this.The tin runs throught the whole in the annular ring and brazes so every component from above and from the bottom. Good, short cables linking to the transformers in the underground of the amplifier assure best electrical properties. Therefore even a 10 Khz rectangle looks like the original with the Challenger. Without overshootings or flabby sides – just the way it should be.
A further specific feature of this amplifier are the power-supply-units. PPP requests from the outset 2 anode power-supply-units. But not enough, we also need the two screen grid voltage for the left and the right bank, three heater circuits, two neg. grid voltages, two referance voltages for the ABR`s, two plus/minus power-supply units for the OP`s, an anode driver voltage…and all these voltages are, partly afloat, assigned to the right and the left bank of tubes of a printed board – just to give you an imagination of the high stage of development of our units. Not to forget the Computer-Interface. All Challengers are equipped with an interface for computer connection, wait and see what we are planning with this facility in the future. You see – with AudioValve units you are hundred percent up-to-date, if not even in the future if you look at the current stage of development in general.
The Challenger produce a perfect low harmonic distortion sprectrum !
These below-mentioned 3 illustrations clarify in a perfect way the excellent impulse acting of the CHALLENGER. The pictures show the replay of a rectangle at 20 - 1.000 and 10.000 Hertz. You will notice that, even at 10 Khz, no overshoots or other “tube-typical” phenomenons are appearing. The impulse replay is faultless and comparable to the rise rate of a transistor. Picture 3 shows a 1kHz sinus at the beginning of power limitation of the amplifier, which counters with a soft “Softclipping”. The effort is now at circa 170 Watt in the mounting of the power amplifier with 6*6550. All schemas are based on an ampliifer final charge of 8 Ohm. So we are not talking about the frequency range but about the power amplifiers real power bandwith – this must not be confounded, since the requirements by DIN are much higher at the power bandwith.
The mono blocks of AudioValve have in the power supply so-called "main voltage phase finder". On the main power socket inside a printed circuit board is soldered, which fulfills different tasks. On the one hand, an NTC reduces the max. inrush current as current limiter, if you turn on the amplifier, this is bridged as soon as all the required voltages are reached in the amplifier and on the other hand, there is a circuit on the pcb, which helps to locate the mains life phase. If the amplifier is switched on, the green LED on this pcb. should light up, then the phase is correctly fed. If the LED does not light up, turn the power plug and check the situation again. If the phase is fed in correctly, it also gives the best musical result.
new feature: self adjust "referenz bias pre selector" for different kind of power pentodes
new feature: live phase finder ( green LED show you right main AC connection )