All my other gear have sold. Bumping this ad for a special Abraxas Audio Parallel Push-Pull True Triode amp with Volume Control. Open to offer or trades.I MIGHT be interested in trades for certain gear, like the following: Line Magnetic or Cayin PP EL34 amps;
Wyred-4-sound SS Integrated amp with remote control and L/R balance;
AVM60V pre-pro;
Conrad Johnson MV52 or MV55. We can work out FMV pricing with cash to equalize either way and use Agon Blue Book to validate, as well as our mutual common sense. Cash is preferred, though. Asking $900, which is negotiable vis a vis trades. I was not sure what to ask for this uniquely special amplifier; so much effort has gone into the final build. I have a real soft spot for unusual and for especially unique tube power amplifiers. Insofar as I know, I have NEVER seen another parallel-feed push-pull (PPP) double-triode power amplifier. Let alone one with these features:
Push-Pull Parallel-Feed Double-Triodes as power tubes; a quad—2 for each channel;
A Switch to select 6BX7 or 6BL7 tubes;
A Switch to select headphones or speakers;
Volume control;
Choke Filtered;
One 5AR4 or 5U4 Tube Rectified;
One 5965/12AT7 preamp tube;
2 X 6C4 phase splitter. Design & Build: This amp turned out to be a project where the sum of the parts doesn't represent the experience of listening to it. It was one of a select few that can get you into the music and away from the speakers and the amp itself. THAT, all said and done, is what WE ALL like to hear, and I will hate to see it go. The push-pull configuration was chosen based on the needs of the speaker i.e. more power than can be conveniently obtained from any reasonably priced SE amp. The 6BX7 was chosen to provide true Triode push-pull operation as opposed to a triode connected Pentode. This puts out 6-8 solid W/Ch of power. I see it as a 6SN7GT-type power amp on steroids!! I have owned a few SinglePower amps, including the MPX3 and the Extreme, and both were modded by Jeff; however, this amp sounds much more refined to my ear than either of them. The detail retrieval from this amp is special. As for all Abraxas Audio amps, this one is also designed from the ground up. A phase splitter-based design, which is always a solid choice, is the circuit format. This amp uses a single 5965 front-end tube followed by a 6C4 (one for each channel) as the phase splitter. The 6C4's are run hard enough to allow a low impedance drive to the 6BX7 outputs. I will supply the buyer with a variety of NOS (NEW Old Stock) lovely 6C4 Tubes.
Vintage Hammond (not the new Canadian versions--but the vintage Hammond audio OPT) output transformers were chosen for this amp. Jeff used these OPTs before with excellent results, and I was certainly not disappointed with their outstanding sound. Ear-selected and electronically measured passive components were carefully selected to bring out the best sound and measured performance in this amp. It took months to build, and then was rebuilt yet again to put in the switching features, headphone jack and to upgrade the power transformer. For the power needs, a transformer that had enough heater current to provide the demands of the four 6BX7s, which is nearly double that of four 6L6's, was selected. In addition, this tranny had an auxiliary 6.3V winding, allowing for an easy heater bias setup. Jeff then provided me with an upgraded Power Transformer that should last forever. THIS IS QUITE A HEAVY AMP. He also added a headphone jack that drove my Sennheiser HD600/650 to PERFECTION with robust power and the best detail and definition I have heard from a tube headphone amp. A choke loaded 5AR4 based power supply provides excellent regulation for the demanding 6BX7 output section. The 5AR4 rectifier was chosen for its efficiency and low impedance. A 5U4 could also be used with a slight reduction in output power. The amp sounded fine on its own, but a touch of global feedback (3db) was added to really lock it in and lower the natural third harmonic produced by such a design. The amp delivers just the right amount of second harmonic due to the inherent non-linearity of the 5965 grid to cathode.
***Disclosure: It has SLIGHT hum on left channel that is barely discernible WITH SENSITIVE HEADPHONES that is not audible when music is playing, but noticeable in a quiet room when music is on pause, with HEADPHONES. The hum is not virtually inaudible my Klipsch Cornwall or Hammer Dynamic Super-12 speakers (with Fostex T90A super bullet horn tweeter, damped with transformer—resistor ladder) unless I am right up in the speaker grill! Hum is ~ 2 mV, which is quite low, but can be discerned with sensitive headphones. As a speaker amp with ~6-6 W/ch, no worries*** I recommend this amp for HIGH IMPEDANCE headphones, with which it performs brilliantly. Due to the modest power, I suggest 8 ohm and higher speakers, which HE speakers tend to be. It drives my Klipsch RB-5 (version 1) speakers in a 15 X 18 X 9 living room superbly. I purchased this amp directly from Abraxas Audio (AKA JL)around 12 years ago. I have not used it much--all the tubes test right at new specifications, just as when I first received the amp. The tubes it uses are: A Quad of 6BX7 OR 6BL7. There is a switch on the amp to select between them. This is an indication of the perfectionist in Jeff, who always designs his circuit scheme for optimum performance. This amp does not require matched tubes, but in my opinion and just logically and electronically, matched tubes are ALWAYS more desirable.
I will provide a matched quad of RCA Coin Base RCA 6BX7GT tubes, which are truly the best brand and the best-sounding construction type. They last a very long time in this amp. For slightly extra cost, I will provide a matched quad of Sylvania 6BL7GT tubes, and if you like, another matched quad of 6BX7GT tubes at a slight upcharge. A pair of 6C4, which serve as phase-splitter for each channel. The 6C4 is one-half of a 12AU7, in other words, a single-triode version of 12AU7. Exact equivalents are M8080 and EC90.
I will supply some really nice pairs of NOS 6C4 tubes for your rolling pleasure, these will be the best-of-the-best, ear-selected USA brands from the Golden Age of vacuum tube manufacture. Each of them MARKEDLY affects the sound. This amp is VERY tunable to you speakers, headphones and taste. A 5695 or 12AT7 tube--these are almost equivalent electronically and can be used interchangeably in this amp or any amp. I will supply one or more of each tube, depending on what I can find in my tube cache. These test as new and are sonically perfect. This amp really needs a perfect testing driver 12AT7-type tube. a 5AR4 rectifier or 5U4G. I will supply one of each; a Sovtek 5AR4 and a Raytheon 5U4GB. Both will test new. I have forgotten my factorial math, but the combinations of tubes that are possible for rolling in this marvelous amp are considerable, so it can be tuned to your system and taste, which the tub set it comes with will allow immediately. NOTE: The pictures do not show the headphone jack and speaker/HP switch--nor the 6BX7/6BX7 switch. Thus amp was customized for me specifically. The pictures of the original design were handy, I will take new pictures if there is interest.
Thanks!
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