Here we have an Abraxas Audio (Jeff Larson) custom built amplifier using 6AR6/6384 Single Ended Pentode(SEP) and switchable to Ultraliner. There are individual bias adjustment pots and test points for each of the tubes. Any 12AT7/5965 type tube can be used as the driver. I bought this amp based on the ravings of some on Audio Asylum about the 6AR6 tube (see links below). I have used it for around 2 years. I have has many amps from Jeff, who I think is the most innovative and competent DIY builder around. He builds amps around tubes he is interested in hearing; rarely does he build the same amp circuit more than once. On his Webpage (no longer up) he mentioned that a PP 6AR6 he built was in his opinion the best amp he had built with respect to sound. So, I asked him to build me this one. I used it to drive my Cornwall and Hammer Dynamic S-12 speakers and estimate the output in SEP is 7-8W and in Triode mode is around 3-4W. I highly preferred the UL mode, though triode was at times charming. I also have used it for my Beyerdynamic DT990-600 and Senn 600/650, as well as AKG702, which are VERY hard to drive properly, and this amp drives them well. It is very quiet on the HE speakers and phones This is a very unusual amp, built with Edcor iron all around. I will send instructions on biasing (basically, 375-400 mV—no more that 400mV, though. The OPT runs nicely cool-warm, as it should. Zero issues. It is very well built with nice components and iron. The volume control is a stepped attenuator. See my feedback under same name at Agon, HeadFi, Ebay, etc. Well over 1,000 very positive transactions, mostly for tubes and tube gear. Some links below on 6AR6 tube sound. Rated 8/10 due to DIY nature--you will not be disappointed. It looks, feels and sounds top flight. I have 6L6/6AR6 adapters, allowing you to sue 6L6B/5881. I like the Russian Coin-Base 6L6WGT/5881 varieties. You can also run 6L6GC, and even 6L6GA/B—but I would bias them no more than 325mV for the GA/GB series. I can sell the adapters to interested buyers for a bit extra. I can also sell the Bendix 6384 I have for extra to interested buyers. I have since purchased very unusual Heathkit-W5 mono-blocks configured to use the 6AR6 in PP UL using the Peerless 16458 OPTs. I sent them to Jeff, who redesigned the drivers—and they now sound fantastic. So, this unit is excess. Thanks http://db.audioasylum.com/mhtml/m.html?forum=tubes&n=105757&highlight=6ar6+sound&r=&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dtubes%26searchtext%3D6ar6%2Bsound http://db.audioasylum.com/mhtml/m.html?forum=tubes&n=216745&highlight=6ar6+sound&r=&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dtubes%26searchtext%3D6ar6%2Bsound http://www.audioasylum.com/audio/tubes/messages/10/105982.html http://pdf.datasheetarchive.com/indexerfiles/Scans-008/Scans-00175358.pdf
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