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Audio Electronic Supply AE-25 Dennis Had Signature Super Amp stereo amplifier. Works wonderfully and is in very good physical condition. Sounds fantastic. Tubes have maybe 300 hours on them. Svetlana KT-88s he bought a number of a few years ago, JJ EL-84s, and Electro-Harmonix gold pin 6922s. My buddy bought the amp on eBay and promptly put all new tubes in it. He emailed Dennis Had to make sure he set the bias properly. Dennis suggested he bias it to 120mA. My buddy used the meter I am including in the sale. It is a custom made unit he found on eBay that he bought for this purpose. I do not have the manual. My buddy agonized over what to set the bias at. He and I could not find a manual for the DJH model and it seemed different enough from the other Super Amps to possibly require different biasing. Note that the letter from Dennis Had, typed out below, indicates what the initial bias should be. I think that refers to initial break in when purchasing the amp new, not what you run it at after it is fully broken in. Shipping will be $125 via FedEx Ground to the contiguous US. Free pickup is also fine.Some info I was able to find/gather online, from my own research, and from my buddys research:In terms of biasing, he emailed Dennis Had, who said 120mA for the DJH version of the AE-25. I contacted Cary and they said 150mA DC and confirmed they meant the AE-25 DJH version. Then there is the number I found on the original superamps.com website (see belows letter from Dennis Had) from when the amp was new at 200 mA DC using KT-88s. That info was a letter written by Denis Hadd for the companys website. So at this point, my buddy would really prefer getting his hands on the manual or info directly from someone who has the manual since there is no consensus. When my buddy checked the bias, it was around 130 mA. He dialed it down to 120mA for now until he can get the manual. He now seems to be comfortable with how to prepare the amp prior to setting the bias current. I didnt ask, but maybe Dennis Had and Cary both said the same thing regarding that part of the bias procedure.Just to review, there were three versions of the AES AE-25 Super Amp (not to be confused with the AES AE-25 amp or Carys current Super Amp mk II). The entry level model of the AE-25 Super Amp was $1200 and had an autobiasing circuit. The AE-25 Super Amp Signature is the mid level version that was $1500 with a number of upgrades and changes including a bias circuit. The top model at $2000 was the AE-25 Super Amp DJH with much larger transformers, a third choke, and some other goodies. The manuals for the base and Signature versions are available online. The one for the DJH version is not. Cary has a standard bias procedure available on its website and it applies to all Carys current amps. However, it is different than what my buddy is getting for responses from Dennis Had or Cary.Letter from Dennis Had at beginning of user manual written to purchasers of this amp:Dear Audiophile Friend:I have spent countless hours designing the Super Amp and this VERY special DJH version. My associates at Cary Audio have, on numerous occasions, asked why I was spending so much time with this product. If I may, I would like to give you the history of the DJH Super Amp.The Super Amp started life as the model AE-25 stereo amplifier offered for the last two years by Audio Electronic Supply. The original AE-25 amplifier utilized a pair of EL-34’s in a basic push-pull configuration. At $800, in factory built form, I felt it was good but not quite approaching the magic of the single-ended triode sound. In fact, I would have to put it in the category of a good amplifier but clearly worthy of improvement. I may sound harsh by this description but once again I am accustomed to Cary, CAD-805 sound. This original AE-25 had EL-34’s, push pull, feedback and good specs. However, I felt, with much work, it could be improved. I wanted to make the AE-25 come closer to the music. I needed it to become an exceptional sounding amplifier.For those of you not aware, I am a triode-crazed audiophile. Do KT-88’s or EL-34 tubes have any merit? They sure do! Simply take a look at the curves when connected in the triode mode. Looks similar to the good ole 300B or 2A3 for that matter. Even the 6L6 looks like a great tube when run in the triode configuration. So, off I went spending enormous amounts of time to create some realistic musical excitement. As I developed the Super Amp I soon discovered that I was enjoying it much too much. I mean, it was push pull in design. I was able to develop some nice triode parameters utilizing an extremely sophisticated output transformer design. I was on my way with the “fun factor”.As I continued to design and listen, my wife, Donna, proclaimed, “you are producing some super sound tonight honey”. That’s it …. Ill call this the Super Amp. Super sound needs a super amp. Thus the name was born. Super Amp!The first public showing and listening session of the Super Amp occurred on January 23, 2000, in Charlotte, North Carolina at the Charlotte Audiophile Society meeting. The raves and thumbs up approval were overwhelming. Several members even placed orders with me at the meeting, which was the ultimate compliment. I have been crazed with this lil ole amplifier since the first showing.For the technically minded, a review of the circuit is in order. The DJH version of the Super Amp operates in a class A/AB mode. The output stage KT-88 tubes are fixed biased, with an equal negative bias voltage to ensure maximum linearity. Utilizing this bias network will permit the user to try many different types of output tubes if desired, a tweakers delight, if you will. Some of the choices may range from EL-34’s, 6550’s to 6L6’s. One might even wish to listen with 6V6’s. All these output tubes will present their own sonic signature, thus allowing the proud owner the ability to change the sonic character of his or her amp at their whim. There is a bias adjustment required when listening with these different types of audio tubes in the DJH Super Amp. The output power is 35 watts through each channel in the triode mode, utilizing KT-88’s, EL-34’s or KT-90’s. You may wish to operate with KT-66’s, 6L6’s or even 6V6’s. The output power with these lower dissipation tubes will yield from 20 to 25 watts output power. Speaking of output power, the DJH Super Amp has a peak envelope power of 57 watts into an average loudspeaker load.There are a number of significant differences between the DJH Super Amp and the basic Super Amp. First, as mentioned above, a separate adjustable bias voltage supply. This is a two stage bias supply that even incorporates a filter choke in the supply. Secondly,channel independent B plus supplies utilizes film and foil power supply capacitors. The front-end driver stage 6922’s have separate left and right channel regulated B plus power supplies. A current source for the 6922’s is provided by separate EL-84 tubes. The power transformer in the DJH version is almost twice the size and capability of the standard Super Amp power transformer. To top off the ingredients, Jensen copper foil and oil coupling capacitors carry the audio signal from the 6922’s to the output stage KT-88 final output tubes.Please remember to initially set the DC bias on the DJH Super Amp at 200 ma. DC current with the KT-88’s, EL-34’s or KT-90’s. Using 6L6’s, KT-66’s or 6V6’s the bias should be set at 160 ma. DC current.In concluding, I am most fortunate to be able to do what I love. I consider my work to be a privilege and I take it very seriously, while never losing sight of the fun factor. I hope I have conveyed this fundamental principle through the DJH SuperAmp. I am honored to be able to contribute, in some small way, to your enjoyment of sound and music.THE END
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