[Joeztech]

They sound great. The first one I did is populated with JJ EL34 outputs and they have a nice soundstage for stereo. Typically they are very quiet with very little hum and noise. The Van Alstine modification was made to the feedback and input stages of the amp. This reduces the low end somewhat and I wound up modifying the input coupling cap to .047 instead of .027 or .033mFd. This brings the bass capability back up but only to a reasonable level with loudness compensation for low level listening. For cases where really loud reproduction is desired, the loudness compensation needs to be turned off and only the normal bass and treble adjustments should be made. The original input circuit was direct coupled and the amplifier does not need to try to reproduce frequencies below 15Hz. Adding Van Alstine's band limiting circuit to the front end cleans up the muddy bass these were known for when new. More filtering in the power supply also helps the low end. When finished the result is much more life like and to my ears sounds better than the solid state amplifiers I had been using for years (including Marantz and Onkyo 80 and 100W per channel power amps).

6GH8A gain and driver stage tube are excellent replacements for the OEM 7199 tubes. The PC board has to be modified or adapter sockets at $24 apiece need to be installed to use them. I decided to just modify the board since good 7199 tubes are now quite expensive.

This latest unit was populated with JJ KT77 output tubes which have slightly more bass output than the JJ EL34 tubes, but only by a small amount. I made the same modifications to the front end and feedback as mentioned above. This last unit was a gift to a friend for Christmas. He and his wife are enjoying great sounds now.

Merry Christmas and Happy New Year!

Joe