A couple years ago, I got one of the small K-502 tube amp kits from AES, and it went together easily and soundsed OK (not great, but not bad, either). The original kit had cheapo plastic tube sockets for the 4 11BM8s, which I never really cared for. This weekend, I decided to replace them with ceramic sockets, and while I had it off the metal chassis, I decided to try out the Hammond 1609 OPTs that I recently got from AES. The sound was much improved over the original cheap OPTs, both bass and high freqs were significantly improved. Next, I decided to try out the UL taps.
Cut 4 etches, to free up pin 7 (screen grids) on the 11BM8s, and wired in the UL taps. Oh, yeah, I added a CL-90 in series wuith the power trannie primary. Now teh 11BM8s don't flare up white-hot on startup.
WOW!!!!!!!!!!!! :shock: :shock: :shock: :shock: The sound was vastly improved, even though the output power was slightly reduced, but now it is a significant upgrade, and clean all the way up to "11" on the volume control. So, a $140 "ugly duckling" kit amp, a $1 chassis (from a flea market find) and 2 $35 OPTs make for a nice sounding, though not overly powerful, amp. The DIY-35 will still blow its doors off, but for a second system, or one for a kid, it's hard to beat. My SWAG is that it went from 8 harsh watts at full output, to 5 or 6 very clean and sweet watts. Those UL taps really do make a difference! I'll bring this one to work, and bring home the "doctored" SCA-35 to donate iron to the next DIY35 project.
/ed brown in NH