ST-70 / AA-100 / was 7591 now 6BG6G
Posted: Fri Mar 02, 2007 9:30 pm
So about a year ago, I built an ST-70 clone with Shannon's driver board, Heathkit AA-100 iron, and 7591's ... the reason I used 7591's is that I bought them to restore the Heathkit, and then realized it was a piece of crap.
I used a nice chassis from Yaeger Audio. The amp sounded pretty decent, but the tube sockets, new ceramic/gold, were junk and the tubes went on and off. They were too cheap to tighten. Yesterday, I yanked all 4 of them out, and put in the "Johnson" style ceramic sockets under the chassis. I also converted the bias test points, which were banana jacks, to plate jacks, an put pin jacks in for the bias test points, and wired it to use 6BG6G's.
As I should have expected, my dozen eBay tubes were all different brands and half bad, so I have some Sovteks on the way from Ned. So far, it sounds pretty good, I didn't look at the bias or check any voltages, I'll do that Monday when the tubes get here.
It looks cool anyway. The plate wires are bright orange Teflon, they look kind of yellow in the pics.
I used a nice chassis from Yaeger Audio. The amp sounded pretty decent, but the tube sockets, new ceramic/gold, were junk and the tubes went on and off. They were too cheap to tighten. Yesterday, I yanked all 4 of them out, and put in the "Johnson" style ceramic sockets under the chassis. I also converted the bias test points, which were banana jacks, to plate jacks, an put pin jacks in for the bias test points, and wired it to use 6BG6G's.
As I should have expected, my dozen eBay tubes were all different brands and half bad, so I have some Sovteks on the way from Ned. So far, it sounds pretty good, I didn't look at the bias or check any voltages, I'll do that Monday when the tubes get here.
It looks cool anyway. The plate wires are bright orange Teflon, they look kind of yellow in the pics.