Originally Posted by PaulDB
PKFMan23 and sacd lover, you're da men. Your clear explanations are excellent complements to the stunning SP amps, which for some reason come to customers without a user's manual.
Back to the adapters, how would I know which 5687 is 6v, which is 12v? Provided I have a multi-meter, is there a way to find out without having to call SP and ask?
I was told Tung Sol 5687 are among the best 5687s. How about 7n7? And where do you get them?
I feel overwhelmed (and positively so) by the possibilities of tube rolling the SP amps provided to the users. These amps pack lots of value and tons of fun!
Thank you all.
I posted this earlier in this thread regarding 7n7's .... you must have missed my comments.
All 7n7's regardless of branding were made by Sylvania .... except the rare, gray glass, tall bottle, round plate National Union 7n7 from the 1940's.
The Sylvania 7n7's come in three styles; 1) 1940's tall bottle, silver coating at the top of the tube, gt style box plates, 2) early 1950's short bottle, silver coating at the top of the tube, gt style box plates, 3) mid- late 1950's/ early 1960's short bottle, gta type triangular plates, with a chrome top ring or clear top. I believe the gt style box plate tubes sound the best .... but the gta type 7n7 is still a very good tube.
Another good tube you can use with the same adapter is the Sylvania 7af7. The 7af7 tube looks almost identical to the short bottle 7n7 gt type box plate tube. But the 7af7 has a distictive round plate constructon. Again, regardless of the brand the 7af7 was a Sylvania tube. This tubes sound quality is much like the early 1950's short bottle 7n7. But the 7af7 has a lighter, tighter bass and a slightly more forward presentation.
As for the 5687 adapters, you order them specifically for 6 or 12 volt operation. The 5687 is wired differently at heater pins 4 and 5 to determine 6 volt or 12 volt operation. I have both voltages and I distinguish between the adapters by simply putting tape on the 6 volt adapters. Any such system will work if you have multiple adapters with the same tube sockets .... and consequently the same appearance.
Where do you get 7n7's? I will send you a pm.