pressure Posted May 27, 2017 Share Posted May 27, 2017 Turned on the Tone King Metropolitan this morning and it started humming pretty loud so I went over to the amp to see which tube was causing the problem. As usual I tapped each tube starting with the pre-amp tubes, checking for microphonics, when I noticed a power amp tube was glowing blue. The glowing power amp tube hummed much lower and started to flame blue. I turned the amp off having identified the culprit. When the tube cooled down I pulled it out. Went to my tube inventory and found an NOS RCA JAN 6V6GTY (Jan 1952). It had 1 less pin and a much thinner base than the bad tube I pulled out. Do I really need 7 pins? The amp is transformed, clearer, tighter and of course no hum. It sounds FAB!!! Old bad tube. Old bad tube bottom with 7 pins. Replacement NOS tube. Replacement NOS tube bottom with 6 pins. Replacement NOS tube box. Link to comment Share on other sites More sharing options...
Gitfiddler Posted May 27, 2017 Share Posted May 27, 2017 65 year old 'new' 6V6! Oh yes!! Link to comment Share on other sites More sharing options...
big bob Posted May 30, 2017 Share Posted May 30, 2017 I like the new JJ 6v6S, probably closer to a 6l6. Sounds great in the Carr. Link to comment Share on other sites More sharing options...
RJLII Posted May 30, 2017 Share Posted May 30, 2017 I like the new JJ 6v6S, probably closer to a 6l6. Sounds great in the Carr. I'll second that. I've used them in both my Victorias. They really sound strong. Link to comment Share on other sites More sharing options...
Kuz Posted May 30, 2017 Share Posted May 30, 2017 To each their own an one of the things that makes this place great, but I have tried all the JJ stuff (froam 12ax7s, 12at7s, 6L6s, 6V6s, and EL84s) and I really hated all of them. Just goes to show how subjective tone is. I have pretty much all vintage RCA preamp tubes in my 4 amps, and Tungsol or TAD for power tubes. Link to comment Share on other sites More sharing options...
pressure Posted May 30, 2017 Author Share Posted May 30, 2017 Thanks for the input about tubes and tone. This is the biggest change I have ever had from a tube replacement and this was a power not preamp tube. I have changed a lot of preamp tubes, new and NOS, and never saw this big of a tone shift. I'm just wondering about the difference in the tube pins and base construction? Link to comment Share on other sites More sharing options...
LittleLeroy Posted May 31, 2017 Share Posted May 31, 2017 Oh Hell, I'll chime in... I've been repairing and building amps for 20 years. I own and operate and one-man repair shop here in Santa Fe and do tube and solid state. Factory authorized service center for VOX, Marshall, Fender, Mesa Boogie, Egnater, Peavey, etc. etc. It's very likely your TK wasn't giving you all it had due to the tube failing over time, thus big difference in output and tone when you installed the new tube. While it's cathode biased and doesn't need a bias reset, I would recommend you replace both 6v6s rather than just one, since they work in tandem to amplify the positive and negative sides of the wave. It's also possible - probable - that the other 6V6 was stressed over time trying to compensate for the bad tube and will fail, too. Or at least get yourself a back-up JIC. The 6V6 tube is an OCTAL, meaning eight pins. But not all 8 have internal connections, so some are manufactured - were manufactured - with only 6 or 7 pins. It depended on what was being made at the time, since all the power tubes with a "6" as the first number are Octals. Therefore you can find 6L6, 6V6 and 6CA7 tubes with 8, 7, or 6 pins. This has no effect on the operation of the tube. I hope this is helpful. Thanks for the input about tubes and tone. This is the biggest change I have ever had from a tube replacement and this was a power not preamp tube. I have changed a lot of preamp tubes, new and NOS, and never saw this big of a tone shift. I'm just wondering about the difference in the tube pins and base construction? Link to comment Share on other sites More sharing options...
pressure Posted May 31, 2017 Author Share Posted May 31, 2017 Very helpful LL. Thanks for that. Link to comment Share on other sites More sharing options...
ElNumero Posted May 31, 2017 Share Posted May 31, 2017 Less is more!!! Link to comment Share on other sites More sharing options...
Farmboyjo Posted June 1, 2017 Share Posted June 1, 2017 Thanks for the info Leroy! It's wasn't even my concern/post, but I learned so much. Great post! Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
212Mavguy Posted June 1, 2017 Share Posted June 1, 2017 Now for the fly in the ointment...ah, controversy coming! The dying tube is a Sylvania, produced for the JAN Philips label to mil specs. Same specs for what OP calls RCA 6v6. That ain't no RCA, it's a GE coin base 6v6 coming out of an RCA box.. Ge gray plates, GE coin base, RCA never did those, unique to GE but the final kicker is acid etched dots on the bottle side, those are a dead giveaway GE. And that's the truth. Pfffffffft. Link to comment Share on other sites More sharing options...
pressure Posted June 1, 2017 Author Share Posted June 1, 2017 Time to look for more GE gray plate coin base 6v6 tubes. That is by far the best sounding 6v6 I have ever heard. Link to comment Share on other sites More sharing options...
big bob Posted June 3, 2017 Share Posted June 3, 2017 Kuz, have you tryed the 6v6s? It's a big bottle and while they call it a 6v6 it performs like a 6l6, more volume and top end punch! If you have not you should try a set their not expensive. Link to comment Share on other sites More sharing options...
Kuz Posted June 3, 2017 Share Posted June 3, 2017 Kuz, have you tryed the 6v6s? It's a big bottle and while they call it a 6v6 it performs like a 6l6, more volume and top end punch! If you have not you should try a set their not expensive. I think I have, but I may try them in my '67 Deluxe. Usually I try to go for the authentic tone and tubes that the vintage amp was designed for, but I really love the big low end from 6L6s and if the JJ 6v6s are a cross between a 6L6 & 6V6 then they might sound good in my '67 Deluxe Rev (giving it a little more low end bass). Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.