NOS Tung Sol 12BH7a

[knotscott]

Anyone else running US made Tung Sol 12BH7a?

I picked up two for my modified Dyna/VTA 70 amps a couple of weeks ago to use as voltage driver tubes. I liked them from the start, but they've really opened up beautifully with some hours on them now. I liked the new issue EH 12Bh7a quite a bit too, but the NOS TS are more open, refined, have more air and really nice texture. It's always subjective and different with every circuit, but these are my favorite over any 12AU7, or even other American 12BH7 I've tried so far.

 

[peterh]

The reason that different tubes makes a difference on this amp is that the feedback is so low. Changing the 7k resistor in the feedback loop to 2k will make the amp much better and independent of tube propertioes.

 

[Lavane]

I have to ask, what's the purpose of the silver mica caps at the input jacks?
I noticed one in one of the pictures.

 

[knotscott]

I have to ask, what's the purpose of the silver mica caps at the input jacks?
I noticed one in one of the pictures.

The silver mica cap is an inline low pass filter at ~ 60hz. The system is bi-amped with the tube amps on midbass/tweeters, and a Linn solid state amp with DSP/active low pass crossover on the woofers.

 

[Mr Boochie]

Anyone else running US made Tung Sol 12BH7a?

I picked up two for my modified Dyna/VTA 70 amps a couple of weeks ago to use as voltage driver tubes. I liked them from the start, but they've really opened up beautifully with some hours on them now. I liked the new issue EH 12Bh7a quite a bit too, but the NOS TS are more open, refined, have more air and really nice texture. It's always subjective and different with every circuit, but these are my favorite over any 12AU7, or even other American 12BH7 I've tried so far.

View attachment 3859776View attachment 3859777

The Tung-Sol and the Sylvania black plates are my favorite 12BH7A.

 

[Lavane]

The Tung-Sol and the Sylvania black plates are my favorite 12BH7A.

View attachment 3859839

I have some Sylvania gray plates that sound pretty darn good too. Sylvania seems to have gotten a lot right. There 12AU7's are pretty decent too. I originally used some in my ST-70 before switching to RCA clear tops, then an old stock 12BH7. I had a Phillips 12BH7 I really liked until one of the triodes shorted out.
I even tried an EH new manufature 12BH7. It lasted less than a minute. It hummed in thae voltage gain socket. Dead quiet in a long tail pair sockets though. I haven't used it since.

 

[mr_macgee]

What timing. I literally this morning pulled out these two sets to try in my MC30's. NOS matching JAN Sylvania's Grey pl. 1971 12BH7A's, and a matching set of NOS Tung-Sol, May '65 12BH7.

The Sylvania's actually made an immediate difference in improved larger sound stage, and imaging, I'm really liking them over my new gold pin Electro Harmonix 12BH7's (tightly matched) I had in there. Haven't yet tried the Tung-Sol's, it may be a while : ) The Russian gold EH's are not going back in.

 

[arts]

I have always loved the curved-plate 12BH7. They were made in Canada and USA, and by several different manufacturers. They are all excellent performers.

 

[byoungman1]

@ mr_macgee ... your Tung-Sol's are from 1955
Matsushitas are another fine choice if you can find them.

 

[mr_macgee]

@ mr_macgee ... your Tung-Sol's are from 1955
Matsushitas are another fine choice if you can find them.

Good to know, Thank you for that! I thought the '55's only had shiny black plates, hence thinking my grey plates were '65's? And since the boxes and tubes are so minty new looking.
I actually have two Matsushitas, but very different looking builds; non matching so left them in the crate. The bane of having mono's (1st world problem) : )

I have always loved the curved-plate 12BH7. They were made in Canada and USA, and by several different manufacturers. They are all excellent performers.

I'll have to keep an eye out of them, those are very different looking plates to mine.
I have a MC225 all boxed up, stored away and will need to pull it out, and do some tube rolling with these pairs of 12BH7's. I think I have EH's in it. Swapping out the EH's made a huge difference in my system. Using the MC30's to hear and roll tubes, it's been very discernible.

I have found out of any tube line, the dark green labeled Sylvania's in various tubes (12AX7, 12BH7, 12AU7's....etc) have been a smoking value and surprised by the sound quality; compared to higher end value tubes.

 

[mr_macgee]

PS> My apologies to the OP, for getting off-topic as I have not yet tried my Tung-Sol's. But, I can say my JAN 12BH7 Sylvania green label tubes that I have just put in today are sounding much better in my amp compared my EH gold pin 12BH7 tubes ( I have 3 new pairs of the EH's).

I know it's all subjective, but I did seem to hear a pretty big difference, and for the positive. I thought socket #1 & #2 made the biggest differences on the MC30's.
I'm pretty surprised how cheap they can be found for, currently on FleaBay.

 

[Mr Boochie]

I have some Sylvania gray plates that sound pretty darn good too. Sylvania seems to have gotten a lot right. There 12AU7's are pretty decent too. I originally used some in my ST-70 before switching to RCA clear tops, then an old stock 12BH7.

I like these Sylvania JAN-JHS 12AU7WA/6189 subtypes in my TV's headphone amp setup.

 

[Mr Boochie]

@ mr_macgee ... your Tung-Sol's are from 1955
Matsushitas are another fine choice if you can find them.

I believe the Matsushita-made 12BH7 is based on older Philips (European) tooling. The ones with the 45-degree tilt in the getter halo. They are very good tubes.