Tubes Asylum

Type 37 and type 76

2.126.105.71

andy evans

I'm enjoying both of these types as input in my SE amp.

Any recommendations for what makes and types you've tried and liked?

In particular GE versus Sylvania 37s?

These all seem to have round plates, so differences may be slight.

Follow Ups:

RE: Type 37 and type 76 - timoteus 14:14:27 04/08/24 (1)
Most of the 76 sound similar. I like the Visseaux 76, World War II era RCA CRC 76, National Union, Tung-Sol, Raytheon, Philco and Sylvania. Not necessarily in that order, but the Visseaux is the best of the 76 and the rarest.

The 37 are all the same sound as the 76 just a bit less gain so I quit collecting them unless they are meshplate. My favorites here are Sylvania and Philco meshplate globes. Equally as good are the Silvertone meshplate in the ST envelope. Silvertone is the Sears Roebuck house brand and they used many different manufacturers over the years so I don't know who supplied Sears with this tube. I haven't been able to match up the meshplate with other known types so it remains a bit of a mystery. This tube is top supported and not free floating like the globes so has a slightly different sound than the globes. Maybe tighter and less ethereal than the globes because the structure is a little more damped and less microphonic. A real winner and cheaper than the globes.

I use these tubes in a DIY Bruce Berman preamp that has a separate power supply chassis so I haven't had any trouble with these tubes being noisy or overly microphonic. All these round plate tubes are really wonderful.
- Comparisons - 37 and 76 - andy evans 08:01:27 04/09/24 (0)
  Thanks Timoteus. Very useful. You have some rare examples.
  My own findings:
  37 GE - very nice+
  37 RCA - very nice-
  76 Bentley - very nice+
  76 Brimar - very nice+
  76 Kenrad - very nice
  76 Hytron - very nice-
  76 Mazda - OK but a bit noisy at times
  These 37 and 76 were the best sound of this type of tube. Some 6P5 were just as good, Sylvania better than RCA and Tung-Sol the least good, rather soft sounding and a more stumpy bottle than the others.
  These were all better than 6G6G and 6V6 in triode.
  
  Edits: 04/09/24
I used the 76 a lot years ago in NOS RCA and other and . . - John PA 07:51:18 04/05/24 (0)
with the preamp I built, with output transformers, what I eventually went with was the Sylvania 27 mesh plate. It is one of the most superb tube I have ever heard. The fine mesh plate, not course mesh plate. They are not the coke bottle style but the earlier. I have NOS from 1929 to 1932.

iBasso DX300MAX Ti. Focal Utopia and Stellia. iBasso SR2. Mr. Speakers, Ether II, Voce stats. Manley, Absolute headphone amp. LTA MZ3, Z10e electrostatic amp. Many other headphones, amps, cables etc.
RE: Type 37 and type 76 - Salectric 19:57:46 04/03/24 (0)
Andy, when I had an Emotive Erato linestage, I especially liked National Union 27's.
RE: Type 37 and type 76 - 6bq5 16:11:45 04/03/24 (3)
these are rather early tubes, and there are not as many makers as there are of say a 12AX7....
Happy Listening
- There aren't any obvious 9-pin substitutes - andy evans 03:03:08 04/05/24 (2)
  The 9 pin tubes came in at the same time as feedback in PP amps and so tended to be higher gain, like 20 or more. Not suitable for a low gain low Rp triode for a line stage. Same with the octals, except for 6P5GT with a gain of 14 like the 76. Plus 6AH4 and 1626. So there's just the pentodes/tetrodes in triode like the 6V6, 6F6, 6G6.
  
  Early tubes are just fine with me. Some of the best ever made.
  - RE: There aren't any obvious 9-pin substitutes - 6bq5 10:50:10 04/05/24 (1)
    I may have miss-typed -
    I did not mean to imply that 9 pins are better, or could substitute for your type 37 or 76 tubes-
    Merely trying to say that there were not as many makers of fire bottles that made 37s and 76s, or 26s etc. as there were/are for the 12AX7, or 6550 types-
    
    There is an aspect of some of the older tubes were made with more attention to detail, and for shorter production runs on given forms, so the constancy of early runs to later runs is higher than that of the tooling that moved from one factory to another and continued to run well after the original maker would have re-built the tooling.
    Happy Listening
    - Ah - thanks! (nt) - andy evans 16:22:15 04/05/24 (0)
      .

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