Tubes Asylum

• RE: Can i use a 12bh7 in place of a 6922 ? - mcgjohn@yahoo.com 10:14:36 03/11/14 (1)
  In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by beppe61 on March 10, 2014 at 05:58:59

  why not try some Russian 6N1P's or the higher gain version 6N2P? They are pin for pin compatible with the 6922's.
  
  they are great sounding tubes, will last a long time, and are available on Ebay from sevral Russian and Eastern sources.
  
  Some sellers are now even offering different vintages (1970s, 1990s, 1960s) on these tubes.
  
  And while you are looking at tube rolling, you should consider what coupling caps are in your unit. changing those out can make a bigger difference than tube rolling.
  
  best
  
  

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  • RE: Can i use a 12bh7 in place of a 6922 ? - beppe61 10:50:41 03/11/14 (0)
    In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by mcgjohn@yahoo.com on March 11, 2014 at 10:14:36

    
    Hi thanks a lot for the very valuable suggestion
    Just to explain the unit is only a buffer or cathode follower where each half drives one channel.
    Very very basic.
    So the question is which would be the best tube equivalent to a 6922.
    Personally i like powerful tube with a very clean sound.
    I would like to avoid softness in sound.
    
    Speaking of capacitors i think they will be very cheap ones.
    But i have not received yet the unit. I hope to get it very soon.
    I want to try to give a more human touch to my cheap digital.
    I am optimistic. I see many happy marriages of tubes with digital.
    It is a strange thing .. the oldest technology with the latest one.
    But the sound is what counts.
    Thanks again for the very helpful advice.
    I have already found a way to spend time ... tubes rolling !
    
    
    Kind regards,
    bg
    
    

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• RE: Can i use a 12bh7 in place of a 6922 ? - BCR 09:48:01 03/10/14 (6)
  In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by beppe61 on March 10, 2014 at 05:58:59

  The 12 means 12 volt and the 6 means 6 volt and never the twain shall meet!
  

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  • RE: Can i use a 12bh7 in place of a 6922 ? - D Mike 12:42:24 03/10/14 (0)
    In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by BCR on March 10, 2014 at 09:48:01

    A 12BH7 can be wired to run on a 6.3 volt heater supply.
    
    But I agree, the two are very dissimilar tubes. Best to save the 12BH7's for another duty and hunt for the 6992 that floats your boat. The 6922 family can sound very good too. The circuit probably matters more than the tube, in this case.
    

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  • Thanks ! i did not know this - beppe61 10:38:50 03/10/14 (4)
    In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by BCR on March 10, 2014 at 09:48:01

    
    Hi, so the first number indicates the heater voltage. Good to know !
    I wonder which are the main differences in the performance of the two tubes
    I think that the 12bh7 is the stronger tube.
    It is very common as a driver for output stages in tube amps of high quality.
    This is to me a great credential.
    What is your opinion ? is the 12bh7 a better tube for driver than the 6922 ?
    The last think i would like to get is a soft sound.
    Thanks a lot.
    Kind regards,
    bg
    
    

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    • RE: Thanks ! i did not know this - Palustris 07:22:12 03/11/14 (1)
      In Reply to: RE: Thanks ! i did not know this posted by beppe61 on March 10, 2014 at 10:38:50

      "Hi, so the first number indicates the heater voltage. Good to know !"
      
      Not in the case of the 6922 which is an industrial number for the 6DJ8. In the case of the 6922 it is simply a coincidence that the tube starts with "6". For instance the popular 5687 is not a 5 volt tube. A 6DJ8 is a 6 volt tube just as a 6CG7 is a 6 volt tube, but once you get into the industrial numbers you can't predict the filament voltage from the number.
      

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      • RE: Thanks ! - beppe61 08:59:52 03/11/14 (0)
        In Reply to: RE: Thanks ! i did not know this posted by Palustris on March 11, 2014 at 07:22:12

        
        Hi and thanks for the helpful information.
        I am trying to make digital more "human" adding a tube buffer after the dac.
        I read that digital mates very well with tubes, better than with solid state.
        Analogue sources are less picky about amplification.
        Everything seems to sound ok with LPs.
        But digital ... sometimes can be really stressing and fatiguing and tubes are said to tame this.
        Kind regards,
        bg
        
        

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    • RE: Thanks ! i did not know this - BCR 12:21:53 03/10/14 (1)
      In Reply to: RE: Thanks ! i did not know this posted by beppe61 on March 10, 2014 at 10:38:50

      Hi,I could not campare the two since you can't swap them in the same amps to hear the difference. I do have a phono preamp that uses a 6dj8, same as a 6922 and it sounds outstanding.
      I use a GE 6DJ8 in that preamp. I prefer GE tubes from the 50's or 60's era!
      

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      • RE: Thanks ! i did not know this - beppe61 00:06:49 03/11/14 (0)
        In Reply to: RE: Thanks ! i did not know this posted by BCR on March 10, 2014 at 12:21:53

        
        Thank you very much again
        I understand the choice is very huge ...
        Nevertheless i will email the seller to understand if the 6V equivalent of the 12bh7 could work.
        I admit i fell in love with the crystal clear and powerful sound of the 12bh7. I think it is a very underrated tube for line stage duties.
        Thanks a lot again
        Kind regards,
        bg
        
        

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• Nope don't try it. - Mechans 06:15:29 03/10/14 (12)
  In Reply to: RE: Can i use a 12bh7 in place of a 6922 ? posted by beppe61 on March 10, 2014 at 05:58:59

  EDIT evidently I am ill informed on the matter so ignore the earlier post which I have erased except for the subject line. I tried to delete it but it wouldn't do it, sorry if there is confusion. I had stupidly thought that your tube was a familiar 12 volt signal tubes seen in many pre amp circuits. Sorry about that.
  
  Steve
  
  

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  Edits: 03/11/14

  • The pinout is only different in the filament connections. - JJ Triode 08:14:01 03/10/14 (6)
    In Reply to: RE: Nope don't try it. posted by Mechans on March 10, 2014 at 06:15:29

    The 6GU7 is a 6-volt version of the 12BH7 and has the same pinout pattern as the 6922/6DJ8 family of tubes. However, the parameters are different (6GU7 has half the amplification factor and twice the plate resistance of a 6922, and draws more filament current.)
    
    You may or may not be able to sub a 6GU7 for a 6922 in your unit. I suggest contacting the manufacturer first if you want to try. 6GU7s are much less expensive than 12BH7s on the NOS market, and Jim McShane among others has good ones, e.g. GEs.
    

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    • 6GU7 bought ! - beppe61 05:46:12 03/11/14 (2)
      In Reply to: RE: The pinout is only different in the filament connections. posted by JJ Triode on March 10, 2014 at 08:14:01

      Hello ! i have bought two here ...

      http://www.ebay.com/itm/290584976629

      Sorry again, when you say that it "draws more filament current", how much more ?
      The unit has only one tube to power in the end ... not that much.
      I will keep a fire extinguisher at hand anyway ...
      If it only the sound is similar to the 12bh7 i think i am done for a long period ...
      Thanks a lot again

      Kind regards,
      bg
      Kind regards,
      bg
      
      

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      Edits: 03/11/14

      • 6GU7 draws double the filament current... - JJ Triode 07:11:46 03/11/14 (1)
        In Reply to: RE: 6GU7 bought ! posted by beppe61 on March 11, 2014 at 05:46:12

        …0.6 A versus 0.3 A for a 6922. This is the most potentially problematic parameter for your preamp or DAC, since a higher drawn current will make the transformer run hotter. Damage could occur even if it doesn't catch fire!
        
        The other differences will not cause a malfunction, but only you can decide if a 6GU7 really sounds better in your application.
        
        A good source for tube data is www.duncanamps.com, click on the TDSL (tube data source locator.)
        

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        • RE: 6GU7 draws double the filament current... - beppe61 08:54:53 03/11/14 (0)
          In Reply to: RE: 6GU7 draws double the filament current... posted by JJ Triode on March 11, 2014 at 07:11:46

          
          I will check first with the seller.
          I could even try a mods myself (i.e. an additional 6V/1A power supply. I have already something at hand).
          Thanks again for the kind advice.
          
          
          Kind regards,
          bg
          
          

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    • RE: The pinout is only different in the filament connections. - beppe61 08:35:27 03/10/14 (2)
      In Reply to: RE: The pinout is only different in the filament connections. posted by JJ Triode on March 10, 2014 at 08:14:01

      
      Thanks a lot for your valuable advice
      But the sound of the 6GU7 is similar to the 12bh7 sound ?
      I liked the clean and powerful sound of the 12bh7 in buffer duties.
      It seemed to me practically perfect.
      Crystal clear, powerful and still extremely not fatiguing.
      Great tube indeed ...
      
      Kind regards,
      bg
      
      

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      • 12BH7 and 6GU7 are identical except for the filaments (nt) - JJ Triode 17:09:31 03/10/14 (1)
        In Reply to: RE: The pinout is only different in the filament connections. posted by beppe61 on March 10, 2014 at 08:35:27

        -t
        

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        • " 6GU7 " - beppe61 00:12:27 03/11/14 (0)
          In Reply to: RE: 12BH7 and 6GU7 are identical except for the filaments (nt) posted by JJ Triode on March 10, 2014 at 17:09:31

          
          Thanks a lot again for the valuable advice.
          Being a fan of the 12bh7 i will email the seller to understand if i can use a 6GU7.
          What a great tube the 12bh7 ... it can be found in high level VTL amps used as output stages driver.
          Very powerful and extremely clean.
          I do not like soft or too much rounded sound at all.
          
          Kind regards,
          bg
          
          

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  • Thanks a lot indeed. - beppe61 06:37:13 03/10/14 (4)
    In Reply to: RE: Nope don't try it. posted by Mechans on March 10, 2014 at 06:15:29

    Hi and thanks a lot.
    Not that the choice is limited ... but i like the 12bh7 tube.
    I read something about it. It is a quite neglected tube, maybe because it was used in television sets ?
    Everyone talks about 12au7 or 6922 ... i wonder if they are really so superior tubes for audio ...
    Actually i tried one 12bh7 in place of a 12au7 in a cathode follower and was shocked how much more i liked the sound.
    Anyway as i am sure the unit will come with a chinese tube no brand, what would be a good candidate for a E88CC/6922, ECC88/6dj8 tube ?
    I like clean and powerful sounds. Not too mellow i mean.
    Thanks a lot again.
    Kind regards,
    bg
    
    

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    Edits: 03/10/14   03/10/14   03/10/14   03/10/14

    • Tesla Rostov made a very nice ECC88 for Siemens - Jay Buridan 07:54:34 03/10/14 (3)
      In Reply to: RE: Thanks a lot indeed. posted by beppe61 on March 10, 2014 at 06:37:13

      Many of these tubes say 'Made in Germany' and the design is a replica of the Siemens ECC88, but the factory and date codes indicate they were made in the Tesla Rostov plant during the Cold War. These have a beautifully clean sound and are not expensive. Maybe tubemonger has them?
      
      Also, I like 12BH7 but it doesn't work in an ECC88 circuit.
      
      
      

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      • RE: Tesla Rostov made a very nice ECC88 for Siemens - beppe61 08:44:18 03/10/14 (2)
        In Reply to: RE: Tesla Rostov made a very nice ECC88 for Siemens posted by Jay Buridan on March 10, 2014 at 07:54:34

        
        Hello and thanks for the advice.
        It seems that the good ones are not that cheap actually ...
        
        http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&LH_BIN=1&_nkw=Siemens+ECC88&_sop=15
        
        Unfortunately i did not find a buffer using the 12bh7.
        And they are really cheap ...
        
        http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&LH_BIN=1&_nkw=12bh7&_sop=15&_udlo=20&_udhi
        
        Thanks again.
        Kind regards,
        bg
        
        

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        • RE: Tesla Roznov made a very nice ECC88 for Siemens - Jay Buridan 12:12:37 03/10/14 (1)
          In Reply to: RE: Tesla Rostov made a very nice ECC88 for Siemens posted by beppe61 on March 10, 2014 at 08:44:18

          I would not trust eBay. See link

          • Here   (Open in New Window)

          
          

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          • RE: Tesla Roznov made a very nice ECC88 for Siemens - beppe61 00:14:39 03/11/14 (0)
            In Reply to: RE: Tesla Roznov made a very nice ECC88 for Siemens posted by Jay Buridan on March 10, 2014 at 12:12:37

            
            Thanks a lot for the site !
            I would also like to try the 6V equivalent of the 12bh7, the 6GU7
            But i have to check with the seller first if it is usable.
            
            Kind regards,
            bg
            
            

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