gypsyseven Posted March 5, 2010 Share Posted March 5, 2010 Any preamp tubes with low gain that stay clean longer? What do you guys use? 12AX7WA SOV/Russia http://www.tubeampdoctor.com/product_info.php?cPath=21_70_71&products_id=459:-k Link to comment Share on other sites More sharing options...
peeper Posted March 5, 2010 Share Posted March 5, 2010 You could try a 12AU7, its the lowest gain of any 12xxx I know of. Link to comment Share on other sites More sharing options...
m-theory Posted March 5, 2010 Share Posted March 5, 2010 On any given hypothetical piece of test equipment, any given new production 12ax7 will measure anywhere from a hypothetical 70 to a hypothetical 120 or so in gain. It's really of no value to make the claim that any given tube is, across the board, higher or lower in gain than another of a different part number or brand. Yes, historically, at7s and au7s were designed to produce less gain that a typical ax7, but this was in a day in which any given hundred-lot of ax7s' might show hypothetical gain of 130 on that same hypothetical test equipment, and out of that entire hundred-lot, only a few would be below that, and those below that would only be below by a slight amount, not 40%. So, back in the day, you could legitimately claim that a 12ax7 was a gain factor of "x," an at7 was "y" percent lower than that, and an au7 was "z" percent lower. Not only that, but manufacturer to manufacturer was highly consistent, so you could truly make A/B comparisons for such things as "tone." Today, knowing that 12ax7's can range from a hypothetical gain of "70" to a hypothetical gain of "120," and this can occur within the same batch received from the same manufacturer, how can anyone assign a blanket assessment of any tube's tone or performance? "Oh yeah, brand xyz is MUCH better than brand abc, because it sounds SO much better!" Oh yeah? Why is that? Are you saying that because you know that both tubes were exactly matched in gain, conductance, triode match, and microphonics, so that you're TRULY measuring like for like and hearing a TRUE tone difference, or are you saying it because you didn't know that the brand abc tube that you tried had a miserably low gain and high microphonics, while brand xyz had no microphonics and fairly high gain? As for swapping out ax7s for at7s or au7s, yes, of course you can find at7s and au7s of lower gain than ax7s, but you can also find ax7s of lower gain than at7s and au7s, so what are you really doing? Do you really KNOW that you're getting a lower gain tube to swap that ax7 with? What we DO know is that you're getting a tube with a smaller frequency response, so it's not going to sound as full. Is that good thing? Maybe, maybe not. That's up to your ears to decide, right? Just be careful of generalizations with regard to tubes. They're virtually meaningless. Link to comment Share on other sites More sharing options...
1984 Guy Posted March 5, 2010 Share Posted March 5, 2010 Holy smokes! You just said what I've thought forever. Touche'! On any given hypothetical piece of test equipment' date=' any given new production 12ax7 will measure anywhere from a hypothetical 70 to a hypothetical 120 or so in gain. It's really of no value to make the claim that any given tube is, across the board, higher or lower in gain than another of a different part number or brand. Yes, historically, at7s and au7s were designed to produce less gain that a typical ax7, but this was in a day in which any given hundred-lot of ax7s' might show hypothetical gain of 130 on that same hypothetical test equipment, and out of that entire hundred-lot, only a few would be below that, and those below that would only be below by a slight amount, not 40%. So, back in the day, you could legitimately claim that a 12ax7 was a gain factor of "x," an at7 was "y" percent lower than that, and an au7 was "z" percent lower. Not only that, but manufacturer to manufacturer was highly consistent, so you could truly make A/B comparisons for such things as "tone." Today, knowing that 12ax7's can range from a hypothetical gain of "70" to a hypothetical gain of "120," and this can occur within the same batch received from the same manufacturer, how can anyone assign a blanket assessment of any tube's tone or performance? "Oh yeah, brand xyz is MUCH better than brand abc, because it sounds SO much better!" Oh yeah? Why is that? Are you saying that because you know that both tubes were exactly matched in gain, conductance, triode match, and microphonics, so that you're TRULY measuring like for like and hearing a TRUE tone difference, or are you saying it because you didn't know that the brand abc tube that you tried had a miserably low gain and high microphonics, while brand xyz had no microphonics and fairly high gain? As for swapping out ax7s for at7s or au7s, yes, of course you can find at7s and au7s of lower gain than ax7s, but you can also find ax7s of lower gain than at7s and au7s, so what are you really doing? Do you really KNOW that you're getting a lower gain tube to swap that ax7 with? What we DO know is that you're getting a tube with a smaller frequency response, so it's not going to sound as full. Is that good thing? Maybe, maybe not. That's up to your ears to decide, right? Just be careful of generalizations with regard to tubes. They're virtually meaningless. [/quote'] Link to comment Share on other sites More sharing options...
marvar Posted March 6, 2010 Share Posted March 6, 2010 On any given hypothetical piece of test equipment' date=' any given new production 12ax7 will measure anywhere from a hypothetical 70 to a hypothetical 120 or so in gain. It's really of no value to make the claim that any given tube is, across the board, higher or lower in gain than another of a different part number or brand. Yes, historically, at7s and au7s were designed to produce less gain that a typical ax7, but this was in a day in which any given hundred-lot of ax7s' might show hypothetical gain of 130 on that same hypothetical test equipment, and out of that entire hundred-lot, only a few would be below that, and those below that would only be below by a slight amount, not 40%. So, back in the day, you could legitimately claim that a 12ax7 was a gain factor of "x," an at7 was "y" percent lower than that, and an au7 was "z" percent lower. Not only that, but manufacturer to manufacturer was highly consistent, so you could truly make A/B comparisons for such things as "tone." Today, knowing that 12ax7's can range from a hypothetical gain of "70" to a hypothetical gain of "120," and this can occur within the same batch received from the same manufacturer, how can anyone assign a blanket assessment of any tube's tone or performance? "Oh yeah, brand xyz is MUCH better than brand abc, because it sounds SO much better!" Oh yeah? Why is that? Are you saying that because you know that both tubes were exactly matched in gain, conductance, triode match, and microphonics, so that you're TRULY measuring like for like and hearing a TRUE tone difference, or are you saying it because you didn't know that the brand abc tube that you tried had a miserably low gain and high microphonics, while brand xyz had no microphonics and fairly high gain? As for swapping out ax7s for at7s or au7s, yes, of course you can find at7s and au7s of lower gain than ax7s, but you can also find ax7s of lower gain than at7s and au7s, so what are you really doing? Do you really KNOW that you're getting a lower gain tube to swap that ax7 with? What we DO know is that you're getting a tube with a smaller frequency response, so it's not going to sound as full. Is that good thing? Maybe, maybe not. That's up to your ears to decide, right? Just be careful of generalizations with regard to tubes. They're virtually meaningless. [/quote'] This is all true, but, generally, substituting a 12AY, or 12AU , or 5751, will give you lower gain, more headroom. Most 12AT7 tubes don't sound all that great in the tone generating stages of an amp, they were never meant to- they were mostly used as current handling devices, (non-tone generating circuits- PI, Reverb, etc. I've also found that most of those tubes, with a few exceptions are mostly avaiable as NOS.at reasonable prices, which most do meet spec. I have bunches of tubes, both new and old and NOS, generally, they all do what they are supposed to do. And, if you get your tubes from a trusted vendor, that tests his tubes correctly, most will be pretty close to spec. Including 12ax7's. Link to comment Share on other sites More sharing options...
gypsyseven Posted March 6, 2010 Author Share Posted March 6, 2010 Thanks so much...I'll just try and we'll see.... Link to comment Share on other sites More sharing options...
m-theory Posted March 6, 2010 Share Posted March 6, 2010 By all means, try and see, although I'd be real tempted to go to a local amp tech or call up someone like Eurobob, and explain what you're looking for, so that they can help you get there. Just bear in mind that, without measuring what you've got now that you want to reduce, gainwise, it's sort of a stab in the dark whether or not what you end up with will actually be lower in gain. Good luck with it. Just be aware that ax7s have a broader frequency response than at7s, so there's that to factor in as well. You might like the reduced response, or you might not. Worth trying. Link to comment Share on other sites More sharing options...
gypsyseven Posted March 6, 2010 Author Share Posted March 6, 2010 I'm not a pro but maybe you can show which preamp tubes should be changed to 12au/12ay...or all of 'em? Link to comment Share on other sites More sharing options...
jaydodge Posted March 11, 2010 Share Posted March 11, 2010 V2 in the schematic (and labeled on the board) ..but in terms of location, its actually the first small tube closest to the input jack and gain knob.. http://img690.imageshack.us/i/valveseniorjaydodge4a.jpg/ Link to comment Share on other sites More sharing options...
gypsyseven Posted March 11, 2010 Author Share Posted March 11, 2010 thank you very much...but since i got Valve Senior i'm only playing my Telecaster through it...Can't believe it sounds better than my Les Paul... So with the single coiled Tele i dont got that problem to keep the amp clean on higher volumes... But i will try an 12au/12ay next month or soo..... Right now there is no need for a chance - just NEED FOR TWEED ! Link to comment Share on other sites More sharing options...
Fadedepi Posted March 11, 2010 Share Posted March 11, 2010 Just my .02... Get a 5751 to replace your 12ax7, you'll be glad you did. This has been my experience with single coils and HB's alike. Faded.... (this is truly keeping it simple!) Link to comment Share on other sites More sharing options...
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