MaxHart85231281734137 Posted January 8, 2010 Share Posted January 8, 2010 hey guys, i found a bunch of old tubes in some old record players and radios layin around my parents house, several preamp tubes I have a question about, I have two little 5 watt tube amps, Blackheart Lil Giant, and Fender Champ 600, one has EL84 power tube, the other has 6v6 gt I have found these tubes 12AX7 12AX7A 12AU7A what is the difference in these, and which ones would match better with those two different power tubes? thanks guys! Link to comment Share on other sites More sharing options...
RSDx Posted January 8, 2010 Share Posted January 8, 2010 hey guys' date=' i found a bunch of old tubes in some old record players and radios layin around my parents house, several preamp tubes I have a question about, I have two little 5 watt tube amps, Blackheart Lil Giant, and Fender Champ 600, one has EL84 power tube, the other has 6v6 gt I have found these tubes 12AX7 12AX7A 12AU7A what is the difference in these, and which ones would match better with those two different power tubes? thanks guys![/quote'] From my (very) limited understanding, the 12AX7's break up a little earlier than the 12AU7's ... couldn't tell ya the difference between a 12AX7 and a 12AX7A, though ... although I'm sure someone who can tell you will chime in Link to comment Share on other sites More sharing options...
StayIn Posted January 8, 2010 Share Posted January 8, 2010 Im not an expert as well, but once i had EL34A instead of EL34 and it fits well! cannot really determine any difference on sound quality think.. Link to comment Share on other sites More sharing options...
mrw1960 Posted January 9, 2010 Share Posted January 9, 2010 I am no expert either, but according to the "The Tube Amp Book" by Aspen Pittman, the 12AX7A is a "Brighter" tube than the 12AX7. It also, I think has something to do where it was manufactured. 12AX7R is a Russian made tube. According to the book the 12AU7 has less output and is used as a phase inverter in higher power amps for cleaner sound.Great for high end audio performance like McIntosh, Ampeg and Leslie amps. Thats all that I have read about. Anyone correct me please if I am incorrect. Hope this is of any help.. Link to comment Share on other sites More sharing options...
MaxHart85231281734137 Posted January 9, 2010 Author Share Posted January 9, 2010 cool thanks for the info, any one else that wants to chime in please do! Link to comment Share on other sites More sharing options...
K.E.B.1281734147 Posted January 9, 2010 Share Posted January 9, 2010 What pre-amp tubes are you using in those amps now? My guess is they're 12AX7. If they are, the 12AX7 is swappable, and the 12AU7A is probably too low power. It might be interesting to swap the 12AX7. Chances are it's old and worn though. Check out this link for more info... http://thetubestore.com/gainfactor.html Link to comment Share on other sites More sharing options...
SamBooka Posted January 9, 2010 Share Posted January 9, 2010 There is an AMP section??? If the tubes are more than 15 years old then the numbers mean something. (12ax7 vs 12ax7a). For current production tubes the a at the end is markting. 12AU7 is a lower gain tube. The general consensus is that these "usually" dont sound that great in amp. I have a champ 600 and wouldnt dream of putting a 12au in there. It WOULD clean the amp up a little but those amps are not clean machines to begin with. That is their charm The best part is this: You can stop listening to my BS anytime and actually TRY the 12AU in place of a 12AX7 any time you want. No harm to the amp at all. Let your ears be the judge. P.S. if the ARE talking about older pre 1980 tubes 12ax7a is a more audio friendly version of a 12ax7. The filament (the part that get the tube hot) runs cooler and quieter than the original 12ax7. So if you HAD to choose.. put the 12ax7a in the LBH and the ax7 in the lower-gain champ. EDIT: In response to KEB. Preamp tubes dont wear out to the extent of power tubes so they may very well be good. I have the original 73 Blackburn 12ax7s in my Traynor YGM4 and they sound great even though they are pushing 40. I have older tubes than that in some of my other Fenders and they are holding up fine. If they arent weak or microphonic they are probably fine. Link to comment Share on other sites More sharing options...
K.E.B.1281734147 Posted January 9, 2010 Share Posted January 9, 2010 EDIT: In response to KEB. Preamp tubes dont wear out to the extent of power tubes so they may very well be good. I have the original 73 Blackburn 12ax7s in my Traynor YGM4 and they sound great even though they are pushing 40. I have older tubes than that in some of my other Fenders and they are holding up fine. If they arent weak or microphonic they are probably fine. That's absolutely correct. Wasn't thinking. Power tubes are the ones that wear out soonest. My mind has a tendency to wander off at times, and I'm only 45! Link to comment Share on other sites More sharing options...
ken361 Posted January 10, 2010 Share Posted January 10, 2010 hey guys' date=' i found a bunch of old tubes in some old record players and radios layin around my parents house, several preamp tubes I have a question about, I have two little 5 watt tube amps, Blackheart Lil Giant, and Fender Champ 600, one has EL84 power tube, the other has 6v6 gt I have found these tubes 12AX7 12AX7A 12AU7A what is the difference in these, and which ones would match better with those two different power tubes? thanks guys![/quote'] try to some pics plz, I would try one of the 12ax7's in your amp because the older tubes sound better then the new production ones Link to comment Share on other sites More sharing options...
MaxHart85231281734137 Posted January 11, 2010 Author Share Posted January 11, 2010 SUPER SONIC AWESOMENESS.. so i took the advice from Sambooka...and I cant say that i am more please, the 12ax7a is way better than the mesa 12ax7 I had in the blackheart, and the old rca 12ax7 i put in the champ really gives it a killer tone, I also tried out the 12au7a in both amps, and like yall said it realllllly kills the volume, and gain, but I can see where having one to swap in and out for just that specific clean tone, truthfully, if it didnt rob the Champ 600 of so much vol and gain, I would have left it in there, it makes that amp sound suuuper clean really nice actually, and with the little 6 inc speaker in there the lower gain tubes sounds better thanks guys! ill try to post some pics soon Link to comment Share on other sites More sharing options...
SamBooka Posted January 11, 2010 Share Posted January 11, 2010 Good point about the not driving the 6in speaker. Lots of guys find that is the weakest link (although I hear they arent bad one broken in, they are still 6in speakers). Have fun Drew Link to comment Share on other sites More sharing options...
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