Microphone tubes...advice?

  • Thread starter Thread starter beeson
  • Start date Start date
B

beeson

New member
Hi everybody,
I'm looking to replace a 6072a tube in a modified Apex 460. Does anyone know where I can find "selected" tubes for a decent price? I'm new to the tube biz :-) Thanks!
 
Speak with Brent Jessee. And also visit his site. That mic will handle any of the 12A*7 tubes. The 12AX7, 12AY7 (that's the one you have) and 12AT7. The 12AY7 is a funny animal, having never been made in Europe, there aren't that many good ones around. I recently replaced 12AY7 (aka 6072a) tubes in a pair of ADK CE mics. After trying many tubes, I eneded up using a matched pair of 12AT7 tubes (NOS GE 5 star 3 mica). They have more gain than the 12AY7 tubes, have much lower noise and sound great. Inexpensive too.

Here's Jessee's site:

http://www.audiotubes.com/
 
Ahh...I see. The stock tube was acutally a 12ax7 but had way to much gain. I spoke with Dave Thomas from Advanced Audio (great guy) and he explained how to modify the 460 with a 12ay7...I did go out and buy an Electro Harmonix 12at7 tube from the music store, but after reading all these posts I'm not sure if I should have bought a $15 tube. I'm only guessing that I should buy one that's higher quality and has been tested for microphonics and low noise? Thanks for the help!
 
beeson said:
Ahh...I see. The stock tube was acutally a 12ax7 but had way to much gain. I spoke with Dave Thomas from Advanced Audio (great guy) and he explained how to modify the 460 with a 12ay7...I did go out and buy an Electro Harmonix 12at7 tube from the music store, but after reading all these posts I'm not sure if I should have bought a $15 tube. I'm only guessing that I should buy one that's higher quality and has been tested for microphonics and low noise? Thanks for the help!
Click to expand...

The 12AT7 has a mu of 60, the 12AX7's mu is 100, the 12AY7's mu is 45 and the mu for the 12AU7 is 19. Those are relative gain specs, so the 12AX7 has the most gain and the 12AU7 the least. I think I paid $40 or $50 for a matched pair of 12AT7 (the ones I mentioned above) from Brent Jessee. There are plenty of relatively inexpensive tubes around. It's the 12AX7 tube that can get expensive, and that's not because it's a better tube, it's just in higher demand. Just make sure you get one with low noise and low microphonics. Internal matching is only needed if the mic in question uses both sides of the tube. Dunno if the Apex does or not.
 
Here's the deal...Big Kenny's got it right!...the GE 5-Star 6072/6072A would be your best bet (3-mica black plate if possible)...but, in an Apex/Nady/MXL mic (most use only one triode), I'd probably opt for the EH 6072A for $10...odds are, you'd never hear the difference between the $10 tube and the $50 vintage NOS GE (the only real difference would be in the audible microphonics/noise if any)...here's some links to help:

http://cgi.ebay.com/12AY7-6072A-12A...ryZ64629QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/6072A-12AY7-JAN...ryZ43375QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/6072-GE-Black-P...oryZ7275QQssPageNameZWD1VQQrdZ1QQcmdZViewItem
http://cgi.ebay.com/3-NIB-GE-6072-T...ryZ67816QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

...I've tried them all...12AT7, 12AX7, 12AU7, etc...the GE black-plate 5 Star 6072/12AY7 is the best of the bunch (for microphone applications)...but the EH 6072A for $10 is a sweet deal... ;)
 
Thanks alot guys. How come those mics only use one triode? What's the diff anyway? I kinda don't wanna buy a tube that hasn't been "selected" 'cause I'm upgrading other components (capsule, transformer, etc.). I wouldn't want the mic to suffer because of the tube....am I making sense? or does it even matter?
Thanks!
 
beeson said:
Thanks alot guys. How come those mics only use one triode? What's the diff anyway? I kinda don't wanna buy a tube that hasn't been "selected" 'cause I'm upgrading other components (capsule, transformer, etc.). I wouldn't want the mic to suffer because of the tube....am I making sense? or does it even matter?
Thanks!
Click to expand...


...some of the more expensive "Tube" designs utilize both triodes (one triode on the input and the other on the output circuit), but most of the cheaper Chinese mics use only one triode for output, I believe...therefore, the only "selected" variable you would want is "low microphonics" ...I would go with a GE 5-star 6072 in that case...if the tube you purchase exhibits any excessive microphonics (noise) than any reputable dealer will swap it out...but odds are the EH 6072A will do a fine job in that mic (IMHO)...
 
You must log in or register to reply here.
Back
Top