Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: knotscott on October 16, 2010, 12:47:16 pm

Title: Which 12AX7?
Post by: knotscott on October 16, 2010, 12:47:16 pm

Hi gang - I've got a number of 12AX7s and am looking for opinions about their sound signatures, favorites, problems, etc, ...anything you'd care to comment on any that you've tried or read about is appreciated.  The near term plan is to put a couple in an 18 Watt Stout, but also have an Champ type with a 6L6.  I've also got a tube stereo system with a Lazarus Cascade Basic preamp that takes (4) 12ax7s...it's sounding good with a set of Nationals in it now, but I'm less certain about what sounds best in a guitar amp.  Most of these are used, test strong, but some may be NOS too...hard to tell. 

Heath by Mullard (Great Britain)
Motorola (Great Britain)
National (Yugoslavia)
Dynaco
Tungsram (Hungary)
RCA
Sovtek
GE

As always TIA!  You guys have been a great source of info and guidance!

Title: Re: Which 12AX7?
Post by: Fresh_Start on October 16, 2010, 02:19:30 pm

Use the SEARCH function.

Try each tube in your Champ-esque amp.  IMHO that's the best tube tester there is, at least for the important stuff like tone.  Besides, I doubt anyone can guess what most of your tubes will sound like.  Also, you would have to be more specific like which RCA 12AX7, which Sovtek (although I'm not a fan of any of them personally), etc.

Not trying to be a party pooper,

Chip

Title: Re: Which 12AX7?
Post by: knotscott on October 16, 2010, 03:15:17 pm

Thanks Chip.  That makes sense....probably lots of variability from tube to tube, not to mention various eras. 

I did try the search function and found lots of comments about Sovtek, EH, JJ, etc. , but not much on most those I have. 

Title: Re: Which 12AX7?
Post by: zendragon63 on October 16, 2010, 03:33:09 pm

Wow--a 12AX7--the gammet on this one ranges from utility to cork sniffing. FWIW--I have tried genuine Mullards that didn't sound as good in one amp as an RCA I pulled out of a Baldwin organ. And noticable dark, bright or sweetness in Sovteks that are supposed to be the same. I have read that the best amp builders take the time selecting/rolling tubes for each stage. There might even be a standardized technique or process for it so maybe one of the pros here can chime in.

It looks like have a variety of good brands to option with so party pooper Chip really has the best advice--your ears and the amp you will use will yield the best tube choice. Regards

dennis