• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Best 12ax7 tubes

Liam Wald

Liam Wald

May 17, 2011
3,489
4,375
California Coast
#1
I need to replace the 12ax7 tube in my SWR 350x amp.
There are numerous manufacturers and a few different types of 12ax7... 12ax7-s, 12ax7-c, 12ax7-a, etc.

I am confused. Does anyone have an opinion as to the best choice?
I play Jazz, Blues, and Classic Rock.

PS; I recently bought an Avatar TB153 and I am really stoked with the sound.
Thanks.
 
#6
I rolled a number of different tubes in my SM400 (including some expensive German tubes) and there was very little if any difference in tone. You want durable and low microphonics. The original Groove Tube my amp came with still tests good as well!
 
  • Like
Reactions: Al Kraft and ahc
#8
i prefer NOS RCA and GE 12ax7a tubes . they will cost a bit
more than modern chinese/russian varieties , but IME, last
at least 3x as long as their modern counterparts and sound
better than most . Sylvania 12ax7's are sleepers, and can
often be had for the price of a new chinese GT or EH
"premium" chinese made tube.

NOS telefunkens ,amperex and mullards are overkill for
bass guitar + cost too much........leave them for the HiFi nuts and guitar heroes .


if the tube resides in gear which sits atop a bass speaker cab,
it can become microphonic and sound like crap. there are
some tubes with heavy-duty construction (like the JAN 5751tubes , 6881 , and some which come in metal cans ) which are somewhat more resistant to vibration .
 
  • Like
Reactions: primusfan1989
#9
Yes, Sylvania 'butterfly plates' are sleepers. I've had great luck with used tubes, Ham radio swap meets are a good place to shop. Use your local dex search for Organ repair shops, those can be great for buying good used tubes.
 
#10
Floyd Eye said:
This amp has only one tube and it's in the preamp. I don't think it makes a difference what tube you put in it, I doubt you will hear much difference.
Click to expand...

I'd always thought the same thing...until several years ago when I swapped a bunch of 12AX7 tubes in a little beginner's guitar amp from the 60s. (A very simple circuit similar to a Fender Champ: a 12AX7 preamp/driver, a rectifier tube, and a 6V6 power tube).

I was absolutely amazed at the tonal differences between preamp tubes from different manufacturers and years. (I used a better speaker cab than the built-in driver.) I no longer remember which tubes sounded better/worse, but some were ice pick bright, some dull, and others very full sounding.

Not sure how obvious the differences would be in more complex designs, but it sure was obvious in that simple circuit.
 
#12
If you spend enough time tube swapping with a vriety of different amps as well as different tubes; especially Telefunken, Mullard, and Amperex vs. any of the Chinese tubes you will find:
* Some amps (like SWR and SVT 3Pro) do not sound very different no matter what the tube
* Some amps like the Mesa WA are highly sensitive and spending $40 for a used Tele is a bargain
IMO/IME
 
#13
That depends. What purpose is the 12ax7 serving? Vintage or modern amp? Full tube amp? Tube pre-amp? Single tube in a hybrid?

Given the other thread you started asking this where you mention an SWR-350, I'd say just buy any old 12ax7 that's been tested for low noise. You could try a sovtek 12ax7LPS, they're a short plate tube designed to sound like a long plate without microphonics issues. JJ and sovtek/eh make good stuff, read some reviews and find one known for reliability and durability, that's what will serve you the best in that amp.

The flip side is that 12ax7s are cheap. Buy a bunch of modern production ones and do some tube rolling and find the one best for that amp. Newer amps like this are designed around new production, easily available tubes, so that may end up being your best option.
 
#15
wcriley said:
I'd always thought the same thing...until several years ago when I swapped a bunch of 12AX7 tubes in a little beginner's guitar amp from the 60s. (A very simple circuit similar to a Fender Champ: a 12AX7 preamp/driver, a rectifier tube, and a 6V6 power tube).

I was absolutely amazed at the tonal differences between preamp tubes from different manufacturers and years. (I used a better speaker cab than the built-in driver.) I no longer remember which tubes sounded better/worse, but some were ice pick bright, some dull, and others very full sounding.

Not sure how obvious the differences would be in more complex designs, but it sure was obvious in that simple circuit.
Click to expand...




There is a huge difference in an actual tube amp. My '61 Fender Brown Deluxe has 3 12AX7s in the preamp and I roll around NOS Mullards, Bugle Boys, Telefunkens etc. all the time depending on what sound I'm after.

My point was that a solid state bass amp with a single 12ax7 in the pre is NOT a tube amp, will never sound like a tube amp and the tube you put in it will make very little difference ( if any) in tone. So you might as well just put a Sovtek or GT in it. I would never dream of putting either of those tubes in a vintage tube amp though.
 
#16
coreyfyfe said:
The flip side is that 12ax7s are cheap. ...
Click to expand...




Some are.I was looking for a spare for my shuttle...So as I'm checkin some random sites, I found everything from 9$..to several hundred $.:eek:...for 1 tube.

For 1 tube...that I hear people saying won't make a lick of difference (that u can hear).
Im just sayin, thers quite a range of prices out there for a 12ax7


Also, as far as Ruby, I saw someone here said that Ruby is the replacement for my shuttle..(It was about 16$ I think)..then again, there are some names that just sound cool. ;)


Anyway, Maybe I get too much of my info here on TB;)


Good luck on the quest..and I'll vote for ruby if that's whats in my shuttle.:bassist:
 
#18
Bassdirty said:
Some are.I was looking for a spare for my shuttle...So as I'm checkin some random sites, I found everything from 9$..to several hundred $.:eek:...for 1 tube.
Click to expand...

Guess I should have qualified that with most new production ;). Some NOS/vintage tubes can get up there, and some people like to charge a boat load for treated/tested/gold-pin tubes but they're really the outliers.

As far as ruby, just save yourself the trouble and buy a few of the chinese tubes directly. Ruby, GT, as well as a host of others just buy tubes, test them for their specs, and rebrand them with their own names. If you buy from a reputable seller who tests and in the case of power tubes matches tubes then there is no need to buy ruby or GT ever.

For reference, here is a list of GT tubes and what they really are. I only checked one set of prices, but tube store sells the JJ EL34 for $29/pair, sweetwater is selling the GT labeled pair of JJ EL34s for $53. Save your money.
http://thetubestore.com/groovetubes.html
 

Latest posts

Top Bottom
Back