Rickresource Rickenbacker Forum

Can anyone recommend a decent 12AX7 tube? I just switched out a couple of JJ Tesla's for two Electro-Harmonix , and while the EH tubes are definitely richer in tone, there's a ton of hum coming out of my amp now. (Tough to say if it's microphonic or just heater noise given the bedroom sound levels I'm currently playing at.) I'd love to find a 12AX7 that runs as quiet as the JJ's but sounds a little fuller. I'll drop big coin if I have to, but bargain basement suggestions are also welcome (of course).

I use one EH 12AX7 in my Cambridge 15 and am thinking about putting them in my new all tube Crate 1512. Pretty darn quiet for me.

Same here. I installed three EH's in my Mesa Boogie Buster Bass Combo amp after deciding that the Sovtek 12AX7's sent me by Mesa were not only too noisy, but also too microphonic.

So far so good with the EH's.

I'm sure there's quieter stuff out there, but these are "good enuff" for a bass amp in a loud rock/pop band.

If you can find NOS American tubes they are probably much better. What were those tubes in the pre amp section of Fenders? 7225's? They were an industrial version of the 12AX7, made especially for hifi's and places where you wouldn't want microphonics and noise. Old RCA tubes were great tubes very reliable, as were Mullards which probably had a superior sound, they were known as hifi tubes. Check on Ebay there are a lot of NOS tubes for sale at varying prices.

"They were an industrial version of the 12AX7, made especially for hifi's and places where you wouldn't want microphonics and noise."

Bob...they were/are 7025

My experience with the JJ tubes were just as good or better than EH tubes as far as quietness. The Ei tubes were once noisy, but they seem to have the problems solved now. Marshall uses them in the ValveState amps, I tried everything else I had, and stuck the Marshall Ei tube back in because it was the quietest and sounded darn good. You might want to try a Marshall dealer or just buy the latest version Ei ECC83. I have one in my Kustom Tube 12 and it really sweetened up the sound, which the amp needed as the Chinese Ruby tube sounded like bees in a jar when using distortion. Sovtek makes a 7025 and they are fairly quiet and dependable, but lacking a bit in sparkle to suit me. I think EH 12AX7 tubes are a bit aggressive in the upper midrange, if you like that character.

Thanks Dave, I thought of the correct number as I was walking home. Are they still better that a 12AX7?

Bob....the 7025 was a low noise version of the 12AX7. Generally considered better for our use in instrument amplifiers. The other guys are correct about noise or no noise and different sound quality from different mfgrs. I suggest that you guys cruise the amateur radio swap meets and just buy all the 12AX7 you can find regardless of the mfgr. Some will have the mfgr name rubbed off but the tube type is etched in the glass. Usually, these small preamp tubes (12AX7 & 7025 & ECC83)can be had for $1.00 or less. Then I test each tube in my amp for the sound I want....saves mucho $$$ and gets the same result without the voodoo bs.

I've tried 3 brands of 12AX7 tubes in the V1 and V2 stages of my '83 Marshall JCM 800 Super Bass head.

RCA 12AX7A: NOS in plain white boxes. Very quiet. Clean and even sounding with creamy harmonics which I think audiophile types love.

Electro-Harmonix 12AX7 EH: Came in the nice looking black boxes with the logo. Not as quiet as the RCA's but sure have the rock'n'roll attitude in the mid range. Rich upper harmonics.

Groove Tubes 12AX7: They suck big time! Boring sounding. No characters at all.

I switch between the RCA's and the EH's depending on my mood of the day.
I'll definitely try the JJ's someday.

My experience with the JJ and Ei preamp tubes is that I will give up looking for NOS tubes unless I run across bargain basement prices on them. I have a couple of NOS Amperex 12AX7A tubes that were given to me, and I found they were worth at least $100 per pair. They go in the C-J phono preamp when the GE tubes **** out. Groove Tubes is just marketing hype. JJ builds their tubes with Philips production tooling in the Czech Tesla factory, from what I have read. The build quality should equal that of just about any tube in history, except for very expensive milspec types that are basically purged from old defense stockpiles. The time to buy NOS tubes was back in the 80's. The 90's were dark days for tubeaholics on a budget. The eastern European factories are producing great product again at reasonable prices. The NOS you buy today is leftover dregs, for the most part, from earlier cherry picking dealers, unless exorbitant prices are paid, and that is still no guarante of quality from some dealers.

I have found the JJ Tesla 12AX7's to be excellent. Also the Tubestore has been a pleasure to deal with. Fast, courteous and their site provides a wealth of information.

I find Groove Tubes to be very misleading. Not only are they expensive but they are really just a tube-testing supplier of tubes made elsewhere.

I think different 12ax7 tubes will sound great in some amps, and sound not as good in others due to the different frequency responces of the different circuits in question. I've tried all kinds of tubes in my various amps, and the EI 12ax7's sound fabulous in my AC30. But on the other hand, my Mesa Dual Rectifier and Sovtek Mig 50H seem to like Chinese or Sovtek or EH tubes more so than EI, NOS or JJ. When I get an amp, I tend to experiment with different tube types until I decide which brand works best, and then stick with that for a given model amp. Hope that helps.

Chinese Ruby and E-H 12AX7 tubes are very high gain. Messy ******* are reputed to like the highest gain tubes. The AC30 likes the Ei tubes because of their superior upper harmonics, probably the best being produced today because they are a copy of the Telefunken long plates. The JJ ECC83S is a copy of the short plate Telefunken tube, thus the "S" at the end. The short plates are less microphonic, so they should work better in high gain amps. You should really try them all, but some people can't afford to do that. The Kustom Tube 12 makes a good cheap preamp tube testing amp (because it only uses 1 tube) after mods are carried out per reviews on Harmony Central. You only need 1 of each tube type to key in on the sonic signature. I haven't put DC on my heater yet, so my Tube 12 has a bit of hum at high gain.

My guitarist just put some NOS Phillips USA JAN preamp tubes in his Fender Twin (sorry, not sure whether or not those are 12AX7's), and MAN! does that amp sound better than I've ever heard it! (edit: And yes, verrrrry quiet.)

I have some NOS JAN Philips 12AT7WC tubes that I tried in my Tube 12, and they howl like a banshee on AC heaters. They might work well on DC heater circuits. Let the buyer beware!