Electro-Harmonix 12AX7

18 Reviews
Out of Stock
USD $‎37.95
From our review of this tube: "The EH-12AX7 tube has a nice balanced sound, a very low noise floor and excellent performance in terms of microphonics. The lack of microphonics may be due in part to the return of a shorter plate structure or better materials. I've had some samples that were tried in various amp stages. Pre-amps, tone stacks and phase inverters, a winner in every location...I have used the EH to successfully tame amps that defied all other attempts to kill microphonics and unwanted feedback. This tube is a winner, buy 'em and try 'em, they may be just the piece you've been looking for."

One other note about the construction of these Electro Harmonix 12AX7 tubes is they have filaments that are almost completely encased in the plate structure. They often don't "light up" when working properly. This is not a problem, it's normal for the 12AX7-EH.

Other Electro-Harmonix tubes12AX7 Types

Additional Information and Downloads

12AX7 Tube Review

Tube Matching Information:
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Electro-Harmonix 12AX7-EH Datasheet (PDF)

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Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Ratings & Reviews

18 reviews

We have a winner!


I was looking to replace the original Groove Tubes 12AX7 R3 in my Carvin BX500 head and was having no luck with about 3 other tubes I tried. Finally I put one of these Electro-Harmonix tubes in and wow! Powerful, punchy bass again!

Perfect For My Fender Super Champ!


I used this in my Fender Super Champ as a replacement for the original Groove Tubes 12AX7, and I'm delighted with the sound. I'm using it along with a matched pair of JJ 6V6S amplifier tubes, and the sound is much warmer and full-bodied. Much better lows. I like it so much, I just ordered a spare :-)

treble sensitivity


I have used a bunch of these eh 12ax7 tubes from time to time and recently tried them in a 65 twin reverb reissue. I realized that they can be a bit harsh in the treble on these already treble oriented amps. In my jcm900 dual reverb 100watt they sound amazing and is what they recommend as a premium upgrade for the preamp section. All in all they are an excellent and affordable replacement preamp tube but I would steer away from using them in bright fender-like amps, especially if you want to warm up the tone slightly.

Chuga chuga


So I put four balanced 12ax7’s two 6ca7’s and two 6l6gc all from EH in my Bugera 333xl infinium and HOLY CRAP!!! I play mainly hard rock/metal and I’ve never had more crunch and amazing cleans it’s not even the same amp anymore I was able to completely ditch my ts9 boost pedal it doesn’t even come close to needing it. Thank you EH for such awesome tubes.

Not good in cathode folllower


The sound is pretty good but don’t use them in cathode follower they will create arcing problems with those spiral filaments, otherwise this is a real great tube .
Awesome customer service and fast shipping 👍