Electro-Harmonix 12AX7 Preamp Vacuum Tube

18 Reviews

Availability: Usually ships within 24 hours.

USD $‎24.95

From our review of the Electro-Harmonix 12AX7 vacuum tube: "The EH-12AX7 preamp 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

Electro-Harmonix 12AX7 | One of the best values


I like these EH-2AX7's... they have strong gain and good tone. I find these Electro-Harmonix tubes to have much of the same characteristics of the Tung-Sol, in a more affordable price. I use these in many of my new amp builds.

Electro-Harmonix 12AX7 | Microphonic in 1 month


I replaced the tubes in my amp with these EH-12AX7 they are what came in it new and had no problem for years now 1 tube has gone microphonic in just a month i hope it was just a bad one time will tell has me wondering if i should have went with a different brand.

Excellent distortion tube


Use it in my old Peavey Classic 30 on drive chanel along with Tung Sol on clean chanel. Sounds sooo much better than JJ on Peavey. Oh and use EH in power section as well.

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 👍

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.