Electro-Harmonix 12AX7EH Tube

The 12ax7EH tube sounds great. I replaced my stock (Sovtek 12ax7WA) preamp tube with the Electro-Harmonix tube and now my amp sounds better than ever. The clean channel is fuller and more rounded while the dirty channel is smoother and creamier than before. Both channels seem much more defined with the EH tube as well, and with none of the harshness that the stock tube offered.

Great tube and such an easy and inexpensive way to improve an amps sound. I'll buy one again for sure.

nice black boxes.... well constructed. Even have nice yellow printed logo.

I've used in an Electar tube 30 with a celestion vintage 30 speaker. Almost zero noise in the clean channel, strong mid tones with a Epiphone les paul, high sustain, perfect for blues/jazz. the distortion channel is very peculiar: "Big Muff like" with minimum gain and "jcm800 like" in the top gain. In general, the sound has strong attack in the mids and defined tone in highs.

I know almost nothing about tubes, but i've tasted so many amps...... I think 12ax7eh are perfect for cheap tube amps.

don't know... i am in Mexico

If you don't want to sound like heavy metal or glam/hard rock, you will like this peculiar distortion

FYI: These are NOT Sovteks! Yes they are manufactured by Sovtek but they are made to completely different specs. Put the Sovteks and EH's in identicle amps side by side and you will hear a marked difference. Oh, and if that doesn't work (i.e. you're tone deaf), you can always compare them visually and see that they are two completely different tubes.

The EH tubes are all Sovteks! New Sensor.

I will be changing back to JJ/Tesla tubes from now on.

The EH/Sovtek tubes are nice for high gain Shredding type
set-ups. I never really noticed until a recent recording session
with the same amp that used to have JJ's in it. The EH's cut thru
nice, but really didn't find a place in the mix. By the way we only
record with 2" tape at Real Recording Studios.

I play a LP, Tele 72 Deluxe & 335. All with Humbuckers.

They do last & I'll keep my old ones for spares.

Really not any support from EH/New Sensor.

They're OK to dealk with.

I've been playing a long, long time & know good tone, even great tone.
Again, these tubes would be very nice for Metal & other High-Gain
applications. I was pushed to purchase these tubes by one of the online
tube vendors that said the "New" EH tubes were the best bang for the buck. I disagree 100%. There's nothing New Old Stock sounding about the New EH tubes, especially the 12AX7's.

If you want something warmer & clearer, try something else.

These are Sovteks!!!! Maybe this EH spoof will backfire on New Sensor.

Its a tube what kind of features do you want?

Very nice and clear. Very nice at high gain settings. I put this in my rocktron silver dragon to replace the stock chinese tube because it was kind of grainy.This tube definately smoothed it out, VERY low microphonics.Has a LOT of gain.I am gonna put this in my Marshall AVT150H.
Pretty midrangey with peaks in treble, so perfect for my music.(Heavy Metal,Thrash Metal, Alternative, Alt-punk, Old school punk.)

Tubes are like lightbulbs, you never know for sure when they're gonna die.So have extras with you, escpecially at gigs.

I have Electro-Harmonix pedals, they are high quality,and so are their tubes, so i have no need for their customer support.

For $8, these are the best sounding preamp tubes I have ever tried.(stock chinese,stock russian,Groove Tubes 12AX7- Mullard reissue,12AX7EH.)

..spiral filament...

This tube came stock in my Peavey Classic 30, 1x12 combo amp, in the first & second postion. Hmm, good bass... what stands out about this tube is it's upper midrange/treble peak. Makes my humbuckers sound slightly coil-tapped or transparent. Great if you use a lot of harmonics. On the clean channel, it yields a glassy Fender tone.

When pushed, the tube has the classic Sovtek buzzy top with lots of gain.

No problems after 9 months. Maintained the same frequency curve; still very quiet.

Nice overdrive with good compression. It's a little brighter than the Sovtek LPS, and twice as bright as the JJ Electronic ECC83S.

If your amp sounds a little too dark, these tubes should clear things up. The JJ is tighter and warmer, so I'll give this 12AX7EH a six.

Er... it's a valve, and it works.

I have this tube in my Ashdown ABM500 head (bass amp.) I haven't tried any other tubes yet in fear of losing the sound that I think this valve gives me. The amp's a hybrid amp, and it has one 12AX7eh in the pre-amp stage. This is blendable with a solid state preamp. Without the tube, my amp is rather bass heavy, but when u dial in some of the valve, the mids and treble increase considerably, giving me a warm, yet punchy tone.

No probs so far. I'll replace next year (these tubes are rather cheap)

Never had to deal with them. Don't like the sound of EHX support from the stories I've heard...

I use the valve when playing anything rock-ish, or retro (for stereotypical SVT sound) I leave this on in the preamp stage most of the time, just to warm my tone up a bit. Personally, I can't see myself using anything else at the moment, as these tubes do wat they say on the tin, and are fairly cheap. I might try out a GT 12ax7 tube one day...

This is a two channel tube with seperate eq for each channel and a footswitch.LOL Its a tube what kinna features ya want??

These 12ax7EH tubes(4 of um)went into my Marshall SL-X head,replacing the stock svetlanas.When I got the amp back it definetly had way more mids.My mids went from 4.2 to about 2.7 on the dial.The overall tone is great though.The gain seems more smooth that the stock tubes,more classic Marshall.I bought them cause a reviewer said they had similar sound to old telefunken tubes and I was looking to get away from the "new" buzzy Marshall tone and looking for the old smooth Marshall tone(if that made any sence).The overall tone of the amp has improved seems just more smooth than befor,more AC/DC type Marshall than befor.When I first installed them though there was ticks for the first few hours,but these have stopped coming through the speakers since,maybe they just need to breakin??

Been in for a month no problems so far.

Dunno

Very good tone,low noise not microphonic.I just used this amp to record in the studio last night with the volume on 9.5 and these tubes were sweet real quiet and great tone.No rattles or nothin like that evan with the amp cranked sitting ontop of the 4x12.I also have the EL34EHs in this amp and they seem to sound great(especially with the amp cranked gettin um glowing)As far as I'm concerned I'd like tyo have a few Mullard's but for that price I'll pass these EH tubes are good enough and at $10ea I can replace um all day long.

Standard 12AX7 tube, apparently quite low noise. As many features as a tube should have. Low, low microphonics as well.

I bought this tube as a replacement for my stock Marshall AVT-20 tube because it was kinda grainy and the 12AX7EH smoothed it out, adding more "bell like" tone to the clean and a smoother distortion on the OD channel. The problem is this: I seem to have lost a good three notches of gain on this tube, which means I've lost a good amount of my amp's capability. Also, the amount of bass seems to be reduced with a more even tonal curve (slightly less highs too, mids are very pronounced when turned up on amp now). I'm not sure if I like it yet (more gain may be needed, I'm gonna switch it back and see)

two days in it's still good, I'd assume so

never tried.

We'll see, I'm not sure yet, but it did clean up my amp like never before :D

All brands of 12AX7 tubes have the same features: 9 pins that allow you to plug it into a 9-pin socket. Therefore nothing to rate on features. I am submitting this review since I am an electronic technician and wish to clear up a few things brought up in the other reviews.

Go to www.watfordvalves.com for the latest comparative reviews of currently available 12AX7 tubes. The European designation is ECC83 for this "valve". Something like a Telefunken or Mullard NOS tube/valve of the finest type would rate a 10. Something like an RCA or GE NOS JAN surplus tube might rate a 9 or so. Some would only rate an 8. I know because I have a couple of NOS Mullard valves in my $1995 Conrad-Johnson audiophile preamp. Telefunken and Mullard NOS valves can easily pass the $100 mark and are worth it in some applications. Your average guitar amp ain't it. Eric Clapton's recording amp, etc., it would be OK. The E-H 12AX7 might rate a 9 in low microphonics, but just barely. In all other categories it would be 8 or less, which is extremely good for a tube that can be had in high quantity for around $10. I paid around $8 each for mine on sale. The gain is higher than the JJ/Tesla ECC83S (also sold by Ruby as the Ruby ECC83S), but usually not considered as good in distortion quality in high gain amps. But this is a judgement call, and some might like the harsher distortion of the 12AX7EH over the bluesier distortion of the JJ/Tesla ECC83S. Great sound for the money, but top guitarists in need of the best sound will still do better with the correct NOS American or western European types. The 12AX7EH is a shorter plate version of the famous Sovtek 12AX7LPS and delivers low microphonics due to the shortened plates and internal structures. It retains most of the sound qualities of it's stablemate.

Preamp tubes should last for thousands of hours, especially in separate amp head units that do not receive the shaking that combo amps receive. The best RCA, Telefunken, Mazda (French), or Mullard tubes would rate a 10, lesser western NOS types an 8 or 9 at the most. The 12AX7EH could be a 7 or 8 at the VERY most, which is still great for $10 each, compared to a $20-$200 NOS tube. This valve is known for very good reliability relative to other eastern European tubes and especially compared to Chinese tubes. I hear the latest 12AX7 Chinese tubes are much better, but the Tesla ECC83S, 12AX7EH, 12AX7LPS, and perhaps the EI ECC83 will easily outperform any Chinese tube I ever heard. The EI tube has a reputation for going microphonic, but my sample hasn't yet, and it delivers clearly better sound than the Ruby 12AX7 Chinese tube it replaced. At only $5 each from Angela Instruments for a shiny plate version, the EI ECC83 may be a better deal than the 12AX7EH, provided they have finally solved the microphonics problem. It is based on the very famous (and very expensive if you ever find it) Telefunken smooth plate ECC83. The eastern European tubes are in a state of rapid improvement right now. Sovtek and Tesla may soon have preamp tubes on par with our best NOS tubes, but they aren't quite there yet.

Buy some extra tubes and be your own customer support. At only $10 a pop (or less), there's no reason not to. If that is too much to ask, hunt down a solid state amp you can live with. Every musician using a tube amp should carry spares and be able to make the diagnosis and changeout when needed.

The 12AX7EH rates about an 8 overall because NOS valves like the GE 6072A/12AY7A are readily available in the $20 range, as well as the higher gain (almost as high as a 12AX7) GE 5751, which would rate a 9, relative to the very best RCA, Mullard, and Telefunken tubes. Don't forget that the new Sovtek 5751 is just a slightly lower gain 12AX7LPS that also has lower noise and microphonics. It might work even better than the 12AX7EH in amps plagued with microphonic tubes or tube hiss, or in need of a lower gain tube for smoother blues type distortion. 6072, 6201, 5751, 5814, 5965, 6189, ECC81, ECC82, ECC83, ECC803, ECC803S, 12AY7, 12AU7, 12AT7 and other types of NOS tubes can be used in place of a 12AX7. Many of these just have a lower gain than a 12AX7, which is good if you want to tone down a gain stage, and bad if you don't. Consult a good tube substitution manual, or look it up on the internet. I have seen a couple such sites before. None of the eastern European 12AX7 types have as much gain as western manufactured NOS 12AX7 types, to my knowledge, and are more similar to a 5751 in gain than a true 12AX7. Just something to consider when you are retubing. And even two tubes with the same type number can be different in other ways, such as if it is designed for DC heater operation only or AC/DC heater versatile. I have some NOS Philips 12AT7 tubes that are high quality, but must be used with DC heater supply or they hum like crazy. 12AX7/ECC83, 5751, 12AT7/ECC81, 12AY7/6072, 12AU7/ECC82/6189/5814 is the order of gain from highest to lowest. Again, consult a substitution manual if you are not familiar with these tubes. I would OK any substitutions with my amp manufacturer if it was expensive and I wanted to maintain my warranty. A blown tube can sometimes take out the next stage. I have a cheap Kustom Tube 12 practice amp for testing preamp tubes for microphonics, and it has AC heaters that reveals any tube sensitive to AC heater hum. The Electro-Harmonix is among the very best of the current production 12AX7 tubes, especially for amps plagued with microphonic tubes. Just don't expect it to perform like a Telefunken ECC803S or high end Mullard.