Groove Tubes GT-12AX7-M Mullard Reissue

OK Not really a review but a suggestion for the reliabilitie problems.
It might be a good idea to burn these in befor turning your amp to "play" mode.After installing them let your amp sit on standby for several hours(go mow the lawn or something)while they "cook".
Running just the heaters in the tubes(standby)will allow the hot getter to suck up any eccess gasses left by the manufacturing proccess.
This may at least help in allot of the failure issues.
I'm no tube builder or nothing but have bit of expieriance w/ tubes and have read allot about them.
good luck

I'm not surprised you guy's are disappointed with the performance of "New issue Mullard Tubes" Mullard only produced tubes in the UK.
I worked for Mullard from 1959 up to factory closure. We never transferred any of our equipment or technologies to these manufactures that are now producing very poor replicas of our tubes and copying the old Mullard Logo and box design.

for the price, I was disappointed with the sound I got from it. Not that it was terrible, it just didn't do anything special. I found the chinese tube (half the price ) and the tungsol 12ax7 are WAY better tubes.

It seems that there is a widespread reliability problem with this tube. Mine hasn't failed yet, but after a couple uses, it's HUGELY microphonic. It's getting worse and worse, it'll be useless soon

cheap, overpriced tube, not worth your money. This is the only GT tube Ive bought and It's the last one I'll ever buy. I'm gonna stick with the better and cheaper chinese and russian tubes.

Its a tube.

It is a 5 out of ten. nothing great. Not as good as some new tung sol 12ax7s I recently pruchased. The tung sols have more shimmer and grind the groove tube is just flat.

Its as reliable as the shipper and postman who kicks it down the street because it says fragile on the box.

They seem very nice.

Blues and rock 44 years. Lots of amps and stuff.

Just plug it in and hope for the best.

When you get one that works, it can really sound quite amazing. I have purchased 16 of these. Half cam from Lord Valve and the other half came from Torres Engineering. I consider each of these vendors to be very reputable. Each 12AX7M has been used in a tone generating pre-amp stage. Not one has been used for a phase inverter.

My experiece has been fairly consistent. Initially, most of my 12AX7Ms sounded excellent. The problem is that they lost their detail and presence very prematurely. After about 5 to 10 hours, they decayed into mediocrity and sounded like a SOVTEK 12AX7A (7025). For a relatively expensive tube, I expected the 12AX7M to be a good V1 tone generator. It typically delivered this in the short haul, but not in the long haul. I expected better and am definitely disappointed.

When working properly, the tone is a little on the dark side. That works great in a bright amp.

The degradation of tone speaks to poor quality materials and/or workmanship. But I have also experienced another related phenomenon. I was using one of these as a V1 tube in a little Epiphone Galaxie 25 that has been modified. About a year ago, someone on the forums mentioned his 12AX7M starting to give him a helicopter sounding effect. After about 5 hours of use, my V1 12AX7M started doing that. It does not happen when the amp is first turned on, but only after about 15 minutes of playing - once the amp starts to heat up. It is like the circuit is cutting in and out. At first, I thought my power tubes - some 1960 RCA EL84s - were going deep 6 on me. But I remembered the Harmony Central review. I replaced the 12AX7M with a JJ 803S and everything was fine.

I have my other 12AX7Ms in other amps. One is currently the V1 in a SUNN T50C. Others are in V1 and V2 in some CRATE VC 50H heads. These sound excellent.

Each 12AX7M in my collection has been tested for output and transconductance. The readings typically are O.K., though I have yet to test one that delivered transconductance and output at industry spec. But in fairness, neither have I ever tested one of these and had useless output levels or dismal transconductance readings.

Inconsistency is a problem. I would not use these live without having a back-up.

I appreciate that Groove Tubes has made a major financial commitment to get these (and other new tubes) out on the market. I shelled out good $ to buy their product. It became obvious pretty early in the game these were not the premium product they were sold as. But rather than deal candidly with their consumers, Groove Tube tried to talk a good game, as they had when marketing these. Like other consumers, I am not at all happy with how they have tried to sweep quality control problems under the rug. Having paid twice what Sovtek 12AX7LPS would have cost, I definitely feel I got burned by Groove Tubes. And like others who feel the same way, I will not be buying any more of their products. With my collection of more than 300 pre-amp tubes, I think I'll get by just fine with my JAN Philips and JAN GE tubes. Still, I give Groove Tubes some credit here because at least they responded.

I will not buy these again. Too inconsistent. The tube needs to sound good permanently, not just for the first five hours. For hours of bland, uninspired tone, I'll buy up cheap SOVTEK 12AX7As at $6.95 a piece. No need to give my money away and pay 4 times that amount to Groove Tubes to achieve the same mediocrity.

Sonically these work great in my Fender Deluxe Reverb Reissue. I put them in the V2 and V4 positions. Much better than the stock EH 12Ax7's. Once properly warmed up they produce a very enjoyable second harmonic when pushed hard. For clean they work just fine, again better than the EH's much more mellow and pleasing to the ear. They are a little darker than the EH's so if your amp is not overly bright they may not work.

Can't really compare them to the original Mullards, all I can do is use my ears and what I hear I like very much.

Like most others this is where thing fell apart for me. I originally purchased 2 at Long and McQuades - not cheap $26 each (I think they are $24 now). They lasted about 45 days, since GT has a 120 day warranty I returned them both to L&M - no problem they gave me two more no questions asked.
THen about 30 days later another one went - again I went back to L&M this time however they were out of stock but promised to get me another one, since I live quite far from the store they promised to mail me the new tube. They did and they didn't even ask for the old one back.

The new one has been in about 30 days and so far so good. My fingers are crossed. 3 out of 5 went bad not a good track record for anyone.

This is more for L&M

They were beyone great. No questions asked returns they didn't even check the tubes just took my word for it. Thats customer service and one of the resons that I keep going back to Long & McQuades.

Thanks L&M the Arts is closer but they have a thing or two to learn about customer service (Carl are you listening)

The tube are great but the lack of reliability will take away 4 points.

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Well, I love my one. Im noticing all the negative reviews on this page from people saying they dont work or fail etc. Maybe I just got lucky then, but mine is great. I have lots of other valves, some of which are NOS as well as some modern ones. This Mullard re-issue really makes ALL the others sound naff in comparison. I only bought one of these as a kind of 'test', but I'm going to buy two more to complete my valve lineup in my amp as I've found something I really like, ..and I don't say that often.

To hell with old original NOS Mullard valves on eBay and fighting it out with everyone else, and all that last minute bidding shit. What a mugs game... ;-]

Mine is fine so far. I suppose just make sure you buy it from somewhere where they let you return it if it fails (..so avoid eBay!)

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They make all my other valves I own sound boring and plain. I love this valve.

No rating needed--plug in where needed. That's it.

When they work.

When they work.

When they work.

See below.

Gave it a 2.

Why?

I have three in my Gibson Super Goldtone head in the Ch. 2 preamp section from the previous buyer. Sound so great, got some more to load the Channel 1, PI, and then load the front of my Germino Classic 45 (repro Marshall jtm-45 head).

What happened? The 12ax7m in PI position on the Gibson produces a periodic "heartbeat" light thumping noise from time to time. Took it out, replaced with a different tube, sound went away.

Even more telling, in the Germino at the onset of musical nirvana (as in, channels patched and cranked to the max), put in the GT's, scratchiness, popping,hissing like Madagascar Stink Beetles (got that from watching Fear Factor, I did). Very sad, because through the noise, I did hear what could have been musical nirvana.

Emailed Greg Germino regarding power tubes in the Classic 45. He said he's personally had to move away from Chinese KT66's because they are hit and miss, and loads his new Germino's with 6l6's. Looks like these preamp tubes have similar issues--when they work, they are worth a little extra, but unless QC is resolved on these things, it would be more COST EFFECTIVE to take a shot on getting real vintage tubes/NOS from a reputable tube reseller, because it darn well looks like I've got at least a 50% unusable factor to these things, plus the hassle of figuring out which are good and which are duds (I don't have a bench tester for tubes, you know). So, if it works out you have to throw one out of two away, that's $40-$50 to get a working tube that still might die later, you're better off looking for some kind of vintage tube that's made better.

Don't know, didn't keep the receipt, and the tubes are more than 30 days from purchase anyways, so I think I just write this off as a small loss. Sad, the Goldtone has some 12ax7m's that work fine, and I've swapped out for other tubes just to make sure the GT's sound best, and they do. Sparkle, life, breath, and a warmth and lack of harshness, all qualities of the original Mullards from most reports.

DO SOME BENCH TESTING ON THESE THINGS, GROOVE TUBES!!!!

Get these things to have the Quality Control they should have for being a premium new tube, and they should fly off the shelf. Like a lot of guys, I don't mind paying $5-$10 extra a tube if I hear better sound, and I know the tube's good quality. I have $$$ invested in my amps, axes, and studio gear, I wouldn't flinch over a little extra on the tube price. Shoot, get some QC on them and a real no-questions asked guarantee for a year, sell 'em for $30.

But poor quality is just poor quality.

Plug 'em in.
Sounds Great.
Then they die.

Sounds Great.
Then They Die!

Bought 3.
1 was bad right out of the $25 box, and was replaced.
Of the 3, 2 were noisy.
One sounded good for about 10 hours, then got noisy,
bassy, and died.

Groove Tubes is there to help you reach into your pocket.
They will replace bad tubes with bad tubes - no questions asked.
And they will never, ever, burden you with specs.

I'll never purchase a GT product again.
If I buy an amp that has GT's I will promptly
replace them with JJ's, EH's, Winged "C", and
give the difference in cost to a homeless person
instead of Mr Pittman and his cadre of lap-dogs.

This is an update to the positive review I posted below. I waited for two months to post my first review to be sure I had avoided the ?honeymoon? syndrome. In accordance with Murphy?s Law, about one week after I posted my glowing review below, two of them died on me. The replacement GT Mullards were bad as well, extremely noisy, so much for GT?s ?awesome test procedure? & QC that they charge up the ass for. In fact I had to go through three GT Mullards in the store before I found one that was ?good?.

So, yeah, they sound good when they work. Doesn?t do me any good if they up and die right after GT?s ?generous? warranty expires. Bottom line, no GT?s for me EVER AGAIN! New Sensor Tung Sol 12AX7s will be replacing this over-priced, Chinese junk. $25 a tube and this is the best they can do?? I took a chance on GT and got burned, what a rip-off! Screw you Aspen, you won?t be getting any more money from me.