Electro Harmonix EL-84eh supposed to be mullard design?

[rjgtr]

Which is why I said "usually". And SED are also Russian...

Ouch, you got me! But they are not Sovteks (thankfully).

I'm very skeptical about what those "exclusive" tube designs really are, and if they're actually much at all like what they're supposed to be reproductions of. I see that you say the GT12AX7M catches "a little of the real Mullard magic",

I've compared them and the construction looks pretty much identical. Of course I haven't disected two tubes. The sound is similar, but I'd bet the real tone differences are caused by the quality of materials in the new tube.

but you're not so impressed with their EL34s.

It's a good sounding tube, but no better to my ears than a SED. So why pay the extra cash?

IMO it's partly a marketing ploy, but it's also a good way to get tubes that won't die within an amp's warranty period. After that, who cares.

Sure, get the poor sucker out of the warranty period!

I don't dislike GT, because they are in business offering a good product and service, but they ask a premium price for it. I choose not to pay that price and get the same thing elsewhere when I can.

[clyde]

Matched tubes are probably a good idea for amps overdriven and played hard. By this I mean current matching as it's far easier on the OPT if they are close. Wildly out-of-match tubes may lead to premature OPT failure
esp. if the OPT is somewhat under-spec'd. (Can you say Marshall?) I doubt that unmatched tubes will give more 2nd harmonics as these are cancelled out by the very nature of push-pull. What you may be hearing is one tube
clipping more than the other due to earlier saturation resulting in an unbalanced wave-form. As always, I stand to be corrected.

[zaphod_phil]

Wildly out-of-match tubes may lead to premature OPT failure
esp. if the OPT is somewhat under-spec'd. (Can you say Marshall?)

We would be talking *wildly* out, and in that case a lot of other things would also be going wrong too - eg loud hum and red-plating.

I doubt that unmatched tubes will give more 2nd harmonics as these are cancelled out by the very nature of push-pull.

They will get cancelled provided the power stage is well balanced. When the tubes aren't too closely matched the power stage loses some balance and more of those even harmonics get through. Furthermore, if the two sides of the PP pair have slightly different amplitudes, that in itself helps create more even order harmonic distortion.

What you may be hearing is one tube clipping more than the other due to earlier saturation resulting in an unbalanced wave-form.

You will get that happening as well, when the amp is getting cranked. However, the other forms of harmonic distortion will sweeten the sound of the amp, even when its apparently running clean.

[MartyM]

Here's what I used in my first little amp, an SE5-A :
GT ECC83S (Gold Series) and an EH -EL84.
The GT was £12 and the EL84 £8.95, so that's about 20 bucks and 16 bucks US.
They seem to sound great, nice tone but a little "fizzy" when the gain is
dimed - I'm liking it, but then again, I like that my first tube amp even
works !!

The build made my "9 opamp" JCM800 sim, seem VERY complicated !!
( but at least that was only a +9/-9 v circuit

MM.

[rjgtr]

Here's what I used in my first little amp, an SE5-A :
GT ECC83S (Gold Series) and an EH -EL84.
The GT was £12 and the EL84 £8.95, so that's about 20 bucks and 16 bucks US.
They seem to sound great, nice tone but a little "fizzy" when the gain is
dimed - I'm liking it, but then again, I like that my first tube amp even
works !!

The build made my "9 opamp" JCM800 sim, seem VERY complicated !!
( but at least that was only a +9/-9 v circuit

MM.

If I remember right the GT ECC83S is a JJ ECC83S which is actually a good sounding tube. If you like the tone that's all that matters.

[dotfret]

There are some Groove Tubes which are made in US, and are better than the "selected" mass - they do the best 6L6, and they have produced Fat Boys which are very like the old ones. you can't just generalise here, they are trying ... (ain't everybody?)
No-one can turn out an exact replica of the old stuff without breaching Health and Safety regulations. All the manufacturers are trying to get close to the Old Sound without damaging the workforce. We just have to wait and see who gets closest...