Any reputable NOS Mullard EL34 dealers in Europe?

[Gtr0]

Hi Folks.

You may, or may not, have read about this 1969 Laney amp in the mods/repair section... I guess it's a supergroup (?? the amp actually has no indication of a model reference at all - I assume it is a LA60BL)... well it had been quiet for a few decades judging by the condition being in extremely clean condition. After a successful change of the filter caps I went on my merry way just jamming away.

But now I am absolutely bummed....

I decided to swap out the 51 year old Mullard EL34 and Mullare/Brimar pre amp tubes and put in a newer production set - I was afraid that if I lost those old tubes to valve-death then - well, I might as well change them now and get used to it.

I tried several brands of modern production tubes and settled on a set of Harma Retros... I think they are Tung-Sol - at least they look like them - but no matter which modern tube brand I try, the amp sounds harsh and over-distorted.

I never used a set of tubes THIS old before (at least not older than 15 or so years old) - but these tubes have some SERIOUS f*&king magic that once is heard can't be unheard... ESPECIALLY in an old lower gain amp like this. It's not like there is gobs of gain/distortion to help cover up the ridiculous tone I am getting now.

I just can't live with it. I need to get the same tubes that are in there - the power tubes are unmarked, but my internet search and comparisons of photos point to them being Mullard - the ones with the several welds up along the plates. They also have two getters, halo, almost stacked on top of each other.

Anyway, I am not afraid to pay good money for them, but I am afraid of getting ripped off - so if any one with this type of experience has any clues - I sure would love to read them :-)

BTW in trying new tubes I tried various sets/brands of pre and power - so the closest I came was using the old pre tubes and changing out the power tubes - but the tone was still a bit F'ed in the A :-(

As always, thank you guys!!!

[Leo_Gnardo]

Did you set bias properly for the new output tubes you tried? Even if you manage to score a set of $$$$ real (not currently made fake Russian) Mullards, bias must be measured and set appropriately.

There's another thing about brand new tubes - even with the bias set properly - they tend to sound bright and razor sharp initially. Takes a while to settle down, anywhere from 10 to 200 hours, depending. Hi fi nuts have noticed this ever since way back when. Some prefer the new extra-present tone - and discard their tubes when they start to mellow out. Others let their amps run a hundred or more hours until they settle down to what's supposed to be tube-like mellowness.

One example in the rock world. Early 90's, self-pronounced "world's greatest musician ever" Yngwie used to demand a brand new set of GE 6550A output tubes in each of his hundred watt Marshalls for every show. Smart local stagehands used to fish a dozen barely used GE 6550A out of the rubbish bin before soundcheck every afternoon before an Yngwie show. I wonder if he still makes this demand, and can afford to have it carried out. Last I saw, authentic GE 6550A's were trading upwards of a hundred bucks apiece. Well, ya know, anything to get the sound...

[Gtr0]

I will double check - I checked the first set I replaced the originals with - a bit on the high side but I let it go just for a 10 minute play through - this amp doesn't have a bias adjust pot in it. Then I just kept my eye on them for misbehavior. I suppose it isn't a fair shot without as best of a bias as possible.

I'll give it a go.

But the preamp tubes were wildly different in this amp - some good old fashioned Sovtek LPS were super bassy and added a lot of distortion - I suppose most people wouldn't mind and in a newer higher gain amp I certainly would want that (which is why I had them on hand ;-) ) - but in this amp it is just too much.

Thanks!!

[Chuck H]

JMHO, but...

For preamp tubes the first one needs to be "right". That could mean a new manufactured tube that happens to sound good or an old Mullard/BB/Telefunken/RCA/etc. After that you can almost always get away with any decent current production tubes for the rest of the preamp. For power tubes I think Leo is right. There can be a burn in time. This is usually the amount of time it takes your ears to acclimate to the slightly different tone Probably the most el34 authentic sounding brand currently made is (believe it or not) the Ruby el34B made by the Shuguang folks in China. Marshall guys like them a lot. In my own experience they are very often too microphonic for use in combo amps, but are just fine for heads. That said...

The old Mullards have a distinctive and thick midrange quality to their overdriven sound. I think all the el34's have reasonable highs and lows, but it's that mid band in the Mullards that balances things so the tone is thick, but still dynamic. I won't promise that the Ruby el34B will do exactly that, but it might be a lot closer than what you've tried. And if you're willing to drop the coin for NOS Mullards I think you could at least try the Ruby's without adding much percentage wise to the cost.

[Leo_Gnardo]

Something else to consider: if the preamp tubes that were in the Laney were good, why not leave them in place. One less major factor in trying to recreate the tone with a fresh set of outputs. When you change everything at once, it leads to confusion. When you change only one thing at a time, you know whether it resulted in an audible change for better or worse, and you can easily back up one step when it doesn't work out well.

[nickb]

It has to be said, but 50 year old tubes are likely worn and so low in gain and that may be the true reason for the tone that you like so much. You'd need to measure them to find out. If the bias current is way low that's usually a good indication of poor condition.

[g1]

I'd agree with Nick. If all the new tubes sound 'over-distorted', you can't rule out that the old tubes might just be weak.
In this particular case it may just be that weak sounds 'good'. This may be one of those cases where a tube tester would be handy.

[Chuck H]

Something else to consider: if the preamp tubes that were in the Laney were good, why not leave them in place. One less major factor in trying to recreate the tone with a fresh set of outputs. When you change everything at once, it leads to confusion. When you change only one thing at a time, you know whether it resulted in an audible change for better or worse, and you can easily back up one step when it doesn't work out well.

At least the first preamp tube. Hell, the amp that turned out to be my most popular model (don't over read that ) was designed with regular current production tubes. Right now I have an NOS Mullard 12ax7 in V1 for my personal amp which is the prototype

[Gtr0]

Tubes are DEFINITELY worn - when I changed the power tubes to new production, the volume jumped about 4 or 5 db - or rather I had to turn down the preamp by -5 db to get a rough volume match in pro tools. And the various sets of tubes I did try weren't entirely brand new - since I have several amps, and always building amps as well, I often swap around tubes to see which tube sounds best with any particular amp. The tubes I have tried have anything from 5 or so hours to being well worn in for sure.

Well, to be honest anytime I have ever heard a new(er) production vs NOS tube shootout I wasn't "$300+ impressed" - but apparently, on this amp in particular, I just happen to like the worn out tube sound.

So I am gonna slap in some new production tubes, proper bias - changing or paralleling resistors if I have to and go from there. I certainly don't want to have to buy NOS, and I certainly don't want to get used to that particular habit if I can avoid it!

[Chuck H]

Well, to be honest anytime I have ever heard a new(er) production vs NOS tube shootout I wasn't "$300+ impressed" - but apparently, on this amp in particular, I just happen to like the worn out tube sound.

Ok, well, I guess the good news is that Mullards, in and of themselves, aren't the magic dust. It's the worn tubes. Because NOS Mullards won't sound like worn out Mullards. So now the question is how to make the amp behave more like it has worn tubes but with minimal circuit changes.


EDIT: I'd probably start with a lower gain tube in V1. Try a 12ay7. If that's not quite enough gain try a 5751. Then a fairly hot bias on the power tubes.

[Mick Bailey]

I like the Shuguang EL34B and Marshall rebrands these for OEM fitting to new amps, though they are the TAD version (EL34B-STR). As far as I've been able to determine by dissection, measurement and observation the only difference between the TAD and regular Shuguang tubes it the glass envelope thickness. I posted here somewhere about the weight difference and electrode similarity. The TAD version is a lot less microphonic and when biased on the cool side lasts a long time.

[nickb]

Tubes are DEFINITELY worn - when I changed the power tubes to new production, the volume jumped about 4 or 5 db - or rather I had to turn down the preamp by -5 db to get a rough volume match in pro tools. And the various sets of tubes I did try weren't entirely brand new - since I have several amps, and always building amps as well, I often swap around tubes to see which tube sounds best with any particular amp. The tubes I have tried have anything from 5 or so hours to being well worn in for sure.

Well, to be honest anytime I have ever heard a new(er) production vs NOS tube shootout I wasn't "$300+ impressed" - but apparently, on this amp in particular, I just happen to like the worn out tube sound.

So I am gonna slap in some new production tubes, proper bias - changing or paralleling resistors if I have to and go from there. I certainly don't want to have to buy NOS, and I certainly don't want to get used to that particular habit if I can avoid it!

Just thowing this out there. I haven't tried it but you should be able to make new tubes sound close to worn ones by adding a small amount of resistance in the cathode. The thing that happens is 'cathode interface resistance' increases with age so putting an external resistor on a new tube should do the same thing, more or less. A cheap and easy experiment. For a WAG try something around 33 ohms 2W ( changed from 1W to be conservative).

I think the big difference between current production and classic era production is one of quality rather than sonic attributes.

[Gtr0]

Ok, well, I guess the good news is that Mullards, in and of themselves, aren't the magic dust. It's the worn tubes. Because NOS Mullards won't sound like worn out Mullards. So now the question is how to make the amp behave more like it has worn tubes but with minimal circuit changes.


EDIT: I'd probably start with a lower gain tube in V1. Try a 12ay7. If that's not quite enough gain try a 5751. Then a fairly hot bias on the power tubes.

I thought a similar thing on the preamp - I have one of those green GE 5751s from who knows when trolling around here somewhere. And yes, perhaps a little warmer than usual bias as well. I have also cleaned up some amps by replacing the 470ohm cathode resistor on the PI with a 1k as per Merlin's book.

I like the Shuguang EL34B and Marshall rebrands these for OEM fitting to new amps, though they are the TAD version (EL34B-STR). As far as I've been able to determine by dissection, measurement and observation the only difference between the TAD and regular Shuguang tubes it the glass envelope thickness. I posted here somewhere about the weight difference and electrode similarity. The TAD version is a lot less microphonic and when biased on the cool side lasts a long time.

I have a pair of those and haven't tried them in this amp yet - they spent their "break in" time in a superlead, so they have several hours on them... I'll give 'em a try.

Just thowing this out there. I haven't tried it but you should be able to make new tubes sound close to worn ones by adding a small amount of resistance in the cathode. The thing that happens is 'cathode interface resistance' increases with age so putting an external resistor on a new tube should do the same thing, more or less. A cheap and easy experiment. For a WAG try something around 33 ohms 1W.

I think the big difference between current production and classic era production is one of quality rather than sonic attributes.

Interesting. Do you mean just cathode to ground?

[nickb]

Interesting. Do you mean just cathode to ground?

Yes.

[g1]

Also, I'd suggest putting it back how it was (old tubes) and swapping them out one at a time to see if there is one particular spot that is responsible for most of the difference, or if it's a little bit in each.
If it's just one particular spot, it makes things a lot easier in terms of having to source NOS.