buying NOS pre-amp tubes - a guide

[hamfist]

  I was going to comment on the other current pre-amp tube thread, but didn't want to hijack it so here goes !
 
  I never really understand why most of you guys put up with the poor modern tubes. Surely, us folks here, are here because we really care about how we sound. We want "the best" !  There are many mediocre old tubes around its true, but I have not met an amp yet (with 4 gain stages or less) that has not sounded better with quality old tubes in the pre-amp. I'm talking Mullards, RFT's, Tungsrams, Brimars etc.  I cannot talk of multi-gain stage amps, as I have never owned one.
  There's also the reliability factor. I have NEVER had an old pre-amp tube die on me - NEVER.
Yes, you can buy dud NOS tubes on ebay if you're unlucky, but I've bought most of my tubes on ebay and only once had a bad one (and it wasn't that bad, just very well used, and rather low output).
  I also have found buying vintage amps has been a great source of great old tubes. The last two old amps I bought contained 2 x Mullard, 1 x Brimar & 3 x RFT 12AX7's (all cracking tubes !), as well as 2 x Tesla EL34's (superb) and 2 x Mullard EL34's (admittedly almost dead !).

  I never actually buy old power tubes because they cost sooooo much, and I have never heard a huge tonal difference with modern power tubes. But pre-amp tubes  ... now that's a different matter. The very first thing I do with any new amp is to remove all the cr@ppy modern pre-amp tubes and replace with quality old glass.

  I have a theory that a lot of people don't use old pre-amp tubes because they don't feel confident about buying decent tubes, they think they will be ripped off. And it's true, one can be easily ripped off on ebay, especially if after Mullards. There are certainly a lot of fake Mullards around.

  What you need to do is to familiarise yourself with what the internals of a real I63 or I65 Mullard look like (great website - http://www.tubemongerlib.com/gallery2/main.php), and always, always get the seller to tell you the etched code on the glass, if it's a Mullard. Find out about the codes, and you can always get genuine "made in Blackburn" Mullards. A Mullard group company uses an etched code with the first three characters telling you the type of tube and the later 4 characters telling you where and when it was made.

eg. a proper made in Blackburn short plate Mullard 12ax7 starts with "I63" or "I65" (a slightly later version of the tube). The last 4 characters always start with a "B" followed by 3 characters which tell you the year, month and week of manufacture.  So the etched code reads something like  I63 BXXX

To my knowledge, there are not fakers out there faking the etched codes (yet !!).   You can get proper Mullards cheap if you buy using the codes, and not by what is printed on the tube. Loads of the tube manufacturers in the 60's and 70's bought tubes off Mullard when their own stocks were low and re-labelled them with their own brand. out of all my Mullards and RFT's , not one is actually labelled as a Mullard or an RFT, they all were bought from Mullard/RFT by other tube manufacturers and relabelled. BTW, RFT's don't have etched codes, but do have a very identifiable shape and internal structure.

  If you follow simple rules, stay well-informed, and always buy from sellers who test their tubes, and buy tubes which test as new, then you can get some great buys, even on ebay.  If the price is low enough, I'll even break my rules, but the price has to make the risk worthwhile.  The best buys are always the tubes which the seller doesn't really know what they've got, but you do !!!

Another point is that buying batches of tubes on ebay is always cheaper than getting pairs or singletons. I always reckon that if I don't want to spend any money at all, I'll buy a quad or sextet of Mullards on ebay, keep one or two of them, then sell the others offf again on the 'bay as single tubes. It's one way of almost getting tubes for cheap, or even for free !

  If you're not happy with the ebay route, then some great tubes can be had from folks selling on thegearpage.net or over at the Plexi Palace forum. These are fellow enthusiasts who will not sell you rubbish.
   There's also Tubetramp, over in the USA, who is basically a great player and a tube enthusiast/nut, as well as dealing NOS tubes. He sells a lot of tubes and always at much better prices than the mainstream tube dealers like KCA or Watford Valves.  Tube Tramp can be emailed at terry_kilgore2003@yahoo.com . I have bought from him and can thoroughly recommend him. He will discuss your needs with you, and your budget, and get you the best you can afford.

  The safest, and most expensive, route is always going to be the mainstream NOS tube outlets like WV and KCA. These are also great places to buy. The advice you get will be excellent, the tubes will be immaculately tested, and you will get some sort of warranty. The prices will also be high, so you take your choice.

BTW, never be afraid of buying from abroad. the prices are cheaper and tubes are so light that they are not expensive to send. Not once have I had a tube go astray either. There are also several guys in eastern Europe selling on ebay who have big stocks of old Eastern European tubes, like RFT's & Tungsrams. CHeck their feedback, and you will find the reliable sellers. For example, Waldemar-kos is currently selling pairs of RFT's on ebay at very reasonable prices. I have dealt with him before and he is a good guy.

[martinw]

 I never really understand why most of you guys put up with the poor modern tubes.............. but I have not met an amp yet (with 4 gain stages or less) that has not sounded better with quality old tubes in the pre-amp............. cr@ppy modern pre-amp tubes

I'm sorry Alan, but just to show that there's another side to the story, I'm going to have to disagree.
This is a very subjective area, and also one where there is a lot of mythology. Personally, I find certain modern VALVES to be crisper and brighter than the old Mullards, Brimars, Mazdas, GEC's and Ferranti's I've compared them with.

We've done an experiment using a Matamp 1224, where we made JJ's sound like Mullard's by reducing the gain of each stage a little, showing that the main difference was the level of gain produced in that case. Beyond that, the differences were indistinguishable.

I'm not saying you're wrong Alan, just that this is one of those areas where subjective opinion means that there is no better or worse, just different. There are some poor modern valves around, but there are also some very good ones. I've used literally thousands of JJ ECC83s (for example) over tha last couple of years, with very few failures, and those were immediately on power up. As for tone, all I would say is that I prefer them. The bottom line is that that is all anyone can say.

I'm an engineer, and I'm afraid I just don't believe things just because some one says so. Show me some data that proves Mullards are "better".  Let your ears be the judge. Sadly many people find this hard to do.

[MrBump]

Very interesting read.

I always thought that it was the power tubes that made the bulk of the difference (i.e. the EL34s that I have in my Orange).  I've never even thought about changing the pre amp tubes.  In fact, I'm not even sure what type of valve is in there...

Mark.

[gwEm]

i've never had problems buying new or old valves by post/ebay yet... indy though reckons hes been unlucky with the valves being damaged in the post. a 40 quid mullard being damaged is definately worse than a 8 quid JJ ;)

as martin says, you can design an amp circuit to make the best of the characteristics of a certain valve. however after doing some A-B tests with PhilKing JJ against various other valves i thought the difference was pretty clear sounding.

i use NOS valves and like them. NOS mullards are generally pretty overpriced i reckon, luckily i was donated some my a family friend. the difference when swapping with the JJs in my Marshall 2204 was pretty clear. some of that might have been down to gain as martin says - i reckon the mullards have a bit less. JJ tubes in my experience are great value for money, but a bit dark and a touch muddy in my amp. having a NOS mullard in V1 has made my amp alot better at handing high output pickups and pedals, probably they have less compression.

i agree that old valves are generally pretty reliable.

i'd love to A-B compare a NOS mullard with a New Sensor reissue. i have a feeling there may not be all that much difference.

[hamfist]

Very interesting read.

I always thought that it was the power tubes that made the bulk of the difference (i.e. the EL34s that I have in my Orange).  I've never even thought about changing the pre amp tubes.  In fact, I'm not even sure what type of valve is in there...

Mark.

In general, the pre-amp tubes are way more important at shaping your final tone, compared to the power tubes. The main exception to this is if you are actually running your amp into power tube break-up - but in all honesty, I don't think there are many folks that do, these days.

[hamfist]

I'm sorry Alan, but just to show that there's another side to the story, I'm going to have to disagree.
This is a very subjective area, and also one where there is a lot of mythology. Personally, I find certain modern VALVES to be crisper and brighter than the old Mullards, Brimars, Mazdas, GEC's and Ferranti's I've compared them with.

We've done an experiment using a Matamp 1224, where we made JJ's sound like Mullard's by reducing the gain of each stage a little, showing that the main difference was the level of gain produced in that case. Beyond that, the differences were indistinguishable.

I'm not saying you're wrong Alan, just that this is one of those areas where subjective opinion means that there is no better or worse, just different. There are some poor modern valves around, but there are also some very good ones. I've used literally thousands of JJ ECC83s (for example) over tha last couple of years, with very few failures, and those were immediately on power up. As for tone, all I would say is that I prefer them. The bottom line is that that is all anyone can say.

I'm an engineer, and I'm afraid I just don't believe things just because some one says so. Show me some data that proves Mullards are "better".  Let your ears be the judge. Sadly many people find this hard to do.

Martin,  It absolutely fine to disagree (and lets face it, we do find ourselves disagreeing a fair bit !!), as most things to do with tone are utterly subjective.
 Personally, I have found every modern pre- tube I have ever used to be rather flat and one-dimensional compared to the best of the old tubes.

  BTW, I hope you are not suggesting that I don't let my ears be the judge      Maybe its the air quality down south that allows the subtleties of NOS tubes to come through.

As for the Mullards that you compared with JJ's, I'm surprised that the Mullards seemed to have ower gain. Over at TGP, it's generally considered, by folks who measure this sort of thing, that current production tubes generally are coming out with noticeably lower gain values than proper NOS tubes. Perhaps the Mullards you used were rather "well used".

[martinw]

Martin,  It absolutely fine to disagree (and lets face it, we do find ourselves disagreeing a fair bit !!)

Do we?  :?

Maybe its the air quality down south that allows the subtleties of NOS tubes to come through.

Having lived for 13 years "down South", much of which in your own county, I can assure you that the air quality here in the Peak District compares very favourably and allows me to hear such subtleties adequately. I'm not suggesting that you yourself are not judging aurally, merely that many don't, and when you are judging with your ears, statements like "poor modern valves" are just subjective opinion.

As for the Mullards that you compared with JJ's, I'm surprised that the Mullards seemed to have lower gain..... Perhaps the Mullards you used were rather "well used".

Ah, TGP, it must be true then!  I've measured the gain of several Mullards (and others like Brimars, Ferrantis etc), some with very little use, others with more. I've found what I've found.

All opinions are just that, I just chimed in because I think people have a right to hear the other side of the debate. I have some old valves here, and if the demand is there I'd be quite happy to let potential customers try both.

Some interesting reading here: http://www.tone-lizard.com/Electronic_Parts.htm

[hamfist]

Martin,  It absolutely fine to disagree (and lets face it, we do find ourselves disagreeing a fair bit !!)

Do we?  :?

haven't you noticed ?

 

statements like "poor modern valves" are just subjective opinion.

yes, absolutely. Nothing wrong with a few subjective opinions. I think most people take them for what they are.

Ah, TGP, it must be true then!  I've measured the gain of several Mullards (and others like Brimars, Ferrantis etc), some with very little use, others with more. I've found what I've found.

I agree that TGP has a fair amount of BS as well, but not so long ago I remember an excellent, very objective, thread started by some guy who deals in valves (there, I said it !) who measures gain on thousands of valves. It was actually quite a boring thread containing all his evidence. And he was finding that modern valves were very variable in gain, and also averaged out at something like 85% the gain of an average NOS 12ax7 (which were nowhere near as variable).  It was thoroughly scientific, and very impressive. It's just that I can't find it now.  :(   - typical !  If I give myself a couple of days to think I might be able to remember the thread-starter's name, and then I'll be able to find it.

[jpfamps]

Some lively debate!!

I tend to agree with Martin regarding current production valves. We've had very good results with recent production valves, and the variety and quality is much better than 10 or 15 years ago.

Regardless, any modern manufacturer who hopes to produce amps in any reasonable quantity has to design their amps using current production valves.

To accurately assess whether NOS Mullards are better than say JJ 12AX7s you would need to test blind a number of examples of each. Only if you could  tell the difference to a satisfactory level of statistical signifiance can you diffinitively conclude that one type of valve sounds better than another IN THE CIRCUIT YOU ARE TESTING THEM IN. The "blind" testing is important, as the placebo effect is very real — indeed this why it is often very difficult to tell whether new medicines are effective.

Once a definitive difference has been established, we can then worry about why this is, and it might well relate to the gain of the valves, and the subtle effect this has on the gain structure of the amp.

As an aside, we were testing some 6V6s in a Tweed Champ, which doesn't have a lot in the signal path, so the effect of the individual components should be more transparent cf a more complex amp. These included new production and several NOS 6V6s. I was changing the valves and my mate (who is a full-time sound engineer) was playing the guitar and telling me what he thought (this actually does not quite conform to the medical "double blind" gold standard because as I knew which valve was which I could have inadvertently communicated this to him).

Anyhow, the results were quite interesting. Firstly, my mate was to reproducibly identify which valves  he preferred. The "worst" valve was a NOS foreign made Brimar. His favourite valve was a new production Tungsol (which incidentaly I didn't like that much in a Tweed Deluxe), followed by new production JJs over both RCA and Phillips NOS. Interestingly, he reproducibly prefered one JJ 6V6 from a pair matched for current draw over the other!!

What can you conclude from this? Firstly new production valves can be very good. Secondly there could well be as much variation between valves of the same brand as valves of different brands. You probably need to test several (probably at least 10s, but maybe even 100s) before you can make a definitive conclusion.

What I think often happens is that someone replaces some knackered valves with some NOS whatever valves with a significant improvement in the sound, and come to the conclusion that brand X is better than brand Y, where they really should conclude that the NOS brand X valves sound better than the knackered brand Y valves in my amplifier.

[hamfist]

Some lively debate!!

I tend to agree with Martin regarding current production valves. We've had very good results with recent production valves, and the variety and quality is much better than 10 or 15 years ago.

Regardless, any modern manufacturer who hopes to produce amps in any reasonable quantity has to design their amps using current production valves.

To accurately assess whether NOS Mullards are better than say JJ 12AX7s you would need to test blind a number of examples of each. Only if you could  tell the difference to a satisfactory level of statistical signifiance can you diffinitively conclude that one type of valve sounds better than another IN THE CIRCUIT YOU ARE TESTING THEM IN. The "blind" testing is important, as the placebo effect is very real — indeed this why it is often very difficult to tell whether new medicines are effective.

Once a definitive difference has been established, we can then worry about why this is, and it might well relate to the gain of the valves, and the subtle effect this has on the gain structure of the amp.

As an aside, we were testing some 6V6s in a Tweed Champ, which doesn't have a lot in the signal path, so the effect of the individual components should be more transparent cf a more complex amp. These included new production and several NOS 6V6s. I was changing the valves and my mate (who is a full-time sound engineer) was playing the guitar and telling me what he thought (this actually does not quite conform to the medical "double blind" gold standard because as I knew which valve was which I could have inadvertently communicated this to him).

Anyhow, the results were quite interesting. Firstly, my mate was to reproducibly identify which valves  he preferred. The "worst" valve was a NOS foreign made Brimar. His favourite valve was a new production Tungsol (which incidentaly I didn't like that much in a Tweed Deluxe), followed by new production JJs over both RCA and Phillips NOS. Interestingly, he reproducibly prefered one JJ 6V6 from a pair matched for current draw over the other!!

What can you conclude from this? Firstly new production valves can be very good. Secondly there could well be as much variation between valves of the same brand as valves of different brands. You probably need to test several (probably at least 10s, but maybe even 100s) before you can make a definitive conclusion.

What I think often happens is that someone replaces some knackered valves with some NOS whatever valves with a significant improvement in the sound, and come to the conclusion that brand X is better than brand Y, where they really should conclude that the NOS brand X valves sound better than the knackered brand Y valves in my amplifier.

Yes I love a lively debate !!

JPF, I agree with pretty much everything you say, and only ever stated my views as my opinion, nothing more.
For me, I always have compared new current production tubes with good old stock ones. All I can give is my "hack guitarist's" opinion, as I can't be bothered to do a blind trial, let alone a double blind trial (though I understand in detail how to do them).

  part of my original post's point, however, was to try and overcome some people's fear about buying NOS tubes on ebay. I think that many folks simply feel under-informed and worried that they will be scammed. With a bit of luck I will have empowered a few folks who have wanted to try a few NOS tubes into having the confidence and ability to buy a couple of nice tubes for not too much money.

 :D

[HTH AMPS]

The amp in use plays a masive part in how various valves (preamp or output) will behave.  For instance, my Marshall Superbass shows a noticeable difference in various preamp valves (I like Brimar for V1, then JJs or EH for V2 and V3).  For EL34s, I tried them all (current production) and nothing matched the warmth and fullness of my NOS Mullard EL34s, there really is a very big difference.  Of course, the circuit could be modded, but then it's not a Superbass is it.

For the most part, I'd say the NOS output valves of various types I've tried have out-performed any current production valve in terms of the tone produced.  However thats not to say there are no good current production output valves - I particuarly like JJ 6V6s, Winged-C EL34s, Winged-C 6550s and the current Chinese KT66.

For preamp valves, it's hit and miss for me.  Many of the US-made 12AX7s can be a bit bright for me, though I'm a Marshall guy and they would most certainly suit a Fender amp down to the ground.  I like mainly Mullard, Brimar, Mazda, GE and RCA preamp valves.

[Pete24v]

I spent a fair bit of time trying different preamp tubes in my MiniMat. I tried 2 old Mullards,  Brimar,  JJ, Ruby, Sovtek and a Cryo Harma. The Mullards and Brimar were to Dark and very low volume, the Ruby and Sovtek were to brittle, the JJ was the one i prefered (it was the original one that came with the amp) at that point, it just sounded richer with a nice sparkle on the top end.  But then i tried the Cyro Harma, this was everything the JJ was bit with more controlled low end, had more of a punch when driven too. 

[hamfist]

I spent a fair bit of time trying different preamp tubes in my MiniMat. I tried 2 old Mullards,  Brimar,  JJ, Ruby, Sovtek and a Cryo Harma. The Mullards and Brimar were to Dark and very low volume, the Ruby and Sovtek were to brittle, the JJ was the one i prefered (it was the original one that came with the amp) at that point, it just sounded richer with a nice sparkle on the top end.  But then i tried the Cyro Harma, this was everything the JJ was bit with more controlled low end, had more of a punch when driven too. 

The fact that the Mullards and the Brimar were very low volume is a pretty sure sign that they were almost dead.

[Pete24v]

I don't think so, 1 Mullard was NOS from a 60yr old guy i know who used to repair old Valve gear, he has a bunch of them still in boxes that he never used.

[hamfist]

I don't think so, 1 Mullard was NOS from a 60yr old guy i know who used to repair old Valve gear, he has a bunch of them still in boxes that he never used.

I suspect that the evidence actually speaks for itself. Good NOS tubes simply are not low volume, low gain.  I suppose even Mullards can have bad ones straight out of the box.