High Gain 12ax7 recommend.

Conker

Can anyone recommend  a sensible priced high gain 12ax7. Using JJ at present. I love the general tone of the amp and it plays ideal with a guitar with super hot humbuckers,however with my other guitar I notice it just needs a tiny extra push. I don't want to put a boost or overdrive in front so slightly hotter preamp tube in v1 and v2 should do it. Any advice welcome.

Maynehead

You can get high gain versions of most preamp valves from places like Karltone or Watford Valves.

Don't expect them to make that much of a difference though. Why not just turn the gain up more?

If you do want to get one though I recommend the Tungsol. Nice sounding and high gain, can't really go wrong with them.

Gagaryn

What amp?

Conker

Hayden classic lead 80 so not super high gain. I am leaning towards some PM tubes high gain 12ax7

ICBM

RFT. The best high-gain 12AX7 ever made, and still not *that* expensive by old-production standards.

mudslide73

ICBM said:

RFT. The best high-gain 12AX7 ever made, and still not *that* expensive by old-production standards.

+1 there are always some on ebay etc. They were OEM in Marshalls post Mullard weren't they @ICBM ?

Maynehead

ICBM said:

RFT. The best high-gain 12AX7 ever made, and still not *that* expensive by old-production standards.

I have an RFT in my amp's drive stage, and while it's gainy it's also very mid focused with no chimey highs. This is great for a dual rectifier for taming the fizz but the Hayden could do with a bit more top end (from listening to youtube vids at least), so using it in the input stage could make the amp sound a bit dull.

Incidentally I found the new Chinese 12ax7-Cs to be almost as gainy but quite well balanced across the sound spectrum as well. They could also be a good choice, and are much cheaper.

PolarityMan

I measured the frequency response of some preamp valves in my jvm and there was basically no difference.

ICBM

PolarityMan said:

I measured the frequency response of some preamp valves in my jvm and there was basically no difference.

True, but what about what you can hear? Not necessarily the same thing.

ESchap

Won't the resistance value of the plate resistors have more effect on the stage gain than the valve itself (assuming the valve is performing at near new values)?  Having said that, there is definitely a grittiness to RFT's that is very nice in the right circuit. 

ICBM

ESchap said:

Won't the resistance value of the plate resistors have more effect on the stage gain than the valve itself (assuming the valve is performing at near new values)?  Having said that, there is definitely a grittiness to RFT's that is very nice in the right circuit. 

Yes. To be clear, the 'gain' of the valve is not very important, it's the circuit that sets that. The difference with valves that sound 'gainy' like the RFTs is more that they seem to introduce more harmonic distortion. I don't hear them as particularly middy either, they're quite a bright yet warm-sounding valve to me - essentially the opposite of something like JJs which are middy rather than bright, but somehow harsh.

RFTs were stock in Marshalls in the mid-70s, yes - that may be partly why I like them so much, they're a perfect match for the amps, especially the 2203/4. Maybe not coincidentally, if the circuits were tweaked with them in place.

Conker

Thanks for the info I will track down a RFT , has anyone tried the PM tubes 12ax7HG out of interest.

ICBM

Conker said:

Thanks for the info I will track down a RFT , has anyone tried the PM tubes 12ax7HG out of interest.

No, but it looks like a perfectly standard Chinese 12AX7 (which is no bad thing in itself, they're good valves) and comes with added marketing BS. "20% more clean gain"… er, right… so it somehow increases the clean headroom of the amp? Which is dependent on the circuit not the valve - unless it actually *reduces* the gain to keep the sound cleaner until you turn up 20% further. "Improved grid resonance" - ie intentionally microphonic?

ecc83

ICBM said:

ESchap said:

Won't the resistance value of the plate resistors have more effect on the stage gain than the valve itself (assuming the valve is performing at near new values)?  Having said that, there is definitely a grittiness to RFT's that is very nice in the right circuit. 

Yes. To be clear, the 'gain' of the valve is not very important, it's the circuit that sets that. The difference with valves that sound 'gainy' like the RFTs is more that they seem to introduce more harmonic distortion. I don't hear them as particularly middy either, they're quite a bright yet warm-sounding valve to me - essentially the opposite of something like JJs which are middy rather than bright, but somehow harsh.

RFTs were stock in Marshalls in the mid-70s, yes - that may be partly why I like them so much, they're a perfect match for the amps, especially the 2203/4. Maybe not coincidentally, if the circuits were tweaked with them in place.

Ah! Was going to ask! See, the gain, "mu" of a triode is set by the relative distances of cathode, grid and anode and valves are made to incredibly tight tolerances (watches have nothing on them!) so if "12AX7" is stamped on a valve it should have the same specification as any other or it AIN'T a 12AX7!

A few years ago I was asked to build a device not many here will have used? It was a switching circuit that allowed two preamp valves to be compared in the same amp, using the same circuit components (the idea was to test if another supplier's product was as good/same as the current one) The "flipping" circuit was tested by two top players with excellent "ears" and the decision was yes, there WERE differences between SOME valve brands, especially as the valves were pushed into distortion but the differences were small and comparing two AMPS with different valve brands would be tricky due to all the other components and tolerances.

Said it before! I am sure there is a doctorate waiting for someone prepared to do a proper job on guitar amp "sound"? We NEVER get any recordings!

Dave.

ICBM

ecc83 said:

Ah! Was going to ask! See, the gain, "mu" of a triode is set by the relative distances of cathode, grid and anode and valves are made to incredibly tight tolerances (watches have nothing on them!) so if "12AX7" is stamped on a valve it should have the same specification as any other or it AIN'T a 12AX7!

A few years ago I was asked to build a device not many here will have used? It was a switching circuit that allowed two preamp valves to be compared in the same amp, using the same circuit components (the idea was to test if another supplier's product was as good/same as the current one) The "flipping" circuit was tested by two top players with excellent "ears" and the decision was yes, there WERE differences between SOME valve brands, especially as the valves were pushed into distortion but the differences were small and comparing two AMPS with different valve brands would be tricky due to all the other components and tolerances.

Said it before! I am sure there is a doctorate waiting for someone prepared to do a proper job on guitar amp "sound"? We NEVER get any recordings!

It's surprisingly hard to get useful comparisons with a recording! I know that sounds like a cop-out - it isn't, it's that the crucial aspect of the 'tone' and 'gain' of an amp to the player is more related to what many people describe as 'feel'… ie how the sound changes as you alter your picking. That's very difficult to capture in a recording even when it can be very obvious to the player with the amp hands-on.

It is possible though, when the differences are large enough - this demo of the Jet City Retrovalves demonstrates it, since they use three real valves as a control and one of them sounds quite a lot different to the other two.



While it's possible that that's just a duff sample, it does agree with what I know of those three types in a lot of different amps - so much so that I guessed the first one with a good degree of certainty before I'd even heard the others.

I otherwise agree with you that the actual 'gain' of the valve is of fairly low importance unless it differs wildly from the design spec though - but some modern-production valves do, and I would agree with you that this means they aren't really the 'correct' type - some rectifiers and power valves more than preamp ones, in fact.

ecc83

Ok IC I will whack that vid over my Tannoys later (but you KNOW I am pretty mutton!) I agree that recordings perhaps don't reveal very much (and if I were a cynical old sod I might say "coz there ain't much to find!") but then, who has done any REALLY well controlled tests with top end mics, converters etc? I would also expect a "re-amped" source not a real player.

The test rig I made for B's was to check that a different brand/supplier's valve was close to the then current production type. IIRC it WAS "differentiable" but not so much that anyone would notice or sue!

I am all for people trying things out and valves are an obvious and easy thing to swap. I just get a bit pissed off when firms make outlandish claims and charge a serious wedge.

Dave.

ICBM

ecc83 said:

I am all for people trying things out and valves are an obvious and easy thing to swap. I just get a bit pissed off when firms make outlandish claims and charge a serious wedge.

So do I - that ad hype for the PM Tubes "High Gain" 12AX7 is a classic example, of both a probably self-contradictory claim and a piece of meaningless technobabble. OK it's not *that* expensive, but it's about twice the price of an equivalent (the cynic in me says identical!) standard Chinese 12AX7.

Using a re-amped source is definitely the best way to objectively compare things, but that does have the both good and bad effect of removing the player interaction. I now believe the subtle ways valves sound different, and yet in a somehow very natural way, when you alter your playing technique is one of their most important characteristics, rather than the sound itself - it's what I find frustrating about so many solid-state and digital amps, that you're forever having to tweak them even when you think you've got them set right… but then you change what you're playing slightly and they then sound 'off' again. Valve amps are far more forgiving and natural in that way.

PolarityMan

ICBM said:

PolarityMan said:

I measured the frequency response of some preamp valves in my jvm and there was basically no difference.

True, but what about what you can hear? Not necessarily the same thing.

I couldnt hear a difference either but since my ears arent perfect i took them out of the equation. I figured if i cant reliably measure it then i definitely cant hear it. Had a chat about this with an amp tech recently and even he thought it was mostly bullshit especially the cryigenically treated ones etc. His view was main reason to go for one over another is actually reliability.

ICBM

PolarityMan said:

 I figured if i cant reliably measure it then i definitely cant hear it.

I don't think that's necessarily true. Measuring equipment is better than ears at some things, but worse at others, and vice versa.

But if you can't hear it *and* you can't measure it, then there's probably no difference! And to be clear, if you're trying to prove there *is* a difference when you can't easily measure it, hearing needs to be backed up by blind testing of some sort otherwise it's very easy to fool yourself unless the difference is huge.

The differences with valves can also be very dependent on the amp - with some amps two valves will sound the same, with others the same two may sound noticeably different. I haven't tried swapping valves in a JVM, but my TSL seems fairly insensitive.

I agree about the cryogenic ones being BS though.

ecc83

"I agree about the cryogenic ones being BS though." Works for exotic blades IC! But then the extreme temperature change is not being undone by subsequent heating.

Frequency response tests are the heart of production line QC. The quickest way to tell if a chassis has the right bits "stuffed" is to check the response. Having spent many hours of the sort of fiddling, widdling, soldering and swearing that is needed to voice an amp it is the only practical way to ensure product consistency.

AFAIK every amp gets a "play test" but that is more I think to pickup gross problems such as a buggered speaker or a miccy or hissy bottle.

Dave.

ICBM

ecc83 said:

"I agree about the cryogenic ones being BS though." Works for exotic blades IC! But then the extreme temperature change is not being undone by subsequent heating.

And that's something where the performance is determined by the physical properties of the material, whereas a valve really isn't.

ecc83 said

Frequency response tests are the heart of production line QC. The quickest way to tell if a chassis has the right bits "stuffed" is to check the response. Having spent many hours of the sort of fiddling, widdling, soldering and swearing that is needed to voice an amp it is the only practical way to ensure product consistency.

I don't disagree at all, but that still doesn't mean that you can't hear small differences that don't necessarily show up by measurement.

Did you watch the Retrovalves video? The differences between the three real valves (or at least between the JJ and the other two) are large, not something you can put down to 'wishful hearing'. I assume they would show up on a frequency response test too, but I don't know.