Modeling for different power valves

S

SparkyG

Experienced
Not sure this is possible but:

Wouldn't it be cool to be able to select different types of power valves for each amp Sim?

I used to own a Cornford Carerra, 5-7 Watt, and switchable between an 8 and 9 pin power valve socket, so you could literally put in what you like, no need to match etc cos it was single ended. I

I did quite a bit of testing with different valves (mainly EL84's) and settled on an original Mullard I bought off ebay, break up wat at a different point and sounded really smooth. Point is, there is a huge difference in tone and reaction from the different types (Mullard, Phillips, Tung Sol, JJ's, Sovtek etc etc.) I had Golden Dragons in my Cornford MK50 ii and that was much smoother sounding than the "rougher" Sovteks.


Of course everyone has different tastes so being able to select power valve types would be great.

Cliff, can this be done in modelling?
 
He's on record saying that the tube type really doesn't make that much difference. Perception of the artists and musicians conditioned by years of 'training' say it does.

You can actually do a LOT with the settings in the bias; there is a tremendous amount of variance in response and feel with just that parameter in the advanced tab of the amp block.

IMHO, Cliff doesn't add stuff that a) doesn't add legit options; b) will expose his algorithms to reverse engineering.

He's said that tube type doesn't really change much. Could be either that he's being very forthcoming or that he's unable to expose those parameters.

I could be wrong, but that's my opinion.
 
Scott,

Thanks for the tip on the Bias, not played with that one yet.

Hadn't read Cliffs position before, I guess that's pretty clear.

Agree though, my limited experience says there is a big difference, Never did it over the years because of the costs of buying matched quad's and stuff, but the single in the Carerra made it easy.
Remember reading an article that Brian May bought up all the available NOS Mullards at one point for use with his AC30's cos they were the only valves he could get his sound with.


Cheers
 
I wonder if anyone has ever bought two or more identical tube amps and put two different types of tubes to do a proper scientific A/B comparison. People usually play an amp for a few months with some kind of tube, then have them changed and compare a few hours/days later and claim the new tubes sound better/clearer/smoother or whatever.

But then you find everyone claiming their tube amps sometimes sound better/clearer/smoother or just plain bad WITHOUT having changed anything in the amp, you know, those days when everything sound muddy and undefined, you come back the next day, and everything sound clearer without even touching a tone pot.

All clips I've heard on an amp that has had its tubes changed and recorded several times to see what difference they make, can be qualified as having subtle differences, hard to hear at first an only apparent after careful listening.
 
too_much_power said:
I wonder if anyone has ever bought two or more identical tube amps and put two different types of tubes to do a proper scientific A/B comparison.
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I don't think it's possible to do this in the same amp. The EL34 and 6L6 have quite different specifications, and in particular, the EL84 has a maximum plate voltage of 800V while the 6L6 has a maximum of 500V. Consequently, amps with 6L6 are often designed to run at lower voltage and higher current compared to EL34 amps (higher voltage, lower current). Power = voltage x current, so they both typically produce about 50 watts per push-pull pair.

The point is that there isn't a single amp designed to operate both each tube type under it's optimal conditions to allow you to make a fair comparison. To do this, the amp would need to reconfigure more than just its bias - it would need to change power supplies, output transformers and probably more. When you change that much, you might as well plug into a different amp. Something you can already do easily on the AxeFX by switching to an amp model based on whatever output tubes you want :D

Granted, there are amps that allow you to swap tubes that AFAIK just modify the bias to allow the tubes to run safely in whatever design they have. And if the end result gives you a sound you like that's probably all that really matters, but this is a long way from an objective test on the sonic differences between output tube types.

too_much_power said:
People usually play an amp for a few months with some kind of tube, then have them changed and compare a few hours/days later and claim the new tubes sound better/clearer/smoother or whatever.
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Very true. Folks often notice just as much improvement replacing old tubes with new tubes of the same type!

Scott Peterson said:
He (Cliff) is on record saying that the tube type really doesn't make that much difference. Perception of the artists and musicians conditioned by years of 'training' say it does.
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I certainly thought he wrote that too, Scott, but when I looked at what he posted I think he was referring mainly to preamp tubes. Either way, as above, I think the tube comparison thing is overrated - IMHO it's a package deal with the entire power amp - why would you want to swap tubes into an amp that's optimised for different tubes?
 
Power tubes can make quite a big difference actually. Try a JCM800 with EL34's and then 6550's - it changes the tone as well as the feel/response. It's a fairly simple mod of re-biasing, changing a few resistors, and moving the negative feedback wire to a different tap (optional). Shouldn't be a big deal to model considering all the amazing stuff Fractal has already done.

EL34's have great chime and lower mids, while 6550's have extended lows and highs and less compression - they can sound great for instance if you are using more preamp distortion and want to keep things tight at high volumes.
 
too_much_power said:
I wonder if anyone has ever bought two or more identical tube amps and put two different types of tubes to do a proper scientific A/B comparison. People usually play an amp for a few months with some kind of tube, then have them changed and compare a few hours/days later and claim the new tubes sound better/clearer/smoother or whatever.

But then you find everyone claiming their tube amps sometimes sound better/clearer/smoother or just plain bad WITHOUT having changed anything in the amp, you know, those days when everything sound muddy and undefined, you come back the next day, and everything sound clearer without even touching a tone pot.

All clips I've heard on an amp that has had its tubes changed and recorded several times to see what difference they make, can be qualified as having subtle differences, hard to hear at first an only apparent after careful listening.
Click to expand...

I owned a THD Flexi 50 that you could pop 6L6, EL34, 5881, KT88, etc. into, bias and then go. The changes are more subtle than you might imagine. They are there, no doubt. Just changing power tubes between sets - and I would match them in that particular amp with a Bias King probe to do so - changes the tone even sticking to the same valve type.

There's a helluva lot more voodoo and perception OVER reality to it all, IMHO, but it has some merit.

To the OP's question though, Cliff has said no multiple times.
 
Different power tubes do make a difference in tone and feel as well as different brands....but... it is subtle compared to the difference of swapping speakers. Using THD yellow jackets, I've tried El84's in my TopHat emplexador and it sounded much different. I also tried 6L6's in place of the stock EL34's and the tone was much different.
I really don't think it's worth giving those type of options in the Axe where you have so many types of amps to choose from anyway. There are plenty of tone shaping options already that make a bigger difference.
 
Here is an example; there was a time when Marshall's came with el34's. That switched for a time to 6550's - the only thing that changed was the bias circuit - everything else was the same. The switch between these two different tube types makes a tremendous difference in the sound and feel of the amp - all other things being equal. Compare a reissue 59 bassman to an original - not even close in my experience. There are several reasons for this not the least of which is the first preamp tube - replace that 12ax7 with a 12ay7 and you will get one step closer to the original. I have found 12au7's that sound like ay7's; and I have definitely found large differences between 12ax7's. As for differences with different runs of an el34's, they definitely exist. And what is an optomised circuit? Jtm 45's have a different value output trans than a model 1987, for example, while maintaining relatively equal voltages. Both will sound great with el34's. Kt66's will yield a different flavor and can be ran in either amp.

But, tubes are just part of the picture, the voltages make a tremendous difference also; there are other aspects of the design that make big differences in tone and feel and if adjusted, these can to some degree mask or "correct" tube differences.

Now it seems to me that the question is - do the axe parameters allow enough tweekability to emulate the differences found in changing tube types or the differences found from one run of tubes to the next?

With the many different amps, extreme tweekability, various eq's, and such - my answer is yes, close enough. All in all, I beleive that what you run the axe "into" is far more important to the sound. This is my opinion (and it is subject to change).

I humbly submit that even though there are differences in tubes, if you can't find what you want with the axe, as it stands today, then you will likely not be happy with another tweek that allows you to change tube types.

Having said all of this, I recall some mods I made to a super reverb once; cathode bias and el34's made for a very interesting beast - it almost sounded as good as a jtm45.

What I am trying to say that the sound pallete is already there. (in my opinion)
 
What happened to the idea of, like the power amp bypass, having a preamp bypass also. So you can run amp A's preamp section into amp B's power amp via 2 amp blocks in series. Not worth the trouble?
 
fuzznut said:
What happened to the idea of, like the power amp bypass, having a preamp bypass also. So you can run amp A's preamp section into amp B's power amp via 2 amp blocks in series. Not worth the trouble?
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Cliff has stated more than once that it would expose some things that would allow other companies to reverse engineer his algorithms so it is not going to happen.
 
i assume power tube choice has some effect on tone.
Otherwise mesa boogie would be wasting resources having switchable power amp sections on their road king range?
I thought that 6l6's were though to sound more clean and american vs El34s which are supposed to sound english.
For me this is just heresay, as i've never changed from 6l6's myself for comparison.
 
Tube types, and even brands, sound different.

Having assorted tube options might be fun to experiment with, but would this over-complicate the Axe?
 
Casper said:
Tube types, and even brands, sound different.

Having assorted tube options might be fun to experiment with, but would this over-complicate the Axe?
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Cliff was talking about brands.
 
One user in the old forum link provided by shredi knight earlier mentioned "Cross-breeding amps", and Cliff mentioned he was thinking about it. Sounds cool...

- Cross-breeding amps - It'd be neat to throw a Marshall front end into a Mesa power amp and see what comes out. (from user scarr)

I've thought about this. Still debating it. (from FractalAudio)

Can that be done now?


Anyway, IF the power tube and/or preamp tube parameters can't be changed (and cannot be "exposed" for whatever reason), then would it be possible to emulate different pre and power tubes based on existing parameters (bias etc), and if so, HOW ? Just throwing it out there... Would be interesting.


Cheers
 
I was also mainly talking about tube brands, not different tube types ( at least that's what I meant to say)

But sounds like it won't happen, no big deal
 
Yeah, there's DEFINITELY a difference in tube types... when I first got my Mesa Mark 3 head (a long time ago... ) i tried using all 6L6's, all EL34's and the standard 2 of each... there's a definite difference in tone... at least at really high gain settings ( is there anything else ? ;-) ) one is colder/harder, the other is a little more warm...

It would give more options, but I am pretty happy with the sound I get already... sometimes too many options can make you tweak more than actually getting to play... but to each his own...
 
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