Do 12AX7 tubes distort more "musically than solid state stages?

[Rick Hardslab]

I was wondering if anyone here reads tape op.  http://sub.tapeop.com/

There's a good interview with Aspen Pittman from Groove Tubes in this month's issue.  Without going too far in depth he said, "In a nutshell, tubes don't dostort in 'ways that matter', yet in ways that 'don't matter' they aren't as 'technically perfect' as a transistor."

Where that leaves us, I am not sure.  But it is food for thought.

[el84]

Hi !

The only thing I can say is that I have make the TubeDriver (by Jack Orman) and recently a only tube-distortion (H.V.: 200volt)
At the end of story ..... I continue to use the TubeDriver like overdrive/distortion in my set-up.

The 'only tube-dist' has a distortion that ........... I don't like very much 

Bye

[Rafa]

Bancika this mey be out of topic, but ill ask anyway,
Im saving some money to build the tube preamp, and possibly Ill do the same as you. Put the preamp and power supply in different boxes.
You get 4 cables from the power supply, 6,3VDC ,242VDC, 250VDC, and ground. If later I want to build a tube poweramp that runs with 250v can I use the same power supply? I mean is it able of suppliyng two circuits, or maybe Ill burn it.
Cheers
Rafa

[MartyMart]

See if you can find a Peavey TG Raxx
They come up quite often and are not expensive, I got a pristine one for £89 - not much more
than a decent stompbox !
Change out the "PV Super 7" 12AX7 valves ( YUK ) and it sounds superb (JJ's), has a large transformer
so the B+ is up around 310V 
Well build single rack space, with 2x outputs for either a guitar amp input or a power amp input ( careful )

MM

[bancika]

there are two problems:
1) 6V output is regulated with maximum current of 1A (7806 regulator is rated at 1A) so putting more heaters will draw more than 1A (two preamp tubes draw about 0.6A. If you put higher rated voltage regulator, or put two regulators or make separate heaters it will work ok
2) high voltage output is not regulated so when you put double load on each B+ tap voltage will be lower. I run simulation in PSUD and it show about 15V drop. You could aim for about 260V when making PSU for one preamp, 10V extra won't hurt and you'll be around 250V when running two preamps. On the other hand, ~15V drop is not much, so you probably won't notice any difference between 250V and 235V.

Keep in mind that transformer(s) must be able to supply needed current. Each triode draws about 1mA so putting another two tubes will increase high voltage draw for only about 4mA but heaters will be doubled to about 1.2A. I recommend taking 2A rated transformer for heaters.

[Doug_H]

The reason I said it was dangerous is that you could "pop the hood" and tap right into your Fender(i.e. amp) preamp and hear the preamp tone as you really crank it, but it would be dangerous.

Oh, I thought you meant it was "dangerous" because of opening another can of worms with this thread.

[MartyMart]

The reason I said it was dangerous is that you could "pop the hood" and tap right into your Fender(i.e. amp) preamp and hear the preamp tone as you really crank it, but it would be dangerous.

Oh, I thought you meant it was "dangerous" because of opening another can of worms with this thread.

Dont we all just "Luuuve" those worm cans ?? !! 
( Southern US accent on the "Love" BTW )

MM

[Gilles C]

When I boost a 12AX7 I hear a modest volume increase (and hence pleasant compression), but a major increase in the richness of overtones.  Technically, I've wondered a few times if some complex behaviour around cutoff is the reason for this.  When I've built circuits using 12AX7s, I usually try to find some magic around cutoff (rather than saturation).  The Real McTube has a first stage that is biased wwaayyy down towards cutoff, and it gives some great tube-drive tones.

Interestingly, the 12AT7 and 12AU7 don't usually sound as musical to me as the 12AX7 (especially if directly substituted for one), so exploring the differences between them might reveal some reasons for the "extra" magic in the 12AX7.
cheers

yeah, boosting is great with tubes. I boost my tube preamp with solid state overdrive (level at 100%, drive at 0%) and it only adds about 10% of volume, but great amount of sustain.
I like 12AT7 in some situations. My preamp originaly had two 12AX7's, but I replaced second one with NOS GE 12AT7. It's only one gain stage and one cathode follower. It drives tone stack better, has more than 50% more volume (which I don't really need), only a bit less distortion and more sustain than 12AX7. AT appears to compress more signal before clipping occures than AX.

The 12AT7 is supposed to have less gain than the 12AX7??? There is something I don't understand. 

Gilles

[Paul Marossy]

This article is very good to read: http://www.dwfearn.com/tvst1.htm
I recommend it to everyone! 

[bancika]

The 12AT7 is supposed to have less gain than the 12AX7??? There is something I don't understand. 

Gilles

yeah, I was suprised too, it must be something about cathode follower.
btw, Rafa, voltage drop would be rather about 20V, but I don't think it's much. you should start with 260V with one preamp connected. + or - 4% won't change much

[brett]

Hi
That thing about the AT7 being louder was quite unexpected for me too.  If it's driving a cathode follower, the load is really high, so we can count out any ability to produce current.  Maybe a case of a bad AX7 vs a good AT7 ?  The Firefly is a good little amp for comparing the AT, AU and AX7s (and offspring).
cheers

[Gilles C]

A bad AX7 could indeed be the reason, unless both were new?

Your post reminded me that I first tried an old 12AX7 (that I got free from a friend) in my tube circuit, and didn't have a lot of signal.

And it was better with a brand new 12AT7 I had...

Gilles

[brad]

The entire electronics world revolved around tubes fifty years ago, but all people want to do now is use one particular tube in one particular way to get one particular sound.  To quote Eric Barbour:

All I see out there are more and more 12AX7 distortion boxes. Again, most engineers have the GOD thing going on in their pointed little heads.  They are so damn conservative.  It's sad, those guys are stuck in the 1970's.  I'm more interested in a parallel-universe 1952 myself.

There are countless weird and wonderful tubes sitting in warehouses that will end up as landfill because all people care about is damn tube overdrive.  Bring on avant-garde Tube Nouveau.

http://www.synthtopia.com/interviews/Eric_Barbour.html
http://www.cgs.synth.net/tube/beam.html

[brad]

Oops...I know I come across as a bit of a jerk

Sorry about that.

[dominatrix_volleyball]

I'm gonna come out of lurking to say I pretty much totally agree with you / Eric Barbour.

Whenever tubes are thought of, 99.99999% of the time it's in the context of some immaculate blues / classic rock standard that's already been achieved half a century ago. If 12AX7s aren't good for anything else, maybe we should just hurry up and get JFETs to outperform them already.

[bancika]

A bad AX7 could indeed be the reason, unless both were new?

Your post reminded me that I first tried an old 12AX7 (that I got free from a friend) in my tube circuit, and didn't have a lot of signal.

And it was better with a brand new 12AT7 I had...

Gilles

I tried two 12AX7 tubes (EI and JJ), both new and AT is NOS

[Ronsonic]

The entire electronics world revolved around tubes fifty years ago, but all people want to do now is use one particular tube in one particular way to get one particular sound.  To quote Eric Barbour:

All I see out there are more and more 12AX7 distortion boxes. Again, most engineers have the GOD thing going on in their pointed little heads.  They are so damn conservative.  It's sad, those guys are stuck in the 1970's.  I'm more interested in a parallel-universe 1952 myself.

There are countless weird and wonderful tubes sitting in warehouses that will end up as landfill because all people care about is damn tube overdrive.  Bring on avant-garde Tube Nouveau.

http://www.synthtopia.com/interviews/Eric_Barbour.html
http://www.cgs.synth.net/tube/beam.html

Preach it bro'.

I've got a pile of walkie talkie tubes that were actually made to operate at pedal type voltages. Let's see what we can do with those. There's millions of 'em out there for cheap.

Like anything else it's about the design. Tubes can sound brilliant or like ass. It's all in how you use them.

Ron

[bancika]

yeah, you can make tubes sound crappy but you can never make solid state components sound like tubes 

[MartyMart]

Like anything else it's about the design. Tubes can sound brilliant or like ass. It's all in how you use them.
Ron

Absolutely !
I have a tube distortion by Martin Owen    www.owenelectronics.co.uk/9916.html
It sounds VERY nice and has a great TMB tonestack, I'm NOT going to pull it to bits
and reverse it, as he's a gent and a very helpful guy who's running a small operation.
Whatever he got up to inside it ... HE got it right !!

MM.

[Arn C.]

My favorite tube I use for a preamp tube is  6sn7gt.  It is an octal base and is about as large as a 6v6 power tube.  I find it fatter sounding than the 12au7, at7 axa, great for blues and early rock.

Peace!
Arn C.