Supreaux ???

[I am the Walrus]

Hello all.
  I just finished up the ROG Supreaux.http://www.runoffgroove.com/supreaux.html I set Q1-3 at about 4.5 volts, as recommended, and got a medium OD effect out of it. I wasn't really blown away by it, so I fiddled with it by ear. I also changed Q3 to a J201, turned the volume control all the way up, put the master volume control at about two or three, and set the trim pots to be the loudest at that point. The new voltages are: Q1-1.88, Q2-5.64, Q3-,2.1. The pedal now sounds incredible. It has amazing sustain and a really compressed distortion. The notes also seem to fade out with an overtone of an octave. I'm new here and have a very limited knowledge of electronics. I was just wondering if anyone could explain why it sounds so amazing, even though the voltages are completely all wrong. I'm playing through a Hot Rod Deluxe and a G&L Legacy, if that matters at all.
  Thanks for any comments.

[antonis]

Didn't know that "Incredible" and "Amazing" are DMM measurable parameters... 

[GibsonGM]

Didn't know that "Incredible" and "Amazing" are DMM measurable parameters... 

It may be that your DMM simply doesn't have those functions, Antonis?   
Mine only goes up to "Super", I would have to spend more money for "Incredible"!

Walrus: much of what we do here is very subjective.  What sounds amazing to you, with your sense of taste and your amp, guitar and playing style....may sound like poo to someone else!  There is no way to "measure" that - as long as the devices inside are working, that's where the math ends...MOSTLY (not always true of course).

All that a designer can do is give you a starting point, maybe that is 'center biased' on an amplifying component or something, the settings that sounded good to them...the rest is up to you!    If you tried your pedal with a Marshall amp, for example, it may sound very muddy and blatty....the Fender is really clean (on the clean channel!)  That's the beauty of this hobby.

Which leads to, are you using it on the clean channel?  Now try it on the yellow channel, and then set that to red, to see what I mean....I use my pedals about 99% on just the clean, to be their own preamp, essentially.     

Oh, and it's worth mentioning...you said "Volume all the way up", so you are pushing the input stage of the amp more, causing just a tad of distortion probably (it expects like 1V AC input, you are sending it near 9V, and the following stages will correspondingly be 'over' what they expect).   That is what overdriving a tube amp is, and it sounds awesome when done well     Then you turn it down, and it is less impressive, ha ha....   

[I am the Walrus]

Thanks for the reply GibsonGM. I understand guitar sound is very subjective, and in the "ear" of the beholder, as you said. I just didn't think the pedal would even work with those voltages. I guess I was wrong. Yes, I was playing it through the clean channel with the volume control on the pedal at full and the master volume on the pedal at about 9-10 o'clock. Rolling of the volume really cleaned up the sound nicely, too.

[GibsonGM]

Sounds like you found a magic combination!  Yeah, some things can tolerate being pretty far out of spec.  ROG probably didn't design it to sound like what you did, but you found something you like - cool!

If you want a clean boost for leads with the HRDx, try an AMZ Mosfet Boost (sorry, Antonis!!)...that is what I use with it - it's pretty transparent and will kick you up over a band for solos.  Also can be considered 1 gain stage, so you could combine them and put tone controls in between and so on, it is a building block.

[antonis]

ROG suggested adjustments are "ideal" for a 3 stage cascaded amp symmetrical distortion circuit..

By off-setting each individual Drain bias, you result in a 3 stage cascaded amp asymmetrical distortion circuit..
(first stage exhibits heavy negative asymmetry, second stage exhibits light possitive asymmetry and third stage exhibits heavy negative asymmetry - possitive & negative are considered in relation to signal waveform..)

Due to high gain, all stage signals are topped (their upper and lower waveform curves are straight lines) but what matters is the slope of their side curves..
That slope should be equal for all symmetrical clipping stages but now is unequal due to asymmetrical individual stage clipping..

You may think it as a trapezoids sequence of equal base length (half of signal wavelength) but unequal height (sum of two consecutive heights equals Drain swing voltage margin) - because I'm lazier even than deadastronaut and a terrible draftsman too.. 

[bluebunny]

. . . because I'm lazier even than deadastronaut . . .

Watch out for laser cannons coming from low earth orbit towards Greece...   

[I am the Walrus]

Well, then I guess I prefer this circuit in an asymmetrical set-up. Who knew? From what I've read, other distortion circuits use asymmetrical clipping, the Boss  SD-1 for example. Thanks for the info.

[antonis]

Well, then I guess I prefer this circuit in an asymmetrical set-up. Who knew?

Your ears, maybe..??

(I know some guys who use their eyes instead of ears - I call them "curve trace junkies"..  )

[nepalnt21]

i think jfets can vary wildly in their specs. if you havent auditioned different transistors (like even different individuals of the same type) in each position, i highly recommend it.

i auditioned different j201s in the q2 position of the SUPREAX DEUX, which is now my new favorite overdrive pedal. each transistor required adjusting on the drain potentiometer (some were WAY different) to get it to 12V, and even then, i ended up adjusting it by ear.

i liked it so much, i tried different ones in the other two transistor slots, also. biased them to 12V, and then did final adjustments by ear for all three transistors (ended up with a drain V around 9V, on Q2, iirc, and the others i left closer to 12V for the dynamic response they give at that point).


took a few hours, and my neighbors hate me (this thing gets LOOOOOOUD!!!) but it sounds frigging AMAZING now!