ultimate distortion pedal - what would it be?

 :

12/12/1996 9:20 AM

frank yang

ultimate distortion pedal - what would it be? Basically what the header asks - if financial constraints were not an issue, nor were mass production (this would be built by hand, one at a time with care :>) and using new parts (not obscure NOS parts someone's been hiding away for years), what sort of circuit (solid-state only, please) would create the best (this is subjective, of course) distortion pedal? Most tube-like would probably be the best starting point. I was just wondering what companies like Fulltone and Klon do to justify their prices. I'm sure workmanship is a large part of it, but what makes their circuits so good, and so prohibitive for mass-manufacturers to copy? And I'm not looking for any trade secrets, I'm just curious. Thanks, and lets see some activity! This board has been kind of dead lately.

 

12/16/1996 7:09 AM

R.G. Keen

Best distortion, solid state, new parts? Two possibilities.   1. Mosfet devices with their soft clipping   2. Opamp circuits with carefully controlled clipping and support circuitry   to avoid letting the hard edges of the feedback network show, ever.   3. Possibly a two stage distortion, one half cycle, then the other.     The clipping method is actually in my mind a second class player. The true   secret of high class clipping is the pre- and post- clipping EQ. The preclipping   EQ determines what frequencies are clipped most, the post clipping EQ determines what harmonics you get to hear. Fourth order lowpass at about 4-6Khz is what my   ear likes for post-clipping EQ. I vary with my mood on preclipping EQ.     Fulltone and Klon justify their high prices by the fact that people will pay them. There isn't any magic inside the boxes, and the circuits are not that   different from others. Mostly, these boxes are made by guys with some electronics smarts (or good help!) who have a good ear.

 

1/24/1997 11:47 AM

Cliff Ducharme

Here's one you can try, although I don't remember all the details (I designed it   20 years ago). Take an opamp (high performance compensated one with bipolar or   FET input stage) and set up an inverting amplifier with gain of approximately   100. Use 47K for Rin and 4.7M for Rf. Couple the output to a common source FET   amplifier and use a pot for the source resistor (include an AC bypass cap). If   you adjust the pot carefully you can shift the DC operating point of the FET   to get symmetrical or asymmetrical clipping (your choice). By tailoring the   the high pass filtering of the coupling network to the FET and adding a low-   pass network to the output, you get get an outrageous approximation to tube   distortion. I used this circuit for years (installed in a volume pedal so that   I throttled the output level with the pedal and controlled the drive at the   guitar) and could go from a clean sound to full distortion by cranking the   guitar and rolling back on the pedal.     I can't give you a complete layout or component values because I designed it on   the back of a napkin and the prototype got lost in chaos of life. I can tell   you that once I got used to feathering the controls, it worked well on stage.   I used it with both a Strat and a Gibson SG driving a Silverface Twin and the   character of the instruments came through, although the clean sound did tend to   be noisy by today's standards.     The dyed-in-the-wool valveheads may say this is heresy - that a FET doesn't clip   like a 12AX7. Well, try it - maybe you'll like it! If not, you can try a   TubeHead-type circuit with a real tube. It's basically the same concept.     As another posting said, the key is the pre- and post- distortion filtering.   Make the filter networks adjustable (or use a prototype board so changes are   quick) and tweak to taste.     If anyone is REALLY interested, I'll try to dig up a clone that I may have in a   junk box somewhere so I can reverse engineer my engineering.

 

1/25/1997 7:13 AM
Christian Landry	I'm interested Cliff. Let me know what I have to do to help. It sounds real cool and simple. Thanks for the tip. Christian

 

1/25/1997 8:59 PM

R.G. Keen

Another interesting sound can be had by noticing that most jfets are symetrical - it doesn't matter which pin you call "source" or "drain" if you get the gate right. If you feed signal into a jfet drain/source with the source/drain grounded and a resistive divider from drain/source to source/drain and the gate tied to the center of the divider, you get some truly strange distortions. The signal inverts every half cycle, and the fet operation inverts along with it. You usually need a volt or two of signal though to get the fet into real operation.

 

4/23/1997 1:38 PM
Jack Orman	Actually, I've used an FET distortion very similar to this for years. Mine uses the Mini-booster FET configuration that is described on my web site, and a variable 2-pole on the output.     http://members.aol.com/jorman/

 

Page 1 of 1