Can anyone help me decipher this?

[nosaj]

"Is it possible to add more gain to an overdrive pedal? I have a few .. Boss SD 1 and 308 Yngwie pedal. My favorite. ( supposed to be clone of DOD 250 gray but have a bit high treble and cut off some bass ... Its possible to build an overdrive pedal with high gain natural sound and no control knob..? "

Adding more gain to an overdrive would be possible by changing the pot to go a farther range I believe. What is a high gain natural sound? and am I correct the no control sound means you cannot tailor it?

Thanks,
nosaj

[Mick Bailey]

It is possible - the closest I've done is a Runoffgroove 'May Queen' which has just a level control and this could easily be replaced by a trimpot to give a fixed output. All of the control would then have to be done using the guitar's volume and tone controls.

Pretty much any overdrive pedal can have the gain increased, but how that sounds depends in the pedal; too much gain sounds like mush and you can't tell a minor from a major. It isn't just a case of increasing gain - it comes down to how the pedal is structured, how many gain stages it has, and frequency response. Adding more gain to bass frequencies swamps out the treble, reduces clarity and introduces a lot of intermodulation distortion. High gain amps are structured so that there are multiple gain stages and a number of frequency-determining components or circuits between each stage. Sometimes the bass is cut early on to prevent the sound from getting too mushy.

Any pedal could have the controls replaced by fixed-value resistors. It may work OK with one guitar/amp, but if you swap guitars you may want different settings.

What is your intention with having no controls?

[J M Fahey]

Op Amps have built-in compensation for stability, HUGE compensation which can easily be seen in datasheets as a constant 6dB/oct rolloff starting at a few Hz (not an typo, Hz, not kHz)
Common types run out of gain at 100X gain around 10kHz (meaning no NFB is possible by definition) so they cease to be Op Amps.
Popular simple Distortion/Overdrive pedals often run 100X/200X (Tubescreamer/Distortion+/etc.) so there is really no gain left.

Of course you can try to increase it: result is muddy opaque mush, as mentioned by Mick, so only real option is to add an extra gain stage.
Some add a transistor, some another Op Amp.

As of "natural" ... a pot set to a given value (say, 1M) is the exact same as a 1M resistor, the OpAmp does not know the difference.

Personally I make a Distortion called "Distorsión I/II" and is exactly that: a single Op amp stage with classic 1M Log pot + 4k7 + .047 cap as NFB which goes from 1X to (nominal) 200X plus a switchable extra Op Amp stage, NFB 1M (fixed) + 4k7 + .047 cap , and printed scale reads "0>10" and concentric "10>20" because that is also true, "Dist II" starts where "Dist I" ends.

There's also some different stage EQ and diode arrays involved or sound would be boring, something must differentiate I and II besides plain gain/distortion but that's the general idea.

Try something like this (takes 5 minutes in Protoboard) and see for yourself.

Trying to pull more gain/distortion from already overtaxed gain stages won't cut it.

Believe me, I tried

FWIW, it's quite popular, Musicians use D1 for Classic Rock "up to AC/DC" , D2 for thrash/doom/whatever .
2 button footswitch, one Clean/Dist , the other D I / D II
No Leds, difference is easy to hear , remember D 2 has no controls and is full blast all the time ... impossible not to notice it .

Each stage has its own clipping, D 2 is not a clean boost by any means.

Well, now you have something to experiment