EQ musings for distortion

[phasetrans]

Yet another distortion box:



You can insert your clipper of choice for U3.

U1 is a bandpass filter with gain. U2 is half a James-style eq. In the minimum position, it largely cancels U1 for a "transparent" tone. At maximum, it results in a typical mid-focused tone.

U4 is an active tilt EQ centered at 1kHz. C16 is to taste, and acts as an extra lowpass element.

Hopefully gives some ideas to folks.

[antonis]

Shouldn't U3 stage be non-inverting..??
(for In-Out signal been in phase..)

[phasetrans]

Shouldn't U3 stage be non-inverting..??
(for In-Out signal been in phase..)

Hahahaha.

[ElectricDruid]

Can we see the frequency responses for some of those stages?

It's quite similar in some concepts to my Hard Bargain design, which was exploring the same ideas. I think the Tilt EQ is a good fit with distortion, tbh. It's a lot of bang for the buck, or in the case for the one control.

One thing you've done that I didn't do is active shaping ahead of the distortion. I had some, but fixed. The bandpass sounds like it could be quite a "cocked wah" sound, but that depends on the Q and so on (hence why I'm curious about the freq response). Adding more midboost with U2 sounds like it could get to be too much, but again, it all depends on the details.

I like the tone shaping with controls both before and after though. That's not seen that often. Usually there's tone shaping at both ends, but the flexible part tends to come after. It needn't.

So...when can we hear it?!?

[phasetrans]

Can we see the frequency responses for some of those stages?

It's quite similar in some concepts to my Hard Bargain design, which was exploring the same ideas. I think the Tilt EQ is a good fit with distortion, tbh. It's a lot of bang for the buck, or in the case for the one control.

I can screen cap all of those from LTSoice this evening, most likely.

One thing you've done that I didn't do is active shaping ahead of the distortion. I had some, but fixed. The bandpass sounds like it could be quite a "cocked wah" sound, but that depends on the Q and so on (hence why I'm curious about the freq response). Adding more midboost with U2 sounds like it could get to be too much, but again, it all depends on the details.

U2 is very gradual, it's mostly for reducing IMD. I wanted shaping before and after to be as useful as possible. I feel like many commercial designs hand you a fixed mid EQ profile, and then a knob for fizziness, and that's it.

Max gain is quite bright, but with only a single clipping stage, I doubt it will do a convincing Friedman impression.

So...when can we hear it?!?

At least a week until I'm back at home, but the breadboard was already out before I left town.

[ElectricDruid]

I can screen cap all of those from LTSoice this evening, most likely.

I'm curious when you get a chance, but there's no particular rush, so don't go crazy about it.

U2 is very gradual, it's mostly for reducing IMD. I wanted shaping before and after to be as useful as possible. I feel like many commercial designs hand you a fixed mid EQ profile, and then a knob for fizziness, and that's it.

Max gain is quite bright, but with only a single clipping stage, I doubt it will do a convincing Friedman impression.

Yeah, i agree - a lot of commercial designs *do* give you a fixed profile, particularly going in. I think, on balance, that's where the biggest difference is made. The rest is tweaking the tone of what comes out, but the tone control going in changes the character of the  *harmonics* that are actually produced.

So...when can we hear it?!?

At least a week until I'm back at home, but the breadboard was already out before I left town.

Like I said, no rush, but I'm always up for hearing an interesting idea developed into something good.

T.

[phasetrans]

LTSpice Bode Plots:

After C10 - R8 either 1k or 3.3k. Pick the value that sounds right to you:



After C12 - 6 plots. Min/Middle/Max on the James with 1k and 3.3k for R8. Green curve is R8 1k and control at minimum. This is within 3dB of flat EQ over the majority of the guitar spectrum. You could scale the EQ to make this work for any center frequency of U1:



After C18 - knobs at noon, R8 1k:



After C18 - Pot 1/2 at noon, tilt EQ minimum:



Let me know if there's any others of interest.