The strong gout - new pieced up design

[strungout]

(Skip to the point if you dont' wanna hear me go on and on).

Well, a few months ago, I built Brian Marshall STUPID box, and thought it sounded great, but (of course) I thought I needed more gain. There was that unused half of the opamp, but being way more ignorant then, I couldn't make it work. I went on to build other pedals. Then came RDV's venture into designland with his HMP, very cool pedal, but (of course) it wasn't still what I was looking for.

The thread for and surrounding it really did help me understand how to go about designing/piecing up together a distortion, what was needed, how a stage affected the next. So, I went a step further than modding the STUPID box, and built something else from it. I re-read "Cook your own distortion" by Richardo X, "A musical distortion primer" by R.G. Keen and a bunch of other stuff, threads, etc, and came up with two distortion stages and a highpass tone control (I was gonna ad the PEQ after whatever I ended up with, cause that thing is just plain cool). But the tone control just wasn't it. I remembered reading "If you need a versatile tone control [...] use the Big Muff", so I did and that made my day. Then I screwed around some more with the rolloffs of my filters (to keep the tone I wanted at about mid setting so I could go bassy or trebly from that) and noticed that the big muff tone control had a gap in between its two filters (I used 22k and 22nf for the lowpass and 10nf and 47k for the highpass, which rolled off everything between 328Hz and 338Hz). I always kept the mids knob turned down on the amps I was using, makes things sound like they're "congested" to me. So I figured I was gonna see what widening that gap sounded like; 154Hz to 678Hz, about twice as much/less. This was fun.
Then I read that article from AMZ about the Big Muff tone control, that Mark Hammer mentioned in a thread a few days ago, so I guess making both resistance variable would let one modify the width of that mids gap significantly?
Then I went through an experimentation phase (not that this whole thing wasn't), putting the tone control between the two distortion stages (meh), PEQ before everything (you know that tone you make when your throat opens up to let your stomach's content flux out? Sorry ), etc. I ended up with the same layout as RDV'S HMP, the one that Alfonso Hermida suggested in his thread about making a heavy metal pedal. I also ended up adding a switch to chose between a 22nf and 1.2nf cap in the PEQ, and as I'm still not sure how to calculate things there, I'll say that it's interestingly dampening.... ¬_¬;;

THE POINT:



So, behold, a pretty generic, uncomplicated, two duals, eye-opening (for me) rather than inventive, versatile, lighter of mids, constantly needing volume re-adjusting when you play around with the settings, maybe needing an allpass filter stage?, distortion pedal that was punned "Strong Gout". The PEQ is an add on for more possibilities, but you can just forget it and connect the volume pot directly out from the tone wiper (I'm planning on eventually making two 2-3 band PEQ for use before and after my pedals).

Still being rather ignorant, I don't fully understand everything that goes on in the circuit, but I know I like the sound. If anyone feels like passing this through a oscilloscope or anything, please do    Comments appreciated.

Ciao and sorry for the lenghtness.

strungout

[petemoore]

Good to see your drawing stuff up to look at !!!

[RDV]

Killer!
Good to see someone else making themselves crazy!

Everyone should design their own pedal. The learning curve is incredible, as well as the frustration.

The info is all here within this forum, and archives, & linked sites to build any damn thing you can imagine.

I'm going to jump back into my design again next week when I go on vacation from work for two weeks, cause it's still not quite what I want. I need to find the range for the parametric that's most useful for guitar, and somehow up the gain to give a more powerful sweep.

DESIGN & BUILD :!:  :!:

RDV

[niftydog]

A Bush is...

my wangs favorite hiding place...

[Brian Marshall]

Looks really cool.  way more complex than the stupid box, but im glad it inspired you (even thought that means u werent happy with it)

The 1M resistor on the input could probably be removed.  that is the only thing i see that looks funny.

[Ansil]

a bush is "a penguin."  duh do we have to ask what my response would be lol.

nice circuit man i look forward to trying it when i get settled in.

[RDV]

The 1M resistor on the input could probably be removed.  that is the only thing i see that looks funny.

It's a pulldown to prevent switch pops.

Regards

RDV

[strungout]

Oy.

Well, I was taking a break (tried  :roll: ) from pedals. Building this thing kinda wore me out (spent a night up cause that's all I could think about   ). And well, after more testing, I'm getting to similar conclusions as you, RDV: the thing work damm well on a small cheap amp, but it kills the dynamics on a good one! It sound constricted and weak.

So, I'm considering major redesign (already ). Split the total gain between 3-4 stages or add a booster stage in front and lower the gain of the next two stages. I'm wondering if this constriction isnt just the proper of metal pedals (soon as there's a signal, there's a high gain output, no touch sensitivity), or is it just that both this and the HMP achieve high gain from only two stages, or I dunno, still trying to figure this out.

Ciao.

"Insane in the membrane, insane in the brain" -Cypress Hill

[Transmogrifox]

Something that I have found works well to tighten up the sound and give it more meat in a good amp is to design a resonant high-pass filter with Q 5 to 10 center frequency at 80 to 150 Hz and use that at the input of the pedal.  With the center frequency at 80 Hz, the HPF is effectively a low boost for guitar frequencies, so this recovers some of the low end grunt that is lost without adding mushiness from the 200-500Hz range.  Combined with the high pass nature of your amp and distortion pedal, it creates a kind of a notch filter between 150Hz and 500Hz (approximately).  This allows you to get the sharp bite on the distortion and still recover some of the low end grunt.  If your distortion is relatively high gain then it may actually sound better to put the low boost on the output stage.  

I recommend a Sallen-Key topography using a single BJT or FET if you don't want to use extra op amps.  If you have a spare, you can get higher Q out of the op-amp set-up.

I can also post a different type of resonant low-boost BJT circuit that accomplishes the same effect of providing the boost at low frequencies while leaving the rest of the spectrum flat if anybody requests it.

[strungout]

Yeah, post away, it's always interesting to see

[strungout]

Ok, wtf?

I've been trying to change my circuit, in the process cleared my projectboard and rebuilt the circuit...it sounded like crap...not as much gain...great. While I was changing a feedback resistor, I hit the string on my guitar by accident...distortion...decent distortion better than with the fb resistor...so, take the circuit above, take out both 100k gain pots, replace the BMP tone stage with a .1uf cap and send the signal to the amp from there, same IC same diodes....how the hell does this work and result in decent distortion? What am I oblivious to?... Gain = (100k+1k) / 1 = 101, yes? Does the Vb ref have anything to do with it?

I'm getting krispy kernels, so if anyone can enlighten me...

[RDV]

I can't give you the answer, but I know that I've had to greatly reduce the FB resistance in the 2 gain stages of the HMP to get a nice clear sound. I suppose too much gain squashes things out. I'm going to change my schematic when I decide which values sound best. Simpler is better often times. Look at the Z.Vex SHO.

P.S.:
I've been there on the krispy kernals front, you have to take a break and come back to it sometimes.

Regards

RDV

[strungout]

¬_¬;;; *cough*

It was the arm off the second stage. It was connected to the OA output side of the fb loop. That made it sound crappier (still dunno why tho). That resistor and the one in the arm, make up a voltage divider, dividing what comes out the OA and feeding it back, so I guess that why I got some ok distortion. It makes me wanna figure it out tho, cause I don't think I've seen a distortion that works like that...

Anyway, alot of things sucks these days. I'll take longer breaks, thnx man.

[RDV]

The 2nd stage should have way less FB resistance cause the signal is aready jumped up by the 1st stage. The one thing I'll for sure do on mine is reduce the size of the pots in the FBs on both stages. Maybe to 100k & 25k, though I haven't decided yet.

Regards

RDV

[strungout]

Thought I was due for a progress report.

Well, this is insane

This time around I used the Fender amp to test the pedal, and I got pretty close to what I wanted, but not enough "depth" and the highs are makin my ears bleed :? Not soft. The distortion is very, hum, like a box of nails, dropping to the ground and spilling its contents? Basically, I used the same stage 1 and 2, but changed some filter values, used half a BMP tone control for stage 3, and stage four is a Parametric bass boost/cut, and treble shelving EQ. The bass boosts shitty hum, wich is less present when using a battery. So, now I'm thinking I'm gonna go the other way and leave the bass alone, but tame the highs.

Anyway, I'd like to go over my circuit and comment what I was trying to do and think I did. If anyone feels like comment back, pls do. Maybe I'll learn a few things:



Ok.

Stage 1:
The 1M is click preventing. The 6nf and 100k form a high pass at 265Hz, the signal is then amplified, soft clipped and filtered by two (is that useless?) low pass, the 100k and 1nf at 1.5kHz, and the 1k and 2.2uf at 72Hz.

Stage 2:
Signal is amplified and soft clipped again. The 250k and 4.7nf form a LP at 135Hz, and the HP formed by the 1k and 3.3uf starts at 48Hz. So, basically I got a band pass between 72Hz and 135Hz? Or do the two filters need to be in series?

Stage 3:
Here, I started experimenting with BMP tone control variations. The BMP tone control pans between a high and low pass filtered versions of the signal, right? So, what I think I did is the same, but instead of a low pass I have a non-filtered version mixed with a high pass (4.8kHz) filtered version.

Stage 4:
Bass is boosted or cut, no resonance tweak, at 35Hz (per a schematic at ESP). Treble is shelved at 2.5kHz, I'm thinking the 10k pot doesn't boost or cut, but is a "less" control...

So, I mostly play around with filters right now, which at these kinds of gain, seem to make or break the sound. Diodes and IC's are the same 1N4384 and 5532.

If my imagination has left some people chuckling, well, good, laughter is good. If there's any suggestions, pls do. Especially about making a softer distortion (without sounding like excess mucus...). It does sound pretty good, but painful. I'm gonna keep reading and re-reading and sifting around.

Ciao.

[RDV]

The 5532 in the clipping section of the HMP made it hum like crazy so I put the JRC4558 back in which is much quieter hum-wise. I did however use a 5532 in the EQ section.

One way to tame the highs would be a larger out cap.

Good Luck

RDV

[strungout]

Hmm yeah, actually I had a TL072 for the first two stages and a 5532 for the EQ cause it was occilating. Ima try that again, and see what those BB's I have do.

Making the output cap larger would roll off the highs, no? I want them there, just not as sharp.

Thnx.