R. Gwinn, Gristleizer  [documentation]

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
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soulsonic
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Post by soulsonic »

Here is probably the most famous DIY build of the Gristleizer from the 70's Practical Electronic article. Complete with gutshots!
Building the Gristleizer.pdf
Building the Gristleizer PDF
(366.91 KiB) Downloaded 775 times
http://www.throbbing-gristle.com/gristleizer/

I had heard of the Gristleizer or "Gristle Box" that TG used, but I wasn't sure if it was the same thing as the Gristleizer schematic I'd seen on some of the DIY sites. I now see that it is indeed the same circuit.
It's really cool seeing one of Chris Carter's originals. I'm a huge TG fan.

Edit:
Scan of the original project article can be found here:
http://rubidium.dyndns.org/cag/pdf/gep.pdf
Screen Shot 2020-06-15 at 21.33.07.png

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Post by soulsonic »

Here is a link to some more Gristleizer related info on Gauss Markov's site.
http://freestompboxes.org/museum/gaussm ... istleizer/

Link provided by Chris (stobiepole).
Thanks!

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Post by greenskull »

I have had my eye on that one for a while, especially when Gaussmarkov mentioned tweaking it to get it to do more later. Please report back if you attempt it.

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Post by stobiepole »

The main plan (as far as tweaking the circuit) is to provide a CV input to bypass the LFO...

A lot of people complain that the LFO is too limited (or that it could do much more), but modifying it too much would compromise that Gristle sound. So a CV input seemed like the best solution - then you can drive the effect with anything you like.

We haven't really spent any time looking where to put the bypass yet. I've got a lot on...

Chris

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Post by R.G. »

There's a schemo and PCB layout at GEO.

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Post by soulsonic »

Thanks RG! That's actually the first place I ever saw any info about it, but I wasn't sure at the time if it was THE Gristleizer. Now I see that they are the same.

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Post by DougH »

So what does it do, exactly? I had a little trouble discerning what it actually did soundwise from the technobabble in the magazine article.

Looks interesting.

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Post by soulsonic »

It's a VCA and a VCF that's modulated by an LFO with selectable waveshapes. Kind of a fancy tremolo/auto-wah thing.

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Post by Gila_Crisis »

I have a question I just finished building one with the pcb from musicpcb.com.
works really fine and I'm enjoy it a lot.
I was only wondering about one thing, the triangle wave setting is a bit weaker sounding compared to the other waveform.
is that normal?
Zwischen Ordnung und Chaos fangt die Musik an

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Post by agoldoor »

Yeah, I found it to be that way.

Question though: did you put the two trimpots on the outside or the inside?

Because I have rewired my gristleizer twice because of ticking noise, and I think it has to do with my having put the trimpots on the outside as pots and then turning them into certain positions that cause the ticking to be quite audible.

I was very excited about my gristleizer until I really played with it. The ticking is so audible in so many positions of the pots that its virtually useless. And of course I made the suggested Electrolytic cap mod to decrease ticking, but it didn't really fix the problem at all.

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Post by mictester »

There's no point at all in putting the trimmers on the outside of the case - they're "set and forget" parts.

The original circuit used 741s everywhere, and hissed quite badly (there's quite a lot of gain there). The fix is to replace the op-amps in the audio path with low noise bipolar ones. I usually use an LM833 (or NE5532) and combine both op-amps into one package. The modulator section does tick if built with 741s - you're pulling quite a lot of current, and the ticking gets worse as the batteries discharge. I use an LM324, for a very significant reduction in current consumption and zero tick! The spare op-amp in the 324 can be used to give a bit of gain to the triangle wave output to make it sound the same as the ramps and square-wave. The other change I make is to use a rotary switch for the VCA / VCF selection with the spare positions used for alternative capacitors to change the filter frequency range.

The input impedance is too low for a modern effect, so I increase it to 1M, and I reduce the output pot to 10k log. I also put a 100Ω resistor in the ground leg of the output pot to prevent it being turned all the way down. The final mod I sometimes add is to give the first stage the option of a clipper circuit in the feedback path - the additional harmonics really make the VCF shine!
gristle-schem-modded.png
"Why is it humming?" "Because it doesn't know the words!"

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Post by Gila_Crisis »

@agoldoor: I left the trim pot as they are. I used shilded cables on the input and output wires and mine is not ticking at all! there's a bit of noise but no ticking. first I built it with the 10uF cap, but the I removed it (because I wasn't quite happy with the square wave) and to my surprise the pedal wasn't noisier!

@mictester: thanks a lot for your hints. actually I'm also thinking putting an on-off-on with some more caps to put in parallel with the 6.6nF in the filter section. I was thinking something like 47nF and 100nF. Am I supposingn it right, bigger values = lower frequencies?

In mine I used an OPA2134 for the audio path (I first used a 2132, which is my favored OPA, but this time it didn't shined as usually) and for the LFO section a TL074 (I also tried a TLC2274, but I didn't get as nicier as with the 074). Btw I think I should have a 324 laying around, I'll give it a try.
Zwischen Ordnung und Chaos fangt die Musik an

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Post by Gila_Crisis »

is this your's mic?
Zwischen Ordnung und Chaos fangt die Musik an

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Post by Nocentelli »

Gila_Crisis wrote:is this your's mic?
I don't think so: mic's pedals are actually invisible
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by mictester »

Gila_Crisis wrote:is this your's mic?
Nope! Mine just has a stomp switch and four knobs, a blinking rate LED and an on / off LED
"Why is it humming?" "Because it doesn't know the words!"

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Post by mictester »

Gila_Crisis wrote: @mictester: thanks a lot for your hints. actually I'm also thinking putting an on-off-on with some more caps to put in parallel with the 6.6nF in the filter section. I was thinking something like 47nF and 100nF. Am I supposing it right, bigger values = lower frequencies?
.
You're right - bigger capacitors, lower frequency. The values I've used are 4n7, 6n8 (the originals), 8n2, 10n, 12n, and 15n. Anything bigger gave nothing that was much use. My own one has 4n7, 6n8 and 10n. The other change that I found useful (for me) was to increase the oscillator capacitors to give very slow ramps. These could be very musically useful in some contexts.

It also occurred to me that it might be interesting to make a version with (perhaps) three sets of controls with an extra push switch to select these - you could have one set up as a tremolo, and a couple of wah-wah effects
"Why is it humming?" "Because it doesn't know the words!"

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Post by mictester »

Nocentelli wrote:
Gila_Crisis wrote:is this your's mic?
I don't think so: mic's pedals are actually invisible
If you're really interested in seeing an anonymous diecast box with LEDs and pots, then I'll post a picture or two. If you want to see some "in the flesh", go and see a few live bands - there's a hell of a lot of them around!
"Why is it humming?" "Because it doesn't know the words!"

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Post by mictester »

Nocentelli wrote:
Gila_Crisis wrote:is this your's mic?
I don't think so: mic's pedals are actually invisible
OK, just to prove a point - here's tonight's prototype:
Apple Green Distortion Thing (not a diode in sight!)
Apple Green Distortion Thing (not a diode in sight!)
Lashed together inside, but it sounds great!
Lashed together inside, but it sounds great!
It's a four transistor, low noise distortion device, and it relies on the unusual square-law characteristic of some transistor configurations. It sounds quite different to most other stuff around, and the only diode in the circuit is a supply protection device!
"Why is it humming?" "Because it doesn't know the words!"

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Post by boblob »

Hi - just to resurrect this old thread...

I've used 2 TL022s for the audio path and oscillator in mine. Really helps reduce the tick. One thing I have noticed to the +- 7V DC at the output (pin 7) of the TL022 at each end of the bias pot. Is that likely to be a problem? I could add a decoupling cap at the end, but it's all boxed up and I don't want to tear it down if I don't have to.

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Post by reneshelle »

Here is my perfboard layout for the Gristleizer. It's quite compact and will fit in a BB sized enclosure. With some very carefull planning it could perhaps fit in a B sized box as well, although I don't know if that would be very practical.

I used as per Mictesters suggestion LM833 in the audiopath and LM324 for the modulation part.

The used schematic is taken from here:
http://www.musicpcb.com/s/Gristleizer-b ... 121709.pdf

The pinnumbers of the quad-opamp is switched around a bit compared to the schem though.

There is added a chargepump to be able to use standart 9v adapter.

There is also added a led to show the speed.

The resistor for the indicator led is also present on the perfboard and is not shown in the schematic.

Notice the jumper between the two trimpots. And don't forget the three wires (the two red ones and the yellow one that is not shown in full length).

I have build it and the layout works.
Gristleizer complete.png

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