Anybody build their Gristleizer yet, comments on it?

[diffeq]

If anyone needs to disable the LFO during bypass, it can be done the same way Aion Refractor uses opposite throw of LED cathode pole, grounding the opamp output. See schematic that shows the point to connect the switch to.

[rankot]

Connect this point to ground for mute?

[diffeq]

Connect this point to ground for mute?

Yes, that disables LFO (and thus, any ticking getting through in bypass). Tried on several builds.

[telebiker]

Is it possible to use TC1044SCPA or ICL7660SCPA instead?

Yes.

Cool. Will try and share results. Thanks for the replies!

[ficelles]

Having a small problem with my Gristleizer build... VCA mode is working fine, VCF all lower frequencies distort very unpleasantly. Have calibrated of course and checked soldering and components, Swapped out all ICs and transistors, probably I have made a mistake somewhere or fried something. Any clues as to where to look?

[Taylor]

It's possible it's working normally - this circuit definitely can definitely distort on larger signals like a lot of basses, especially active ones. The Gristleizer's whole claim to fame is being a distorted destructive effect made famous by industrial band Throbbing Gristle, so it's not going to be the best for clean/synthy filter sweeps.

Could you post a clip? Might make it easier to say if it's functioning normally or not. Putting an attenuator on the input might also be a good thing to try to see if the signal you're feeding it is too hot.

[ficelles]

It's possible it's working normally - this circuit definitely can definitely distort on larger signals like a lot of basses, especially active ones. The Gristleizer's whole claim to fame is being a distorted destructive effect made famous by industrial band Throbbing Gristle, so it's not going to be the best for clean/synthy filter sweeps.

Could you post a clip? Might make it easier to say if it's functioning normally or not. Putting an attenuator on the input might also be a good thing to try to see if the signal you're feeding it is too hot.

Thanks for the reply, will try and record something later and post it. Turning the guitar or bass volume down makes it clean up of course. Maybe not surprising that my Wal makes it distort, but even P90s on my Gibson do it. I guess I was comparing my build to some of the youtube Gristleizer demos with very clean VCF sweeps.

[Edit] just realised I left out a rather key bit of info... I carelessly got the power polarity the wrong way round first time I fired it up. I replaced the ICs and transistors but as yet haven't swapped out diodes and caps, perhaps should have put that in my first post!

[ficelles]

A 100k resistor on the pcb input has made it much more to my taste - not too clean but now the distortion isn't so overpowering. Thanks for the tip

[Taylor]

Oh, heh, that's not even my PCB, but somebody else's, so I don't know what changes they may have made to the circuit. Anyway, glad you got it sorted.

[ficelles]

I know, shoulda said. I made your Meatsphere which is a great circuit

[ficelles]

A better input pad:

[jackwithoneye]

Hi,
I'm building my gristleizer, Taylor's board.
LFO speed pot and output level pot are working as it should, but the audio signal doesn't seem affected by the LFO variations.
I'm having only a triangle waveform shape on my oscilloscope (DEPTH pot middle leg) , whatever rotary switch position i'm on after some testing i must have burnt something, i don't have anything anymore on the center lug of the depth pot, but the led still blinking at the speed pot rate. Bias, Shape and offset making no difference.
First, i wanted to check about the rotary switch connections before further investigations.

Could you confirm that, regarding the schematich and pcb references, that's good :

schematic => PCB switch connector
A0 => 1
A1 => 2
A2 => 3
A3 => 4
A4 => 5
B0 => 6
B1 => 7
B2 => 8
B3 => 9
B4 => 10

all good?

and which waveform should be on switch positions :
A1+A0/B1+B0 position =>?
A2+A0/B2+B0 position =>?
A3+A0/B3+B0 position =>?
A4+A0/B4+B0 position =>?

[Taylor]

Hi,
I'm building my gristleizer, Taylor's board.
LFO speed pot and output level pot are working as it should, but the audio signal doesn't seem affected by the LFO variations.
I'm having only a triangle waveform shape on my oscilloscope (DEPTH pot middle leg) , whatever rotary switch position i'm on after some testing i must have burnt something, i don't have anything anymore on the center lug of the depth pot, but the led still blinking at the speed pot rate. Bias, Shape and offset making no difference.
First, i wanted to check about the rotary switch connections before further investigations.

Could you confirm that, regarding the schematich and pcb references, that's good :

schematic => PCB switch connector
A0 => 1
A1 => 2
A2 => 3
A3 => 4
A4 => 5
B0 => 6
B1 => 7
B2 => 8
B3 => 9
B4 => 10

all good?

Yes, that's right.

and which waveform should be on switch positions :
A1+A0/B1+B0 position =>?
A2+A0/B2+B0 position =>?
A3+A0/B3+B0 position =>?
A4+A0/B4+B0 position =>?

I don't have one built up anymore, but I think the first position should be ramp up, then ramp down, triangle, then square.

[jackwithoneye]

Hi, i can't figure out a solution to make it work.





i putted the optinnal 10uF capacitor on a switch and used the
diffeq trick with a switch to switch off LFO :

If anyone needs to disable the LFO during bypass, it can be done the same way Aion Refractor uses opposite throw of LED cathode pole, grounding the opamp output. See schematic that shows the point to connect the switch to.

Voltages :
sorry i misdraw the tL74 with 2 more pins, but you got it



This is the musikding kit, the rotary switch is plugged as told in the previous post.

The Depth pot leg2 seemed grounded, but i can't find where it comes from. (so i can't monitor any waveform on this lug). swapped pot, without success.

i resolder solder joints, and swapped TL072, no result. I don't have any extra TL074 to swap testing it.
Diodes are ok.
Based on the scematic, i checked all the +9 and -9 rails spots, it's all good.

Bias and depth pots have no effects on the audio signal.
And the LFO acts normally with the LED ( and background noise ticks) but not on the audio signal.

Any ideas?

Thanks

[Taylor]

If depth pot center lug is grounded, either you have the pot turned down all the way or somehow bridged to ground where it shouldn't be. So that would keep the LFO from modulating the FET. I would maybe remove your LFO kill mod switch while you're trying to get it working. I always recommend getting it working first before doing mods to eliminate the mods from the equation.

I see three toggle switches. One is the filter/amp switch, one is your LFO kill mod, but what's the third?

Also, I always recommend the plastic body rotary switches. It looks like MusikDing has provided a metal body switch which in my experience have a different pin layout. That might be the issue. Use your contonuity meter to figure out how the rotary is connecting. The throws for a particular pole should be symmetrical around the pole lug, like in the drawing in the PDF. I think those metal rotaries have the pole between position 1 and 2. If that's right, it would make all the wiring wrong and mess everything up. Let me know if you get what I mean here, if not I can draw a diagram.

[jackwithoneye]

Thank you for your answer Taylor
Ok i'll remove my 2 mod toggle switches. The second one is the optionnal 10uF cap, anti-ticks, which i putted on a switch. ( i didn't know if i would keep it or not)

I'd carefully checked continuity on the 2P6T before everything, and i can confirm how it's routed :





Blue wires are A1&B1 (pcb 2&7), green A2&B2 (pcb 3&8 ), Yellow A3&B3 (pcb 4&9), orange A4&B4 (pcb 5&10), red A0&B0 (pcb 1&6)
As you see,i putted jumpers over lug 4-5-6 on A, and B, to avoid dead positions on the rotary switches. So, square wave should be over position 4,5 and 6.

i assume that's i have been meticulous on this, and when i check continuity, over different lugs when it's wired, it makes sense regarding the rest of the circuit and the rotaru switch position.
I have a doubt on the FET, as i don't know how to test it, and how it should react, or give information on scope or not.(i'm still a noobie...)

[jackwithoneye]

After desoldering mod switches, i got the waveform, on the depth pot lug2, it looks ok, so the rotary seems to be wired correctly. That's a good point. Apparently, it was the switch (or the cap) on the optionnal 10uf spot which was problematic. (i dont know why, the cap was properly polarised)


The bad point is that i still don't have any guitar audio signal on the output.

edit: i'v set the shape and ofset trimpoots to get a better triangle wave shape, now it's better than on the picture

[Taylor]

OK, that's good, so your LFO is working. Using an audio probe, does your guitar signal appear at pin 1 of the TL072?

[jackwithoneye]

OK, that's good, so your LFO is working. Using an audio probe, does your guitar signal appear at pin 1 of the TL072?

yes it does

[Taylor]

OK, so your input stage is working right up before it hits the FET. Early on you said you had audio coming out, but it wasn't affected by the LFO. Now, your audio is not coming out of the output at all.

Have you tried messing with the bias pot after you got your LFO working? If you're not able to get any audio out regardless of how bias is set, I would think something may be wrong with your FET. If you can get your hands on another 2n3819, I would swap it out.