Anybody build their Gristleizer yet, comments on it?

[lulu_joe13]

I am trying to fix my rather road weary gristleizer. The vcf is working fine but I get no output when I switch to vca? Any suggestions of how to trace this. I have a mult and an audio probe but looking at the schematic I can't figure out which traces and components are the vca. Any help would be much appreciated. JoeF.

[BetterOffShred]

So I've finally built my Gristleizer board, and hooked up all the pots and rotary switching as per the wiring diagram in the build document.

I've used a 2N3819 JFET  and 2N3904 and 2N3906 as indicated
7660 power chip (measured +9.35v and -9.27v) outputs
1N34A diodes
TL062   (Started with TL072)
LM324  (Started with TL074)
3P4T switch
Stock Pot values C100k for Bias
100k Trimmers for "Shape" and "Offset"

So it fired up and I get sound through it, the volume works, the Bias knob changes the color as it's moved, the LED flashes and changes rate with the speed pot, and there is some tick, which goes away when Depth is turned all the way down (which I assume means the depth pot is actually working) but other than that there is very little actual Tremolo type sounds.   The DPDT for VCF/VCA also definitely changes the sound, one being more trebley as reported elsewhere, but still no real pulsing sounds.   
I tried flipping my 2N3819 around and it seems to have no effect really.   The 3P4T selector has minimal effect on the sound, though some is noticeable with what little tremolo sound I can hear.  I used the Meter to identify the A)1-4 and B)1-4 and wired according A-1 B-6 as per the drawing provided. 

So am I just needing to find a real sweet spot on the shape and offset trims here? Or does something sound fundamentally wrong?  I don't think I will have access to a scope, so I'm not sure if that's an option currently.  Everything else I've read, people plugged it in and had choppy tremolo goodness on 3 of the 4 modes, having to really only dial in the triangle wave.  So plugging mine in and having barely noticeable tremolo on any setting which doesn't seem to get better with crude turning of the shape and offset trimmers audibly at all concerns me that something else is jacked up.   I know the LFO is working because the LED is blinking and I get tick that goes away..   Anyway  I'm open for some suggestions if anyone has any!   
Thanks

[Taylor]

I am trying to fix my rather road weary gristleizer. The vcf is working fine but I get no output when I switch to vca? Any suggestions of how to trace this. I have a mult and an audio probe but looking at the schematic I can't figure out which traces and components are the vca. Any help would be much appreciated. JoeF.

The VCA/VCF switch just switches between a cap and a resistor, and in VCF mode adds another cap in a feedback loop. The parts are the 6n8 caps and 47k resistor directly next to pin 6 of the TL072, right side of the board. So your issue probably lies in that resistor, or the switch wiring.

[Taylor]

So I've finally built my Gristleizer board, and hooked up all the pots and rotary switching as per the wiring diagram in the build document.

I've used a 2N3819 JFET  and 2N3904 and 2N3906 as indicated
7660 power chip (measured +9.35v and -9.27v) outputs
1N34A diodes
TL062   (Started with TL072)
LM324  (Started with TL074)
3P4T switch
Stock Pot values C100k for Bias
100k Trimmers for "Shape" and "Offset"

So it fired up and I get sound through it, the volume works, the Bias knob changes the color as it's moved, the LED flashes and changes rate with the speed pot, and there is some tick, which goes away when Depth is turned all the way down (which I assume means the depth pot is actually working) but other than that there is very little actual Tremolo type sounds.   The DPDT for VCF/VCA also definitely changes the sound, one being more trebley as reported elsewhere, but still no real pulsing sounds.   
I tried flipping my 2N3819 around and it seems to have no effect really.   The 3P4T selector has minimal effect on the sound, though some is noticeable with what little tremolo sound I can hear.  I used the Meter to identify the A)1-4 and B)1-4 and wired according A-1 B-6 as per the drawing provided. 

So am I just needing to find a real sweet spot on the shape and offset trims here? Or does something sound fundamentally wrong?  I don't think I will have access to a scope, so I'm not sure if that's an option currently.  Everything else I've read, people plugged it in and had choppy tremolo goodness on 3 of the 4 modes, having to really only dial in the triangle wave.  So plugging mine in and having barely noticeable tremolo on any setting which doesn't seem to get better with crude turning of the shape and offset trimmers audibly at all concerns me that something else is jacked up.   I know the LFO is working because the LED is blinking and I get tick that goes away..   Anyway  I'm open for some suggestions if anyone has any!   
Thanks

It sounds like all of the sections are basically working, except perhaps the transistor itself. We know that your LFO section is oscillating, and the Bias knob changing the sound indicates that if the transistor were working right, you'd have a cyclic effect. It's possible that it's down to getting the trimpot settings tuned right, because if the LFO signal getting to the FET is too far offset for example, it will have a small amplitude and not really sweep the VCA/VCF enough to give an audible effect.

I might try a new 3819 to eliminate that as the issue, and maybe just reflow the solder joints on the diode and passives surrounding the FET, in case something is shorted there that's keeping the LFO from modulating the FET.

[lulu_joe13]

Thanks Taylor! Fantastic pcbs and support! Love my Gristllzer!

[BetterOffShred]

It sounds like all of the sections are basically working, except perhaps the transistor itself. We know that your LFO section is oscillating, and the Bias knob changing the sound indicates that if the transistor were working right, you'd have a cyclic effect. It's possible that it's down to getting the trimpot settings tuned right, because if the LFO signal getting to the FET is too far offset for example, it will have a small amplitude and not really sweep the VCA/VCF enough to give an audible effect.

I might try a new 3819 to eliminate that as the issue, and maybe just reflow the solder joints on the diode and passives surrounding the FET, in case something is shorted there that's keeping the LFO from modulating the FET.

Thanks for looking at my post!   

I have 3, and I actually got out of bed last night after laying there a while thinking about it and tried another one of them, with the same results.   I have one left I'll try when I get off work, and then a load of J201's and 2N5457's etc (with different pinouts of course) which I can try if that one doesn't work, hmm I even have some MPF102's.  I'll put on the reading glasses and reflow all the solder on the back of the board as well, though it looks pretty good to me. 

This is my first PCB build, and I put everything on top, where the values are marked, and soldered the back, that's correct right?    Built tons of stripboard layouts, but never a PCB
And then looking at the board with the label side up, pot connections at the bottom, I hooked the pots up as:
321  321  321  321   
I had them the other way before (123) and the volume and speed worked backwards so I assumed the others did too. 
Also, right above the pads for the trim pots (outside the white box) is another hole which seems to be linked to the wiper of the trim pad? Is that the case for all 4 locations for using a larger variety of trim pot?  I used the small variety and just soldered to the holes inside the box.   

EDIT:  Another thing I noticed was that the "Minimum" speed of my LFO seems much faster than videos I've watched, and I think a few pages back it was indicated this speed was tied to the 470n cap right next to the TL074.   I definitely have a 470 in there (474J100), I took tons of pictures so I've basically been agonizing over every component value which I checked every single one, including resistors.. ugh.

Thanks again for looking.

[Taylor]

This is my first PCB build, and I put everything on top, where the values are marked, and soldered the back, that's correct right? 

Yep, that's right.

And then looking at the board with the label side up, pot connections at the bottom, I hooked the pots up as:
321  321  321  321   
I had them the other way before (123) and the volume and speed worked backwards so I assumed the others did too. 
Also, right above the pads for the trim pots (outside the white box) is another hole which seems to be linked to the wiper of the trim pad? Is that the case for all 4 locations for using a larger variety of trim pot?  I used the small variety and just soldered to the holes inside the box.   

That's right, the extra hole is just to accommodate different types of trim pot, and it sounds like you've got the pots in the right way now.

EDIT:  Another thing I noticed was that the "Minimum" speed of my LFO seems much faster than videos I've watched, and I think a few pages back it was indicated this speed was tied to the 470n cap right next to the TL074.   I definitely have a 470 in there (474J100), I took tons of pictures so I've basically been agonizing over every component value which I checked every single one, including resistors.. ugh.

Could you post a photo of your build? Maybe there will be something that pops out as a problem.

[BetterOffShred]

Could you post a photo of your build? Maybe there will be something that pops out as a problem.

Yes I know everything is too long, I don't have access to my drill press so I figured Id "Squid" it up and try it out, though I'm not really that great at making neat wiring to be honest!
thanks!

[BetterOffShred]

Well I reflowed solder and double checked components, tried a j201 with legs bent to match socket, that didn't work either.  I checked voltages at all places on the board that are shown in the schematic and I have matching values in all locations. 

One thing I've noticed is that as I leave it plugged in, the "minimum" speed becomes faster and faster as if I'm slowly turning the knob up but I'm not.  This is really strange as I indicated earlier I thought the minimum speed was way faster than the other videos I've watched.  So yeah. I'm kind of blown away right now.  Not sure what to try. I think I'll try a different 470n and maybe some 1N4148 diodes instead of the germaniums.. I can post crazy high resolution pics of everything if anyone is willing to look.  This has me at a loss

[BetterOffShred]

Alright so my 2N3819 is not the same Pinout as other units .. I threw it on my mega328 tester and figured out what was what.  So now I got chop, but the rate is still way fast after I put in an 800n, and it still speeds up over time.

[lulu_joe13]

@Taylor. OK. So I have also built your Tap Tempo Tremelo and added a 5v CV out. I am wondering if I can add an input to the Gristlizer to use this instead of the internal oscillator? I want to switch not sum.
And while we are at it. Where would I grab the internal oscillator to send it out.
Covered previously? Tx. JoeF.

[Taylor]

@Taylor. OK. So I have also built your Tap Tempo Tremelo and added a 5v CV out. I am wondering if I can add an input to the Gristlizer to use this instead of the internal oscillator? I want to switch not sum.
And while we are at it. Where would I grab the internal oscillator to send it out.
Covered previously? Tx. JoeF.

Assuming you've added filtering on the TAPLFO's PWM output to get your CV out, you could swap between that and the wiper of the depth pot on the Gristleizer. Off the top of my head I don't remember the scaling of the LFO coming out of the depth pot, so the two LFOs may or may not sweep through the same range when you switch between them.

To send gristleizer's LFO out, you'd just take it from the depth pot wiper, and I'd probably add an opamp buffer so that whatever you're modulating with it doesn't affect it oscillating.

[Taylor]

Alright so my 2N3819 is not the same Pinout as other units .. I threw it on my mega328 tester and figured out what was what.  So now I got chop, but the rate is still way fast after I put in an 800n, and it still speeds up over time.

Do your +9V and -9V rails stay stable over time? If something is weird with the power supply it might cause that drift.

[BetterOffShred]

Alright so my 2N3819 is not the same Pinout as other units .. I threw it on my mega328 tester and figured out what was what.  So now I got chop, but the rate is still way fast after I put in an 800n, and it still speeds up over time.

Do your +9V and -9V rails stay stable over time? If something is weird with the power supply it might cause that drift.

Thanks for the reply Taylor  I'm sure I'm getting annoying, but this is really weird!  I've built tons of effects and I'm no slouch with a soldering iron, which of course are famous last words I'm sure!  That being said I'm beginning to suspect my D1 (the schematic has it as D1, but it's D2 on the board itself) is damaged or something.  If it was not operating correctly it could be allowing both sides of the speed cap to approach the same potential, thus speeding up over time?   

The 9v +and- were consistent every time I checked them while I had it plugged in for like 10 minutes.   If the Diode doesn't fix it, I'll leave it plugged in for like an hour later tonight and record before and after values.   Thanks again for looking,  I really want to gristle 

[BetterOffShred]

Yeah totally that diode.  I went to pull it out and it was broken in half.  Luckily some D9E's I ordered for my Laika and/or Harvey Dent board I bought from Dino (thanks boss) arrived today from Bulgaria.  So I sockets one of those and it's amazing.   I'll spend a little time dialing it in but it's working great!

[Taylor]

Great to hear! Weird about the broken diode, there's no significant current flowing through there, but I guess that's glass for you.

[BetterOffShred]

Yeah I threw the DVOM on the D2 and it was like -2.1v on one side and like -1.5v on the other.  Then the suspect diode.. -7.8v one side .. 0.0v the other.  So yeah. That cap was slowing reaching the same potential on both sides raising the speed.  It sounds really great now.  I tried for funsies to get a 2n5457 to drive the circuit but it wouldn't.  The 2N3819 sounded good so why mess with success.  I have a little tick in the square wave setting but I dialed in the triangle really lush and the ramps both sound super great.  I haven't tried any of the detick stuff yet and I have long leads on everything as I was troubleshooting it so I'm moving forward with boxing it up.  I love it.

[lulu_joe13]

Tx again Taylor. JoeF.

[peAk]

Hey Taylor,

Just finished up my Gristleizer and everything is working nicely.

My only question is, and I ask this even after reading through these 17 pgs, what was the end result of getting rid of the LFO ticking? From what I have read this is what I have came up with:

1. Use the optional 10uf cap

2. Run a large electro cap across the +/- TL072 (Is this the same as using the optional 10uf cap?)

3. Use shielded cable for the input/ouput

4. Disconnect the LFO LED

The only one I have tried is the optional 10uf cap and I seem to be getting some ticking still. Now mine is still unboxed so I assume some of the ticking could go away with it boxed?

Anyway, what are your thoughts/experiences with this and what would you say has been the most successFUL with eliminating the LFO tick?

Thanks!

[BetterOffShred]

I believe the earlier suggestions for a "De-tick" cap were on pins 4 and 11 of the TL074, which I tried on my build and had no luck with.   It says it needs to be fairly large, so I just got some 470u's in that I'll try again.  I had a noticeable tick reduction by going to a LM324 and a TL062, but it also required me to readjust my wave shape and offset trimmers.   It was actually easier with the LM324.  Mine now only ticks slightly on the Square wave setting, and I haven't shortened any of the wires or used shielded cable yet as I've been extremely busy with work and haven't had any soldering iron time.   The other 3 settings are so damn good I don't even care about the square wave setting.  I have a few different Trem's and the VCA stuff is so nutty this pedal just rocks.   Hope that helps a little!