**Gristleizer Build Report!!!** Sound clips for normal people inside!

[jacobyjd]

Finally a real build report for this goddamn thing!!! Many thanks for the superb effort, Josh.
I made my board at the same time, but still need the rotary switch and JFET. I'm actually thinking of making it a non-stomper.... maybe something to set on the amp with controls and switches on the front so I can twiddle the knobs without bending over.

That's not a bad idea--I know the one in the youtube video is built that way.

However, that video is a little misleading in some aspects--I thought this thing would self-oscillate. It does not--you have to have some sort of input, so take that into consideration. I could see that setup working well for some crazy feedback manipulation, or you could probably mod it pretty easily to oscillate.

I may end up hooking mine up to my cacophonator to do some cool ambient stuff, just to see what I can come up with.

Yep, that's what I was thinking. Put something in front of it that self-oscillates.

Josh misunderstood my comment. I'm going to put mine last in the effects chain and just sit it on top of my amp to make twiddling with the controls while playing easier.
   Having it self oscillate to make a self contained noise unit isn't a bad idea either, though!!

No problem--that's what I figured. I just wanted to clear up that this isn't a noisemaker--based on the info in various places on the net, I was under the impression that it would self-oscillate. YMMV though.

Sounds great! The VCF stuff reminds me of the old leslie simulator circuit, from which I think the original Phozer was based on. Psychedelic, man... 

I know what you mean--the VCF can get pretty wild.

[Tonemonger]

I know that circuit ! - Its from an old english mag. Never quite got it happening , I'll have to dig it out again.
A lot like the sort of thing that Lovetone would make.

[loss1234]

HERE IS THE dc TO dc converter part number and mouser code

Mouser #:      580-NMH0515SC     
Mfr. #:    NMH0515SC
Desc.:    Low Power (1.5W-9W) DC-DC Converters - SIP 2W DUAL OUT 5-15V Dual Output

thanks

[thedefog]

Anyone try this guy with ICs other than 741s? Like a TL071? Just wondering because I'm going to be starting my build next week.

[jacobyjd]

Anyone try this guy with ICs other than 741s? Like a TL071? Just wondering because I'm going to be starting my build next week.

TL071s should work fine--AFAIK, any single opamp will do for the GM project layout--just make sure your pinouts match! If you're doing your own layout, any opamps will do.

[Taylor]

Isn't the 741 supposed to be pretty junky? Do you guys think that's kind of the point?

I probably won't build this, but I might do a layout for dual opamps if anyone's interested.

[jacobyjd]

Isn't the 741 supposed to be pretty junky? Do you guys think that's kind of the point?

I probably won't build this, but I might do a layout for dual opamps if anyone's interested.

Well, the effect is definitely intended to be more of a lo-fi thing...mine doesn't come off that way in a lot of settings though.

In all reality, when we're talking the world of guitars and amps, the negative characteristics of the 741 don't really make themselves apparent to me. If you think about it, there are a lot of circuits that use 741s to good end.

The only real advantage I could think of (besides marginally better fidelity, I suppose) is space saving, and for that, a quad opamp paired with a single would probably serve better.

[Taylor]

Yep, now that I see there are 5 singles, a quad plus a single would be best. If there was enough interest, I could even do a fancy double-sided Gerber layout and we could all go in on the board manufacturing, but something tells me there wouldn't be enough takers.

I just found a free CAD program for Mac, so I'm kind of itching to use it on something.

[tiges_ tendres]

Yep, now that I see there are 5 singles, a quad plus a single would be best. If there was enough interest, I could even do a fancy double-sided Gerber layout and we could all go in on the board manufacturing, but something tells me there wouldn't be enough takers.

I just found a free CAD program for Mac, so I'm kind of itching to use it on something.

I'd be down for at least 3-4

[Dan N]

Yep, now that I see there are 5 singles, a quad plus a single would be best.

No! Don't run the audio in the same chip as the lfo! I speak from experience  .

[Tonemonger]

 Found it !
PRACTICAL ELECTRONICS July 1975.
So the good old 741 was probably state of the art.
Taylor- If you could re-model it you would probably make a lot of people pretty happy .
The veroboard layout in the mag. is 26 lines of 43 holes.

[Taylor]

No! Don't run the audio in the same chip as the lfo! I speak from experience  .

Perhaps IC1, 2, and 3 could be in a quad and IC4 and 5 could be a dual? 2 ICs instead of 5 is a decent improvement, right?

Although LFO ticking seems more inkeeping with the industrial background of this effect...  

I like board-mounted pots, so I'll probably do those, because it wouldn't preclude offboard pots if that's what you like.

[Taylor]

Started a thread about this so as to not derail this build report thread too much:

http://www.diystompboxes.com/smfforum/index.php?topic=79078.0

[deathfaces]

AWESOME REPORT!

I've been working on one of these for a few months, due to time. Could you sketch up the rate led circuit for me? i checked the GM notes and don't understand the "led plus load to the collector" part.

Again, fantastic report, i'm super stoked to get mine up and running.

[jacobyjd]

AWESOME REPORT!

I've been working on one of these for a few months, due to time. Could you sketch up the rate led circuit for me? i checked the GM notes and don't understand the "led plus load to the collector" part.

Again, fantastic report, i'm super stoked to get mine up and running.

This should do it for you: http://www.diystompboxes.com/smfforum/index.php?topic=79078.msg657184#msg657184

The base of the transistor goes to the LFO, as stated...which is pin 6 of IC....um...1(? Don't hold me to it ) on the Gaussmarkov project site.

[thedefog]

Hey guys,

I finally got the money to get the remaining part order for my build (yes I'm that poor). I just finished populating up the pcb last night, so now I just need to do some wiring and I'll fire it up and let you know how it went, along with some audio/pictures.

I ended up using the 741s, as I had lots of them and they're super cheap. Didn't socket them, so I can't swap out to try others (sockets are more expensive than the chips!).

It may be a few days or so... Plus I have to figure a work-around for the selector switch. I didn't plan on using the standard rotary, for cost reasons (and the fact that I have tons of normal switches).

Ray Wilson over at Music From Outer Space has a nice solution for 4 waveform selection that he uses in his Sound Lab Ultimate. It's a combination of a 2-way selector switch and a 3-way, where the two way selects between a square & the lower 3 way switch with triangle - ramp up - ramp down. See in this picture of my build here: http://www.flickr.com/photos/33480248@N05/3657649691/sizes/l/in/set-72157620494189044/

[glacial23]

1. there's an extra pad for the FET on the gm layout--it definitely skips a hole, so check the schematic before you cut the leads. I didn't, and I had to relocate it to the underside of the board. No biggie--I only had one of those

THANK YOU!

This solved the problems with mine not working, I think. It's definitely sounding much better!

Now to finally think about an enclosure for it...

[deathfaces]

Fired this up last night and it makes sound, but not the right sound. Unless bias is cranked, it sounds like a clean guitar signal and the LFO in parrellel, lots of ticking, almost like an oscillator because depth knob adjusts the amount of tick. Ticks even without input. Shape and offset trimmers appear to do nothing.

"7. Watch your wiring--the LFO can get ticky (even w/ some bleedthrough to the bypassed signal) if you're not careful. The higher you crank the Bias control, the worse it'll get. "  = What do you mean by this? Watch wiring how, because my wiring appears sound, but still ticksssssssss

Advice?

[jacobyjd]

Fired this up last night and it makes sound, but not the right sound. Unless bias is cranked, it sounds like a clean guitar signal and the LFO in parrellel, lots of ticking, almost like an oscillator because depth knob adjusts the amount of tick. Ticks even without input. Shape and offset trimmers appear to do nothing.

"7. Watch your wiring--the LFO can get ticky (even w/ some bleedthrough to the bypassed signal) if you're not careful. The higher you crank the Bias control, the worse it'll get. "  = What do you mean by this? Watch wiring how, because my wiring appears sound, but still ticksssssssss

Advice?

Mainly, I'd suggest keeping all connections to the rotary switch/depth/bias/speed controls away from any signal connections. If you're not hearing much effect on the signal, something is wrong--the effect should be very obvious with the bias cranked. Is your power supply regulated? Make sure you're getting the proper +/-9v to all necessary locations.

The shape and offset trimmers are only to fine-tune the sine wave LFO.

It sounds like your problem might be with the rotary switch wiring--re-check that, because your LFO might not be hitting the audio signal at all

[deathfaces]

It sounds like the LFO isnt hitting the signal at all, like you suggested.  I checked the wiring in the rotary and on the stomp, and the signal appears to be heading in the right directions.  I'm using a charge pump with a ibanez 9v adapter so it should be pretty good. Pretty stuck here...

Here's some photos, maybe you can see something i cant.

High-RES: http://www.mediafire.com/?ng4fmm1ax0c