Anybody build their Gristleizer yet, comments on it?

[jacobyjd]

Just to get my thoughts down on mods (and maybe so someone who's farther along can do some leg-work for me  ), here's what I'd like to try:

-Expression for LFO speed would be nice, as Strategy mentioned
-Some sort of filter range controls--a lot of us have experienced that it's mainly at the treble-heavy end of things. I'd like to be able to...swap sweep caps maybe (a la a Crybaby sweep switch)
-Additional LFO(s)--for modulating the main LFO, or other dastardly possibilities.

[Taylor]

There are 3 ways to do a speed exp. pedal. The really easy way is to just use a plastic switching jack that subs the exp. pot in where the speed pot was in the circuit. This disables the panel speed pot. You need to use a plastic one so the sleeve doesn't ground out to the enclosure.

Then there's the series way I mentioned a few posts back. This brings the speed pot control into play but only to limit the max sweep of the exp. pedal, which if you're using a Moog exp. pedal (my favorite) you've already got this built into it.

The third is parallel, where the panel speed pot and exp. speed pot are totally democratic. This involves sending the voltage to both of them separately, dividing it with the pots, and mixing the 2 voltages together with a resistive mixer.

Extra LFOs would be fun. Another neat thing you could do that would be a little easier would be to take the LFO out, send it into a delay pedal, and run it to its own voltage control input. So the delayed LFO could control its own speed. This is the kind of wacky stuff that's fun to do with modular synths.

[disorder]

just wondering if anyone actually fit this in a 1590bb. I see the board fits fine but the additional rotary switch, dpdt switch, and bypass switch it might be cutting it close.

[Skruffyhound]

I haven't boxed it yet, but I think it should be fine.

[Taylor]

I built mine in a BB. It fits fine, depending on how you orient the pots.

[Strategy]

Anyone try expression pedal input yet? I put one on my LFO rate pot today - a 6-pin stereo neutrik (plastic body) so that when I insert the pedal it should disconnect the pot. Not working though. pot controls LFO rate when nothings plugged into the jack, then as soon as I insert the expression pedal it disables the LFO altogether. Ideas?

should I post a pic perhaps?

- Strategy

[Taylor]

You probably have the jack wired wrong for your expression pedal. They're all different. If you're using a Moog, the positive and negative should go to the sleeve and the ring, and the divided voltage should go to the tip. You may need to bust open your exp. pedal to check how the pot is connected to the jack.

[Strategy]

Taylor

You may be right but I took a couple hours off from working on it and lo and behold I think I see the problem- I put the jack on such that the two pots connect together when inserted but, the connection to the board is then broken. I'm going to turn the jack the other way, re wire it and see if that works!!

Failing that I'll try your suggestion!

Its amazing what some food/coffee/stepping away will do for trouble shooting 

- Strategy

[Taylor]

Yeah, I find invariably that once I've lost hope, and come back to it an hour later, it's something facepalmingly obvious. Though in my case I suspect the coffee may be the cause of the problem, not the solution - too much of it, specifically.

I only said that because I built something expression-controllable for somebody and when he got it the expression didn't work at all, even though it worked fine for me. Found out that the connections and pots inside expression pedals have no standard or correlation with each other.

[Strategy]

this could still be an issue- not the coffee, but the non-standardness of expression pedals. This is a Roland EV-5.. I now have control over the LFO rate via pedal, BUT, it's erratic. To complicate matters, the pedal pot is connected to yet another pot that attenuates the range of the pedal. I'm confused by what I see inside this thing.

Symptomatically, the largest sweep range brings the pedal into some pop-snap no-sound-at-all territory with the pedal rocked all the way back, then goes slow to fast, faster and then...SLOWER again! 

I tried a "peep" photocell passive controller thing and, it's cool but doesn't get it very slow...the variable resistance may not be equivalent to 10K. But that's a start.

Will keep prodding at this...

- Strategy

[Strategy]

I can't seem to make it work...well, it's still a kick ass pedal! If anyone comes up with a replicable scheme for exp pedal input using a 'known quantity' pedal like the Moog, and can sketch a quick diagram of it, I'll try again later. Now to try the LFO out mod!

- Strategy

[Strategy]

LFO OUTPUT MOD is a success! using the + pad of the optional electrolytic cap as Taylor outlined in the documentation.

Depth attenuates the LFO output which is great, meaning no attenuator needs to be added. Was a little extreme going into my Memory Boy CV input, but sounded great on my Doepfer filter module. LFO output is active even when pedal effect is bypassed, which is great too.

OK, pics on Saturday of the final product.

Thanks to all who helped me with this fun project and thanks to Taylor for the layout and pcb run!

- Strategy

[Taylor]

Are you using the Moog exp. pedal? If so, I can draw up a diagram of how it should work tomorrow.

[Strategy]

@Taylor, no, I'm using a Roland pedal, but, I will probably get a Moog pedal because I need more expression pedals and the music stores around here (and Craigslist) have pretty good amounts of these almost all the time...and I need more expression pedals.

Thanks for the diagram!

I spent a long time last nite running Weird Sound Generator through Gristleizer, then Stage Center Reverb, then Memory Boy with the delay time modulated by the Gristle LFO. Pretty killer sounding...creepy crawly warbly synth noise music sounding like the first Cluster album or something.

- Strategy

[Strategy]

GRISTLEIZER BUILD PIX!

A team of experts was deployed to investigate the Gristleizer build.




FINDINGS
- LFO output during initial testing seemed fine with Memory Boy and Doepfer module CV inputs, but today when in use, the normal effect seemed to 'dim' in voltage when the LFO CV output was used. Further testing must be done to see if this mod causes some kind of voltage hogging/starve side effect.

- Enclosure from 1990s computer peripherals and mystery surplus rate knob appear to be 100% resistant to sharp ferret chomp attempts

- Janky hand drilling resulted in slightly off kilter LED alignment

- Effect sounds great all around and was a fun build with room for more mod experimentationbv

[Taylor]

Hey, really cool. Finally a post about electronics my girlfriend will care about - it has tiny furry creatures in it.

That knob is boss, I am a bit of a vintage knob fan.

Need to get on that diagram... firing up MSPaint...

[Skruffyhound]

Nice enclosure, good job. I like the AB switch for output to Flatscreen or printer, can you post those mods

[skweeegor]

This pedal will be my first self sourcing/non kit adventure, and I've got a really noobish, ignorant question here. I see that this pedal takes 9V and I've seen people mentioning that they've built power supplies for them. Can it not just be powered with a 9v dc wallwart or is there something wrong with that picture that I'm missing?

[Taylor]

The Gristleizer needs to run on a bipolar power supply, which means both positive 9v and negative 9v. But my PCB has a built in voltage converter section, so you feed it a regular old +9v supply and it sends negative 9 volts to the parts of the circuit that need it.

So you don't need to build a separate power supply for this PCB, those comments would be regarding some older PCB without the built-in charge pump.

[skweeegor]

Awesome, thanks.