Need some help for debugging ( or not ?) my gristleizer !

[flapi]

Hi Everybody !

I've just bought a gristleizer kit from smashing guitars ( http://smashingguitarsasheville.com/products/gristleizer-kit-pcb-version-2), and i've built it and adjusted it with an voltmeter ( i don't have any scope).

Well, at first, i can say that my gristleizer works : i can hear differences between the four lfos mods, and it does have a good response when i turn lfo and depths knobs.

BUT when i'm in the vca mod, the bias pot seems weird : i've got sound, louder and louder when i'm turning the pot all the way up, but when i'm turning it all the way down, it acts as a level control, and my gristleizer has a volume near to zero...

Is it normal ? For information, when i use BIAS pot in the vcf mod, it reacts as it should do, the bias pot controls the cutoff / resonance of the filter...

Well, thanks for any answer, tricks, help... Maybe i don"t have any problem, maybe i've got some... i don't know what to do, as it's the first i built, and i don"t know anybody who gets one...

And happy new year !

[digi2t]

First off, my unit is a Taylor Livingston (musicpcb.com) unit. It's very different from the EA units, but the units do essentially the same thing. When I first built mine, I had issues with the bias control as well, but....

It may be that your unit is not quite in the zone insofar as tuning is concerned. I screwed around for a while trying to set mine up via voltage, but when I finally did get it hooked up to a scope, I was was nowhere near the ball park. Once I scoped it, and could see that I had proper waveshapes, then my bias worked properly (or better). In any case, I find that the bias is only a "small tweak" adjuster, just to get you into the zone. I've never had to crank that knob, just small adjustments to really focus the waveshape.

Just my opinion, I used multi-turn trimmers instead of single turn trimmers for tuning my Gristleizer. I originally built mine with single turn trimmers, and it was just a bitch to tune accurately, even with a scope. With the multi-turn's, and a scope, you'll get it dead on. I found that the bias is very interdependant with the shape and offset adjustment. I just never got mine right using the voltage method.

I invested in a USB scope. 200$, and it plugs into my laptop. One of the best investments I ever made... next to my DMM. Also, I thought about buying the kit from EA as well, and I'm glad I didn't. Taylor is a cool cat, and he always answered my questions promptly when I was troubleshooting my Gristleizer build. I sent EA 2 emails concerning their kits, and I never got an answer.

Cheers,
Dino

[flapi]

Hi !

Thanks for your answer.
Well, i found what was wrong : i didn't use at first a log pot for the lfo speed, so everything i checked was wrong... Now it's ok, but i used a bad pot, so i'll need to rewire it later, when i would have bought a good 10k log pot.
But you are right, it's difficult to speak with the guys from endangered audio... but they also helped me. Well, it's like that. Hopefully, i can use a voltmeter..

Could you give me informations about your own gristleizer ? I think that i will build another one, it could be interesting to get a different one !

thanks for all !