Quack Cyborg Mutation?

[strungout]

Oy.

I was messing around with a Dr. Quack, trying to get it to work with an LDR while getting rid of the distortion it was producing, when I happened to recreate that thumping sound I was having on a previous attempt, but this time it sounded better along with the distortion. The result is a synth-y, slap bass, sitar-ry, ring mod with a rough wah... *cough* Anyway, here's some clips for you guys to get an idea:
http://www.freewebs.com/fkstilt/index.htm I think the first sample almost sounds like a piano... Might need to right-click save 'em. Go, I'll wait. They were record thru windows recorder and heaphones mic in front of my bullet reverb amp, sc bridge pickup, tone @ max bright. Like the other effects like this I heard, it sounds more like a sitar the thinner the signal going in is, with out-of-phase pups for instance.

So, now, here's the schem, and  some info on what does what.

The LDR/LEDs are bound together in electric tape. Light-tight enough. The LDR specs mesured from 20M+ dark (can't read higher) to under 100R light(held up to a desk lamp). With the LEDs in the circuit, and the LDR side hooked to my DMM, I read 20M+ again, but with the guitar signal (big swing across the guitar strings) it only goes down to about 0.8M. It needs to be connected to Vb for the effect to work, otherwise it's just a lousy sounding wah.
I chose to try 2 LEDs in series because I wanted more light, and with 2, they both totally turn off. Otherwise the LED stays dimly lit, as it's supposed to in the DQ circuit. The LEDs are HD RED 1.9V @ 30mA (that's what's written on the package, no MCD marking).
The connection between the buffer output and the MFB filter can be open and it seems to just take out the clean version of the signal, you can hear the bare effect better.Likely, the 470K resistance connecting to it can be changed to affect the clean to effect ratio.
The GAIN pot following it adjusts the loudness of the thump @ the expense of the sitar.
The higher the value of C out, the thicker the thump, the lower value it is, the thinner the sitar is.
The control labeled TONE affects the sound like using a pot to control a wah would. Search the best tone for the thump or the sitar.At some setting, it sounded like a small 3-4" speaker being driven too hard.
The gain resistor in the EF will make things sound more synth-y the higher value it is (it was 2.2M when I recorded the clips).
Now that I think of it, the 100K pot in series with the LED's probably isn't doing anything that the sensitivity control does (took it out, always at max, replaced with jumper). So either would work..

Transmogrifox once told me that thumping sound was probably due to the fact that the light resistance of the LDR doesn't go down low enough for it to sweep far enough to wah. I think what I need is a brighter LED to implement the LDR/LED in the DQ, but that's another story.

Any comments, suggestions and the likes are very much begged for. Especially as how to make this as easy to reproduce as possible. It'd be great if someone with a breadboard could whip one up and tell me what they think. I'll mess with it more in the kindwhile.

Ciao.[/url]

[Transmogrifox]

I generally epoxy the LED and LDR head to head (or some other durable glue).  The electrical tape is fine for light-tightness...I know it's working for you when you're getting greater than 1 MEG from the LDR.

Use 1 LED so that you're not limiting your maximum current capacity.

The reason it sounds so trashy is that you aren't filtering any of the AC off with anything more than the slow response of the LDR.  I ended up putting a 5th order lowpass filter on my envelope follower to get a clean sound, but the distortedness is what gives the filter some of it's quack and attitude, so you may just want a single capacitor to filter it.  This may also help increase your range.

I think you do want a dim glow on the LED, but just barely enough to keep the filter down near its minimum range.  Just make the capacitors a little larger if it rests too high, then increase sensitivity....Keep it up, you have certainly made a lot of progress from the last thread about this.

[strungout]

ok, so I tried your suggestions (thnx btw). Adding some capacitance did improve the sound, but I still got no wah, guess the LDR just won't go low enough in resistance for it to work. The reason I thought I needed a brighter LED is because the wah works great if I modulate the LDR with my thumb (no distortion even), so I figured the LED was the problem. But anyway, one of my LDR leads broke and now it's unuseable. Guess I'll just take that as a sign to order one or two vactrols from SBE or something. Soon as I get some money  

One good thing tho, the lack of filtering is probly the reason why my Uglyface is so much thrashier than the one from the soundclips I heard. I'll have to try it out.

Ciao.

[RLBJR65]

Those clips are cool! I think I'd keep it and build the wah again.