death by audio robot

[illcom]

I would like to build this one
it souds amazing if your into that kind of fuzz 8bit sound
http://www.youtube.com/watch?v=NZKeGsWRRm0

[illcom]

That would be a start

[jkokura]

Looks like the centre of that circuit is a 16 pin IC of some kind, and my bet is it's a PIC or some kind of programmed computer or something like that. But I'm cynical and pessimistic about stuff like that.

Jacob

[madbean]

It's an HT8950---voice modulator. Apparently it's pretty close to this (maybe exactly): http://www.generalguitargadgets.com/projects/20-modulationecho/124-dh-pitch-shifter

It's actually 18-pin. Anyway, I ordered a couple of those ICs. I'm pretty curious about this thing. It looks like a lot of fun!

[jkokura]

See there, my cynicism strikes again. I was so pessimistic I didn't even bother to count the pins. I would build this though, if it were possible. Crazy noisemaker.

Jacob

[gtr2]

that thing is sick 

[eniacmike]

It's an HT8950---voice modulator. Apparently it's pretty close to this (maybe exactly): http://www.generalguitargadgets.com/projects/20-modulationecho/124-dh-pitch-shifter

It's actually 18-pin. Anyway, I ordered a couple of those ICs. I'm pretty curious about this thing. It looks like a lot of fun!

I am going to give that ggg project a shot. I ordered an IC from small bear. It looks like a lot of fun.

[eniacmike]

I built up the ggg project tonight. I am having problems with the dry mix controls, but I will try to fix that later. I am getting sound off the chip and it is really fun.

here are my notes:

this layout is really bad and baffles me in alot of ways. It is HUGE yet resistors are still standing up none of the spacing is really right except for the ic's and the electrolytics.

the oscillation knob is crucial to dialing in the sounds. I am still trying to figure out exactly what this thing is doing to the input. The 7 position does go from low to high but it doesn't really have any tuned intervals. I want to say it almost goes from male to female like if you had a voice changer/gender changer.

I get some really cool chimey sounds like the guitar is a wind chime or something. and I get a really cool almost tremolo/vibe sound out of it in certain settings.

I haven't been able to get the robot or vibrato settings to work. I don't have a momentary switch but I tried just tapping the pins with a wire connected to ground and it doesn't do anything. neither does holding the ground wire to the pin.

also it seems like the chip can't really handle guitar level signals. It overloads if you pick normally, the best way to play with it is soft finger picking or muted strings. that being said it also lacks sustain.

I am going to play around with it somemore tomorrow.

[eniacmike]

okay I got the momentary switches working now and I got the mix working. I think part of the problem is the opamp is running on 3.1v so it is rail clipping. the schem shows a really weird power supply portion for the board and two different layouts for single battery and dual battery operation.

but some cool sounds in it. I am waiting on a big enclosure to come in so I can box it up and then I'll post a video.

[illcom]

hey Eniacmike
thanks for trying all that
I'm looking foward to seeing your video

[madbean]

Mike, you could put another 10k resistor to ground before C3 to form a voltage divider with R4. This would knock down the input signal to the chip.

[eniacmike]

Thanks! I will try that I think I can tie on the the leg of r4 and then to the wire that goes to the 1st lug of the dry mix.

I was getting some really cool sounds yesterday with it. dropping the clock speed you get some really cool bizzare trem/vibe sounds. Like depending on what note you play and the dynamics the speed changes. It was really bizzare I guess when it maxes out the sample with bigger waveforms or louder wave forms has to adjust the sample speed or something. I have no experience with digital though so I might have it completely wrong.

This project is really weird becuase there seems to be alot of room for improvement but in the end you are still going to have an extremely lo-fi sounding effect. I read some talk about using a compander/expander before and after the chip but it sounds like alot of work for an 8bit toy.

[madbean]

I actually thinking about the compander thing this morning as I was mulling over your 'hot signal' problem. It seems simple enough to breadboard as is, so I might have a go at that when my chips finally get here from HK.

[eniacmike]

I tried the voltage divider and it doesn't really change anything. the distortion I am getting almost sounds like crossover distortion or at least it sounds kind of like the zvex machine pedal.

also when I roll back the volume it isn't really feeding enough to keep the holtek running. I also get weird unpredictable volume swells during sustain at times. It sounds really cool but I can't seem to repeat it.

the only sounds this gets that is close to the dba robot are the octave up and the octave down. I can't get the fuzz tone or the arpeggiator. it does get alot of other cool sounds (mostly crazy dissonance augmented 5ths, semitone down, etc)

[illcom]

I wonder what the ggg project would sound like if you were feeding a fuzz into it
And when your talking about rolling back the volume is it the effect volume or the guitar's
I hope you'll find a way, i'm not paying 250 for a dba robot, and I would like to build this one
Anyways , nice work
Pat