building a REAL bitcrusher/aliaser

[Fleetdog]

Caress, I was wondering if we could get an update on this.  Specifically, what chips did you wind up getting and how did your bit crusher turn out?

[dirk]

Doepfer is soon comming out with a bitcrucher and samplerate reducer.
http://www.doepfer.de/a1891.htm

[bighead]

This guy has some awesome bit crushers. I can't find any of his layouts anywhere so I am assuming he only offers them for sale. Check out the BugCrusherMicro and the  BabyBugCrusher9volt. These things sound great.

http://www.bugbrand.co.uk/pages/sounddevices.htm

[dano12]

This guy has some awesome bit crushers. I can't find any of his layouts anywhere so I am assuming he only offers them for sale. Check out the BugCrusherMicro and the  BabyBugCrusher9volt. These things sound great.

http://www.bugbrand.co.uk/pages/sounddevices.htm

+1 on Tom at Bugbrand. Very cool guy. I don't know about layouts, but he does have a lot of schematics available:

http://www.bugbrand.co.uk/pages/electronics.htm

[Fleetdog]

Actually, it seems he has the schematic and a layout for the BugCrusher on there.

That may be worth a build, but if I could truly get a binary representation of the wave at any give time, I have some interesting ideas about really dropping bits to loose resolution without adjusting the sample rate.  The main problem I'm having is finding suitable chips.  I do think I found a few promising ones on mouser though. I'll have to do a bit more research before placing any orders though.

[darron]

i  checked out the bug. though cool, it just doesn't get that flawless tone like an atari or garage band's bitcrusher filter. the AD/DAC sounds more interesting

[caress]

Caress, I was wondering if we could get an update on this.  Specifically, what chips did you wind up getting and how did your bit crusher turn out?

i actually haven't had time to perf it up because of way too many other obligations, although i plan on getting started before the spring...    you should ask sir hc, though, as i plan on using his schematic as a jumping off point.

dirk, the doepfer version looks pretty rad.   i'm thinking about getting one, pending pricing...

theharvestman.com  makes some really cool modules including a nice bitcrusher.  i emailed him about some info, but didn't get a response...  his tyme safari is pretty amazing as well!  definitely max/msp-ish.   

[Fleetdog]

Do you still have that schematic?  I'd love to take a gander at it.

[caress]

i thought i might revive this as i've built one up with a great enclosure i might add... but have had some issues. 

as for for the changes i've done -
i've used switches for the a/d->d/a bit conversion to switch from 8 bit->1 bit.
i'm running the lm741s on +/-12v and the digitals on +5v.

the problems i've had are -
the ad0804 gets pretty hot.
the input lm741 gets REALLY hot, too hot to touch actually.
it worked great for about 2 minutes, then kind of shut down.  i probed and was not getting signal past the lm741 -- i triple checked my connections and reflowed my solder joints, i switched the lm741 and even wired another directly to the pads (bypassing the socket in case that was the issue).

there was some intermittent signal once or twice, but i couldn't connect it to anything that i was doing... i'm so confused and so close to the end!   

any help?

EDIT: i forgot to add i'm using this schematic:
http://experimentalistsanonymous.com/diy/Schematics/Fuzz%20and%20Fuzzy%20Noisemakers/Digital%20fuzz.bmp
and the "digi fuzz" by sir h c as another reference

[caress]

this is really a final bump.

but as an update, i got everything working fine after i messed with it a bit more.  turns out i had +9v and -12v, so i was probably a bit misbiased... i got the +/-12v and it fired up right away!
everything working great for 15 min or so.  then i shut off the pedal and did something else for a minute, then came back to turn it on and i get nothing.  argh...

still the same problem with signal not passing to pin 6 on the lm741 and the ad0804 getting hot.  it was working just before!  aaah

[e45tg4t3]

hi there...
the schematic has got a little error... you should wire resistors between the adc outputs and the switches so you don´t pull the outputs oft the adc directly to ground...
IMO about 5k-10k would bei enough...

Best Regards
Benny

[caress]

how come the adc outputs can't go directly to ground?  what will happen?

[Fleetdog]

It seems to me that the switches are backwards.  As drawn the switch decides if the output of your A-D is tied to the input of the D-A or if the output of the A-D is tied to ground and the input of the D-A is left open circuit.  When you drop a bit, you want to open the circuit of the A-D output so it isn't trying to dump current to ground when that bit is high (could be your heat issue) and you want to tie the input of the D-A to ground (or +5V) so you know the value of that input is steady and not just a floating open circuit which could look high or low to the circuit at any given moment. 

If you reverse the switching like this, I don't think you would need resistors between the switches and ground.  I think what Benny was pointing out is that as drawn if you want to drop a given bit you tie that output directly to ground. When that bit is low, you don't have a problem.  When that bit goes high though, you just shorted 5v to 0v the poor little output section for that bit i is trying it's hardest to source a ton of current (something it is likely not good at).  That could easily heat your chip (possibly cook it all together).

[e45tg4t3]

yeah that's what i wanted to say...^^ but if you gonna reverse the switches like mentioned you should connect the inputs of the ADC with resistors to ground(10k should be OK)... because inputs need logical high or low otherwise they could cause problems... well either way it should work then... would you post some clips if it's working?

Best Regards
Benny