Bit swapper?? Worth trying?

phector2004 · January 22, 2011, 09:29:50 PM

Hi everyone,

I don't know where to post this, but does anyone have a clue what this circuit would sound like? It LOOKS distorted, but not due to clipping, rather in a strange way I've never seen before

Basically, I was messing with Falstad's sim, and ended up throwing in some digital components. Swapping the ADC outputs with the DAC inputs gave me this "fat" output. The circuit itself is probably very flawed, but the results are intriguing. Is it worth getting some ADC/DACs to test this out?

Taylor · January 23, 2011, 12:21:13 AM

I think if you zoomed in on that waveform, you'd see that you have some extremely high frequency modulation going on there. I'm guessing that that particular setup would probably either sound like a bunch of hissy digital hash or else it would sound like your input due to the modulation being above the range of human hearing.

But, yes, you will get some interesting sounds by swapping bits around, dropping bits, etc. You'll want to get some old ADC/DACs though, because modern ones don't send the individual bits separately. Some of the old 8-bit ones will be ideal.

If you search something like "digifuzz" here, someone posted a circuit to do just this some years ago - it has part numbers you can try, though I recall there being some debate over whether the DAC chosen would work or something...

caress · January 23, 2011, 12:53:08 AM

hmmm in my experience bit swapping using older ADC/DAC doesn't sound significantly different than just dropping bits (bit crushing).

phector2004 · January 23, 2011, 01:06:56 AM

Thanks for the replies!

The Digifuzz looks like a "Deluxe" model of what I have going on above, using an EEPROM to do the swapping... Unfortunately there aren't any samples, but if I ever find some old DAC/ADCs (and finish my never-ending to do list!) I'll give it a shot.

Cheers,

Phil

MarcoMike · January 23, 2011, 08:34:24 AM

I guess the content in "harmonics" in the output signal, that way will depend only on the "switching" frequency... if you manage to make it proportional to the actual signal pitch, maybe...

Hides-His-Eyes · January 23, 2011, 09:17:52 AM

Instead of swapping them, try redistributing randomly?

phector2004 · January 23, 2011, 12:09:29 PM

Quote from: Hides-His-Eyes on January 23, 2011, 09:17:52 AM
Instead of swapping them, try redistributing randomly?

How would that be done? Decade counters?

I still need to see if the circuit sounds any good before adding special features!!

slacker · January 23, 2011, 12:15:19 PM

Just mix the bits up at random. You get all sorts of craziness doing this, signals than get louder as they decay for example, you can also get a lot of horrible noisy stuff, which may or may not be a good thing.

Processaurus · January 23, 2011, 05:07:20 PM

400 Hz is a better signal to sim audio circuits with than 40 Hz. 40 is sub bass...

darron · January 24, 2011, 12:06:41 AM

wait... it says T=3.34s

?

Taylor · January 24, 2011, 12:29:09 AM

That means the elapsed simulation time since opening the sim. It doesn't mean anything when looking at a static screen grab.

darron · January 24, 2011, 01:32:35 AM

Quote from: Taylor on January 24, 2011, 12:29:09 AM
That means the elapsed simulation time since opening the sim. It doesn't mean anything when looking at a static screen grab.

ah. i was thinking it meant maybe the x axis and the 5V was the y axis... that's better.. the universe is restored (:

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Bit swapper?? Worth trying?