3 position waveform select -> ext. audio mod

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BijouBittersolie
 
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3 position waveform select -> ext. audio mod

Post by BijouBittersolie »

I can't remember where, but I heard mention of a mod that replaces the stock 2 position waveform selection switch with a 3 position switch of which the third position would allow external audio to be selected instead of the VCO. Did I just dream that?

BYE

Jonnay
 
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Post by Jonnay »

Maybe it was on the Synth DIY list? I seem to recall someone mentioning something like that there.

From the mods page:
Use any panel mount jack, and connect the sleeve to ground. The tip should be connected to one side of a 100K resistor, the other side is connected to the negative side of a 1uF capacitor, and the positive side connects to the point where R70 and C17 touch.
If you were to do a 3 position switch, it would be almost exactly the same (assumine you ground the sleeve), except R62 and C17 are interposed before it.

C17 is a 1uF capacitor, so you're covered there. The only difference is about 120K Ohm of resistance. Now what does this mean? I am not 100% positive on this. I think the Resistor and Capacitor make a passive lowpass RC network. If this is the case, your signal might be affected... it really depends on the cutoff frequency. (which I can't figure out. Math is hard.)

It might also affect the volume of the incoming signal. Now if this is the case, you could replace R62 with a variable resistor, so that you could change the volume of the incoming signal. You would also get an overdrive control for free. WHUTE!

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controlvoltage
 
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ey wal-lah!

Post by controlvoltage »

Perhaps your dream looked a bit like this (only with better visuals?):

Image

click 'n save as I don't have a lot of webspace...

--basically the waveforms go directly to the switch, then from there to the filter/envelope/output.... so if you add a third position it will interrupt the audio, and if you run external audio to that point it will be processed thru the filter and sequencer envelopes... I plan to do it real soon (I love beat-sync'd filter/envelope effects like crazy)

I have about 7.5mb of 303 schematics and mod notes collected so far if anybody would like them... I could email a zip file or you could host it... all just stuff found on the web so far, only a note or two of my own

Danjel
 

could u please send me the mods?

Post by Danjel »

send to [email protected]

I have been working on some mods including CV in and Gate in. I did the CVin so far and then made an external Sample and Hold circuit with it's own LFO and noise sources to modualte the 303. It has made some pretty extreme results!

I am especially trying to get details of the devilfish mods.

cheers,
Danjel

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controlvoltage
 
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Post by controlvoltage »

Sent!

Robin whittle is notoriously secretive about his Devilfish mods, although he'll probably tell you all you wanted to know about corsets and spanking if you ask him. :)

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controlvoltage
 
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Post by controlvoltage »

Jonnay wrote:...
I think the Resistor and Capacitor make a passive lowpass RC network. If this is the case, your signal might be affected... it really depends on the cutoff frequency. (which I can't figure out. Math is hard.)
I think that the cutoff frequency is the inverse of (1 divided by) 2 times Pi times the R value times the C value, or "one over two Pi R C."

I might not be remembering correctly. In any event, it only works as a filter if the arrangement is correct... just a resistor and capacitor in series will not work this way, you have to tap off of the circuit in a certain way which my ASCII skills are probably not up to.


Wave in----^^^^^-------------o
...........|......................|
...........|......................=
...........|......................|
...........---------------------------o

textbook lowpass filter. it's really just a frequency divider, if you tap off from both sides of the resistor you will get the highs... if you "look" at both sides of the capacitor as in this example you get the lows... basic stuff, sorry if I didn't explain it very well. :)

BijouBittersolie
 
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Joined: Wed Apr 06, 2005 10:33 am

Post by BijouBittersolie »

Ya I must have read about this mod on synthDIY. I think I will have to try it out once I clear some space on my bench.

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