CASIO SK-1 bypass Anti Aliasing filter! (diagram and MP3)

djsynchro · November 09, 2006, 06:15:29 PM

This is a mod (not a bend) to bypass the SK-1's "melody" filter.
The cutoff frequency is about half the sampling frequency which is quite low on the SK-1 (9.38 Khz)
Bypassing the filter results in a much brighter sound.

I made a ZIP archive with a text file and pics for 2 different ways of doing the mod
(From the component side of the board and if you can't get there because of your bends
also from the PCB side). All you need to do is solder a 1k resistor, and cut another one.

There's an MP3 inside the ZIP file with me playing the SK-1's preset sounds
after the mod was done. As you can hear they're now way brighter.
You can also hear some buzzy high harmonics, that's the aliasing.
I'm leaving it for yourself to discover what it sounds like with some of your bends in action!

It's in the "stuff" section at www.stikka.net
If you like the mod and feel like letting me know in the guest book, I would love that.

Synchro

andy_wheels · November 11, 2006, 08:50:05 AM

that's a great mod dude! nice one. i've always felt a bit gutted about the dullness of the sk sound and now it can be bypassed. woohoo!

nice site too. like your stickka sticking photo's. is that amsterdam?

djsynchro · November 11, 2006, 02:46:37 PM

Let me know how you like it after you've done it!
I'm so excited about this mod, circuitbending is all about generating weird (in)harmonics and a brutal lowpass filter is about the last thing you want in an 8-bit low sampling rate machine.

Yep they're pictures of Amsterdam.

moswei · July 11, 2007, 11:59:34 AM

That is a great mod.Any idea how to do it to an SK-200? cheers

djsynchro · July 22, 2007, 10:32:52 PM

You need the service manual to locate the in and output of the filter, bridge it with a resiistor, then cut the filter.
I actually had somebody who builds electronics look at the schematics for me.

pbdlugoss · April 05, 2010, 07:17:07 AM

Is there any chance I can still get the zip file for this mod?

It seems to have been removed from the site.

angrydroid · April 08, 2010, 03:51:42 PM

Maybe this will help...
http://www.experimentalistsanonymous.com/diy/Schematics/Circuit%20Bending%20and%20Modifications/SK-1%20Filter%20Bypass%20Mod.zip

It's a good mod. Best of luck.

Dj Task Manager · October 21, 2013, 10:10:07 PM

Hey, any documentation out there to do this to an SK5? Also is there a filter on the recording in that can be bypassed?

CHeeerssszzzz xxx

wax+wire · October 24, 2013, 09:40:07 PM

also keen to do this to my SK5