Moog Music Forum

hi all, im trying out a new project that i need some help with.

first of all, im trying to create a cutoff filter sweep on bass guitar.

i need an alternative to the ep2 expression pedal, i need something like a control voltage that can be timed - for instance say i wanted the voltage to go from 0% to 100% in the time span of 30 seconds or even 48 seconds (which could be set digitally somehow) to create a full spectrum cutoff filter sweep. i would like an alternative like this so i wouldnt have to multitask, which would cause a more uneven sweep than the gradual sweep that i could achieve from another timed cv. but how can i do this?

thanks

btw, it is heard very often in edm.

http://www.youtube.com/watch?v=Y9Goid0p4pg
2:00 - 3:00

http://www.youtube.com/watch?v=kd_hvAl_VkE
1:00 - 1:30

http://www.youtube.com/watch?v=-ce2H8PRsHo
0:40 - 1:25

It will get complicated if you only want to trigger this at certain parts of a song.

You need a very slow LFO set to ramp up- Moog Mp 201 may do that with one of its CV outs going to a MF 101. I'm not sure if it can be set that slow- for some reason I can only get my MP 201 ramp time up to about 10 secs.

I would probably try the Eventide Mod Factor myself. I'm not certain but it looks like it has a "Ramp LFO" that could easily be set to control the Lowpass Filter and timed to a slow BPM (digital clock).

For example- So with a BPM of 30 and an LFO set to sync at 16 beats your filter sweep would take 32 secs.

You can do this quite easily with MP-201 but the length of the delay might be an issue for you.

Something like:

Initial state OFF (so it starts at 0V)
Channel Mode: Gate
Gate Source: Foot Switch
FS Mode: Momentary
Gate/EG: Envelope
ENV Shape: Linear (or whatever your application calls for)
(H)old, (A)ttach, (D)ecay all set to 0 (if that is what you want)
(S)ustain level: 4096 (for 5V)
(R)elease rate: whatever you like but 4096 (which I think is only about 3 seconds; check with Amos on how to possibly tweak this)
EG Looping: One-shot

The rest you can mess with. The Gate Source can be a midi note as well.

This is pure CV voltage and if you don't have an MP-201 you will find them difficult to find at this point and potentially expensive.

Otherwise, I would recommend building something based on alot of the freely available schematics that are out there. Check Muffwiggler and their DIY section. The MISS10 series by Muff wiggler E.A.S. (Mike) specifically will give you enough ammo to build something for minimal cost to suit your needs.

Hope this helps.