[sdiy] noob questions

[Metrophage]

Hi Luke,

> Been lurking on the list for awhile now, and I've been working on a
> couple DIY projects. I want to get a couple filter kits form EFM. So
I 
> guess what I need to know is: can I just send an regular line level 
> signal into the filter? Will I need some kind of pre-amp? And will I 
> need a vca after the filter?

Analog synths typically generate and process signals which are much
hotter than most line levels. Usually 10 Volts peak-to-peak. Most audio
equipment seems to output 1V pp or less, so a pre-amp is usually needed
to process most external signals. I have quite a few EFM modules here
which aren't hooked up, so I can't check the signal levels now. Last
time I needed an external input I copied the one from Digisound 80.

A VCA after the filter might be useful if you are playing "pads" or
something into the VCFs and want a bit more articulation. Probably more
useful is VCA for cutoff and/or resonance CVs. Also, envelope
generators for the VCAs would be handy. Some simple fun can be had by
making using a pre-amp and envelope follower together, for funky
auto-wah sounds. LFO is another fun thing to tweak the VCFs with. These
can all be simply expanded upon with extras like an inverted envelope
output, slew limiter, etc.

All of the stuff you were mentioning can be a lot of fun. Keeping the
design modular allows one to try any sort of combination.

CJ

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com