FX Schematics

[MACHINE MEDIA]

> can anyone advise me on which schematics (from Leper's for instance) would
> be interesting to build for a synth. Yes, I know they're all Guitar
> stompers.

I don't think anyone could advise you on which ones *you* would find 
interesting :)  Keep in mind that alot of effects that sound great with 
guitar aren't all that with synths and vice versa.  The great thing about 
using stomp box schematics to build effects is that most of them were 
designed for single 9VDC power supplies and designed with low tolerances 
using cheap parts -- the hardware usually cost more than the circuitry 
inside.  Unless you are planning on stepping on them, kicking them around 
stage, and playing them with your feet -- you don't need such hardware.

> 1) a nice delay line 

Most analog delay lines (including most of the ones at Leper's) used the 
Reticon SAD 1024 IC -- they don't make them anymore.  However, Panasonic 
makes a replacement.  I reccomend getting their book "BBD Series For 
Audio Signal Delay."  They make BBD's and even the clock chips to go with 
them.  You might be better off designing a delay from the ground up using 
modern parts than trying to replicate an old one.

> 2) a pretty raw distortion 

The sky is the limit here.  Imho, most tube effects do not sound good 
with synths.  Many of the classic distortion pedals became classic 
because of their subtle charm -- most of the distortion boxes out today 
seem designed for people who can't play for audiences that can't hear.  
Anyhow, synths have much higher output voltages than guitars, so you will 
probably want to change the box's input -- maybe losing the first gain 
stage or changing the value of the input pot (typically a voltge divider 
to ground).  Otherwise, the signal might distort so much at the input it 
will make the remaining knobs useless (I've noticed this using guitar boxes 
with synths).

If I were to build a distortion box I would try to combine as many 
different elements and adjustable stages as possible, with knobs, man, 
lots of knobs eg. input level 1, gain 1, input 2 mix (dry and output 1), 
input level 2, gain 2, out 1&2 mix, FX mix, output gain, etc.  Create a 
cornucopia of clipping. Freak out to all the colors of the overdrive rainbow.
Throw in phase switches, pass filters, sustain, make it modular, go nuts!

> 3) a pretty lousy echo (verb)

For analog electronics, this is pretty much the same as a delay.  
Before digital, most reverbs were mechanical eg. plate, chamber, spring. 
Marshall Electronics tried building an analog reverb but it was too 
thermally unstable to go into production.  If you find a way of creating 
a diffused reverb effect without using DSP or tranducers, I'd like to 
know about it!!  As far as guitar effects went, most echoes were tape and 
most reverbs were spring.  I still have no clue how those Morley 
rotating drums work -- anyone know??

PEACE OUT :)
MARK