Moog Music Forum

I don't quit understand how the s+h modulation works, but I can hear it in action .
In the manual there's a short section about it with a graph but I still don't quit get it.

So if there's anyone who can explain this in a simple matter, please do.

But I have also another question. It seems when using s+h mod it sounds pretty random. This I like, but is there a way to control it so it generates a random pattern but repeats itself. Kinda of a loop. I hope this question is a bit clear.

SH is really simple actually.
It is nothing more than a slice or snapshot of a waveform fed into it. At the time the sample is triggered it holds the voltage level of the waveform until the next trigger and sample.
If you sync the trigger to the sampled waveform it should give the effect you are looking for.
To get an idea of what is happening draw a series of sinewaves with 1" from peak to peak on a graph paper.
The Y Axis is the voltage of the wave. Now, divide the X Axis evenly. at the X,Y point is the voltage that is held until the sample point.
So, if you have it synched to the wave you will get repeated patterns. Sort of. You can really bring it closer of you feed the output through a Quantizer.

Clear as mud?

The sample and hold circuit takes a sample or a snapshot of the incoming voltage and holds that voltage until the next clock signal when it takes another one. The most common voltage input to be sampled and held is noise, which when analog is infinitely random. So, a random voltage being sampled at the rate defined by the LFO knob produces a random output. On a modular synthesizer, anything can be sampled, but noise is the most common source.

Just Me wrote: If you sync the trigger to the sampled waveform it should give the effect you are looking for.

Ok so how exactly can this be done on a Moog RME.

Let's say I have a basic patch, and use modulation bus P with source: S+H / Destination pitch .

And how do I choose what s+h uses as snapshot? Is it predefined that it uses noise?

Yes it's predefined as noise.

You can plug any waveform into the S/H input jack. This cuts off the noise and uses the CV at the TIP of the plug as the sample source. (You could use a pedal or CP-251 LFO output or the Voyager LFO or, or...

Sampling the voltage of an LFO will give you a pattern like you were asking about. S&H on a sine wave results in a distinct up and down stairs pattern. Other waveforms will give you other patterns

So I would have to buy a VX352 and something to control the S+H input, like the cp251 ?

If you have the rack voyager, yes you need the vx352. If you have a normanl keyboard model, it's the blue Jack on the back lableled s&h in.

Ok, thanks for the help, I really appreciate it