What is "sample and hold" for?

[igor12]

Can somebody explain an application of a sample and hold circuit and where it can be used in the stompbox world?

[frequencycentral]

A sample and hold requires two inputs, a clock (of LFO) and a voltage for it to sample, white noise is the most common voltage used. The output of the sample and hold will then be a clocked series of random voltages 'sampled' from the random white noise source. You can apply this output to a voltage controlled filter (look at the Maestro FSH) and it will make the filter cutoff frequency go up and down by random amounts. Add an integrator between the sample and hold and the filter's control voltage input and you can make the filter 'slide' between the random cutoff frequencies. There's lots more fun things you can use them for, basically to control anything with a control voltage input.

...........have a listen to the start of 'Andy Warhol' by David Bowie, that's sample and hold modulating audio oscillators.

[iaresee]

Here's sample-and-hold in action on an isolated track:

http://dl.getdropbox.com/u/870088/sounds/modfactor/step-wah.mp3

The effect is an envelope-controlled wah, but instead of a continuous envelope control the pedal samples in the input voltage and changes it at step intervals set by the clock rate. Gives you a choppy filter effect.

[nelson]

It's also used to good effect in analog sample rate reducers.

In that case instead of a noise source being "sampled" you're sampling the instrument signal at a frequency determined by the clock.

[rogeryu_ph]

Here's sample-and-hold in action on an isolated track:

http://dl.getdropbox.com/u/870088/sounds/modfactor/step-wah.mp3

The effect is an envelope-controlled wah, but instead of a continuous envelope control the pedal samples in the input voltage and changes it at step intervals set by the clock rate. Gives you a choppy filter effect.

Sounds like a Slicer or slow gear effects?

[iaresee]

Here's sample-and-hold in action on an isolated track:

http://dl.getdropbox.com/u/870088/sounds/modfactor/step-wah.mp3

The effect is an envelope-controlled wah, but instead of a continuous envelope control the pedal samples in the input voltage and changes it at step intervals set by the clock rate. Gives you a choppy filter effect.

Sounds like a Slicer or slow gear effects?

I suppose. I've only seen the NAMM video of the Slicer and it seemed to incorporate S&H and a bunch of other stuff...flanger, wah, etc. Slow gear though, not really, I don't think. The Slow Gear was an envelope detector that adjusted output gain, right? So it raised the gain as your signal grew in strength, giving you attack-controlled fade-ins. Here's a Slow Gear type sample: http://dl.getdropbox.com/u/870088/sounds/modfactor/slow-gear.mp3

[igor12]

OK, I think I see. Thanks for the knowledge!