LF398 IC "Sample & Hold" - Any Use for Guitar?

[Box_Stuffer]

I bought 10 of these for $1 , but I have no idea if they can be used for guitar effects. I got them from stompboxparts.com, so I assumed there was some reason they sold them. I have seen some videos of people making all sorts of random sounds with them in synthesizer modules, but I can't find anything that applies to guitar.

[garcho]

A "sample-and-hold" circuit in audio is something of a random waveform generator. If you're making a guitar pedal that uses waveforms for control, as opposed to signal (those would be your guitar waveforms!), then something that generates a "s&h" signal can be useful. Pedals that have LFOs are the type that could benefit from s&h; the trick is knowing and crafting the right type of control volt/amp. Think tremolo/vibe, chorus/phaser/flanger, etc. In my opinion, s&h sounds best when the playing involves strumming big open chords, letting them ring out. Have anything in mind?

[Box_Stuffer]

Have anything in mind?

From what I understand - based on the videos I watched - the chip is basically taking tiny snippets of the waveform as it passing through at certain intervals and those are the tones being emphasized, so it's not completely random. It's kind of like time-lapse photography. I have only heard a constant steady tone passing through in the synth demos, but I have not heard a dynamic signal such as a guitar chord.

The only schematic I have found is the one from the data sheet, so I guess all I can really do is experiment. It may be so crazy it's unusable.

[Krystal]

The Lastgasp Laboratories Tone Mosaique uses an LF398. Seems like a fun device !
https://drive.google.com/file/d/1WNhuoYv-ZTVCALuVt1SabrOR-AI9hzyq/view

[ElectricDruid]

There are two ways you can go with S&H for guitar.

The first way is at low frequencies, as a modulation source. The classic "S&H" effect is feeding it a noise source and then sampling that using a slow clock. That gives you the typical "random levels" waveform, which can sound great with resonant filters, flangers, or phasers. If the source is not random (say, another LFO instead of a noise source) you can get interesting shifting cycles of levels - something with more pattern.

The second way is to feed the guitar audio direct into the S&H. For this to work, you'll need to sample at a much higher rate, at least KHz. This gives very digital-sounding "bitcrush" type sounds (although it's not technically a bitcrusher) as what you're doing is producing a under-sampled copy of the original input, complete with crazy amounts of aliasing distortion. This is what that Tone Mosaique linked above is doing.

So...yeah, lots you can do with them!