harmonic exciter

[Br4d13y]

what exactly does this circuit do?  i have an lm324 and want to know if it is worth building

http://www.experimentalistsanonymous.com/diy/Schematics/OOP%20Japanese%20Electronics%20Book/harmonic-exciter.gif

[Mark Hammer]

It is a version of what used to be widely known in the industry as the Aphex Aural Exciter.

IC1 in the upper left provides a gain stage that feed a state-variable filter formed by the other three sections of IC1.  That filter feeds its highpass output to the 100R resistor and diode to ground.  That provides some clipping of whatever high content is retained.  That high end and added harmonic content is then blended back in to the dry signal to achieve a clean mix that sounds brighter and crisper.

This is an "effect" whose proper clients are things like snares, acoustic guitar, Strats with underwound pickups, and other things that already have lots of top end, particularly if played through a PA.  One of the reasons why you have no idea what it does is because when people walk into a music store, plug in any humbucker-equipped guitar through one of these, and plug into a big amp with 12" speakers, you simply won't even be able to tell if its on.

[Br4d13y]

thanks mark, ive been looking for some lm324 designs