Some simple tone controls

[The Scum]

The latest issue of Electronic Design had an interesting circuit, a passive variant of the ol' tilt control:

http://electronicdesign.com/article/ana ... ntrol.aspx

About $2 of parts there...$5 with a fancy knob. Simple enough that it could be wired up simply hanging on the back of the pot.

The article mentions a couple of caveats - 6 dB loss, and prone to loading. It wants a low impedance driver, and a high impedance load. Gee, like most modern I/O interfaces already provide.

Sounds like it could be really useful in the sidechain of a compressor. The compressor would set up the drive & loading correctly, and I can lower the threshold 6 dB to compensate for the level loss. I think I need to see if there's a 50K pot in my junk drawer.

In digging for that URL, I turned up an analysis of the classic active tilt control - a similar circuit in the feedback loop of an opamp:

http://www.edn.com/article/520749-Imple ... filter.php

The main differences being that it doesn't have the 6 dB insertion loss, and that the cutoffs look like opposed symmetrical shelves, where the passive version's cutoffs seem to fall to -infinity.

[germaniac]

Cool circuit, thanks for posting!

BTW, you know, that's essentially the tone control circuit in a Big Muff fuzz?

http://freecircuitdiagram.com/wp-conten ... ontrol.gif

The main difference is, the symmetrical component values of the ED circuit give a "flat mids" response, whereas the asymmetrical values of the Big Muff give a "scooped mids" response. . . .

Joe

[strdsk]

Very cool! Thanks for sharing!

[Knights Who Say Neve]

Cool, thanks for the post.

[themagicmanmdt]

be sure to mess around with the 'duncan tone stack calculator'. that thing is wonderful. it includes a fully adjustable schematic. i mean, seriously, download it, love it, and then paypal donate to the developers. (i'm not affiliated in any way, i just love it.)

[The Scum]

BTW, you know, that's essentially the tone control circuit in a Big Muff fuzz?

I kinda figured...and it looks like "classical" highpass and lowpass filters with a crossfade control between them.

I'll bet a bunch of fuzzes/distortions have similar tone stages.

Not to mention the Tonelux tilt control.

mess around with the 'duncan tone stack calculator'

Oh yeah, I've played with that. It is pretty useful...particularly in a "you can't get there from here" way, showing that it's hard to get a truly flat response with the controls centered.

I've since graduated to ltSpice, another free package that's very useful. I see Duncan has some tube models to plug into it, too!