KMD Analog Delay Question/Tone control

[trovador]

Glad you found that version.

[trovador]

A great deal, actually. Split that 27k resistor into a 15k and 12k in series, with the 15k "first". Run a .01uf cap from the junction to ground. If you find that doesn't cut enough treble on successive repeats, use .012uf.

Is the mod that you suggest similar to this "low pass" mod on the DM-2:

http://www.jhspedals.com/products/mo...w-pass-toggle/

[trovador]

Mark, I think I got it. I'll give it a try.

[Mark Hammer]

I think it's similar, but the delay time is too short to tell the difference between fixed lowpass filtering applied to the entire delay signal, and "progressive" lowpass filtering of the subsequent repeats.

But, yes, what I suggested is somewhere in the same neighbourhood, in terms of moving the delay repeats a little more in the background.

Remember the earliest days of "3-D" gaming? Games like Wolfenstein and Doom would make many people nauseous, because everything, whether foreground or background had the same resolution and "crispness" so it was hard to allocate your attention just to stuff in the foreground, as you moved and the perspective of everything shifted. When Nintendo 64 came out, and they started leaving foreground stuff nice and crisp, and blurring the background, 3-D games started being far more playable, because the added depth of field allowed the user to allocate their attention as they wanted, without distractions fragmenting your attention.

Dulling out the repeats has a similar effect. It perceptually distinguishes the dry and wet signal so that the wet signal turns into ambience and "landscape", as opposed to what you just played, only repeated. I wouldn't say that it mimics reverb very authentically, but it certainly moves the delayed sound more in that direction, and "de-clutters" your sound when using delay. You'll find you can tolerate higher delay levels in the mix, because dry and wet are easier to mentally separate.

As noted earlier, the trick is to find a suitable rolloff point that is far enough below the primary lowpass filtering of the delay signal that its' effect between the first and second repeats will be noticeable, and subsequent repeats lose a little more top end, a little more, and a little more. Similarly, you can't have it so low that significant top end is copped immediately and it doesn't seem to change with additional repeats.

A lot of analog delays that use a single 4096-stage BBD will aim for something around 2khz-4khz as their rolloff point for the wet signal. Higher than that and you can't get anything more than 300msec...if you still want it clean. Aim lower than that and you can't get anything suitably bright at short delays, for mimicking slapback. So, if the top end is going to extend out to the 2-4khz end, then having a gentle rolloff starting in the 1khz zone should achieve the goals we've set for ourselves.