PCM 70 Circular delay

MKeditor

Experienced
I just realized my circular delay block simulating the Lexicon PCM 70 Circular delay has become all out of wack. I'm starting to rebuild from scratch because all the threads about this have become AWOL. Anyone have a current block based on Stave Lukather's patch?

"Circular Delays:
It's a 3 tap delay ( so it's one delay with 3 taps, and NOT 3 individual delays as many, including I, thought in the past ). No high or low cut on this one either.

The first delay is 292ms, damped 3db, and panned to the right
Second one is 584ms, and panned to the left.
Third one is 888ms, and panned to the middle.

The way it's panned etc, it sounds like the echos cross from one side to the other in a circular manner. If you would record a stereo clip of this preset, and then convert it to mono, the repeats would appear to come in groups of three. The first one (292ms) is damped 3db ( which is like cutting the volume in half), the second one (584ms) is not damped and is 3db louder than the 292ms, and the last one (888ms) is 3db louder than the 584ms.

So each repeat in a group of three gets twice as loud (3db) than the previous one. The reason for the last (888ms) getting twice as loud as the one before (584ms), is because its' panned to the middle, which means it's sounding through both left and right, instead of just one. When forcing this to mono, it means that this third (888ms) repeat gets twice as loud as the second (584ms) because the second is only sounding through one speaker.

It has about the same number of repeats as the other one ( around 10), maybe just slightly less. The real magic is the diffusion control. It makes the delays sound fuzzier and fuzzier with each repeats. It basically schmears the high transients in the sound. Some liken it to sounding like a pseudo-bit reducer. This parameter isn't all that common, but other units can do it, the Axe-FX Ultra being one of them. I seem to remember other Lexicon and some Eventide units have this parameter as well. Basically, if a unit can do a 3 tap delay with diffusion, it can do the Circular Delay thingy just as good as the PCM70s.

You can create something similar by just rolling of the high cut, or adding some drive in the feedback loop if your particular unit allows that. To be honest, if you in a live setting set the level of the delay as low as Luke, you probably ain't going to be able the difference between the diffusion or some regular high cut. Luke uses this instead of reverb, and has it alot lower then the Panned Delays presets.

Here is a clip of a real PCM70 with the circular delay:

 
Just to clarify, +3 dB is not twice as loud. +6 dB is twice the signal level, however our hearing is not linear but rather logarithmic. +10 dB is perceived as twice as loud.
 
The quote I posted is from a discussion thread from HugeRacks that has been referenced many times to replicate Luke's circular delay. I'm working on getting it fly on the Axe-fx. I can't get the diffusion to sound anything like the PCM70.
 
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