PCM 80/90 notes...for the sick and twisted.

[mixsit]

When I first got into these units, I went into them a little deep. (maybe too deep) Anyway, just for fun, for what it's worth...

Delay timing in the 80.
The delay lines (Voices) are preceded by the Diffusion parameter, that when used (any value >0) causes an extra 20-30 ms of delay on the voices. (Presumably processing time need to break the ‘voice’ up into echo- clusters?) What’s unexpected is this added 20-30ms is not indicated in the voices’ delay values. In other words, if you dial up a 70ms delay and then add some Diff’, you now have a 90-100ms delay that says "70". The shortest delay possible is now 20-30. (...or, you thought you knew what 70ms felt like, but now your all out'a whack!?)

In most of the algorithms, ‘voice diffusion’ is separate from the ‘reverb diffusion’, which sounds different on the reverb’s delays, and only seems to add 4 or 5ms to them.

In the 90, the ‘Reflect Delay’ is shown in the book to be post- diff’ but is actually pre (at least in Chamber and Plate, not sure about Random Hall), so it isn’t effected.

Another timing problem.
In both the 80 and the 90, the Shape parameter, used to contour the early reflections decay, does not simply extend the envelope in time in it’s lowest settings as you might expect, but enables a group of reflections out about 200ms beginning abruptly with any value >0.
The effect is very noticeable on small to med. room sizes (10-40m) and/or short R/Ts (<1.5 sec), giving the reverb a distinct rhythmic feel that may or may not be appropriate. The effect has no ‘link’ with reverb ‘Size’, so it’s timing’ can not be changed. I wish it could, because one of the reverb designs I find difficult to get right, is a diffuse ‘backwall’ return component, timed as needed for the song. (Pre-delay isn’t quite it) I hate to say it, but this is the same type of fixed-group-reflections I grew to hate in the old Quadraverbs, and the Q2. Thankfully, there’s plenty of workarounds.

A cool feature in the 90’s ‘Concert Hall’ program, ‘Spatial EQ’, can be set to remove most all of the mono signals in a mix, leaving paned instruments and a wonderful view of the stereo effects and echoes. Just adjust the premix, instant ‘wet’ control. (Great for poking around in a mix to check out the effects and backgrounds.)

Wish list: A second crossover and gain control in the reverb ‘Time’ row. There are times I would really love to have seperate mid and high R/T times with level control. Anybody?

There was a company threatening to make midi program controller software for Lexi’s (And others), so you could see the edit parameters on the p/c. This would be a great feature. I keep checking but so far….. (tbsystems.com)

see ya
Wayne @ CathouseSound