In the reference manual, the LED on each PC module is described as a Clipping LED, but there is no guidance as to how to interpret them. In practice, they change colour gradually through amber and red, which suggests they are not actually sensing clipping (whatever that means in floating-point digital processing). For those module that have meters, in many instances, the clipping LED has turned red long before the simulated needles are also well into the red. This is often where you want them to be, for instance with the Tape module, or any of the "analogue warmth" (i.e distortion) based modules. So, in practice, I just use my ears until the things sounds right, a practice that I know many of you think is the definitive way in any case. Nevertheless, I am still curious to know what the LEDs are actually telling me - are they simulating some kind of analogue overload or are they telling me something meaningful about the digital domain?

It depends on the FX in the signal chain.

Some are designed to be overdriven and emulate overdriving hardware. Some effects will flat out clip.

When mixing a large number of tracks... more than ten, I often normalize them to minus 3dB so they go into the effects with reasonable levels, but not too hot.

I'm general, the light is a distortion caution. When I see it, I reduce gain somewhere in the signal chain to try to fix it.

Really, it is very handy to have signal level detected for heat between effects. I find the feedback very valuable. I do wish it had a hold feature.

Yes, I agree the ability to see what is happening between stages is very useful. It's just it would be so much more useful if I knew what it is actually measuring.
 

Red is clipping according to the original literature released for Pro Channel.

I have noticed that if you put a MONO plug in on a stereo track or vice versa, sometimes it will screw up the clipping indicator.  I seriously ignore them because they are buggy as hell.

This has come up before, and if I'm remembering correctly, they are not actually clipping levels, but more like "activity levels" or "overload levels" or something.  Not sure if that is true, but you can certainly hit the red (without holding red) mulitiple times on multiple PC modules without any discernible clipping sounds.

It's a shame that Cakewalk doesn't actually explain what they are.

Feeding a 0.0 dBFS test signal through a PC module shows a red clipping LED.
At - 0.1 dBFS the LED is still orange, so it seems to be accurate as a clipping indicator.
 
Of course only tested with PC modules I own, so cannot confirm for every module.
 
Best,
Klaus
 

Just don't let them turn red unless for some reason or other you find a specific module sounds BETTER clipping.
 
Generally, in my experience, they really really do not (and I like nasty, hateful noises).
 
If one of the modules DOES sound "good" to you getting slammed to red... mayhaps you are actually looking for a different effect that could be better accomplished with a different plug designed to clip (in which case I'd suggest the Tube Drive or Sat Knob modules).
 
Seriously... red to me almost always sounds a bit raunchy even if it's only blinking a little... and not in a good way.
 
YMMV

i guess I've never noticed clipping when it goes in the red... I mean, when I hear clipping I really hear that horrid  h@kkccggg sound (my alphabetization of clipping noise, ain't it appropriate?).  I think of it like gain staging, where the same thing occurs on a track or two that you get the red peak light on.  I'll listen to it solo to check for noise or adjust some parameter related to the track, but if it sounds good like it is, I leave it... no big thang.