Optical compressors

[mcasey1]

Whats your opinion on the use of optical compressors for guitar?  I was considering building a DOD 280A optical comp.  Any advantage in smoothness or quiet operation with an optical based circuit?

[markm]

I would have to say the Flatline Compressor is one of the better Optical circuits around. It does the job quite well.
Being a Country Picker though, a little "color" in a compressor to me is not a bad thing so I do lean more toward the Orange Squeezer or a DynaComp.
As far as the 280a is concerned, these do tend to clamp very hard when the comp is set beyond 1/2 way and on my "to-do" list is to try and mod the circuit a bit to make it more realistic in terms of it's clamping.
Some of the other optical comps I haven't tried as of yet but, I'm not a big fan of 'em thus far.

[Mark Hammer]

1) LDRs don't clip.  FETs and OTAs can and do.

2) LDRs have noise but only the same sort of thermal noise you'd expect from any fixed resistor.  FETs and OTAs can introduce more noise.

3) Simple floor-pedal compressors tend to use simple rectifiers that don't remove all the envelope ripple.  The settling time of many LDRs tends to "smudge" the rectifier output, removing some of the ripple that the circuit itself didn't eliminate.  That's a plus, but generally comes at the cost of slower decay/recovery times.  If slow recovery is what you like, great, if not you're stuck.  You CAN, however, find fast LDRs and adapt an existing circuit to use one.

4) Illuminating an LDR requires providing a light source.  That can up the current requirements and shorten battery life.  Of course that's only a concern when running off batteries.

[blanik]

slightly OT, does anyone knows what the BBE Opto-Comp (their optical compressor) is based on?
(the guy at the store probably wouldn't let me open it...  )

R.

[markm]

To my unknowing knowledge of BBE, I beleive this comp is of their own design and is a scaled-down version of their rack unit.