question about compression/program levelling

[abdullahrawk]

hey all.... i know this isn’t technically a “home recording” question but i believe the issues involved are similar in scope. i have a (kind of) basic question about using a compressor in conjunction with a small p.a. set-up. i tend bar at a small pub and the owners recently purchased a small sound system so we can play music on the weekends. however, since we don’t have a d.j. it basically consists of someone making a bunch of mix cd’s so no one has to man the mixer for too long. the problem with this obviously, is that the cd’s aren’t normalized (i think that’s what it’s called) and sometimes there are wild fluctuations in sound levels between songs (imagine a track from the original issue violent femmes cd preceding a track from gwen stephani’s latest cd). so i purchased a compresser but can’t figure out how to set the parameters in order to “normalize” these homemade mix tapes so the sound level of the program is consistent. any suggestions? thanks in advance!

 

[Massive Master]

It might not be the greatest sounding thing, but go with a very low threshold (-20, maybe lower) and a very small ratio (1.25 or 1.5 to 1). Medium attack and release for starters...

Basically, this is going to keep almost everything in the compressor to a point. The louder the program material gets, the more gain reduction.

If the *quiet* stuff is digging in too far, back off on the ratio until it's just touching reduction. Louder stuff might dig in 7 or 8 dB.

 

[SonicAlbert]

There's a unit designed exactly for what you need. It does the job brilliantly, and it's called the "Compellor" and is made by a company called Aphex. It will level everything off without artifacts and you won't even know it is doing it. Kind of amazing really, and a little different than a typical compressor.

Short having a Compellor, what you might need is a limiter. A limiter raises the volume of everything, then cuts off the peaks so you don't get distortion. A lot of compressors are also limiters or can be switched to limiting mode.

What compressor did you buy?

 

[abdullahrawk]

hey thanks for the feedback guys!

i would definitely be interested into looking at that aphex compellor, but right now it just isn't in the budget!

the compressor i purchased (used) is a Behringer MDX4400 Multicom Pro. it does indeed have a limiter in addition to the compression settings. the manual says something about "limiting the program material by 6 db and then increasing the overall volume/output by 6 db" but it's pretty vague to me. the threshold knob for the limiter goes from 0 db (fully counterclockwise) to +12 db (at 12:00 position) to OFF (fully clockwise). where should this knob be positioned in order to limit the program material by 6 db? i guess i'm just confused because to me the term "limit" denotes a negative value and the limit threshold parameters are in positive increments. anything else i should know?

 

[Massive Master]

If you're going that route, just put on something that's very loud and adjust the limiter for 6dB of gain reduction.

If the limiter doesn't read gain reduction, set your ratio at around 10:1 with a fairly quick attack and a fairly slow release and bring the threshold down (again, while playing something you know is very loud) until you're getting around 6dB of reduction.