compressors

[colterphoto1]

you can never have too many compressors for live sound.

Right now my DBX 2x15 eq features on-board limiters for use with mains for speaker protection.

I have a DBX 266XL which is gate/compressor/limiter. That can run the lead vocal and kick drum.

I have a little Symmetrix 525 with one channel out, think its the stereo/link switch being inop. Maybe I could just bypass that?

Need more, would like to have two ch for vocals and another two for bass/kick at least. I know the 166XL is the same as above without limiter so would be good for lots of other channels, but what is the difference between that and the 1066 unit? I've studied the literature and can't figure it out.

Or does anyone have preference on other units to use (on the cheap). The sound guy for Speed City used to use a Peavy Gatekeeper which gives 5 channels of gate- great for the drum kit.

I wish my Mackie board allowed inserts on subgroups, that's a neat way to use compression or limiters- to add one on a subgroup insert. But that's not available right now.

[Coytee]

Showing my ignorance here...

I thought one of the negatives about today's music was it's compressed? Why would live sound be compressed?

Wouldn't the compression of live sound be the fertilization of the compresson problem? (compressed live then compressed more when edited)

?

Shall I just go hide under a rock instead of showing my ignorance?

[colterphoto1]

when mixing live sound there are a couple of problems, one is too many 'open' mics that aren't being used. A device called a Gate slams the door shut on mics with no signal going to them, giving more gain before feedback and cleaning up the mix. (imagine a couple of backup vocal mics that are just picking up stage noise and amplifing it)

A compressor acts as a soundman's third hand, when the occasional vocal scream, drum hit, or errant bass note gets too hot, there's no time to turn it down in time. A compressor acts at a set threshold (where it starts taking effect) and 'dials down' that signal at a prescribed ratio like 2:1 where it takes 2 db of additional signal to let 1 db through.

Then a limiter is a hard ceiling through which no signal can punch, this saves woofer, drivers, and ears. Suppose someone drops a mic or 'THUMPS' on one that is turned way up. Instead of blowing out the whole pa, the limiter kills the signal at a prescribed level.

These are absolutely necessary for good quality live sound and nearly invisible to the audience if used properly.

M

[DrWho]

Here's one of the best sounding and easiest to use comp/gates I've come across:

http://pro-audio.musiciansfriend.com/product/PreSonus-ACP88-8Channel-CompressorGate?sku=184109

Though I guess it's not really that cheap (about $100 per channel?).
It's the only one I've come across that actually has all the features I
want....and its extremely easy to use.

Here's my opinion on compressors...(and it's just that, an opinion).

I
don't like to run comp/limiters on the FOH because you lose at least
10dB of headroom and usually more if the limiter is going to actually
protect the system. Also, the kick is almost always slamming into the
comp/limiter which means you end up with pumping vocals
(since they're usually the next loudest signal) - even with a shallow 2:1. I truly believe that
the best protection for a sound system is a sound guy that knows how to
control volume (which is the only purpose of that position in the first
place if you think about it). When I step behind a console, the first
thing I do is bypass any limiters on the FOH....though when I step away
from a console, I turn it right back on because noobs blow stuff up.
Though usually it doesn't matter, noobs will blow stuff up regardless
of the protection being used. Anyways, it's amazing how much cleaner
a system will sound without a limiter in the chain....even when you
don't think you're slamming into it.

Modern amplifiers don't
have the problem of going crazy when they're clipping either....and if
you're actively bi-amping, then your tweeters are a whole heck of a lot
more safe - especially with DC blocking. Proper gain structure is
key....the loudest kick or the highest drop of a mic should be nowhere close to being able to blow stuff up.

As far as compression
being "bad"...it is being used to alter the tonality of the
instrument/singer. The best way to think of compression is that it
makes the quieter sounds louder. When done correctly,
compression actually enhances detail that would otherwise be masked and
it can be used to bring voices/instruments forward in the soundstage.
It can also be used to make something sound more full - which is a big
plus when you've got a chick and her stick (girl playing guitar). I
treat mixing live-sound like
playing an instrument....you are creating sound that is pleasing and
expresses emotion. The compressor is but one paintbrush for shaping the
tonality of the music.

That said, I
don't like to use compressors as "auto-mixers" or crutches for
musicians that don't have control over their dynamics. I like to call
that "suck removal" and not mixing....real mixing can only take place
when the band is good. When the band sucks, you're doing everything you
can to hide that they suck so that people don't start puking their
opinions everywhere. Suck removal usually isn't that much fun, but
certainly requires a very different level of creativity. I know some
older sound guys that have just given up on suck removal altogether -
and instead they just let the suck shine in its full glory. I guess
polishing turds gets old after a while, but hopefully I don't become
jaded enough to intentionally let crap fly out of my speakers and smear
the faces of the crowd. When it gets really bad, I just turn off the PA and come back for the next band.

[colterphoto1]

whoa Doc, gotta disagree with you on a lot of points here. I pray that you're talking quite generally about using a two channel gate/comp/limiter on the main outputs of a sound system. What I'd like to discuss is using these tools with more thought, as inserts to particular channels on the board.

First as far as the kick drum pumping the vocals, if you have the vocal mic gated at all, unless the drummer is ferociously loud on stage, his kick won't affect the vocal channel. I think the problem you're stating is using a compressor on the main mix. That is indeed a crutch and to be avoided unless you ant your live act to sound like a CD. I'd use only bit of peak limiter there to kill the sound of any on stage stupidity (and there is plenty of that around). We can't all mix profesional bands all the time, in fact guys like you and I probably rarely get the opportunity.

Another technique for keeping instruments from affeting the compression of say a lead vocal is to use the side chain feature. This allows you to link an eq to the compressor so that only the frequencies you WANT to affect the comp channel do so. For instance for a vocal insert, make a reverse smiley face eq so that very high and very low sounds do not affect the compression.

Expansion makes quieter sound louder. Compression makes loud sounds not quite so loud.

Compression has nothing to do with the 'tonality' of the singer. But careful compression can help someone with bad mic technique (who screams at it without pulling away somewhat), and also can clean up the sound of the band by keeping kick and bass at a fairly level volume so the errant hot note doesn't come screaming through the PA. It's done in recording all the time and it's the type of over-compression that plagues the main mix of modern recording aching to put every last decibel on the CD. Compression carefully applied to a particular instrument in accordance with the sound the artist wishes to realize can be very much a part of the creative process.

Not using these widly accepted tools for professional sound reinforcement is an act of pure ego. Stating that 'the band's not good enough' or 'I'm so good I don't need compressors' is nonsense. As a mix engineer we owe it not only to the talent, but to our audiences, to make every act sound as good as it can. But yes, I've turned the mains completely off before and let the guys carry on with just monitors when I just couldn't stand the stage volume any more. It's one way to get those pesky gf's of lead singers off your back 'I can't hear Johnny!' - sorry honey, that's all stage volume, get the guitars to cool it and we'll talk.

Michael

[colterphoto1]

looks like the 1066 is the same as the 266XL, but better circuitry for better s/n ratio.

[DrWho]

First as far as the kick drum pumping the
vocals, if you have the vocal mic gated at all, unless the drummer is
ferociously loud on stage, his kick won't affect the vocal channel.

Just for clarification, I'm assuming that you've at
least got the vocal mic "isolated" enough for it to be the loudest
signal in its own channel...if that's not the case, then it becomes a
case of suck removal. My comment about pumping is on a FOH limiter
where the two signals are combined. There is no way for the limiter to
know which is which....and a sidechain just removes the protection you
were trying to achieve in the first place.

Another technique for keeping
instruments from affeting the compression of say a lead vocal is to use
the side chain feature. This allows you to link an eq to the compressor
so that only the frequencies you WANT to affect the comp channel do
so.

Just another suck removal technique...like my point
above, the vocal should be the only thing in the vocal mic. But let's
say you can't do anything about it and use the sidechain so that the
kick doesn't cause the vocal to pump....well you've still got kick
information in the vocal mic, so now your kick drum pumps with the
vocal compression. Sure, it's a lot less noticeable, but not all
scenarios are just a kick and vocal...I'd say cymbals and guitars are a
way bigger issue here. But again, just keep the crap out of the mic in
the first place. Anything else is a compromise...and it's usually a
compromise that won't exist if you're not lazy about mic placement and
working with the band to create a good sound. This isn't about being
elitist...it's about being realistic to the physics at hand.

Expansion makes quieter sound louder. Compression makes loud sounds not quite so loud.

Not true. Expansion makes quieter sounds quieter. Compression makes quieter sounds louder.

Sure,
depending on your frame of reference a compressor makes the louder
sounds quieter, but that's only because you didn't adjust your output
gain to compensate - an absolute must if you want to maintain proper
gain structure. And from the same uncompensated gain situation, an
expander makes the louder sounds louder.

Expanders widen the dynamic range and compressors reduce the dynamic
range. And just to throw this out there, a gate is to an expander as a
limiter is to a compressor (gates and limiters are just high ratio
expanders and compressors).

Compression has nothing to do with the 'tonality' of the singer.

Well
what would you call converting a weak voice into a full voice? Or
changing a thin kick into a fat kick? Or ducking the bass? Or tightening up background
vocals? Or moving the lead singer from the back of the soundstage to
the front? I do it all the time in both the studio and in live sound
and is one of the sole reasons I use it in the first place! []

But careful compression can help someone with bad
mic technique (who screams at it without pulling away somewhat), and
also can clean up the sound of the band by keeping kick and bass at a
fairly level volume so the errant hot note doesn't come screaming
through the PA.

That's all just suck removal. Either the
band member wanted to play that note louder, or just isn't skilled
enough to play the notes at the right volume. It will always sound
better if the band member played the note at the right volume in the
first place, period. The reason I make this distinction is because the
"cat's meow" of compression has nothing to do with minimizing
mediocracy. In other words, there are reasons for using compression
that extend beyond crappy sound....and to limit compression to the use
of suck removal is totally unfair to the art of comrpession. Is every
situation ideal? Heck no - and that's not the point.

It's done in recording all the time and it's the
type of over-compression that plagues the main mix of modern recording
aching to put every last decibel on the CD.

I agree that
compression is used in the studio all the time to make a mix sound
hotter....why? because a hotter mix will sell more copies. It sounds
louder because the quieter sounds are louder...basically removing the
space in the music that would normally gives our ears a chance to
relax. The record label doesn't want to let your ears relax because
they're trying to capture your attention and get you to buy the CD. How
many times do you just skip a station on the radio because you didn't
hear anything right away? If the consumers weren't so stupid in their
music selection, then the record labels wouldn't have to push such hot
mixes. However, a lot of people listen in the car which usually has a
relatively high noise floor....you gotta compress the music so that the
quiet details in the music can be heard above the noise floor.

Not using these widly accepted tools
for professional sound reinforcement is an act of pure ego. Stating
that 'the band's not good enough' or 'I'm so good I don't need
compressors' is nonsense.

If you think I've implied any
of that, then you have sorely misunderstood everything I wrote. If
anything, I'm trying to point out that compressors can and should be
used for more than just suck removal....If you're in the art of only
suck removal, then you're not experiencing the best that live sound has
to offer. It's like a Metro driver talking about how he soaps up his
rear wheels so that he can experience the joy of a power slide....in
the meantime, the ferrari driver is talking about experiencing a 100mph
power slide. It's simply not the same level of enjoyment....at least
not until you experience the ferrari.

Just one other
comment....the problem with gates on vocal mics is that they will pump
the stage noise - especially when you've got loud guitars. Also, it's
incredibly hard to bypass the gate on every single vocal channel
inbetween songs when the band is talking to the crowd. Ever try hitting
5 gate bypass switches while muting all the effects channels AND muting
the guitars before the cables get pulled out for a swap? If you've got
a simple solution I'd love to hear it. If I had my own gear, I'd be
wiring pedals into all my gear...

One of my favorite uses for a
gate is on toms since the natural ringing of the drum head usually
results in a mucked up mix. A gate with decay control allows you to
change the shape of the tom's natural decay. And thankfully, not many
drummers are trying to use brushes on their toms. Depending on the
band, you might have to ride the gate bypass on the snare gate for when
the brushes come out.

[colterphoto1]

we're not so far apart. I don't think we're going to have to wrestle behind the board or anything like that.

Tonality deals with tone or pitch. We're not talking about the black dots here, just the loudness of the black dots. It's just semantics.

I use the gates just a little, if someone utters a sylable it opens up. Gates on toms are the way to go, tightens up the mix a bunch. The Peavey Gatekeeper is great for that.

[colterphoto1]

woohoo, just won a Peavey Gatekeeper 5 ch gate for $53 delivered! Great for tom mics.

[colterphoto1]

Just paid $67 for a like new DBX 266XL gate/comp

That makes four channels of gate/comp (two with limiters) and 5 channels of gating. That should do it.

[Professor Thump]

Why can't we just get along?

Excellent points from both of you mix masters.

It is too bad there isn't more money in live sound. Because it is a difficult and thankless job (especially in rock bands) and doesn't usually pay for equipment unless you do regional or national tours. I don't think there is any thing harder to mix than setting up levels on several signal processing items:

1. EQ - Gotta optimize the gain before feedback, especially with monitors. This is an art in itself trying to stay loud while not feeding back the system. Do you ever have enough parametric EQ's?

2. Compressors - These get a bad rep because the the big recording studios are abusing them for a binary like "loud sound". I really am disappointed in this aspect since there are not many new popular recordings with any dynamics. (that is a discussion for another thread). The point I am making is that with skill a compressor can help. Usually you are using it to keep a novice singer who doesn't' know how to use a mic (proximity effect) audible. It is also necessary for drums, to keep the mix louder but warmer.

If you have a really inconsistent drummer he is going to hurt people in the audience. Dynamic THUMP is great but there is a limit. I agree with Mike (Dr Who... Michael won't let me call him Mike or Micky [] ) you can get that pumping sound as the kick drum bleeds into the vocal mic. So isolation is key for minimizing pollution of the main vocal mic. God forbid you have a drummer who sings.

I remember the first time I used a Comp/Limiter from dBx. I was sorely disappointed that it sucked all my gain. I had a big PA with EV MTH2's and Deltamax 1152's for the high pack and (4) K bins (similar to MCM's) with plenty of power. but I was in a tent at the fair in Michigan. It was hard to get loud without getting a lot of noise from the large signal path of electronics. I realized that I had a lot to learn.

Less is more in this case. Comps can only help so much. If the band sucks you suck! Period! You can help them sound better but crap in is sheet out.

Rule of thumb... use the Compressor sparingly.

3. Active Crossovers - If it is right it is right. But how do you know. I have been spoiled by working in labs all my life. But it is easier to measure now because the test equipment is cheap. Portable to me was a TEF 12. Nice monitor on that "portable" PC dude! If you crossover point is set wrong you are either blowing up drivers or not optimizing your gain potential.

Active Xovers are best but it is easy to bump a knob.

So pay attention to your Xover.

Oh to be young again and full of..... of..... THUMP!