DUer Guitarists, what exactly does a compressor do?

[freethought]

In articles and like in the various guitarist publications the players often say they put the signal through a compressor before they put it through distortion, wah, and the like. I have seen a few of these pedals, Boss, DoD etc... What do these compressors do sound-wise? Some players seem to regard these pedals as a "must". One fellow I asked said "It evens the guitar's sound out." and left it at that. Is that accurate?
I have an oppurtunity to buy a Boss CS-3 from a classmate for $50.00 or so. Is it worth it?

[bullimiami]

1. evens the sound out is not a bad description.

a compressor makes the loud parts lower while leaving the softer parts alone.

distorted guitars are pretty well compressed already. clean guitar sounds can vary a lot in volume between finger playing, strumming, picking and the strings and area of the guitar you are on.

i dont really consider a compressor a must have for live guitar.
compression does also have a tendency to increase the sustain though which you might like.

compressors may have all or some of these controls

threshold. the level above which the signal will be reduced.
ratio. the severity of the gain reduction. for ex 2:1 for every 2db the input signal gets louder the output increases by 1db (this is a very moderate setting) to say 10:1 for every 10db the input signal increases the output goes up only 1db.
it may also have an output or input gain control.

if you think of a microphone savvy singer that moves the mic away when they hit their stong notes. they are doing physically what a compressor does electrically. evening out the levels.

i hope that helps.
you should probably play with the unit and see if you like it.

[ProfessorGAC]

One Nit To Pick

Limiters clamp down on the loud parts and leave the soft parts alone.

A compressor squeezes from both directions. It limits the high signal and raises the volume of the lower signals. This is ESPECIALLY true of stomp box compressors. They are commonly used to improve sustain because as the string vibration begins to subside, the compressor gently turns up the volume to keep the amp sound louder to it falls off at a lower rate than the string volume itself.

I agree with everything else, but there's a difference between limiting and compression.
The Professor

[bullimiami]

6. picking back at you prof....

virtually no compressor increases the gain of soft passages, it is not a common function built into them, they are almost universally top down gain reduction.

otoh something like a boss cs-3 compressor/sustainer does. the sustain is an agc circuit and is really a seperate function from the compression.

the difference between a compressor and limiter is the slope or ratio of the compression.
a compressor/limiter at 2:1,4:1 would be compressing but at 100:1 or infinite slope would be limiting.

[ProfessorGAC]

I Have Three And They All Do It

I have a Boss pedal, i have a TC Electronic Rack mount, and i have a Yamaha amp top unit. They all boost the low end by amplifying the floor as the signal decays. So, i'm picking back at ya again!
The Professor

[ProfessorGAC]

8. I Have Three And They All Do It

I have a Boss pedal, i have a TC Electronic Rack mount, and i have a Yamaha amp top unit. They all boost the low end by amplifying the floor as the signal decays. So, i'm picking back at ya again!
The Professor

[ProfessorGAC]

9. I Have Three And They All Do It

I have a Boss pedal, i have a TC Electronic Rack mount, and i have a Yamaha amp top unit. They all boost the low end by amplifying the floor as the signal decays. So, i'm picking back at ya again!
The Professor

[bullimiami]

10. well prof they must all be made for guitar.

i have a studio full of compressors and none of them increase gain of low signals.

i would bet that all 3 of these are described as compressor / sustainers somewhere in the literature.

[ProfessorGAC]

One Nit To Pick

Limiters clamp down on the loud parts and leave the soft parts alone.

A compressor squeezes from both directions. It limits the high signal and raises the volume of the lower signals. This is ESPECIALLY true of stomp box compressors. They are commonly used to improve sustain because as the string vibration begins to subside, the compressor gently turns up the volume to keep the amp sound louder to it falls off at a lower rate than the string volume itself.

I agree with everything else, but there's a difference between limiting and compression.
The Professor

[ProfessorGAC]

3. One Nit To Pick

Limiters clamp down on the loud parts and leave the soft parts alone.

A compressor squeezes from both directions. It limits the high signal and raises the volume of the lower signals. This is ESPECIALLY true of stomp box compressors. They are commonly used to improve sustain because as the string vibration begins to subside, the compressor gently turns up the volume to keep the amp sound louder to it falls off at a lower rate than the string volume itself.

I agree with everything else, but there's a difference between limiting and compression.
The Professor

[mitchum]

2. I think it is detrimental to the sound of the electric guitar...

but it can be quite useful with a bass

[Sammy Pepys]

4. Think of it as a magic elf....

When you play guitar, you can vary the volume level of the music from very soft to very loud, and everywhere in between.

What this magic elf will do is compensate for the difference in volume. When your playing is real soft and delicate, the magic elf will turn the the volume up to a level you've selected so these softer passage will still be able to be heard.

Likewise, if you're thrashing about on your guitar, the magic elf will bring the volume down. It will also continue to turn the volume up as your guitar fades out, increasing the perceived sustain of the instrument.

Basically, the volume of your playing is kept at a consistent level. Compressors have different controls, as mentioned in previous posts, to determine what gets turned down, what gets turned up, how much...stuff like that. You basically have to play around with one to get a feel for it.

For an example of a real-life application, I play a Rick 330 electric 12 string that I pretty much use a compressor on it 100% of the time. Ricks like mine are traditional compressed two squeeze all the competing frequencies together and get that famous jangle, but also because at least on my Rick, a really light touch makes mine respond the best. If I was playing without a compressor, the volume level would be so low I'd have to compensate by turning the amp up a couple of notches...but with a compressor I don't have to do that...it bumps the volume up for me and preserves the characteristics of the lighter touch that make it sound a lot better than beating the hell out of it.

[freethought]

5. Does not sound like a bad idea,

I can see where it might be a good idea. I'll play a little with the CS-3, then I'll decide.
It also sounds impressive that one can create some more sustain or squeeze it for less.
Let me get back to y'all.

[Sammy Pepys]

7. To get a good feel for a compressor....

Play as lightly and delicately as you can and gradually play harder and harder....that help you see exactly what it does. But also play in your normal fashion to see if it's something you like. Most folks I know don't use one full time for their normal playing

I don't use one much on my six strings, but in addition to using one on my Rick I like to kick it on occasionally when playing very high up on the neck on the G, B and high E strings...it helps beef up those notes and adds a cool "roundness" to them.

For the record I use a regular old MXR Dynacomp.

[freethought]

11. Well, I tried it!

I actually liked how it made the guitar sound. The only thing that really seemed to surprise me was this "POP" that comes through the amp when you pick a string.

The offer to sell it to me was a steal. I guess I'll keep. We'll see how it works used in tandem with other effects.