Compression - Uses in a Live setting?

[David Jayne]

What? Of course it's active! It's an opamp or FET boost typically, never passive, and never disengaged from the circuit. I'll repeat: an active gain boost circuit is an inherent, always-on part of 99.9% of compressors in all formats.

OK, 'active' was the wrong word. I should have said 'automatically increases level' or some such. As in 'Expander.'
Point being, some folks think a compressor can make quiet notes louder, which it does not. They only make loud notes quieter.

 

[KJung]

OK, 'active' was the wrong word. I should have said 'automatically increases level' or some such. As in 'Expander.'
Point being, some folks think a compressor can make quiet notes louder, which it does not. They only make loud notes quieter.

I do not think this is correct. You are describing a limiter, which only controls peaks. A true compressor, as described in other posts, will also, at least to a limited extent, increase the volume of 'softer' notes also.

I personally don't see the need for a compressor as part of a backline rig, although I guess if you keep the ratio low enough and threshold high enough, it can result in your amp performing a bit better by controlling the transient peaks a bit, without adding that quashing to your sound.

 

[David Jayne]

I do not think this is correct. You are describing a limiter, which only controls peaks. A true compressor, as described in other posts, will also, at least to a limited extent, increase the volume of 'softer' notes also.

Sorry Ken, but nosirree. It doesn't work that way. It SEEMS that way, but it ain't.

 

[Stu_Bass]

When a compressor is triggered (threshold + attack time) it lowers the signal above the threshold (threshold + attack time + knee slope + ratio). This reduces dynamic range (compresses) the signal. When the signal goes below the threshold (threshold + release time) the overall gain rises and the entire signals level is raised (across the full dynamic range) this raises the lower level signal also and makes signal that would have been below the threshold of hearing audible. Therefore the signal (note) is heard longer and you perceive it as "sustain" No? This is my way of looking at it. You can also hear this phenomena (pumping) as the notes level is increased by the release of the compressor. Unfortunately, with the rise in the signal level also comes the rise in the noise floor.

 

[KJung]

Sorry Ken, but nosirree. It doesn't work that way. It SEEMS that way, but it ain't.

I'm surely no expert, since I avoid these things like the plague. I just did a bit of cruising around the web searching for 'limiter versus compressor'.

I believe you are correct, and your 'seems that way' comment nails it. A compressor is different than a limiter, which is the point that some are making above, if I have this correct. A true compressor can be set to greatly reduce the initial attack, and then this reduction level is 'reduced' as the note fades, increasing sustain and making a softer note 'seem' louder. Then, the 'make-up gain' amplifier is used to put the entire signal back up to the original line level volume.

Here's a representative blurb:

Besides serving as an automatic volume control, a compressor can also make notes sustain longer. To increase a note's sustain requires raising the volume of a note as it fades out. That is, making the trailing part of a note louder to counter its natural fadeout is what makes it seem to sustain more. To do this with a compressor you'll set the threshold low enough that the volume is reduced most of the time. Then as the note fades the compressor reduces the volume less, which is the same thing as raising the volume. For example, when you play a note on an electric bass the compressor immediately reduces the volume by, say, 10 dB because the start of the note exceeds the threshold by 10 dB. You don't hear the volume be reduced because it happens so quickly. But as the note fades over time, the compressor raises the volume which gives the effect of adding sustain.

 

[Eublet]

I'm surely no expert, since I avoid these things like the plague. I just did a bit of cruising around the web searching for 'limiter versus compressor'.

I believe you are correct, and your 'seems that way' comment nails it. A compressor is different than a limiter, which is the point that some are making above, if I have this correct. A true compressor can be set to greatly reduce the initial attack, and then this reduction level is 'reduced' as the note fades, increasing sustain and making a softer note 'seem' louder. Then, the 'make-up gain' amplifier is used to put the entire signal back up to the original line level volume.

Here's a representative blurb:

Besides serving as an automatic volume control, a compressor can also make notes sustain longer. To increase a note's sustain requires raising the volume of a note as it fades out. That is, making the trailing part of a note louder to counter its natural fadeout is what makes it seem to sustain more. To do this with a compressor you'll set the threshold low enough that the volume is reduced most of the time. Then as the note fades the compressor reduces the volume less, which is the same thing as raising the volume. For example, when you play a note on an electric bass the compressor immediately reduces the volume by, say, 10 dB because the start of the note exceeds the threshold by 10 dB. You don't hear the volume be reduced because it happens so quickly. But as the note fades over time, the compressor raises the volume which gives the effect of adding sustain.

That's it. It compressor doesn't "boost" the gain of low signals. When the signal falls below the threshold, you are just running at unity, but since the overall gain is hotter to compensate for the compressed peaks, the softer notes are louder. The amount of compression (threshold and ratio) determines how much more gain you have to put back in the signal to match unity gain of the signal with the compressor off.

 

[bongomania]

OK, 'active' was the wrong word. I should have said 'automatically increases level' or some such. As in 'Expander.'
Point being, some folks think a compressor can make quiet notes louder, which it does not. They only make loud notes quieter.

Keep digging. Naturally a compressor is the opposite of an expander, but the fact is the "system" of compression involves first "making loud notes quieter", and then boosting the whole signal, such that quiet notes become louder relative to the rest of the signal.

In practical application of a compressor, quiet notes are made louder, due to an active boost. No, it is not a dynamically-controlled boost, it is just an across-the-board boost.

Compressors don't boost anything. They only reduce gain, not increase it.

 

[bongomania]

...compressor doesn't "boost" the gain of low signals. When the signal falls below the threshold, you are just running at unity, but since the overall gain is hotter to compensate for the compressed peaks, the softer notes are louder.

Let's not get our terms mixed up further. The compressor boosts the gain of the entire signal, including the low level sounds. It does not dynamically boost "only" the low level sounds.

 

[Eublet]

Let's not get our terms mixed up further. The compressor boosts the gain of the entire signal, including the low level sounds. It does not dynamically boost "only" the low level sounds.

Correct! You are just doing a better job of explaining it than I am.

 

[EricF]

Here's the very simplistic way I explain compression/limiting*...

Your "compression" setting creates a ceiling - more compression equals a lower ceiling. Your notes will not go louder than the ceiling. Your "volume" (make-up gain) setting is the floor. By lowering the ceiling and/or raising the floor, you are limiting the dynamic range between the loudest and quietest notes. By lowering the ceiling, the output volume is also reduced. To re-gain the lost volume, the floor needs to be raised. Thus, compared with the original (un-effected) signal, the louder notes get quieter, and the quiet notes get louder.




(Yes, I know there's a lot more to compression than this, I'm intentionally trying to keep it simple for people trying to understand the basic concept.)

 

[David Jayne]

Let's not get our terms mixed up further. The compressor boosts the gain of the entire signal, including the low level sounds. It does not dynamically boost "only" the low level sounds.

Jeeze, 'keep digging' yourself
I understand exactly what you are saying, and I understand exactly how it works. I am well aware that you are an expert on this topic.
Semantics, friend. A LOT of people DO NOT understand how it works, and believe that the comp will 'dynamically' boost low level signals, like an expander does. THAT is the point I was trying to make.

 

[attackbass]

I play rock mainly and use an EBS compressor... I use it mainly to boost my signal and add a litle punch and extra grit (using it in tube mode) to my sound... i have the compression at a very low subtle level just to add what i want. I'm not a fan of over the top compression.

I probably don't need it - it just adds something i liek to my tone

 

[bongomania]

Jeeze, 'keep digging' yourself
I understand exactly what you are saying, and I understand exactly how it works. I am well aware that you are an expert on this topic.
Semantics, friend. A LOT of people DO NOT understand how it works, and believe that the comp will 'dynamically' boost low level signals, like an expander does. THAT is the point I was trying to make.

I'm not trying to pump myself up as the expert here. It's just that every single statement you made, up to the point where you mentioned dynamic control like an expander, was false. It's not semantics at all--it's a question of plain, accurate speech using normal words.

 

[markjazzbassist]

Live i always let the FOH engineer put the comps on. i personally don't like my sound compressed since i naturally compensate for it (due to my inability to play with a comp over the years). if FOH wants to compress it, i could care less, and i let him (the professional) take care of it.

i am a rare case here, most of the TB crowd love compression.

 

[theophilus762]

for live shows with my band, i really dig in, and with all the movement/jumping on stage, its harder to pay attention to technique. i use my compressor to even out my technique.

 

[David Jayne]

It's just that every single statement you made, up to the point where you mentioned dynamic control like an expander, was false.

.... The sustain effect happens because as the note dies down, the compressor relaxes it's effect on the note, until it's not doing anything at all, at which time the note rapidly fades.

From my very first post on the subject. Incorrect?