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Compressor before preamp??
Old 24th February 2013
  #1
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Compressor before preamp??

Whats the best way to hook up a compressor?
Should I plug it in before a preamp or after, and what's the difference?
Also, is there any difference between compressing BEFORE recording versus AFTER recording??
Old 24th February 2013
  #2
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travisbrown's Avatar
Compressor is expecting a line level signal. Put it after the preamp.

Likely that a mic level signal would never be enough to ever engage the compression circuit.

As far as tracking with compression....the only question is, you afraid of commitment?
Old 24th February 2013
  #3
RiF
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Quote:
Originally Posted by travisbrown View Post
Compressor is expecting a line level signal. Put it after the preamp.

Likely that a mic level signal would never be enough to ever engage the compression circuit.
Exactly.
A preamp's task is to amplify a low microphone-level signal coming from a microphone up a line-level. So a mic needs to go ALWAYS into a preamp first.

If you want to use a compressor later in the mix, you don't need the preamp anymore, because a mixing console or audio interface will output it's signal at line-level already.
Old 24th February 2013
  #4
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Wouldn't there be a lot more noise if you compress after recording?
Old 24th February 2013
  #5
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Are you recording to tape?
Old 24th February 2013
  #6
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nikodemos's Avatar
 

Quote:
Originally Posted by ThroatCaptain View Post
Wouldn't there be a lot more noise if you compress after recording?

this is why you have to use a proper mic preamp....to amplify the tiny current output of the mic to line level signal , retaining a useful S/N ratio. It is the other way around that would probably cause such a problem. Don't forget that a microphone expect a certain impedance load connected on its output in order to be properly amplified and later on processed....learn more about impedance bridging

...however there are some compressors hot enough to drive a microphone's output like the 1176 or the LA2A , however these devices still have an input impedance quite lower than what a microphone (and especially a ribbon or a dynamic) should require to perform according to specs...although the whole impedance relation thing tends to be a matter of taste too.

bottom line.....mic amps are there for a reason
Old 24th February 2013
  #7
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No tape, just digital.
Old 24th February 2013
  #8
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Another thing worth noting is that if you plug a condenser mic into a compressor, you don't have phantom power. It won't give any sound.
Old 24th February 2013
  #9
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Quote:
Originally Posted by marksquier View Post
Another thing worth noting is that if you plug a condenser mic into a compressor, you don't have phantom power. It won't give any sound.
Along with everyone's affirmation that the mic needs to visit a preamp first thing, this is just one more great point in support of that logic. No 48v, no dice.

Most pro engineers I know track with light compression going in -- not super heavy, squashed, pumping compression (they can do that later if necessary), but some light to moderate compression to help even things out and add some harmonics from the get-go. Sometimes even two analog compressors in series, such as two distressors, can be used in sync to get a really nice signal on the way in. The first one fast attack/fast release to tame really ridiculous peaks, then the second one with a little slower attack/release to moderate the overall level.

This streamlines the mixing process, makes it a bit easier to balance levels, and tends to make the artist sound better to themselves when they hear a take immediately played back. All good things, I think.

Old 24th February 2013
  #10
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Would there be a big difference in the noise floor compressing before recording VS. after recording??
Old 25th February 2013
  #11
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...anybody?
Old 25th February 2013
  #12
Gear Maniac
Yes. A huge difference.

If you compress a signal that is not line level, ie. direct from a mic, it will be much noisier.

Try it out for yourself and see. Preamps are designed to have a low noise floor and raise the signal to be "line level", which is the level at which the compressor wants to see the signal.
Old 25th February 2013
  #13
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Yes, I understand that now but I'm talking about this:
Mic-preamp-compressor-computer
VS.
Mic-Preamp-computer-compressor-back into computer

Noise floor difference??
Old 25th February 2013
  #14
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At line level with a balanced connection, I don't see how you'd have any substantial difference. It's as much noise as one extra trip through your interface/converters will add. If you've set all your input and output levels properly you shouldn't have a problem, IMHO.
Old 25th February 2013
  #15
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Quote:
Originally Posted by rcb4t2 View Post
Are you recording to tape?
Why do you ask? Is compression different between tape and digital?
Old 25th February 2013
  #16
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The main reason why people would compress during tracking is if you're recording to tape. Tape has a much higher noise floor so you'd want to compress BEFORE you hit that noise.
Otherwise, you'd just be compressing the sound towards the noise.

With digital, the noise floor is much lower but I guess you COULD compress during tracking just to avoid peaks from clipping.
Old 25th February 2013
  #17
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nikodemos's Avatar
 

Quote:
Originally Posted by marksquier View Post
The main reason why people would compress during tracking is if you're recording to tape. Tape has a much higher noise floor so you'd want to compress BEFORE you hit that noise.
Otherwise, you'd just be compressing the sound towards the noise.

With digital, the noise floor is much lower but I guess you COULD compress during tracking just to avoid peaks from clipping.
compression and dynamics processing in general is much much more than overall level control and avoiding clipping.

Compressors can be extremely versatile sound shaping tools providing the engineer with extreme power on his hands......so much power that can easily ruin a recording as well as making it better
Old 25th February 2013
  #18
Gear Nut
 

Well yes, of course.
But you can only minimize tape noise and prevent digital clipping BEFORE you record.
You can dial in some punch and character after recording.
Old 25th February 2013
  #19
RiF
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Quote:
Originally Posted by ThroatCaptain View Post
Yes, I understand that now but I'm talking about this:
Mic-preamp-compressor-computer
VS.
Mic-Preamp-computer-compressor-back into computer

Noise floor difference??
No.
Unless you're using an old Soundblaster 16 for conversion, of course.
Converters have a signal-to-noise ratio of well over 100dB, so no worries here.
Old 16th August 2018
  #20
How about between a tube mic and my sound card's preamp?

Since the mic needs no phantom power and is already powered, is this ok?
Old 16th August 2018
  #21
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travisbrown's Avatar
Quote:
Originally Posted by JeffSanders View Post
How about between a tube mic and my sound card's preamp?

Since the mic needs no phantom power and is already powered, is this ok?
I suspect you might not have enough gain out of the mic to get any meaningful gain reduction. Compressor is expecting line level signal. It is possible to sometimes use a compressor as a sort-of preamp if it has sufficient make-up gain, but that happens after the compressor circuit, so kinda pointless if you have a following preamp.
Old 16th August 2018
  #22
If you are like everyone else, you are recording in 24bit, Correct? If you are, then there is no need for a compressor in the recording stage.

You do not need to record as hot as possible anymore , when in 24bit. this means you can have your PEAK dB level between -24dB to -10dB PEAK and your signal will sound Perfect. This also gives you 10dB of room for any occasional peaks. so no need for any compressors.

24bit has 256 more times the resolution than 16bit has, this is why you do not need to record hot!!

Just my take on it
Old 16th August 2018
  #23
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Quote:
Originally Posted by ThroatCaptain View Post
Wouldn't there be a lot more noise if you compress after recording?
Recording a preamp only should be very low noise.

Also, if a singer is used to singing live through a PA, He likely doesn't use any compression. By adding it in the signal chain, you will alter how he sings.

Experienced singers know how to "Work a Mic" They back off a mic when they sing loudly and get right up on it when they sing soft and intimate.

When you use compression in the signal chain, you neuter their skills to work a mic properly. Its isn't going to matter weather they sing close of far from the mic, the volume is going to be the same which will affect their psyche, and therefore their performance. Its like driving a car with no breaks.

Best place to use a compressor is when you're mixing for vocals. The track will have far less noise and no additional coloration. What's on the drack came from the singer and the Dynamics that exist come from the singers skills, not a box that overrides those skills.

Once the track is done, if you need to slam it to get it to match the rest of the instruments, so be it. Thing is you are working in a controlled environment at that point and can micromanage any changes you make until you get ideal results.

If you later find out You don't like it you can wipe it out and start over from scratch. Plus you can try out a dozen different compressors till you find the ideal one for that recording. When you use one tracking, its a one shot roll of the dice. You'll either have the ideal sound or you wont and when you don't you blow the entire track.

Compression is allot like distortion. Once its applied to a track you cant undo it when you get it wrong. You can add more but the options for removing it are dam near impossible. The only tool you have to un-flatten a crushed signal is to use an expander which makes peaks greater and valleys deeper.
If you've ever tried it you'll know there has to be some dynamics left for an expander to trigger. If the dynamics are flat you're totally screwed. Even with some dynamics left an expander doesn't always trigger reliably.

If you Need compression to sing then its often better to split the mic signal and record one track with it and one without. Believe me, you'll thank me when you have that backup track without compression when you find that excellent take was destroyed by too much flattening.

There are also cases where you may be using something like a pitch shifter and want to maintain the dynamic levels so the pitch lock remains steady. Its no different then singing live and you do what you must in those cases.

I would suggest you use Half as much compression as you actually think you need. The goal isn't to make the job singing easier by compressing the voice. If anything you want to make the singer "work" his ass off to get good results and that includes maintaining his dynamic levels. If you want to smooth the edges off, fine. If you flatten the dynamics I guarantee you the singer will lay back singing, and the result will be lifeless emotion, and no impact at all.
Use only what you need to get the track recorded, no more.

Without dynamics there is no emotions. No emotions, its not even music any more, its white noise, irritating and lifeless.
Old 16th August 2018
  #24
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travisbrown's Avatar
Quote:
Originally Posted by CJ Mastering View Post
If you are like everyone else, you are recording in 24bit, Correct? If you are, then there is no need for a compressor in the recording stage.

You do not need to record as hot as possible anymore , when in 24bit. this means you can have your PEAK dB level between -24dB to -10dB PEAK and your signal will sound Perfect. This also gives you 10dB of room for any occasional peaks. so no need for any compressors.

24bit has 256 more times the resolution than 16bit has, this is why you do not need to record hot!!

Just my take on it
This is very true; but it only accounts for using a compressor for dynamic control, not the tonal shaping that some comps do simply by effect of their particular topology. When recording to a DAW, some want to use their special HW compressor for some gestalt magic that they feel can't be achieved with plugins. Or simply because they paid for (a) HW compressor(s) and feel they should use it (them). <Cut to me looking over at rack B in the studio>

You probably come from the same era as me where compressors were primarily thought of as safeguards against wild dynamics and being able to keep material up in the VU meter to reduce the S/N. And that all changed with the dynamic range afforded by 24bit conversion.

But in general, completely agree that if one is simply wanting to capture a clean input signal, there is usually little reason to need a comp for control.
Old 12th September 2019
  #25
Ba1
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Being new to recording, this thread has been very helpful!

I'm recording using a Tascam Portastudio 424 MK2 (cassette) and then dumping it into a Korg D1200. As expected, I'm getting a lot of noise in the initial cassette recording. Some of it is welcome aesthetically, but at times it can be way too much. It was mentioned earlier in this thread that using a compressor when tracking can cut the noise floor for tape? Would this work in my situation? If so, how can I go about it? Ultimately I'd rather keep the noise than loose the dynamics.

Thanks!
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