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Can I plug mic straight into compressor?
Old 19th September 2012
  #1
Gear Nut
 
🎧 5 years
Can I plug mic straight into compressor?

Hey helpful anonymous internet person;

I have a simple home setup; motu 8pre into cubase

Recently I purchased an Alesis 3632 Compressor.limiter/gate

My signal chain is Mic- into compressor- into motu- into computer

A friend of mine informed me that this is not how the compressor should be used; that the signal chain should be something like:

mic into mixing desk- line out into compressor-line into motu (or something...unclear here)

he basically told me that the compressor should be used the way an effects loop in an amp is used....ie that the compressor should be employed in a way that it is part of the desks signal chain

I think he was trying to say that the compressor cannot function properly with just line-level mic signal....that it would need some gain from the desk to push the signal into the compressor

Can anyone shed some light on this for me please would really appreciate anyone taking the time to type as I am a little lost

There is no mention of this in the manual

ie

Can I run the mic direct into the compressor is this 'right' or 'wrong'

Old 19th September 2012
  #2
Your friend is right.The electrical signal from mics are pretty weak.So we use some devices named preamps to...amplify this signal to line level that most audio outboards like compressors accept.
So you should send the mic to Motu to use the preamp.Then you send it to the compressor and then it goes back to Motu to the AD (analog to digital) converter in order to record it.
Old 20th September 2012 | Show parent
  #3
Gear Nut
 
🎧 5 years
Thanks

There are no outputs on the motu 8pre unit

So sending the mic into the motu and then into the compressor is not an option

i guess if i had a desk that could amplify the mic signal, by turning up the gain, and then send the signal into the compressor, and subsequently from the compressor into the 8pre, this would work?

or is desk gain going to give me crappy audio?

starting to think I have opened a can of worms purchasing two compressors that I cannot use....

..........or I could purchase some cheap single channel preamps to drive the mic signal before it hits the compressor.......
Old 20th September 2012
  #4
Lives for gear
 
Jimsi's Avatar
 
🎧 10 years
Only one compressor that I know of that has a DI for an high impedance mics/instruments and that is the DBX 163x and i use it for bass and have used with high impedance mics...I am sure others had the DI but in general you'll need a mic preamp with your Alesis compressor...
Old 20th September 2012
  #5
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Vintageidiot's Avatar
 
2 Reviews written
🎧 10 years
UA/UREI/Teltronix compressors have the designation LA in reference to a limiting amplifiers in the topography. You can get up to 30db or so from it. So an LA3A can be used as a preamp actually.
Old 20th September 2012
  #6
Lives for gear
 
🎧 10 years
1. Compressors/rack HW effects need line level, so a pre amp needs to come first.
2. Even if you have an outboard pre or console to run into the compressor, your interface is not designed for line level inputs.
3. The 8 XLR/TRS combo jacks on the 8 pre accept low impedance mic level or TS/TRS high impedance for instruments. (line level is low impedance).
4. You need an interface with an insert point.
5. Learning and understanding the differences between:
Mic level
Instrument level
line level
Balanced and unbalanced

Will save you from spending money on equipment that's not compatible with each other. Downloading manuals on gear you are considering purchasing is a good idea as well.
Old 20th September 2012
  #7
Lives for gear
 
🎧 15 years
Hi
Essentially as previously posted.
Your mic on it's own is too 'quiet' to really 'drive' a compressor, so you need to amplify it before going into the comp.
As suggested, your interface is really designed for 'mic' level (quiet) signals so your compressors output will be too much for it, so you need an ATTENUATOR, of say 20 or 30dB. These are simply resistors in a fancy 'box' (often a male / female XLR fitted to a short metal tube for easy use).
The choice of 'preamp' is yours, from something really cheap to very expensive.
The attenuator can be about 10 Dollars or thereabouts.
The comment about some compressors having significant 'gain' is correct, a LA2A has about 50dB gain which would make a half decent mic preamp, BUT it really needs to be fed a much larger signal than from most mics to make the compression action start to work (the threshold does not go down far enough).
The action of amplifying the mic into a comp is fine, but having to attenuate after the comp to go into the interface is less than ideal. It WILL work but is not the way to the best overall quality. The main penalty is a bit more noise (hiss hopefully) but even this may not be so important depending on careful setting of level controls.
Matt S
Old 20th September 2012
  #8
Here for the gear
 
🎧 5 years
Your interface has ADAT IOs.. I'd search an used Alesis AI3, 8in/8out 24bit/48KHz with adat in/out to link to your 8pre, so your signal chain could be:

mic -> 8pre in1 -> routing to adat out1 with motu cuemix -> ai3 out1 -> comp in -> comp out -> ai3 in1
Old 20th September 2012
  #9
Lives for gear
 
Vintageidiot's Avatar
 
2 Reviews written
🎧 10 years
Oh yeah, I should have mentioned that is when using a tube mic, which already has a strong enough signal. Some people do use LA compressor right after the tube microphone or maybe a fet with an external phantom power.
Old 20th September 2012
  #10
Here for the gear
 
🎧 5 years
another thing.. pay extreme attention on your gain levels thru the signal path to avoid distorsion/clipping and/or noise:
Ins & Outs Of Gain Structure
Old 20th September 2012 | Show parent
  #11
Gear Nut
 
🎧 5 years
Quote:
Originally Posted by Manfrensengensen ➑️
1. Compressors/rack HW effects need line level, so a pre amp needs to come first.
2. Even if you have an outboard pre or console to run into the compressor, your interface is not designed for line level inputs.
3. The 8 XLR/TRS combo jacks on the 8 pre accept low impedance mic level or TS/TRS high impedance for instruments. (line level is low impedance).
4. You need an interface with an insert point.
5. Learning and understanding the differences between:
Mic level
Instrument level
line level
Balanced and unbalanced

Will save you from spending money on equipment that's not compatible with each other. Downloading manuals on gear you are considering purchasing is a good idea as well.


thanks so much to everyone for the input

I get that the motu 8pre is designed for low impedence mic level....but I decided to experiment tonight with the following signal path

Mic INTO cheap preamp (tube ART) INTO compressor OUT OF compressor INTO motu

I know this is going against the advice offered in this thread

The mic was an AD 2020 which I was experimenting with as a drum overhead

The way I worked it was the preamp perameters (gain/output) were at like 75% output

The gain on the compressor was at zero

I had the gain on the Motu preamp at zero; and I also had the -48 decibel (or whatever it is) engaged on the Motu; so effectivle the motu is adding no (or as little as possible) gain to the signal

The diodes on the motu showed that the signal was in the green and not clipping

The first thing I noticed, was that that the signal on the daw was BLACK...ie far thicker and blacker than ever i'd seen

Normally I can isolate individual snare/kick hits on the visual representation of the signal in cubase, but this was just a thick fat black signal......not sure if this is a result of my efforts at compression, or because the signal was turned up quite high on the pre amp....will a/b with out compressor later....I felt good about this because I figured this would = loudness, come mix time

On the play back I was very suprised to hear the detail I had captured.......I could really here the toms resonating in the mic (which is positioned over heat at roughly head-height (standing)...I could here myself humming away to myself as I was drumming....seemed to be a lot of life in the audio, and everything seemed louder than anything I was used to before....

However i did feel that tonally the audio seemed a little brittle

anyway another friend told me that if the final part of mysignal path was line out of the compressor in to the MOTU, then I would be back to line level going into the motu....I think he meant that the xlr leads are carrying more of a boosted signal........

thanks again

will try to attach mp3 when i figure out how
Old 20th September 2012 | Show parent
  #12
Gear Guru
 
Karloff70's Avatar
 
🎧 10 years
Quote:
Originally Posted by Vintageidiot ➑️
Oh yeah, I should have mentioned that is when using a tube mic, which already has a strong enough signal. Some people do use LA compressor right after the tube microphone or maybe a fet with an external phantom power.
Love my G7 mic straight into blackface LA-4.
Old 20th September 2012
  #13
Gear Nut
 
🎧 10 years
Not sure about the Alesis 3632 Compressor for additional gain

Only with compressors that have a fair bit of gain in their make-up gain circuit.
Old 21st September 2012 | Show parent
  #14
Gear Guru
 
Karloff70's Avatar
 
🎧 10 years
Quote:
Originally Posted by Protoolie ➑️
Only with compressors that have a fair bit of gain in their make-up gain circuit.
And/or mics with plenty output, like some tube mics.....
Old 21st September 2012
  #15
Lives for gear
 
🎧 10 years
It prob work ok with the Motu pad on and the pre turned off.

Don't judge your recording level by the visual waveform or where the knob is set on the outboard pre.
Judge your level using the meter on the track. Record so levels are around -18 average with peaks around -12 to -6. I've recorded even lower and it's fine with 24 bit recording.
Old 21st September 2012 | Show parent
  #16
Gear Nut
 
🎧 5 years
yeah pad on pre off seems to work

the compressor is doing some very wierd **** to my drums; going to take a lot of experimentation to get a feel for how threshold-ratio-attack-release perameters are affecting the audio

for instance; with a heavily compressed signal on the overhead; it seems to be accentuating this horrible mid range/hi end 'slap' from the kick,

My internal mic in the kick sounds nice; but when i bring up the overhead it has this lousy note that messes up my kick sound

so I guess with compression on drums...less is more?

I can hear the compressor swelling certain audio, and sucking the life out of the audio at other points....

steep learning curve.......all over again
Old 22nd September 2012
  #17
Lives for gear
 
🎧 10 years
Setting a compressor is one of the toughest things to learn as a newbie. The reason for this is that unlike with reverb and other effects where you can hear the obvious effect, a properly set compressor is often the opposite of "obvious". I would suggest setting your pre amp up first (with the compressor in bypass or taken out of the chain, get it passing a good signal to the interface, and then fire up the compressor and start experimenting with it. Going: mic --> pre -->compressor --> interface, is a standard set up and should give you what you need to use the compressor effectively. Learn how to get a "transparent sound" with only the loudest peaks slightly reduced at the interface first, and then you are ready to start experimenting. The hardest part about using a compressor for the first time is figuring out what it can do to improve your sound. Experimenting with compression ratios, attack and release thresholds, hard vs soft knee, and input/output gain settings require a good line level signal at the input before you can actually hear the results. Use the bypass mode often to listen to the compressed vs uncompressed signals. Good luck! The fun is just beginning.
Old 22nd September 2012 | Show parent
  #18
Moderator
 
narcoman's Avatar
 
🎧 10 years
Quote:
Originally Posted by zealy ➑️
I had the gain on the Motu preamp at zero; and I also had the -48 decibel (or whatever it is)
I believe this is the phantom power switch - in the way you described you are using it you will want this off.
Old 22nd September 2012
  #19
Baz
Lives for gear
 
Baz's Avatar
 
🎧 15 years
this can be used as a pre, especially for something like e-guitars or drums

JLM Audio Shop - FC500 Fet Compressor
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