How to compress two microphones on one source while tracking?

armansrsa

New member
I have a mono compressor which I like to use in my signal chain while tracking acoustic guitar but as time goes by I find myself recording guitar using a spaced pair of SDC's and now I am looking for the ability to compress both signals together before my signals hit my DAW.

Up until now, when recording using 2 microphones on one source, In my DAW, I have always first combined the two tracks into one stereo group track and end up compressing that one while mixing but to be able to do this while tracking is confusing for me still. How can this be achieved? Will I need a stereo compressor for this task or will two mono compressors be ok? Does the answer depend on how I pan the two signals?
 
To do it while tracking it would be best to get a two-channel compressor that has the option to do a stereo couple.

You can use two separate mono compressors, but you would have to make sure you can use the same settings on each. Variatons in how they compress may affect the stereo image in your mix.

Pan the signals how you like.
 
To do it while tracking it would be best to get a two-channel compressor that has the option to do a stereo couple.

You can use two separate mono compressors, but you would have to make sure you can use the same settings on each. Variatons in how they compress may affect the stereo image in your mix.

Pan the signals how you like.

Thanks for the reply. I understand.

If I was only going to pan both signals to the same place, then could I use different settings on each compressor in mono?

Also, is there no way to combine the signals by using a small mixer and then I can just compress the one signal with a mono compressor? Or is there a reason why I shouldn't do that? The reason I ask is because that is the way i did it in my DAW. I normally just bus the two signals and compress the bus.
 
Thanks for the reply. I understand.

If I was only going to pan both signals to the same place, then could I use different settings on each compressor in mono?

Also, is there no way to combine the signals by using a small mixer and then I can just compress the one signal with a mono compressor? Or is there a reason why I shouldn't do that? The reason I ask is because that is the way i did it in my DAW. I normally just bus the two signals and compress the bus.

Yes you could get a small mixer instead of a two channel compressor but if you have to add another piece of equipment anyway, why choose the mixer over the compressor , especially if you mix in the box already?
 
Because then I could compress both channels as one signal? Is there never a time where that would be beneficial? That is the way I do it in my DAW and it sounds good so I just wanted to recreate this in the tracking phase if that makes sense. Also, I could get a mixer for 50 euro or so and a decent compressor will cost a lot more. I am open just need your help weighing up the pros and cons... would you choose getting another compressor?
 
1) You're going to sum it to mono. Your spaced pair will no longer be spaced.
2) A 50-Euro mixer is probably going to be an extremely noisy mixer.
3) I can hardly see a time where you'd want to compress an acoustic guitar at the input. Unless you're using a Vari-Mu or something just for the character of the unit.

If you're trying to compress a stereo signal (again, during tracking, I really can't think of a decent reason why), you're going to need a linked stereo set. With a spaced pair on acoustic guitar, even using the same settings, the body side is very likely going to tilt the signal towards the neck side.

And unless it's some character unit that you're using for the tonality, you're very likely going to get much better results ITB. Certainly won't be doing the signal any favors by passing it through a $50 mixer...
 
Even if you use the exact same settings, if there is any difference in the source signals the two compressors will behave differently. It might not matter to you in this situation, but it's something to keep in mind.
 
Thanks for the reply.

1) I get that it is going to be summed to mono but sometimes, I capture the guitar or other instruments using two microphones just to be able to blend the volume of the two to my liking not to really have it as a stereo signal which I pan one L and the other R. does that make sense or is that just weird? let me give you another example, I sometimes record the Cajon which is usually miked from behind and from the front to be able to capture the complete sound and this is almost always going to end up as one mono track down the middle. In this case, if I am planning to sum the two to mono could a mixer be the thing?


2) Ok your point is valid re the mixer but is there no mixer that I can use that won't add noise?

what about this?

Mix 2:1 - Radial Engineering

3) I sometimes compress guitar when tracking because I like the character/sustain of the sound. I also gave other examples of percussion instruments with big transients where compression might be beneficial while tracking just slightly taming the peaks.

So having explained all this, what do you think? With the Cajon and bongo I really do need to compress while tracking, just a bit to watch out for those transients and I also like the sound compressed. So having said this, would appreciate your feedback.

thanks a lot!
 
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yeah , that is what I was thinking which is why I thought the best way may be to compress it as one signal. Of course, that wouldn't work if my idea was to then pan the two tracks differently but if my intended use was one mono track....
 
So having explained all this, what do you think? With the Cajon and bongo I really do need to compress while tracking, just a bit to watch out for those transients and I also like the sound compressed. So having said this, would appreciate your feedback.

You don't really need to compress to prevent clipping, you just need to set your gain lower. Have the performer hit the thing twice as hard as he thinks he'll hit it for real and make sure that peak is something like 6dB below 0dBFS.

While I'm not completely against compressing while tracking, I don't see why it's such an issue. I do it when it's convenient and I know the material really well. If it weren't an option it would not handicap me in any way. In fact, if I have any doubts I bypass it.
 
I have a mono compressor which I like to use in my signal chain while tracking acoustic guitar but as time goes by I find myself recording guitar using a spaced pair of SDC's and now I am looking for the ability to compress both signals together before my signals hit my DAW.

Up until now, when recording using 2 microphones on one source, In my DAW, I have always first combined the two tracks into one stereo group track and end up compressing that one while mixing but to be able to do this while tracking is confusing for me still. How can this be achieved? Will I need a stereo compressor for this task or will two mono compressors be ok? Does the answer depend on how I pan the two signals?

I would suggest not worrying about the compressor on the 12th fret position (if that is how you are micing).

The hole placement is usually the one that could use some help. That being said, unless you are really sure of the 'character' that the comp on the way in is necessary, I wouldn't use it.

You can always run the recorded digital track back out to the analog compressor later if needed. Well, depending on your interface..

I used to do the same myself man. It just makes more sense to me to capture first. Listen second. Process last.

It not 1970 anymore. lol
 
You don't really need to compress to prevent clipping, you just need to set your gain lower. Have the performer hit the thing twice as hard as he thinks he'll hit it for real and make sure that peak is something like 6dB below 0dBFS.

While I'm not completely against compressing while tracking, I don't see why it's such an issue. I do it when it's convenient and I know the material really well. If it weren't an option it would not handicap me in any way. In fact, if I have any doubts I bypass it.

okay but I appreciate that advice but I still would like to learn to do it even though you don't think it is a good idea to compress while tracking
 
It's fine for you to record however you like. Trouble is, it's just a technique that seems to offer no advantages at all, and we've moved on. We also don't bother to squeeze every last dB out of our input channel. Headroom and hiss is no longer the driving force making us do that. We can capture the full dynamic range and don't need to compress to try to get a less noisy result. If you want to do it because you just like doing it, and it's never given you grief, it's a valid technique. We just don't ever need to do it. I can't think of a reason I'd want to do it with two input sources simply because unless you pan both dead centre, with two mics you get a small left/right shift as their spectral frequency content changes, and unless you make sure the compression can track accurately (which is hard with tonally different sources) then the imaging problem gets worse. If you have a spectrum scope that shows stereo field, insert it and then watch the very confused stereo field when you add compression - the image fills up with different l/r shifts on the guitars 6 strings - the bass might shift left, the top string shift right, and the ones between moving between the two. It just has a negative impact on accuracy and quality. Sometimes a nice effect, but once you've added the 'effect' you can't get shot of it.

I do a fair bit of stereo recording and imaging is always a problem when recorded direct. Adding extra artefacts seems such a pointless idea?
 
with two mics you get a small left/right shift as their spectral frequency content changes, and unless you make sure the compression can track accurately (which is hard with tonally different sources) then the imaging problem gets worse.

Well, using a stereo compressor with the channels linked resolves that. It sums the signals at the input of the detector and applies the exact same gain reduction on both channels. The main downside to that is if there's a big difference in content between the two channels. The result would be awful if one channel was a vocal and the other channel was a kick drum.
 
Trouble is that on a real stereo source, the difference is small, but two mics on a guitar isn't really stereo = one being thin, weedy and with loads of HF and the other boomy and heavy in the LF - so the compression works differently - the heavy strum, triggering compression on the neck mic that does odd things - especially when there's panning. Sounds very strange.
 
Right, which is the different content scenario I mentioned. I think we would agree that this is why doing the compression later would be preferable, so you can try different things without being stuck with the results.
 
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