I’m fairly certain that over the years I’ve read that Multi Band Compression is both “a miraculous savour of” and “an evil plague upon”, audio. Less dramatic commentators often suggest that it is something along the lines of “a useful and powerful tool that can nevertheless cause great damage ....” and various fora state unequivocally that “all mastering engineers” use them, and that “no serious ME would ever allow one in the studio” This is all very well and good, but you’ve probably got one anyway so what can you do with it?

I suggest that you can think of MBC (see what I did there?) as being two tools rather than one. The first is a compressor that you can instruct to work on only a part of the audio spectrum; the second is an EQ that you can instruct to work only on a certain levels of signal within an audio band. Yes, they end-up being the same thing, but you typically reach for them for different reasons.

Let’s take a look at the compressor function first, and let’s start with the single idea that probably makes the biggest difference of all. Even though the tool you have is called a “Multi Band Compressor”, try thinking of it as being several “Restricted Band Compressors” in a single box. Start off with all of the bands bypassed and then add one. If you need to compress the bass end of mix, add one low band, solo it (if you have that facility) and adjust the bandwidth or crossover points until it contains just the audio you require, then set the compressor functions as needed (assuming that you know your way around standard comp controls, if not leave the multiband beast alone and go figure them out). 

If that’s all you need to do leave all the other bands bypassed and you have the job done. Obviously you need to undo the solo at some point (obviously – ahem). Google the infamous Andy Sneap C4 compressor setting for heavy guitar – this is exactly what he does. If you need to compress audio in another band then you can do that too, but consider it to be a different process that you just happen to be able to do in the same interface. Once you have done everything you needed to do, bypass the rest and leave it alone.

OK, so what about EQ? Well, if you have a 3 band MBC you can think of it as 3 band dynamic EQ, 4 band MBC = 4 band EQ (there’s a pattern here if you look carefully).  Let’s say you have a piano part that gets a bit strident when the player gets carried away with the right hand in the chorus. You can EQ the offending frequencies to tame the sound, but then the part gets dulled all the time, even when it was sitting quite happily in the mix. You can automate EQ so that it pulls down the highs only on the loudest parts (this is highly effective but strewth it can sap your will to live) or you can apply an EQ that has effect only on the louder parts. Set your MBC so that any one of the bands contains only the offending frequency range, set the threshold to just catch the parts that are loud enough to be a problem, compress for gain reduction to taste and off you go. Again, bypass everything that you don’t use.

Once you’ve got your head around multi band compression have a think about what you could do with multi-band expansion!

Here’s just a few cool things you can do with a MBC

• Dial-in a dB or two of top end gain reduction when the signal is hot for an ad-hoc tape emulation.
• Set a high band to catch sibilance for an uber-controllable de-esser.
• Tame resonance (I find this particularly useful on strings and drum-kits).
• Push or pull a solo part in a mix (v useful for guitar solos when you don’t have the multitrack).
• Control prominent instrument transients in a mix.

I’ll say this again, if you don’t know how to use a standard (ie single band) compressor then don’t waste your time here, go practice and come back when you have that mastered.

Also note that MBCs do introduce phase shift to your signal; it’s usually not a problem but be aware that it is happening.

(Also also note that if you are using Waves C6 (which I like a lot) it doesn’t bypass properly, I queried what I was hearing with Waves support and their developers confirmed this behaviour).

Like many people who work with audio I use a variety of monitors for mixing and mastering.  Most frequently I’ll work on monitors, but check edits and details using the ‘phones and also do a sanity check on a more restricted monitor (a mono Avantone Mixcube or a pair of £20 Aletec Lansing computer speakers in my case).

My trusty Sennheiser HD250 Linears have been quite adequate for my needs for a long time, but recently I’ve been getting a little stale on my monitors and decided to buy myself a pair of better headphones.

Now I reckon that “which headphones should I buy?” must rank alongside “recommend me a microphone” and “what preamp do I need?” in terms of persistence.  And it’s pretty well unanswerable, so here’s the answer. Ahem!

Firstly, read this

http://www.soundonsound.com/sos/jan10/articles/studioheadphones.htm

Done? Good, then I’ll continue.

I read the article, did some online reading and shortlisted some headphones (Sennheiser HD600, HD650, Beyerdynamic DT880 Pro and AKG K702) to try.  Problem number one, I didn’t find a dealer that I had time to visit that had all of them in stock.  I managed to try a pair of HD650s and a pair of DT880 Pros, but in different locations on different days. I figured from this imperfect exercise that I preferred the sound of the HD650s, thought the DT880s were a little “scratchy” sounding (I use the “ “” marks because that’s actually a bit unfair, they’re not really scratchy, just a little harder and brighter – more on this later). I really didn’t want to make this decision into a major project so I decided that as I had tried the two top placers in the SOS magazine article I’d select between them and be done; I ordered a pair of HD650s from DV247.

The package arrived the following day, I prised the new babies onto my head (I can confirm that the headband does loosen-up after a few days use) and played some reference tracks that  I use, along with a track that I’d been working-on, whilst I did some computer admin. They sounded gorgeous, even without being broken-in at all. I found a couple of bits that needed some attention in the track that I was working on, which pleased me, but mainly just listened to music for a while (until my head started to collapse under the pressure (they really do ease-off).

The following day I did some work on the bass end of the track and nailed a problem that I’d been struggling with for a few days.  Ever so pleased, until I listened on my monitors and found that my perfect bass balance sounded light, as it did on my hi-fi and on the kitchen system. Read-up a little (as I did) and you’ll find that the HD650s are renowned for being warm, smooth, slow, relaxed, a little recessed in the highs, a little overblown in the low-mids and a little uneven in the bass; so why the hell did I buy them?!?  Should have got the DT880 Pros!  Apparently Bob Katz (much respected here) prefers the HD600s (as do many others) and there is a rabid contingent of K702 fanciers in the wings.  Basically the three ‘phones I didn’t buy are much-loved, the one I did is considered to be pretty flawed. Simply wrote in my diary, “Oh Bugger!” and went to bed.

The next day I called DV247 to check the details of their 30 day return promise and found that it doesn’t apply to headphones (because they are designed for body-contact use)so my plan to order the DTs and do a proper studio comparison and return the loser rather withered. Oddly, having pretty well decided that I’d made a mistake and should have bought the Beyers (even though I’d decided that I didn’t like the sound so much) because of the internet communities almost unanimous love of them, and their superior analytical capabilities (because of that harder, brighter sound), I found myself actually rather relieved and with little choice but to push-on, I pushed-on.

Now here’s the odd, but telling thing. We all know that you need to take-time to  get used to the sound of a new or different piece of kit, and that when you do you can “adjust” for its vagaries. Well a few days ago I revisited my difficult bottom-end (excuse me) with the HD650s.  I tried again, got a result I thought was spot-on and switched to the monitors. Guess what? They sounded pretty well the same as on the HDs.  Check in the living room – good to go, kitchen system – AOK.  So what happened and so-what?  This was not a matter of “the cans are bass heavy so I’ll allow for that”, I simply mixed to what I heard – to the sound in my head! If this seems a little esoteric and new-agey consider this; your eyes physically invert the images you see and your brain filters that image so that gravity causes things to fall downwards and trees row upwards.  In a perceptual experiment a test subject was equipped with a pair of spectacles that “corrected” this image inversion and following a period of seeing everything upside down his perception changed and he saw things the right-way-up again – he didn’t learn to “allow for it”, he saw it.

So what does this mean and why should we care?  It means that when one poster on gearslutz says that the HD650 is woolly and muffled and the HD600 is better in every way, and another says that the HD600 is thin and shrill and the 650 is perfect, and one reviewer says that the 650 is bass heavy, another thinks it’s bass light, they may well all be correct.

What, you expected a recommendation?  OK, figure-out the mechanics of what you need (isolation, comfort etc), what you can afford, shortlist and try a few options in  budget, and then just buy whichever you like.  In a few weeks it'll probably make very little difference!