Posts Tagged ‘Multiband compression’

The scary thing that is…Multiband compression

Hi people!

Yes, I know, I must be mad attempting to explain this one. But it’s a major part of mastering, so I have to try.

Note:Please have plenty of coffee to hand, this could take a while

Before I go any further, I need to say this. In my opinion, the multiband process is for fixing the dynamics across the spectrum, not for trying to be clever/creative with it. The idea, is that the low frequencies should be there at the same time as the highs. This is heavily dependant on correct release times.  If you get them wrong (and I certainly have in the past), you can make quite a harsh sound.

Introducing the controls

1:Band crossovers These select the crossover frequency between the different bands, in conjunction with…..

2:Crossover slope This selects how steep the crossover is between the bands. Not all models come with this option, but I find it priceless in achieving a more natural sound for different material .

3:Lookahead This gives the option of the compressor reading ahead by a few milliseconds to prevent threshold crushing from higher peaks. It actually gives you the choice of how much you want the compressor to react. From pumping to clean attacks. Once again, this option isn’t available on all models, but is incredibly useful in creating the sound you want.

4:Clean/vintage mode Another option that isn’t available on all models. This one makes the difference between a clean “what you put in is what you get out” sound, or the vintage option will add slight distortion to emulate hardware. It wont work on everything, but can blur the edges on material that could use a bit less clarity.

5:Band Low gain This sets the volume of the band selected when the level is below threshold. So….when that band isn’t into compression(below threshold), it will be at the set level. The really useful thing with this particular model, is that the upper&lower levels can be set, which sets the total amount of gain reduction.

6:Threshold The level where compression starts to happen in the selected band. DO NOT LOOK AT THE DISPLAY TO SET THESE!!. How far back from threshold compression starts to set in, is dependant on the knee setting (11).

7:Band hi gain This sets the amount of gain reduction. So even if you’re pushing the threshold incredibly hard, the reduction will be restricted to the set amount.

8:Band Ratio How much gain reduction for every db increase in input above threshold. Basically, a setting of 2:1 means a 1db increase allowed for every 2db above threshold. Remember when setting up, raise the ratio…raise the threshold. Don’t go mad using high ratios!, what we’re doing is balancing the dynamics across the spectrum. This isn’t the place to ramp up the volume!.

9:Band attack time How many milliseconds of signal allowed through, before compression starts, after threshold is reached. Same principle as with a standard compressor, in that the attack time depends on the gain and length of the peaks, but they vary per band to suit the needs of the spectrum. More explanation later.

10:Band release time If you’re reading this, you should already know how important the release time is. Once again, in multiband it varies to suit the spectrum. Usually starting short for low bands, and increasing through the others….usually!.

11:Band knee setting Self explanatory, this sets the knee of the compression per band. The model shown has soft/medium and hard, giving incredible control in attaining the correct compression curve. And again, not found on many models.

12:Global controls These make it easy to change all the band  release times for example. I’ll explain further later.

In addition to these controls we have the bypass/solo and mute buttons, which do exactly that for the selected band.

The Add and Delete buttons are another unique feature of this model. Giving you the option to add and have upto 6 bands, or delete them and even make this a dual band compressor (no idea why you would though). Experience will aid you in knowing how many bands you need. It really depends on the material.

Up to now, this may have seemed like an advert for the model I have used as an example. The fact is, I wanted to cover almost any control you may encounter, and it had the most.

Setting up

First step is to divide up the different areas of energy using the crossovers. With all the thresholds, ratios etc set to zero, drag the band1/2 crossover up and down between 60-100 hz. Listen to the image to find the right point. It’s like it swings left and right as you scan down and up. The sound will be more solid when you hit the right spot. I’m not going to give you any numbers for setting these, as it is totally dependant on the material.

Listen to this clip. You may hear the image change as I am dragging the lower crossover (band1/2) down from 100-50hz, then back up to 120 hz, then finally in the correct position at 79hz. Don’t be hard on yourself if you can’t immediately, but this technique is essential in mastering.

You want to set up all the crossovers using the same method. Keep paying close attention to the sound image. Get them in the right place, and it will stay more solid. If you have a selection of crossover slopes, test them now. Find the one that sounds most natural, then adjust the crossover freq’s again to suit.

Find the problem band

Before I go any further, the thing to remember, is that this is basically a dynamic eq. We are pinching certain parts of the spectrum to match the rest. So..take a listen to the individual bands, solo each one and have a listen to what’s going on. This step will become easier and faster with experience, as you start to be more critical with your analysis skills.

Are the lower bands too dynamic, so are stomping over the higher ones?. Is the low end heavily compressed and the mids too energetic?. Have some idea before jumping onto the settings, as you want to match the wrong to the right. No good adding 4db of gain reduction to an already squashed bass area. The mids and highs will sound unnaturally lifeless to match it.

First steps with the gain reduction

Soloing things in mastering can be quite counter productive, as we are working on the whole sound, and no band is an island (apologies ) . What I mean is, soloing each band and setting them up and expecting it to all be fantastic when you turn the solo’s off, isn’t going to work!. The idea is to have them all working together to make one sound.

However….for your first steps in setting up multiband, it can be less confusing to tweak the problem band in solo, and then match the others to it. This gets round the problem of making one band sound unnatural to the rest, forcing you into making wrong settings. Although you will still end up tweaking the settings for that band, once the others are close. The whole setup of multiband is very fluid.

Right, due to this being a long winded/complicated subject, this is going to be a multi part post. Apologies readers, but check back next week for part 2, where I’ll start guiding you through the other settings.

Thanks for stopping by

Tone