Also known as MB or MBC.

These divide the incoming audio signal into multiple bands, with each band being compressed independently from the other.

The beauty of this is that with full band compressors the whole signal is treated, so when a peak is detected, the whole signal is compressed and so other frequencies are also subjected to compression.

Multiband compression only compresses the frequency bands chosen, so a more fluid and less abrupt result is gained. Instead of having one peak trigger the compressor into compressing the entire signal, the multiband allows for individual bands to be compressed. On some compressors, you even have the option of selecting bands that will not undergo any treatment. In essence, a multi-band compressor comprises of a set of filters that splits the audio signal into two or more frequency bands. After passing through the filters, each frequency band is fed into its own compressor, after which the signals are recombined at the output.

The main advantage of multi-band compression is that a loud event in one frequency band won’t trigger gain reduction in the other bands.

Another feature of the multiband compressor is that you are offered crossover points. This is crucial, as you are given control over where to place the frequency band. Setting these crossover points is the heart of the compressor and crucial in processing the right frequency spectrum with the right settings. For example: if you are treating the vocals in the mid range but put your low end crossover too far into the middle range, then the low end compression settings will also affect the mid range vocals.

Multiband  compression can either be a friend or enemy. It all comes down to how you use it and when. It can be a great compressor for controlling problematic frequencies, or for boosting certain ranges in isolation to others. I tend to use them to rescue poor stereo mixes and with the aid of new features like crossover frequencies and threshold and ratios for each band I can have more accurate processing.

However, use with care.

Often I get asked the same question about which to get; active monitors or passive monitors with a separate amplifier?

To answer this, I need to first explain the differences between the two.

It is commonly understood that active monitors simply have a built-in amp and therefore need no external amp to drive them, and that passive monitors need an external amp to drive them. Whereas this is true as far as the power is considered, it is a little more detailed than that when it comes to how each unit functions.

What we really need to look at is the crossover, which splits the signal into the appropriate frequency ranges before they’re sent to the individual drivers.

In passive designs, the monitor contains a set of passive components to split the input signal up into the various frequency bands required for each driver. The high-level input signal required to drive the speaker comes from an external power amplifier.

In active designs, the cabinet houses multiple power amplifiers connected to each driver, each amp drives a driver. The frequency band splitting is performed on the line input signal directly prior to the amplifiers.

While we are on the subject, let’s not forget the ‘powered’ monitor. Normally, in active systems there is an amp for each driver, in powered systems there is usually only one amp powering the both drivers via a normal passive crossover.

Each design has it’s advantages and disadvantages.

In the case of the passive design, you are afforded a great deal of flexibility as you can choose different amps to power them and this can sometimes be a great situation to be in as the better the amp, the better the output signal. A better amp will also deliver far more headroom than a weaker counterpart and the frequency representation can also be better, especially in the higher frequency spectrum. This ‘mixing and matching’ gives the user a lot of room to try various amps and to optimise the best monitor and amp combination. It is also cheaper to buy a passive system as build costs are much lower than an active system.

In the case of the active system, the crossover can be more detailed and accurate, thus providing a more precise ‘frequency splitting’. This design also incorporates better amp matching for the drivers and therefore affords a more stable and better protected system. However, a good active system can cost considerably more than the passive counterpart.

At the end of the day it comes down to budget, studio requirements and space.

A passive system and separate amp take up more space than their active counterpart, but the mixing and matching of amps to monitors is very appealing and much easier to integrate into an updating studio environment. By just changing the amp, you can change the ‘colour’ and performance of the passive monitors.

Active systems come into their own when the budget starts to creep up. A good active system can actually end up being cheaper than the passive + amp alternative, and can deliver better results, or rather, more precise results.

In today’s markets, the mid to upper price ranges, active systems do offer some distinct advantages. We have talked about precision and detail of amps to drive the drivers, better crossovers etc, but we also need to think about driver protection circuitry. This is as important as the drivers and amps. You tend to find that this circuit protection tends to go hand in hand with active designs. Shorter cable lengths within the cabinet, connecting amp to driver, also negates a lot of problems that prevail due to badly shielded cables and the long lengths used.

At the budget end, things are not so rosy. Due to market competition, monitor manufacturers try to keep costs down as low as possible, and invariably compromises have to be made, and it’s usually the drivers and amps that give way.

The powered monitor will usually cost less than the active counterpart as it uses the one solitary amp to drive the drivers. So, it’s worth looking at these options before parting with your hard earned paper.