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Control Room

Maximum headroom

Behringer Composer and Autocom

Article from The Mix, December 1994

Two models of compressor

The Behringer range of products are fast becoming known as much for quality as value. Bob Dormon looks at two of their compressors - the Autocom, and the Composer - and finds that regulating your levels has never been easier...

A quick flick through any self-respecting music production magazine (did somebody say The Mix?) and you'll find a boundless selection of compressors available in the semi-pro audio marketplace. Like a newly privatised utility, companies promising more for your money are springing up all over the place. Even if you were satisfied with what was on offer before, dynamics processing is such a growth area that a compressor will nowadays do rather more and cost you rather less.

In the September issue, the Aphex Easyrider 106 was put through the mill; a no-frills compressor if ever there was one. Behringer offer an antidote to such 'squash and go' simplicity with their MDX 1000 Autocom.

Autocom MDX-1000

This unit can be configured for auto or manual operation, so that the attack and release times are derived for you by detection circuitry which examines the program material. The sales blurb makes repeated mention of the word 'intelligent' - the idea is that the compressor's circuitry can operate on auto-pilot if required, or take a back seat when you feel like exercising the old grey matter.

Having both options increases the flexibility of the Autocom, as do the external sidechain inputs. But if you're after that little bit extra, such as XLR connectors or an expander section, then Behringer will happily sell you the MDX 2000 Composer. It also offers an auto mode, but more on that model later.


Behringer's 1994 products catalogue comprises some twenty devices. Nearly all are 1u rack units, and come in the company's distinctive livery of brushed aluminium with a fine white legend.

A different sort of legend lies behind the 'earhole' logo, involving an 'amusing episode' from the eponymous Ulrich Behringer's schooldays. After showing off his perfect pitch during a music lesson, he came to be nicknamed, 'Behringer - the ear'.

Maybe it loses something in the translation, but once past the CV-ish preamble, the manual rallies to a pleasing finish. Namely, the five year guarantee. The usual asterisk and fine print apply, but all in all the conditions look reasonable. What is also quite surprising is that all the illustrated products have their prices printed next to them (in Sterling including VAT and Deutschmarks), and very attractive they are too.

On the face of it, the Autocom, although straightforward in both appearance and operation, has not suffered as a result of its overall simplicity. This dual compressor has stereo linking and balanced inputs and outputs, when used with 1/4" stereo jacks. The two channels are identical. Three diminutive black rectangular switches control bypass, hard/soft knee response and auto/manual modes.

All of them, including the remaining power and stereo link switches illuminate in tasteful hues of red, amber or green when active. However, the right channel lights extinguish as soon as stereo link is implemented. When used in this mode, the left channel 1 acts as a master control for both, ensuring that uniform adjustments are made to preserve the stereo image.

A 40-step switching action enhances the action of the slim grooved control knobs, useful for noting/recalling settings. Unfortunately, if counting isn't your forte, auto mode will only take care of the attack and release controls!

Threshold covers a range from -40 to +20dBu, and compression ratios begin at 1 and climb to 8:1. the last eight clicks eventually take you to a limiting setting. The fact that around a third of the ratio control's adjustment is taken up by the range between 1:1 and 2:1 indicates that Behringer expect this device to play a part in the compression of stereo mixes. And indeed, stereo mixes is one of the areas where they suggest using the auto mode.

If you're happier with a knob in your hand, (Ooh-er, missus - Ed) then switch to manual, to alter the attack and release times. At 1mS (to 2secs), the fastest attack time is a little sluggish for some transients, resulting in some ugly blips with heavy compression. Oddly enough, it disappeared when switched to auto.

The release response between 50mS and 3secs is well spread out, and dealt with snappy snares and beefy bass drams with no trouble at all. Having set up the compressor's 'pulp function', the output level control's variable gain of ±20dB allows for any compensatory adjustments.

Eight red LEDs complete each compressor's visual readout of the gain reduction imposed on signals, but there's no output metering.

"The five year guarantee is very comforting and indicates Behringer's confidence in their products."

In Use

The Autocom behaves much in the way you'd expect from a compressor when in manual mode. Having the soft knee option is handy for sounds like slow bass and meandering pads, whereas percussion performs better without it.

As mentioned before, sounds would blip as the Autocom raced into action to compress them in manual mode. This is fairly typical of a compressor. Thoughtful adjustment of the threshold, ratio and attack settings help contain this effect, but auto mode seems to save the day on most occasions. You can crank up the ratio and wind down the threshold and still get an earhole-friendly result.

Letting 'auto' decide your attack and release times on a variety of sounds from drum loops to vocals, avoids some of the erroneous characteristics of typical manual operations, and you still get to use soft knee if desired. Trying to emulate the auto behaviour in manual revealed medium speed settings on both the attack and release. Hence no blips. With different sounds, the auto mode response did vary slightly, but not a great deal. In general, the front end of sounds survived pretty much intact. Pumping and breathing are kept at bay even with extreme settings, yet the release time gradually gives in to the inevitable, as noise creeps in as the signal dies away.

The Autocom itself is very quiet and also a very cool machine, barely reaching body temperature during hours of use, in spite of an internal mains transformer.

Behringer's distinctive front panel design makes operation quick and easy.

Composer MDX 2000

If you want to get even cooler, then splash out another £106 and you can have the MDX 2000 Composer. The main compressor section is much the same as the Autocom, with a faster attack time (0.5mS) and longer release time (5secs). The compression ratio has a marginally better spread of adjustment around 2.5:1 and 5:1.

You also get switches for external keying and key listen. These are useful for sidechain control, and allow the sidechain to be permanently wired to a patchbay without the need to unplug when not in use (a necessary evil with the Autocom).

Either side of the compressor section are two additional features: an expander/gate and a peak limiter. Each have an LED above their control knobs which illuminates when signals are subjected to these processes. The expander/gate also has a fast/slow release switch, to adapt its response to the program material.

In between these two LEDs are two 8-segment LED meters. The first all-red display is for gain reduction, while the other shows input (when in Bypass) and output levels (when Composer is active). The first four segments of this meter are green, with amber marking 0dB and the remainder in red going up to +15dB.

This level metering is quite different to what I've seen on compressors of this type. They have a slow fade time, so that you can clearly appraise what's going on. With some signals like slap bass or percussion, the sound is over in the twinkling of the eye. Having the option of peak-hold metering is very useful in such situations.

What you don't get on the Composer is the hard/soft knee option that exists on the Autocom. This is done for you by a process that employs the buzzword of the Nineties; 'Interactive Knee Adaptation' or IKA for short. IKA curve characteristics are designed to permit '..inaudible compression' for low level signals, producing a soft knee effect. With more extreme gain reduction settings, the IKA adopts hard knee processing.

Round the back, you can see where some of the extra money's gone. XLR connectors and 1/4" stereo jack sockets are provided, with independent switching to allow +4dBu and -10dBV operation for each channel. The external key (sidechain) access is via unbalanced jacks only, providing a send and return for easy routing to EQ or other effects. This is an improvement on the Autocom, which provides only a return, so you have to split the incoming signal first for sidechain/keying applications.

The mains input for both units is the same IEC type and can be configured for 100-120 and 200-240VAC (50-60Hz), but not even the European Union seems able to resist the rise of the US-style 2-pin mains plug. It's just as well that they come in sturdy pressed steel cases, with the aluminium front panel reinforced with double thickness mounting ears.

"Snares and bass drums just weren't quick enough for this attack number, and were duly dynamically dealt with without a murmur or a blip in the process."

XLR connections and IEC mains input indicate high specification of the Composer.

In Use

The most noticeable/audible feature of the Composer compared to the Autocom is the faster attack time of 0.5mS. It's only double the speed of the Autocom, but makes dealing with fast attack transients a pleasure rather than a potential pain. Snares and bass drums just weren't quick enough for this attack number, and were duly dynamically dealt with without a murmur or a blip in the process.

A brief foray into auto mode produced much the same results as the Autocom, utilising moderate attack and release times. And if auto provides the sort of effect you're after but you're concerned about wayward transients slipping through the net, then the peak limiter can be brought in to police these dynamic miscreants.

The peak limiter also enjoys having the word 'interactive' used to describe its function. The attack time is virtually zero, and it works over a range from 0dB to over 15dB. The 'Interactive Gain Control' circuit (IGC) has two stages: the clipper and the programme limiter. The clipper works on fast transients, whereas the peak limiter is introduced should any of these transients last for more than 20mS. If so, then the peak limiter steps in and reduces the overall level for 1 second, by an amplitude value that prevents a repeat request for assistance by the clipper.

As they work interactively, one or other of the two controls will be implemented, depending on the program material involved. The intention is to reduce potential distortion in the limiting process, and achieve optimum performance. It seems to work.

The expander/gate, believe it or not, has an 'Interactive Ratio Control' circuit (IRC). This is designed to produce more gradual expansion around the point of threshold, in order to avoid the often abrupt nature of expanders. The expander adjusts to the programme material '...equipped with a soft, interactive non-linear ratio curve', the effect being an increased ratio, thus greater attenuation for low level signals.

In use, the expander/gate worked more appreciably as a gate. The fast/slow speed options deal effectively with short and long sounds respectively, 'though I missed the option of being able to select the expansion ratios. This became apparent when attempting to revamp a recording of a conference that suffered excessive background noise. The Composer attenuated these sounds so well, that the overall effect was hard on the ears. Noise would appear with the speaker and then disappear entirely, only to reappear with the next sentence. A more subtle expansion was needed, so the noise masking wouldn't be so obvious, yet this was not really possible.


Both the Autocom and the Composer are sensibly priced devices. They're not lightweights, and my impressions are they would provide many years of active service. The five year guarantee is very comforting and indicates Behringer's confidence in their products. For the same price as the Composer, you could also get the Multicom MDX 2400, which offers four compressor/limiters in one box. It's nice to have the choice between these three models, since peoples exact requirements will obviously vary.

A surprise for those expecting to purchase some Teutonic technology is that 80% of Behringer's production is based in China. This South-East Asian arrangement goes a long way to explain how Behringer can offer you such a lot for your money.

Overall, these Behringers are flexible yet friendly compression devices, which are as worthy of your cash as they are of your rack space.

The essentials...

Prices inc VAT: Autocom: £236; Composer: £342; Multicom: £342.

More from: Behringer, (Contact Details)

Spec check


Input type: RF filtered, servo-balanced input
Nominal Operating Level: +4dBu/-10dBV
Max Input Level: +20dBu balanced and unbalanced
Output type: Electronically servo balanced output stage (Optional transformer-balanced output). Automatic level correction for unbalanced use (Correction 6dB)
Max Output Level: 26dBm balanced, +20dBm unbalanced
Bandwidth: 5Hz to 50kHz, +0, -1dB
THD @ +4dBu: 0.05% typical
THD @ +20dBu: 0.1% typical
Noise & Hum, unity gain: > -100dBu
Noise & Hum, fully off: > -106dBu
Crosstalk @ 20kHz: > -85dBu
Power: 100-120/200-240 VAC 50-60Hz
Power Consumption: 9 Watts
Fuse: 160mA slow-blow
Weight: 3kg


Input type: RF filtered, servo-balanced input
Nominal Operating Level: +4dBu/-10dBV switchable
Max Input Level: +20dBu balanced and unbalanced
Output type: Electronically servo balanced output stage (optional transformer-balanced output). Automatic level correction for unbalanced use (Correction 6dB)
Max Output Level: 26dBm balanced, +20dBm unbalanced
Bandwidth: 5Hz to 50kHz, +0, -1dB
THD @ +4dBu: 0.01% typical
THD @ +20dBu: 0.1% typical
Noise & Hum, unity gain: > -94dBu
Noise & Hum, fully off: > -97dBu
Crosstalk @ 20kHz: > -85dBu
Power: 100-120/200-240 VAC 50-60Hz
Power Consumption: 9 Watts
Fuse: 160mA slow-blow
Weight: 3kg

Previous Article in this issue

Nuclear Vision

Next article in this issue

Styling & profiling

Publisher: The Mix - Music Maker Publications (UK), Future Publishing.

The current copyright owner/s of this content may differ from the originally published copyright notice.
More details on copyright ownership...


The Mix - Dec 1994

Donated by: Colin Potter

Coverdisc: Mike Gorman

Control Room

Review by Bob Dormon

Previous article in this issue:

> Nuclear Vision

Next article in this issue:

> Styling & profiling

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