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Drawmer DL221 Dual Compressor Limiter

An intelligent, multi-purpose compressor.


Drawmer have already become a studio legend thanks to their immensely popular noise gate, but their compressor seems destined to share its success.


If you are in the market for a Drawmer compressor, you probably don't need to be told what a compressor is for, and if you're a regular H&SR reader, the chances are that you'll already know more about the subject than some studio engineers.

Although it doesn't cost a great deal more than a common or garden compressor, the DL221 offers low noise and distortion and has the added benefit of an inbuilt peak limiter which is set to catch transients that may have escaped a slow attack setting in the compressor section.

In order to make the unit even less obtrusive in operation, the compressor's release characteristics are to some extent modified by the programme dynamics which reputedly makes setting up somewhat less critical and significantly reduces low frequency distortion. The two displays are also worthy of comment as these may be switched to monitor either input or output signal levels, or gain reduction.

The DL221 is, strictly speaking, a dual channel unit in which each channel is independent of the other, but for treating stereo material, a link switch enables both units to track a common control signal derived from the sum of the two inputs. This is essential if dramatic and undesirable image shifts are to be avoided when there is any significant difference in programme dynamics between the two channels.

Side chain access may be affected from the rear panel and this is useful for inserting equalisers into the signal path, for de-essing for example. In order that you know what signal the side chain is responding to, a side chain listen facility is built in.

Construction



It's another bloody 1U rack box - and it's black: Next.



"The compressor's release characteristics are to some extent modified by the programme dynamics."


Control Range



The threshold control; the control that sets the level above which compression takes place, is continuously variable between -24dB and infinity. As this control only affects what goes into the side chain, the overall input level may need to be set by adjusting the output level of the previous piece of equipment in the audio chain.

Ratio controls the amount of gain reduction that takes place once the threshold has been exceeded and this is variable from 1:1 to 20:1, giving a range varying from no effect at all up to true limiting.

The time taken for a compressor to respond to an input which exceeds the threshold setting is called the attack time, which in the case of the DL221 maybe varied from 50uS to 5mS. Once a signal peak undergoing compression falls back below the threshold, the time taken for the effect of the compression to 'wear off' is set using the Release control. This may be set between the limits of 50mS and 5S, but in order to avoid long recovery times following short lived transient peaks, some cunning programme dependent circuitry prevents partial recovery between waveform peaks.

An output gain control functions as make up gain so that the signal level emerging from the unit can be compensated for any losses incurred at the hands of the compressor circuitry. Ranging from plus to minus 20dB, this should be adequate for any normal application.

Of course with any signal processor it is nice to be able to check the results of your handiwork against the original untreated input, and this is what the bypass switch lets you do. Additionally, it's this switch that gives you access to the 'side chain listen' facility whereby the side chain signal, including any equalisation you may have patched in, is switched to the output.



"It is not only the quality of the results that can be achieved that is important, but also how easily they can be achieved."


As mentioned earlier, there is more to the display than meets the eye. Comprising ten dual coloured LEDs, the meter shows either signal level or gain reduction. In Signal Level mode, 0VU corresponds to +4dBv, green LEDs indicating levels below 0VU and red ones values over 0VU. A single yellow LED signifies 0VU. In Gain Reduction mode, it's all change with all the LEDs showing red apart from the 0dB marker which remains green at all times. This is calibrated to indicate up to 22dB of gain reduction.

The peak limiter has no controls as such, just an in/out switch. This is preset to arrest transients that attempt to exceed a +6dB threshold and has a 50uS response time, the release time being dependent on the nature of the programme dynamics. Though the display does inform you when limiting is taking place, an additional LED beneath the limiter switch serves to ensure that such events do not go unnoticed.

Looking to the rear of the unit, it can be seen that all connections (except the mains of course) are made by quarter inch stereo jacks and as well as the usual input/output sockets, there are also connections for side chain access. A captive lead is used to supply the mains and though this may look like a cost saving measure, it's more reliable than a connector and is not prone to accidental disconnection during use. The 50mA fuse is also readily accessible from the rear panel.

Performance



For studio use, it is not only the quality of the results that can be achieved that is important, but also how easily they can be achieved. They say that time is money and it's no good having a compressor which performs brilliantly if you have to fiddle with the controls all day to get the effect right.

However, Drawmer need have no worries on that score and I'm sure they're correct when they say that the programme dependent release characteristics have a lot to do with making the setting up less critical. On the face of it, it would seem that this part of the circuit works in a similar way to the Aphex Compellor reviewed in the May issue of HSR though the Compellor does have other tricks up it's sleeve, as you might infer from its price. Whatever the method used, the result is a more transparent compression than would normally be obtained from a high quality 'non-intelligent' compressor and this is particularly valuable on percussive material which can so often be rendered lifeless by some compressors.



"A good compressor should be seen and not heard."


Indeed, so well did this unit perform that there is very little to comment about; no trying to find out exactly what this or that switch does, no struggling to stop it pumping, it just got on with it's job and let me get on with mine, which is what separates a lot of budget gear from well designed professional products.

The amazing thing is that this compressor is in a price range that puts it within reach of the serious home studio owner as well as the high budget pro operation. Whereas a busy pro studio might buy one Aphex Compellor and then buy half a dozen Drawmers to take care of the routine work, the small studio might well have one Drawmer and possibly one or two less sophisticated units to handle less exacting applications. The problem here is that having bought a Drawmer, your run-of-the-mill budget unit suddenly seems exceedingly nasty, but then that's progress for you.

Conclusions



Speaking as the owner of what I would like to think is a good home recording set up, I could find no cause to criticise the DL221: it was a doddle to set up and conformed to my philosophy that a good compressor should be seen and not heard.

As far as the pro studio is concerned, it must be remembered that a compressor is an unnatural device and so its design is necessarily a compromise between several conflicting factors. What this adds up to in practice is that given several different compressors with good noise and distortion characteristics, there will still be a difference in sound, and in the final reckoning it comes down to personal preference. To some extent this depends on whether the compressor is required for unobtrusive level control or for creating special effects and the Drawmer's extra limiter is a real bonus as an extra line of defence if you regularly use slow attack times to emphasise percussive transients.

For the small studio, the side chain access and monitoring is a significant selling point as it means that the unit can be conscripted into use as a de-esser or a de-popper with the simple addition of any equaliser you have lying around.

I've said it before but I don't mind repeating myself on this occasion, the only trouble with Drawmers is that the owners (in this case HHB) always want them back just when I've decided that I can't do without one.

The Drawmer DL221 costs £321 excluding VAT, and was loaned for review by; HHB Hire And Sales, (Contact Details).

Further information on the DL221 is available from; Drawmer, (Contact Details).



Previous Article in this issue

ART DR2 Digital Reverb

Next article in this issue

Studio Mains Supplies


Home & Studio Recording - Copyright: Music Maker Publications (UK), Future Publishing.

 

Home & Studio Recording - Sep 1985

Donated & scanned by: Mike Gorman

Gear in this article:

Studio FX > Drawmer > DL221 Dual Compressor


Gear Tags:

Compressor

Review by Paul White

Previous article in this issue:

> ART DR2 Digital Reverb

Next article in this issue:

> Studio Mains Supplies


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