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DRAWMER SP2120: A Psycho on the Loose…

Anybody who has been around the audio industry for a while will know the name Drawmer. It has been associated with a number of industry milestones over the last 28 years, particularly in the area of Dynamics Processors and Studio Compressors. However, most of these products have been limited to the rarefied atmosphere of high-altitude-audio, where only sonic Guru’s and rich equipment junkies live.

Well you don’t need to have a degree in scratch mixing or a doctorate of higher production diagnostics to need the Drawmer SP2120 (which could have been called ‘5150’ in our opinion). You just need to be the owner of a pile of expensive speakers in a nightclub. This particularly applies if you have been getting that 3:00 AM phone call complaining that: #1, “suddenly no bass” or #2, “I was just running it normally…. and poof!”

5150 is LA Police slang for ‘Psycho on the Loose’ (according to Eddie Van Halen), so the 2120 could be sub-jargon for those small but annoying psychos that have a pathological hatred of properly functioning sound systems. If you are affected by these, and would like to ‘SWAT’ one, Drawmer have just the box to stop those annoying sleep depriving phone calls.


You might say, “So what. I’ve got a compressor across the system and they still blew it up!” Well that’s part of your problem. A compressor, or system controller, may be making the problem worse and certainly won’t stop a determined volume freak.

The SP2120 is not a compressor: it is a limiter. As the last link in the chain before your crossover or system controller, it acts a level output controller with the capability of handling up to +27 dB input gain with the maximum output determined by you regardless if input level. This is where normal compressors and system controllers run into trouble, (especially digital ones).

Once your impaired DJ or band mixer starts pushing the signal path into clipping, two things happen. The first is that the signal component now contains a lot of DC, which can overheat speaker voice coils, and second, the additive effect of all the boosted preamps can send several volts to your compressor causing its input to distort severely. Also, you will most likely have a non-infinite limiting ratio set and unless it is in hard limit with a brick wall peak stop, you will have clipping amplifiers.

Even if you have a good quality compressor set for hard limiting, at high compression levels it does not sound good and the DJ’s etc will be looking to bypass it somehow. And there is your next problem; no protection at all. They will, of course restore it before you arrive with the re-cone kits. (See excuse #2).
Enter the SP2120. Saying good-bye to repair bills is as follows, (assuming you have installed it correctly).

Step 1: Insert key to ‘unlock’ front panel and adjust VU meter pre-set until the peaks of the incoming audio illuminate the red end-stop 0dB LEDs.

Step 2: Adjust max output level pre-set until sound system volume reaches the maximum permitted SPL as specified by the installer or client. Remove key... and sleep soundly.

This operation can be set while the venue is running in a matter of 30 seconds with no interference to the entertainment and you don’t need to be a digital wizard because the SP2120 is a totally analogue device. That’s the main reason it is so effective and can handle such high input.

Though it is dead easy to use, the dynamics processing is about as sophisticated as it gets.

How Does it Work?

All you need is the key and a screwdriver. The first action is you calibrating the 16-segment Left/Right bar graphs to the incoming audio. This dictates the point at which ‘protection’ processing commences. The second adjustment sets the absolute volume level to which the sound system is allowed to perform.

If the SP2120 receives increased signal levels, the transparent ‘protection’ circuitry is activated which maintains the specified system volume level without degradation in sound quality. Hence, you can’t hear it ‘pumping and breathing’ like a normal compressor will and it also does not ‘suck down’ the top end. There is also no bypass function so even if the unit is visible to the operator, there’s nothing to touch.

For the Tech-Heads

The SP2120 greatly benefits from Drawmer’s 25 years experience in designing industry-standard dynamic processing devices. The SP2120 signal path combines a mixture of ‘multiple time constant’ circuitry and Automatic Gain Control (AGC), which allow small overloads to sound louder - even though they’re not.

It’s all technology from Drawmer’s studio pro audio products. Though this product is a departure from Drawmer’s conventional studio market, Drawmer distributors and installers dissatisfied with other protection systems currently available encouraged its concept and development.

What’s it got?

  • Key Holder access only
  • Takes only minutes to install
  • Dual 16 segment Left/Right bargraphs for ‘at a glance’ level metering
  • ‘Protection’ processing 16 segment bargraph display
  • No sound quality loss even during heavy protection processing
  • Once installed and calibrated completely eliminates the possibility of ‘unauthorised’volume levels
  • Eliminates sound system abuse and the resulting cost of chassis speaker re-cones, HF diaphragm replacements and amplifier repairs
  • Reduces ‘call-out’ costs of sound system service/repair engineers
  • Reduces sound system ‘down time’ and the consequential loss of venue income
  • Isolation transformer output option

The Drawmer SP2120 gives a wide variety of venues, such as clubs, theatres, pubs, schools, universities etc. and the opportunity to comply with the local legislation regarding noise levels. Install it anywhere you need level control and say goodbye to the late night psycho calls!

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