Technology

Symetrix 562E: WINDOWING EXPANDER/GATE

Released at the last Winter NAMM show, the Symetrix 562E Windowing Expander/ Gate is a full-featured 2-channel gate or downward expander. In addition 1/01/1999 7:00 AM Eastern

Released at the last Winter NAMM show, the Symetrix 562E WindowingExpander/ Gate is a full-featured 2-channel gate or downward expander.In addition to all the usual controls and adjustments, a feature calledWindow Advance allows the entire leading edge of transient signals topass through the 562E cleanly. Thus, the full impact of a drum's attackis allowed through at even the fastest settings, without clicking orpopping.

The 562E under review spent last summer in my FOH effects rack,along with a couple of popular gates by other manufacturers. I used the562E for drum inputs on many live shows, mostly on kick, and the drums'attack sounded so natural that on several occasions visiting engineersdoubted that the gate was working at all. Only by reducing the gate'srange to zero and opening it up while they listened on headphones couldI convince them that it was, however transparently, gating their kickdrum. The Windowing Expander/ Gate provides the full impact of thedrum's leading edge, and it may be the best tool for cleaning up thekick for live sound that I've heard.

To recap, a gate on a drum input will automatically shut it off whensignal falls below an adjustable threshold. This both eliminates theoff-axis sounds of adjacent drums and allows the live engineer to turnthe drum channel up louder than would normally be possible withoutfeedback. Obviously, there are other applications in live sound, suchas turning off noisy inputs and taking room ambience out of vocal mics,and there are a host of uses for gates in the recording studio.

The Window Advance is a four-stage, all-pass filter that delays thesignal through the gate just long enough (about 20 microseconds) forthe detector to open before the signal has started passing through theVCA. The gate's envelope is able to track the attack of fast-risingpercussive transients by anticipating them, thereby eliminating the"click" that occurs when the waveform is "chopped" on fast attacksettings. The Advance switch has two settings, marked Min and Max, andmy trials on drum kits revealed that the Max setting should be used toopen the gate as quickly as possible. This setting adds a bit of phaseshift at higher frequencies, but this is by far preferable to missingthe transient on the percussive sounds.

Front panel controls include a knob that, at full counterclockwise,offers 80 dB of gating. Turned clockwise, the control provides downwardexpansion at a ratio of up to 1:3. When the signal falls lower than 25dB below the threshold, the expander ratio reverts to 1:1 in order toprevent low-level breathing. Similar in concept to compression,downward expansion scales the signal back by a ratio rather than justshutting it off, and it is better suited than straight gating for noisereduction tasks requiring subtle control.

The Threshold control is accompanied by a green and a yellow LEDthat shows when the signal is below or above threshold. A vertical rowof four red LEDs displays gain reduction of 3, 12, 30 and 60 dB. Otherfront panel controls adjust attack, hold and release times with agenerous range of settings. The fastest attack time setting (fullycounterclockwise) is labeled Auto and is meant to be used with theWindow Advance setting; it ensures that the gate opens enough beforethe signal needs to be turned on so that it doesn't click.

In order to tune the gate's detector to ignore unwanted sounds thatcould trigger it inadvertently, a lowpass filter sweeps up to 1k and ahighpass filter sweeps down to 400 Hz. The EQ filters are 12 dB peroctave, providing minimal phase delay that the Windowing feature keepsup with easily.

Rear chassis connections include XLR and 11/44-inch TRS jacks forbalanced and unbalanced connections. Each channel also has a TRS insertjack for the key signal (tip wired return, ring wired send). The keyinput may also be used to trigger the gate from an external source. Athree-way switch on each channel sends the filtered or unfiltered keysignal to the channel's output so that the key signal can bemonitored.

Symetrix's new gate easily meets the high level of engineeringstandards set by the company's other recent analog and digitalproducts. At a list price of only $579, the 562E offers performance notavailable in gates costing much more.

Symetrix Inc. 14926 35th Ave. W., Lynwood, WA 98037. Phone 425/787-3222; fax 425/787-3211. Web site: www.symetrixaudio.com.

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