Test Drive: Symetrix 528 Voice Processor

by Jerry Vigil

Perhaps one of the handiest tools in a production room is a mike or voice processor. Gear that falls under this category usually consists of several processors built into one. This frees up outboard gear for other things and gives you a box designed specifically for processing your voice tracks. One of the nicer mike processors available is the Orban 787A (Test Drive - December 1989), but with a list price at $1,995, the 787A finds itself out of reach of many budgets. On the other hand, the 528 Voice Processor from Symetrix provides a quality processor at a price almost one-fourth that of the Orban.

The 528 is not a new box. It has been around for over three years, and price combined with performance explain why the 528 is the choice of many. Fitting in one rack space, the unit gives you a de-esser, a compressor, an expander, and a three-band parametric equalizer. Operation is simple and the output supplies the user with more than ample processing of the voice, whether you're looking for a highly processed sound for a special effect, or just simple gain control and/or EQ.

Taking the front panel and going from left to right, our first knob to play with is the MIC GAIN. This sets the gain of the internal pre-amp and is variable from 23dB to 50dB. A line level input is available if you choose to use an external pre-amp. To the right of the MIC GAIN control, a CLIP LED illuminates indicating output levels above +16dB. +48 volt phantom power is accessible by flipping a switch on the rear panel.

The next set of controls are for the de-esser. A nice feature of the de-esser not found on all mike processors that have de-essers is the DE-ESS FREQUENCY control. This function allows the user to select the frequencies which will be affected by the de-esser. The range of frequencies is from 800Hz to 8kHz. Directly below the frequency control is the DE-ESS RANGE control. The range control is variable from 0dB to 20dB. At zero, the de-esser is inactive. At the maximum 20dB setting, the selected frequencies will be attenuated 20dB. Because the FREQUENCY can be set as low as 800Hz, the de-ess function of the 528 operates on frequencies well below those associated with "ess" sounds. This added feature makes it possible to do a little more with this de-esser than with those operating on fixed frequencies; however, the frequency control sets what is called the "corner" frequency which basically means you won't get the effect of "notch" filtering -- all frequencies above the setting will be cut. Just to the right of these controls is a BYPASS switch which will remove the de-esser from the circuit and leave the other sections of the processor in line. The compressor/expander section and the EQ section each have bypass switches also, so any combination of the three sections can be set up quickly.

Next on our little trip from left to right are the compressor and expander controls. Those of you who don't like having too many knobs to worry about will appreciate the compressor and expander of the 528. The only controls you have to concern yourself with are the COMPressor THRESHOLD, the EXPANDer THRESHOLD, and the COMPression RATIO. There are no attack and release time controls to bother you. The 528 uses a "program controlled interactive dynamic range processing technique" (whew!) which analyzes the input and automatically adjusts attack and release times to best suit the input. As far as we could tell, this "PCIDRPT" did the job just fine. The compressor threshold can be set from -50 to +20dB. The expander threshold is variable from 0 to -60dB. The compression ratio is adjustable from 1:1 to 20:1.

Working interactively with the downward expander, the compressor offers a nice "punchy" sound that remains quite clean, even at high levels of gain reduction. The expander helps eliminate noise as well as "pumping" and "breathing" when high compression ratios are set. The compressor can be used without the expander by simply setting the expander threshold to the full counter-clockwise position. The expander can be used without the compressor by setting the compression ratio to 1:1 (also the full counter-clockwise position).

Our next stop is the parametric EQ section which, when used together with the compressor, supplies the necessary additional processing to end up with a hot, compressed sound with emphasis on your favorite frequencies. There are three sections to the equalizer, one for low frequencies, one for the midrange, and the third for the highs. Each section has three controls: CUT/BOOST, FREQUENCY, and BANDWIDTH. The cut/boost range is a healthy -30dB to +15dB. The FREQUENCY control sets the center frequency to be boost or cut, and the BANDWIDTH control sets the range of frequencies to be affected on either side of the center frequency. On the low end section, the center frequency is variable between 16Hz and 512Hz. The center frequency on the midrange section is adjustable between 196Hz and 6.3kHz, and on the high frequency section the range is 686Hz to 22kHz. Bandwidth for each section is variable from .05 octaves to 3.3 octaves. If you're familiar with parametric EQ's, you'll notice that the specs of the EQ on the 528 are pretty good. Being able to adjust the bandwidth to a narrow .05 octaves means that this EQ works very well as a notch filter. The wide and overlapping ranges of the center frequencies on each of the three sections effectively doubles the boost and cut range on many frequencies.

To the right of the EQ section is the OUTPUT GAIN control. Gain is adjustable from -15dB to +15dB. To the right of the output gain control are two horizontal LED level meters. The top one measures OUTPUT LEVEL. To its right is a CLIP indicator which lights up at 3dB below clipping. The bottom meter measures GAIN REDUCTION and is switchable between the compressor/expander and the de-esser. You can check the gain reduction of the compressor section or push the button on the far right side of the panel and check the amount of "de-essing" taking place.

Moving around to the back panel presents still more nice features of the 528. Aside from two input jacks and one output jack, there are two long barrier strips. These barrier strips, or rows of connectors, provide access to various stages of the processor and are best used when sent to a patchbay. These "patch points" will let you take the output of the pre-amp and send it to any outboard gear you like before returning it to the 528 where it is then sent to the de-esser. Likewise, you can take the output of the de-esser, send it to Peking if you like, then return it to the input of the compressor/expander. Next in the chain is the EQ, and you can access the output of the compressor/expander before it goes to the equalizer; and finally, you can access the output of the equalizer before it goes to the output.

But wait! There's more! If you want to really get into the intricacies of the compressor/expander section, you also have access to a "sidechain" output of the compressor/expander. This sidechain is basically a second and separate "copy" of the input signal. This second signal is what is used by the 528's "program controlled interactive dynamic range processing technique" (the PCIDRPT mentioned earlier) to control how the compressor reacts to the input. By taking this sidechain signal, passing it through an equalizer, and sending it back to the 528, you can alter the way the compressor operates and not affect the output signal with the EQ. Let's say for instance that you want to make the compressor "sensitive" to high frequencies, but you don't want to boost the highs at the output to do it. If you boost the highs in the sidechain (which you won't hear at the output), the compressor will react to those frequencies when they exceed the threshold setting. The sidechain can also be used in this same manner to control how the expander functions. Believe it or not, there are practical applications of this feature, but we won't get into them in this review. If anything, access to this sidechain should just let you know that the 528 is a versatile box.

On one of the barrier strips is a "stacking input" which allows two 528's to be used through a single output. In fact, any line level device can be "stacked" at this connection. Inputs on the 528 include one balanced XLR mike input, one ¼-inch TSR connector line input, and terminals on one barrier strip for a line level input. Both the terminals on the strip and the ¼-inch TSR connector accept balanced and unbalanced signals. Outputs include one ¼-inch TSR connector, unbalanced; and a balanced output at one of the barrier strips. Last stop on the back panel is the phantom power on/off switch.

List price on the Symetrix 528 is $679. We have seen it priced for under $500. For the dollar, you get a lot of voice processing power. The range on the compressor will provide more punch than you could want. The EQ section is very nice. The only drawback to voice processors of this type is the inability to store and retrieve settings. Unless you use a sheet of paper and actually draw your ideal settings, you can't save them; but when you consider the quality and the price, drawing circles and lines doesn't seem so tough. For more information on the Symetrix 528, call Symetrix in Seattle at (206) 282-2555. ♦

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