dbx 160A Compressor
Any modern-day recording or live-sound production is going to use a compressor. The type of compression will vary, the way it is used will vary, and whether the engineer is using software emulated compression or hardware will also vary. dbx will not vary in its offering of high-quality compressors, and to exemplify this we are going to look at the dbx 160A.
The 160A comes from a long line of dynamic predecessors. The 160 begot the 165, the 165 begot the 160X, and the 160X begot the 160XT. Each one of the compressors at one point was an industry standard, and now the 160A can make the same claim.
It is ready to live in a studio or hit the road, being built in a sturdy steel chassis. Weighing only 4.5 lbs, the unit measures 1.75" high, 6.5" deep, and 19" wide, taking only 1 rack space (1.75"H x 19" W).
It is not difficult to operate the 160A due to its simple design. As you can see in the above picture of the front panel there is only the threshold, ratio, and output gain potentiometers (rotating knobs). There is a bypass switch, a slave switch (used to stereo-tie two units), an over-easy switch (soft-knee or hard-knee characteristic), and a display switch (allows you to monitor the input or output level meter). Lastly, there is the level meter and gain reduction meter.
The rear panel offers a number of connections: there is the IEC receptacle (connection for a power cable), a detector input (allows for side-chaining effects*), and a stereo-strapping jack (only used when operating two 160A's in a stereo configuration). The inputs and outputs allow for the compressor to be used in a balanced or unbalanced system. You may either use the 1/4" balanced/unbalanced input or XLR balanced input, and for output connections you will find a XLR balanced or 1/4" unbalanced jack. If a ground-loop is present in your system you may try eliminating that by using the ground-lift switch. You will also find a meter calibration trim pot allowing you to adjust the "0" dB reference point. This is beneficial when the source is using a different reference for 0dB.
After removing the top lid of the 160A you will find that the inside is not terribly complicated. The IEC receptacle is grounded to the chassis and connected to the transformer. The transformer connects to the main board where we also find the front-panel and rear-panel components making connection. Hovering above the main board is the meter board which is secured with two mounting screws behind the front face-plate. It is then connected to the main board with a ribbon cable which utilizes 14 tiny pins.
The main board is a printed circuit board (PCB) which contains clusters of resistors, IC chips, and capacitors appearing as suburbs from an airplane's point of view. While each component is essential to the 160A, arguably the most important component is the dbx V1B** VCA (voltage-controlled amplifier). This chip controls how the gain is reduced as the power of the source is increased. Without this chip the 160A would be an expensive paperweight.
Looking forward as technology improves we can be confident that dbx will lead the way with industry standard compressors. It will only be a matter of time before we see dbx improve upon the 160A once again thus raising the bar for others to reach.
*For a better idea of what side-chaining is please go http://www.soundonsound.com/sos/nov06/articles/sidechain.htm
**The V1B VCA is a trademark of dbx
Pictures courtesy of http://www.dbxpro.com
