DBX-RM160 Compressor Limiter

DBX-RM160 Compressor Limiter

The DBX-RM160 is a combo unit combining two dbx 160 units into a single rackmount device.

The dbx 160 is a single-channel compressor/limiter combining sophisticated technology and user-oriented features in a compact package. Unique circuit designs, such as true rms level-detection and feed-forward gain reduction, place the 160 in a completely different class from conventional compressor/limiters.

The dbx technique of true rms level-detection gives you audible benefits. Most compressor/limiters use some form of peak detection, with fast response characteristics that can have a disturbing effect on program material. True rms level detection closely simulates the response of the human ear. Even at high compression ratios, the gain changing action of the 160 Series is highly listenable and natural sounding.

Because of the unique feed-forward approach, dbx 160 limiters can achieve infinite compression with complete stability and inaudible distortion. The dbx approach is quite unlike gain reduction in a conventional compressor/limiter. Traditional gain reduction is accomplished by sensing signal level at the device's output and applying a correction signal, via a feedback loop. At progressively higher compression ratios, the feedback loop's gain increases, distortion increases, and eventually instability or oscillation occurs. To avoid this problem, many conventional units restrict the maximum amount of feedback, thus restricting the maximum compression ratio to some lower ratio, such as 10:1 or 20:1. The dbx 160 is free of the instability of excessive loop gain, and can provide infinite compression (approximately 120: 1.) lower ratio, such as 10:1 or 20:1. The dbx 160 is free of the instability of excessive loop gain, and can provide infinite compression (approximately 120: 1.)

SPECIFICATIONS (per each 160 subunit)

• INPUT
• Type
• Balanced (differential) transformerless
• Actual Impedance
• 50 K-ohms (25K -ohms when used in unbalanced mode, one side tied to ground)
• Connector
• Jones-type barrier strip
• Maximum Level
• +2 1dB (8 .7V)
• OUTPUT
• Type
• Single-ended, ground-compensated; suitable for driving balanced or unbalanced loads
• Actual Impedance
• 25 ohms (typical); will drive low or high impedance loads
• Connector
• Jones-type barrier strip
• Max. Level Bridging (1 OK-ohm or greater Z)
• +26dB (15.5V)
• Matching (600 -ohms)
• +24dBm (12.3V)
• Output Level Adjust (Continuous)
• +20dB from unity gain point
• Protection
• FET circuits prevent power turn-on or turn-off transients from reaching the output
• DISTORTION*
• 0.075 % 2nd harmonic at infinite compression at +4dBm output 0.5 % 3rd harmonic typical at infinite compression ratio
• EQUIVALENT INPUT NOISE (Unweighted)
• 78dB m, typical, (input shorted)
• ATTACK TIME** (Time to reduce signal by 63% of level change)
• 15 mill iseconds for 1 Od B level change above threshold. 5 milliseconds for 20dB level change above threshold. 3 milliseconds for 30dB level change.
• RELEASE RATE**
• 120dB/second
• COMPRESSION RATIO
• Continuously variable from 1: 1 to 120: 1 (infinity)
• THRESHOLD
• Continuously variable from 10mV ( - 38dB) to 3V (+12dB) 
• INDICATORS
• One L.E.D. indicator turns "on" to show when the input level is below set threshold; another turns "on" when the input level is above threshold. A steady-state, sine-wave tone exactly at the threshold voltage causes both L.E.D.'s to remain dimly illuminated.
• METERING
• Range
• 60dB (-4 0dB to +20dB)
• Function
• Switchable for input level, output level or gain change
• Calibration
• Rear panel potentiometer sets "OdB" for any level from - 10dB (250mV) to +10dB (2.5V)
• POWER REQUIREMENTS
• 117V AC, 50 or 60Hz. 8 watts maximum.

*The wideband distortion figures appear to suggest that 3rd-harmonic distortion is dominant. Thus, an un weighted T.H.D. (Total Harmonic Distortion) figure would be similar to the 3rd -harmonic value. However, the specific breakdown of distortion is more informative. 3rd-harmonic distortion in the 160 Series decreases linearly as the frequency rises: at 100Hz 3rd-harmonic distortion is 1/2 the value at 50Hz, etc.

**Attack and release rates automatically vary with rate of change of program level (attack and release rates "track" the signal envelope.) Specifications are subject to change without notice.