The 5043 Duo Compressor/Limiter is a powerful approach to dynamics processing for the Portico Series, designed with both tracking and mixing applications in mind.
The Portico 5043 embodies two independent Compressor-Limiters (Channels A and B) housed within a half rack, 1U module. They can be used independently (on two distinct tracks), linked as a stereo pair, or connected in sequence to provide two separate control slopes. When used as a stereo pair, linking the DC control circuits via the front panel A/B button enables the level of each channel to be held in a constant relationship. Rear panel TRS connections are provided to link multiple 5043s. This linking may also be extended to some of Rupert’s former AMEK CIB and DMCL units.
Buss or Line Input Selection
Any number of Portico modules that are equipped with the “TO BUSS” button may be sent to the BUSS input of the 5043 which makes it the ideal choice to form the core of a simple and cost-effective Portico mixing system. The Line input, when selected, provides a dedicated, transformer-balanced 10K impedance bridging input so that the 5043 may be inserted or included in any appropriate part of the signal chain at Console line-up level.
How It Works
To control gain, a V.C.A. or Voltage Controlled Amplifier (or Attenuator) is used. There are many types of voltage control devices, including tubes, discrete and integrated solid state circuits and naturally non-linear devices, each one having its own characteristic behavior that reflects sonically on the final performance, providing a character or signature that can be musically attractive (or not!). The Portico 5043 makes use of a very accurate, low noise, low distortion V.C.A. having essentially no signature of its own.
Feed Forward or Feed Back?
The Portico 5043 provides a choice of feed-forward or feed-back compression modes. The FB Button allows the user to switch between the two modes.
If the V.C.A. control voltage is taken from the 5043 input (i.e. before the V.C.A.), the V.C.A. knows right away that a gain change is required and there is an almost immediate response. This is known, logically, as a “Feed-Forward” compressor.
If the V.C.A. control voltage is taken from the 5043 output, (i.e. after the V.C.A.) it cannot act immediately on the V.C.A. because it has already been modified by the compressor circuit through which it has passed. This is known as a “Feed-Back” compressor. The two compression characteristics are quite different; there is more “Overshoot” and both the attack and recovery ramps are changed, providing the user with powerful choices.
Almost all of Rupert’s earlier designs were “Feed-Back”. They were more musical and sweeter than with “Feed-Forward” designs; however, the “Feed-Forward” design provides greater accuracy. Each is useful in its own way.
For signals below the “threshold” level that has been set, a compressor provides a linear path allowing signals to be amplified without the gain being adjusted in any way. When signals exceed the “threshold” level, the gain is reduced in a controlled manner that depends on the Ratio that has been set.
GAIN range provided is from -6dB to +20 dB. ?As already noted, when compression has taken place, it may be necessary to increase the overall gain to restore the apparent program level
Range from 1:1 to LIMIT (i.e. 40:1)
Range from -30dBu to +20dBU
Range from 20 mS to 75 mS.
Release / Recovery Time
Range of RELEASE time is 100 mS to 2.5 Seconds.
When the LINK Push-Button is engaged on both channels and the two channels, A and B, set to approximately the same values, GAIN control on both channels will be the same to preserve Stereo balance, levels normally being controlled by the channel with the higher signal level.
Cascading the two independent sections of the Portico 5043 Compressor- Limiter provides extremely powerful and comprehensive control of Dynamic Range.
When an external audio connection is made from the output of one channel to the input of the other, the overall compression characteristics become a composite of the two. For example, Channel A may be set up as a Low Ratio compressor and Channel B may be set up as a High Ratio Compressor or Limiter, to produce powerful composite characteristics:
When the LINK Push-Button is engaged, the signal passing through, channel A, may be used to control the amplitude of channel B. For example, the level of music through channel A can be controlled by speech on channel B, i.e. reducing the music level to make a “speech-over” announcement.
Two Peak LED METERS are provided that show OUTPUT LEVEL and GAIN REDUCTION. These are switched between Channel A and Channel B on the central METER SELECT Push Button.
Output level meter covers the range from -10 to +22 dBu and above which is regarded as overload.
REDUCTION is calibrated in dB covering the range +1 to 22 dBu, reading from right to left,
RND Portico 5043 Compressor-Limiter Duo
|Continuously variable from 6 dB to +20 dB.|
|Continuously variable from 36 dB to +22 dB.|
|Continuously variable from 1.1:1 to Limit (40:1).|
|Continuously variable from 20mS to 75mS|
|Continuously variable from 100mS to 2.5 Seconds.|
|Feed-Forward or Feed-Back VCA control.|
|S/C or LINK:|
|Multiple 5043’s may be daisy-chained via the rear panel jacks. When an individual channel is engaged, it’s control voltage appears at the rear panel LINK jack. When both channels are engaged they are linked together internally and their control voltage also appears at the rear panel LINK jack.|
|LINE or BUSS input select:|
|Selects rear XLR input or Buss Input jacks to accept Portico series buss outputs.|
|Maximum Output Level:|
|Balanced and Floating Transformer Output||+25 dBu.|
|Total Harmonic Distortion and Noise:|
|@ 1kHz, +20 dBu output level, no load.|
|Main Output, compressor bypassed||Better than 0.0006%.|
|Main Output, compressor engaged||Better than 0.02%|
|Measured at Main Output, un-weighted, 22Hz-22kHz, Terminated 40 Ohms.|
|With Gain at Unity, Compressor disengaged||Better than â€“103 dBu.|
|With Gain at Unity, Compressor engaged:||Better than 92 dBu|
|Main Output, Unity Gain||@ 18 Hz, â€“3 dB.|
|@ 150 kHz 3 dB.|
|Measured Channel to Channel:||Better than 80 dB @ 16kHz.|
|Monitors INPUT LEVEL and GAIN REDUCTION of either Channel A or Channel B.|
|Voltage Range:||9 to 18 Volts DC, 9Watts|
|Connector:||5.5mm X 2.5mm DC jack, Center Positive|
|Current consumption:||@ 9VDC = 1.0 A typical
@12VDC = 730 mA typical
@15VDC= 570 mA typical
@18VDC= 480 mA typical