Orban 464A “The Co-Operator” Stereo Compressor


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Bob Orban is one of the unsung heroes of recording & broadcasting. His products are in use all over the world and have been for around forty years. Orban is not as well-known in the UK as in the USA but, in the 80s and 90s, plenty of UK studios had an Orban De-esser, equaliser or – if they were very lucky – a compressor. They’re not flashy or high-tech, but they are flexible & accurate and they sound great. Orban gear has definite mojo

Though aimed primarily at the broadcast industry, Orban gear found favour in recording studios. The qualities they bring from the broadcast environment – great build quality, modular construction and great attention to detail – make them ideal in a studio environment

The 464A is another piece from a small range of Orban VCA compressors, each designed with different goal in mind. Orban’s raison d’être was broadcast, so many had features aimed at broadcasters. The 464A is a combined gated Leveller, Compressor, High-Frequency Limiter and Peak Clipper. It works well as a bus leveller / compressor and can also limit absolute level via the clipper section

The high-frequency limiter is the least-understood part of the 464A. It has its roots in radio broadcasting where over-modulation can cause massive high-frequency distortion and lead to large fines from the regulators. To avoid overmodulation, Orban designed a peak clipper and variable high-frequency limiting using pre-emphasis

“The HF Limit Pre-Emphasis switches select the pre-emphasis for the high-frequency limiter. These are all 6db/octave curves which are up 3db at 1/(2πT)Hz, where T is the time constant in seconds. 25 μS produces the least high-frequency limiting; 150 μS produces the most. Generally the pre-emphasis curve should match that of the medium protected (see the preceding “Example Control Settings” and the following table).”

If that explanation is as clear as mud, here’s the quick version: “Varying the pre-emphasis changes the amount of HF limiting”. In a studio environment, as usual, tweak till you like the way it sounds

Initially it’s hard to hear the effect of the high-frequency limiting and it takes a suitable signal – such as loud sibilance or cymbals – to kick it into action. In most broadcast setups the calibration would be done once and then left static. In the studio it’s just another tool to be tweaked to suit your ear

“Orban co-operator is a great device! Very ‘warm’ sounding but still natural. It took me a while to get into it but after reading the manual i found that there´s really not a gate but a compressor gate to reduce pumping effect making it more natural compression when compressing material with great dynamics. Also the hf-limiter is fantastic especially with DAW recorded material, and it can also be reversed into hf-booster but that i didnt find too useful”

“Een 464A is daardoor wat ‘rijker’ uitgerust dan een Compellor want er is op de 464A een HF-limiter, een pre- en deemphase schakeling en zelfs een clipper aanwezig. some more magic” – A 464A is what ‘richer’ equipped than a Compellor because there is on the 464A A HF-limiter, a pre- and deemphase circuit and even a clipper present.

Like most Orban gear the 464A rewards experimentation. It’s easy to setup as a basic bus compressor and, with a little experience, you’ll quickly find the release times & curves that suit the material you’re working with. It’s pretty hard to make the 464A misbehave & sound unnatural but it is doable – just work with thresholds & release times till you find the effect you want. Like the 414A, the release shape is switchable and can make a big difference to how audible compression is

Again, like the 414A, the 464A has a gate threshold control. This sets the threshold at which gain reduction is held between peaks and has the effect of reducing gain reduction pumping during silent passages. It’s not a gate in the traditional sense. The manual explains this very well

Overall the 464A Co-Operator is a great-sounding compressor / leveller with lots of uses. It’s not a monster for smashing drum rooms but excels at unobtrusive gain reduction and peak limiting. Coming from the broadcast industry stereo L-R matching is spot-on and the signal path is clean

The 414A has a front panel power switch & stereo link switch. The other controls are as follows: 

Channel A (repeat for channel B)

  • Gain Reduction Meter
  • HF Limit
  • Peak Output Level Meter
  • Input attenuator
  • Gate Threshold
  • Gate LED
  • Release Time
  • Release Shape switch
  • Levelling switch
  • Compressor switch
  • HF Limiting switch
  • System in / out switch
  • Meter Calibration
  • Pre-Emphasis
  • Output Attenuator
Each channel has output level & gain reduction LED bargraph meter and an HF limiting LED indicator. The Gate Threshold also has an LED indicator. With the exception of the front-panel pots for Input Attenuation, Gate Threshold and Release Time, and HF pre-emphasis and meter calibration knobs, all the other controls are Schadow pushbutton switches Threshold is adjustable separately so it's possible to setup operating levels (gain stage) the unit with the input & output attenuators and use the threshold control to control the depth of compression. If you're pushing gain reduction quite hard you'll need to tweak up the output controls to match levels in bypass. The metering has a separate calibration pot so it's possible to configure the unit for unity gain, set the metering to correspond with your DAW metering and vary the internal gain-staging to make best use of the dynamic range of the unit As usual, the 464A is beautifully constructed with premium-quality components in a zinc-passivated steel chassis. It has extensive RF filtering internally. The excellent manual gives complete instructions on balanced & unbalanced connections, grounding & electrical safety gain-staging and the theory of operation of the various elements in the signal path. Gain reduction is via a Class-A proprietary VCA Inputs and outputs are balanced on barrier strip connectors and jack sockets. XLR connectors can be fitted by removing blanking panels and using the pre-drilled mounting holes Mains input is 220 Volt AC (switchable internally to 110 V) via a captive power lead with a standard UK power plug
Standard 1U device suitable for 19" racks. Switchable 220 / 110 Volt with a back-panel fuseholder, fixed power cable and standard UK power plug
Operating manual ftp://ftp.orban.com//464A/464A_Manual.pdf
Excellent condition for a vintage piece, unmarked apart from tiny chips and a slight ripple in the left hand rack ear which has cracked the paint. Tested & working 100%. The pots & switches have been cleaned & lubricated. The bypass switches can create pops but this is to be expected with directly-switched bypass circuits in older equipment, particularly when switching bass-heavy material Vintage gear All vintage gear will have case scratches and marks. It may also have, or develop, noisy pots and switches. I make my descriptions as accurate as possible and note any existing defects. I test each item before shipping but please understand that vintage gear will not be perfect and adjust your expectations accordingly