Stereo Buss Compressor

Stereo Buss Compressor ciruitry is based on one of the worlds widley recognized stereo mix compressors and is a "must have" for many recording engineers.

The compressor is cloned from our good old SSL4044E desk, dating back from '85. The SSL mixbus compressor is an integral part of the mixer's main quad fader and autofade system - cards 82E26 and 82E27, and as you can see if you compare these to my schematic, a series of changes have been made for rehousing the circuit. The main changes concerns the electronically balanced input and output and the removal of unneded components regarding the autofade and main fader circuits. Another change is that the sidechain is common to both VCA's, making better tracking abilities - your mix wont' "tilt" so easy when you're compressing heavily. We did things like that to the SSL in the old days. This might seem like a big change, but actually the sonics are preserved very close to the original, and tracking errors are cancelled.

TheMalKjos is a stereo VCA-style compressor designed with the recording, mixing and mastering engineer in mind. It features a remarkably clean audio path, precision stepped pots for accurate recalls, sidechain input, electronically balanced I/O (base model) Handmade in the U.S.

The C2 compressor houses two independant mono compressors, or in STEREO mode, the left-hand controls operate both audio channels, with the right-hand controls not used, giving true Stereo operation. The C2M version has one set of controls and two audio channels for Stereo use, whilst the C2R is a dual channel remote expander for building up to 8 channel systems controlled from one C2M or C2.

The characteristic sound of this unit arises mostly from the fast response at the onset of compression, which when delayed to occur around the mid range attack settings (after 0.3 to 3 milliseconds) results in a window through which transients can still pass. When used accross a mix, or with any dynamic programme, this has the effect of adding 'punch', as the sidechain 'breathes' around these transients, while still controlling overall levels. CRUSH mode has been developed as an extension of this 'musicality', adding to and accentuating the factors involved in producing the character of the unit. CRUSH may sound surprising to those interested in more gentle applications, being capable of exaggerated compression effects, but in conjunction with the fast limit settings also introduced with this unit, it allows the C2 to be used for a much wider range of applications than the C1.

Operation:

  • Fast attack and limit settings for protective limiting.
  • Crush mode gives f.e.t 'overcompression' with tailored frequency response, and higher distortion, for 'huge' dynamic effects.
  • External sidechain inputs, (for ducking etc.)
  • Power fail bypass for broadcast or live sound.
  • Ratios 1.5:1, 2:1, 3:1, 4:1, 10:1 and Limit.
  • Attack 0, 0.1, 0.3, 1, 3, 10, and 30 m/sec.
  • Release 0.1, 0.3, 0.6, 1.2, and 2.4 seconds.

Options:

  • External fader level control input, (to order) (stereo mastering etc).
  • Extra dual channel slave units, for multichannel applications, (film / surround formats etc.).

Circuitry:

  • New generation of Voltage Controlled Amplifiers.
  • High slew rate amplifiers, with hybrid f.e.t/ transistor inputs (Analog Devices).
  • High current push-pull transistor outputs.
  • Total symmetry throughout signal path.
  • No electrolytic capacitors used in main signal path.
  • All inputs and outputs balanced.
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WAVES

Based on the renowned master buss center compressor of the SL 4000 G console, the Waves SSL G-Master Buss Compressor captures the unique sound of the original’s IC input and twin VCA gain-reduction amplifier design

Prized by top engineers for its ability to “glue together” tracks, the SL 4000 G master buss center compressor is ideal for taming piano dynamics or adding punch to drums and percussion. Now, the ultimate finalizer that transforms a mix into a finished record can be yours - in the box.

Threshold is continuously adjustable from -15dB to +15dB.

Make Up Gain is continuously variable from -5dB to +15dB.

Attack offers a choice of six attack rates: 0.1; 0.3; 1; 3; 10 and 30 ms.

Release time can be set to 0.1, 0.3, 0.6, 1.2 seconds, or automatic.

Ratio is switchable between 2:1, 4:1, and 10:1.

Rate-S sets the Autofade duration, from 1 to 60 seconds.

Analog allows disabling of analog emulation.

In serves as a bypass button.

API is showcasing the 2500 Stereo Bus Compressor, a rack-mountable 19-inch unit with dual channel design. The API 2500 functions primarily as a stereo bus compressor but can be used as two separate units via single compression settings. The 2500 boasts a range of parameters that make it both uniquely versatile and incredibly musical.
With threshold settings between -20dB and +10dB and a variety of ratios to selectively vary the compression from almost zero to infinity, the 2500 performs subtle compression to brick wall limiting. Transients can be squashed with an attack time of 0.03ms or allowed to stand tall with an attack time of 30ms. Release times vary between 50ms and 3s. Depending on the application, the unit offers hard, medium or soft knee compression.
Unique to the 2500 is the use of Audio Toys Inc.'s (ATI) patented "Thrust" circuit before the RMS detector. Used successfully in the ATI Paragon Series live consoles, the circuit delivers a low end "punch" that rivals competitive units. This effect can be bypassed or moderated with a 2dB/oct high pass filter, or left fully in at 4dB/oct.
API pushes the envelope of flexibility further with selectable "Old" or "New" compression. The "Old" style uses the "feedback" type of compression found in the API 525 and the Fairchild 600, etc. The "New" style uses VCA modulated compression by an RMS detector, much like many of the dbx and SSL boxes. "With the API 2500, users get the best of both compression worlds in a single box," noted Paul Wolff, API's chief engineer.


The MALK is a rack-mountable 19-inch stereo compressor which uses/utilizes a twin VCA gain-reduction amplifier design which was at the heart of the mixbus compressor of SSL4044E. with the recording, mixing and mastering engineer in mind.
electronically balanced input and output, sidechain input which is common to both VCA's, making better tracking abilities - your mix wont' "tilt" so easy when you're compressing heavily.but the sonics are preserved very close to the original, and tracking errors are cancelled. it also has
The characteristic sound of this unit arises mostly from the fast response at the onset of compression, which when delayed to occur around the mid range attack settings (after 0.3 to 3 milliseconds) results in a window through which transients can still pass. When used accross a mix, or with any dynamic programme, this has the effect of adding 'punch', as the sidechain 'breathes' around these transients, while still controlling overall levels. CRUSH
"Thrust" circuit before the RMS detector. Used successfully in the ATI Paragon Series live consoles, the circuit delivers a low end "punch" that rivals competitive units. This effect can be bypassed or moderated with a 2dB/oct high pass filter, or left fully in at 4dB/oct.

 

sidechain is common to both VCA's, making better tracking abilities - your mix wont' "tilt" so easy when you're compressing heavily. We did things like that to the SSL in the old days. This might seem like a big change, but actually the sonics are preserved very close to the original, and tracking errors are cancelled.

 

which is an integral part of the mixer's main quad fader and autofade system - cards 82E26 and 82E27, and as you can see if you compare these to my schematic, a series of changes have been made for rehousing the circuit.
The main changes concerns the electronically balanced input and output and the removal of unneded components regarding the autofade and main fader circuits. Another change is that the sidechain is common to both VCA's, making better tracking abilities - your mix wont' "tilt" so easy when you're compressing heavily. We did things like that to the SSL in the old days. This might seem like a big change, but actually the sonics are preserved very close to the original, and tracking errors are cancelled.
The characteristic sound of this unit arises mostly from the fast response at the onset of compression, which when delayed to occur around the mid range attack settings (after 0.3 to 3 milliseconds) results in a window through which transients can still pass. When used accross a mix, or with any dynamic programme, this has the effect of adding 'punch', as the sidechain 'breathes' around these transients, while still controlling overall levels. CRUSH mode has been developed as an extension of this 'musicality', adding to and accentuating the factors involved in producing the character of the unit.
twin VCA gain-reduction amplifier design

The exterior:

Here are some pictures of the exterior look of the design.