It’s a FET Compressor with a Soft Knee
The AwTAC Channel Compressor is a versatile, classic (if not elegant) sounding compressor with simple to use controls designed to stack well in a mix while providing everything from “just a little” to “suck all the air out of the room” amounts of compression. Our approach was to design an old sounding, not overly modern behaving compressor that can sound great on every channel of a console, build up well in a mix and be very quick and easy to get dialed in.
The AwTAC Channel Compressor has a great subtle vibe which wont accidentally do too much, is never too grabby, and can easily be dialed in from fairly transparent operation to completely in your face. It does this effortlessly while maintaining a feels like it’s London 1970 attitude.
The AwTAC Channel Compressor is transformer balanced on its input and output for big iron sound and weight.
Every single stage in both the audio and sidechain circuit is comprised of carefully tuned discrete transistor amplifiers.
The AwTAC Channel Compressor features a 10K bridging input that will not load a converter feeding its input.
The AwTAC Channel Compressor attenuates input signal after its input transformer, so it is possible to drive high level to the input for more transformer coloration if desired.
The sidechain uses a FET for its control element, which controls the gain of the input amplifier. The FET is in the sidechain only, the input amp is a bold sounding bipolar transistor amplifier which could work as the line level receiving amplifier in a console.
The FET sidechain does not shunt signal from the input amp, but rather controls the gain of the input amp, so its easy to think of the sidechain as somewhat of an “auto-fader” if such a thing existed. What this makes for is a very very smooth sounding compression circuit that, while FET controlled, tends to feel a bit like an optical type compressor. The circuit maintains all the speed usually associated with FET compressors but has a very, very smooth quality commonly associated with optical compressors.
- Drive Pot sets the level to the FET Controlled Amp in the compressor circuit. Below unity, the Drive Pot will raise the level fed to the compressor. Above unity, the Drive Pot will raise the level of distortion in the compressor. Since the sidechain will not distort the FET controlled amp, the Drive Pot is there to add distortion when desired.
- HPF Switch engages a 6 dB/ Octave High Pass Filter to the side chain at 375 Hz. Seems like a high cut off point until you listen to it, the gradual slope allows your low end to breathe for a much more natural sounding vibe. Absolutely excellent on program material.
- Reduction Pot controls the amount of compression applied to your input signal. Turn clockwise for more compression, fully counterclockwise for Off.
- Attack Switch is a three position toggle switch which selects Fast (1.5 mS) in the up position, Medium (15 mS) in the down position and Slow (40 mS) in the middle position.
- Release Pot sets the release time from 75 mS to 3.4 Seconds. Fastest setting is full counterclockwise.
- Auto Switch engages an auto release circuit when the toggle is in the up position. When engaged, Release Pot orientation has no effect. The auto circuit is program dependent and very, very, smooth.
- Blend Pot is the fader for the Blend Amplifier which sets output level for the Parallel, uncompressed, circuit. Only the Parallel Blend signal is effected by this pot. Blend circuit provides +9dB of gain “in hand” similar to what is found on a proper console. Unity gain is denoted by the hash mark at 1 O’ Clock. Full Counter Clockwise mutes the Parallel Blend signal.
- Output Pot is the fader for the Make-up Amp which sets the output level for the Compression Circuit. Only the compressed signal is effected by this Pot.
- Bypass Switch activates the relay controlled true bypass. In the up position, the compression and parallel blend circuits are engaged. In the down position the entire circuit AND transformers are bypassed at the edge connector: input signal comes in off the edge connector, through the relay and back out to the edge connector completely bypassing the Channel Compressor circuitry. When powered off, the unit defaults to “bypass” so signal will flow through with the rack off, no need to unpatch.
- Meter is an 8 segment peak detecting LED meter which displays gain reduction only in the following steps: -0.5 dB, -1 dB, -2 dB, -3dB, -4 dB, -6 dB, -10dB, -15dB The meter is always on, even with the unit in bypass.