Control Elements
M/S Stereo Mastering Compressor - ToolMod Pro Audio - TM132
M/S Stereo Mastering Compressor Home | Stereo Mastering Home

Compressor mit Envelope, Soft Knee und Crest

Control Elements Details and Specials
1 Weight Control, determines the control signals that feed the control section of the compressor.
Center position - M and S channel are weighted identically
the channel with the higher level controls the compressor
M position / all to the left - only the M channel controls the compressor
S position / all to the right - only the S channel controls the compressor

With stereo operation, Weight controls the left/right balance
(L = M; R = S)
The Crest setting affects the behaviour of the ac/dc converter.

With Weight in the center click position, both channels determine the compressor equally. All other positions force the compressor to operate controlled by either the M or the S channels.

At center, both channels are precisely linked. No modulation of the stereo base width takes place by the compression. In all other positions, the linking is reduced or even switched completely off. This may cause nice effects, since the compression will not only affect the level but also the stereo base width, which is modulated by the compression. In most cases, such settings will result in a strange behavior of the stereo panorama, like shifting instruments that are not located in the center more to left or to the right by the compression.
Please treat this control carefully and check for these effects!

The Envelope Control can reduce the distortion of low frequency signals with short release time settings that is based on physical side effects. All frequencies below the scale setting of the envelope control are affected by this function.

The HUE filter is located in the internal side chain and affects the mid & range. At center, the filter is off. Turning to the right reduces the mid/high range which will result in less compression of the mid/high range and vice versa if you turn the pot to the left. You will get a more or less mid/high frequencies in the compressed output signal, depending on the position of the pot and the switch that determines the frequency range under regulation.

Since the compressor regulation is proportional to the spectral density of the input level, the effect of the Hue filter depends on the levels in the mid/high range (high mid/high level = more effect and vice versa).

Autogain is an analog computation circuitry that compensates the loss of gain caused by the setting of the compressor. The calculation is based on the settings of threshold, ratio and attack.

Side Chain Insert
The Side Chain Insert allows to integrate external equalizers and filters into the regulation loop of the compressor. These units can modify the frequency response of the regulation and therefore the entire behaviour of the compressor.

The format of the side chain insert is identical to the operation format of the compressor:
OpMode M/S -> S-C-Ins, M/S
OpMode L/R -> S-C-Ins, L/R

Like audio inputs and outputs, the side chain insert is electronically balanced and can handle levels of + 30 dBu.

Operation Mode:
The compressor can be used in M/S Mode or Stereo Mode. The mode is determined by the combination the format of the input signal and the position of the INP-MS switch (pos 4.):

Input L/R - INP-MS not pressed -> M/S Mode
Input M/S - INP-MS pressed -> M/S Mode
Input L/R - INP-MS pressed -> L/R Mode
Input M/S - INP-MS not pressed -> L/R Mode

The OUT-MS swtich (pos 5.) determines only the format of the output, not the operation mode.

Stereo Mode:
With Stereo Mode some functions behave differently:
Weight -> regulates between L and R instead of M and W
Base Enhancement -> MUST BE SET TO OFF
elliptic EQ -> MUST BE SET TO OFF
Balance -> controls the linking of L and R instead of M and S

Matrix Options:
With the factory standard, the bypass switch is a hard bypass that disables or enables the entire module. If the module is used within an M/S processing chain this would cause a change in the format depending on the bypass switch.
Jumper settings in the module make it possible to alter the function the bypass switch to 'compressor only'. With this setting, the matrix stage are always on but the compressor is switches by the bypass switch. The INP-MS and OUT-MS switches are working in both settings.


2 Threshold Control
regulation takes place with input levels above threshold
control range +18 dB to -32 dB
3 Stereo Base Enhancement; OFF (@ center position),
8 % or 16 % over base
4 INP-MS, selects the input format
normal - input in stereo format L/R
pressed - input in m/s format
5 OUT-MS, selects the output format
normal - output in stereo format L/R
pressed - output in m/s format
6 Soft-Knee control with range from 0 dB to 12 dB. In the 0 dB position, the transition from the unregulated level range below threshold to the regulated range above threshold is hard. Any other position causes a soft knee characteristics, which means that the transition takes place over a level range that matches the setting of the control.
7 Crest Selector, 6 position stepper switch
RMS - long integration time, RMS characteristics
Peak - short integration time, peak characteristics
M - medium integration time, compromize between peak and RMS
- see Details and Specials for more
8 HUE Filter frequeny selector, 3 positions, 4, 7, and 10 kHz (see 9.)
9 HUE:
Side Chain Shelving Filter that affects the high mid and high range with +/- 6 dB range and selectable frequenceis (see 8.)
Modifies the behavior of the compressor regulation for the selected frequency range (more or less mid/high frequency compression)
10 Envelope Control
improves the compression of low frequency signals
range 0 = Off to 120 Hz
- see Details and Specials for more
11 Fill mixes the uncompressed input signal to the compressed output signal. This function can cover unwanted side effects of hard compressor setting. The range is from off to - 4 dB.
12 Attack control with range from .05 ms to 30 ms for 10 dB attenuation. Determines the response time of the regulation to an increase in level
13 Release control with range from 50 ms to 3 sec. Determines how fast the compressors reduces the attenuation when the input signal drops down.
14 LT-Int adds a second release component, that is calculated by a long time integration of the signals envelope. The control can add some variety to the compression. In addition it makes possible to reduce the release time setting without causing low frequency distortion if an appropriate setting is selected.
15 Color adds 2nd harmonics to the output. With the pot all to the right, ~ 2 % static harmonics (static = with no compression) are added and ~ 6 % of dynamic harmonics (dynamic = amount of harmonics depends on the gain reduction) at 10 dB gain reduction are added. The relation between static and dynamic harmonics can be internally adjusted and adapted to your needs. The absolute percentage depends on the output level. The values above refer to + 6 dBu/+ 4 dBV.
16 Color Routing:
M/S (center position) - Harmonics are mixed to M and S
M (to the left) - Harmonics are only mixed to M; only the center of the stereo signal is affected
S (to the right) - Harmonics are only mixed to S; the center remains free from harmonics, harmonics appear in the room only
17 Balance determines the linking of the compression in the m and s channels
@ center - M and S are precisely linked,
to the left - M -> compression is reduced in the S channel
to the right - S -> compression is reduced in the M channel
(see right column for more details)
18 Ratio Control, adjust the compression ratio for signals above threshold.
control range 1:1 = no compression
2:1 = a signal of 10 dB above threshold is reduced to 5 dB
20 : 1 , quasi limiter operation, 10 dB above threshold is reduced to 0.5 dB
19 elliptic Equalizer, 3-position switch, OFF, 300 Hz, 600 Hz
increases the crosstalk in the low frequency range to 15 dB @ 300 Hz or 600 Hz to center the bass foundation
20 LED indicator for Side Chain Insert / O/P to S-C switch (see 23.)
21 3-position switch; Limits the maximum gain reduction of the compressor to 5 or 10 dB
22 Gain control with calibrated center position and center detent, range > +/- 20 dB. The gain control affects the output level post compressor
23 3-position switch; Activates the side chain insert or switches the side-chain input to the output
This function makes checking the setting of external eq's an filters a lot easier - see Details and Specials for more
24 LED chain with 10 LED's, displays the actual gain reduction
display range from 1 dB to 25 dB
25 Disables the Autogain function
- see Details and Specials for more
26 Bypass switch