Heritage Audio MCM20.4 User manual

MCM-20.4

PRELIMINARY USER GUIDE v1.1

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rights are reserved. No part of this manual may be reproduced, copied, translated or transmitted, in any
form or by any means without the prior written permission of Heritage Audio S.L.

Heritage Audio S.L. reserves the right to make improvements to the products described in this
manual at any time without notice. The information in this manual is intended to be accurate and reliable.
However, Heritage Audio S.L. assumes no responsibility for its use; nor for any infringements of rights of
third parties which may result for its u se.

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DESCRIPTION

The MCM-20.4 is a 20 x 4 channel summing mixer.
It employs a unique configuration, offering 20 input channels arranged as follows: 16

are implemented in 2 rows of 8 channels each, being the remaining 4 assigned to the
master section, hard panned left and right in pairs. Unlike classic consoles employing a
complicated switching matrix for subgroup assignment, the channels have a fixed­assignment in groups of eight. This arrangement not only makes the unit fit in a four­unit rack space, but greatly helps in making it affordable. Each channel features center
detent Pan and Fader concentric controls plus balanced insert and mute switches.

The insert send points always have the signal present, so they can be alternatively used
as direct outputs for recording without additional patch bays.

The 16 channels implemented on the front panel feature aux sends. A total of 4 different
sends can be assigned, with a maximum of 2 per channel simultaneously. AUX 1 and 2
or 3ST can be assigned on a per channel basis, but not all 4 sends can be used on the
same channel at the same time.

Each group has its own stereo fader and balanced insert point and all 4 stereo subgroups
are passively summed into the master bus. The gain is restored by means of a 1073 style
class A, transformer coupled, mic preamplifier, featuring a total of 4 transformers (2 in
each channel).

The master section is also provided with its own balanced insert point.
All connections on the back are made by DSUB 25 connectors following the Tascam*

protocol, with the exception of the master bus connections, which are by dedicated
XLRs.

Comprising vintage quality sound with sophisticated routing options, the MCM20.4 is
the perfect partner for hybrid setups, integrating analog gear with your DAW.

Lots have been written on the pros and cons between active (current) and passive
(voltage) summing topologies. Some may claim one is better that the other but truth is
active summing is less susceptible to noise and voltage, passive summing has a nice,
vintage sound associated with its gain makeup circuit.

The smart hybrid summing topology used in the MCM20.4, where the channels are
current-summed ( active ) into their corresponding subgroups and the subgroups voltage
summed ( passive ) into the master section, has proven to give massive headroom and
lower noise without making any compromises to its vintage characteristic sound.

Preliminary User Guide v1.1

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FRONT PANEL OVERVIEW

The front panel is laid out in 4 rows, 2 of 8 channels each featuring grey knobs and 2
with blue knobs carrying the aux sends sections. Further right are the related subgroup
controls and aux sends master faders.

Right side of the unit comprises the master section controls.
Controls per channel are as follows:

- ON: When pressed, the related input is added to the subgroup bus. When

depressed, it’s muted.

- INS: Turns the insert on. The insert send always have the signal present, whilst

pressing the INS switch activates the insert return input.

- FADER: Attenuates the signal sent to the subgroup bus from unity to minus

infinity. Fader all clockwise means unity gain, whilst 12 o’clock means an

approximate 20 dB of attenuation. (Or -20dB of gain ).

- PAN: Places the signal within the stereo spectrum, left, center, right or any

intermediate setting. The panoramic law follows a standard in which if a 0dB

signal is hard panned, it is -3dB when center panned.

- AUX SEND LEVEL AND / OR PAN: The aux sends are implemented on the

blue concentric knobs below each channel. If AUX 1 and 2 are selected, inner

knob is aux1 send and outer is aux 2 send, whilst having Aux 3 selected inner

blue knob turns into stereo level and outer becomes pan.

- PRE: Takes the aux signal from the channel PRE or POST Fader.

- 3ST: Chooses between AUX 1 and 2 or 3ST.

Controls per Stereo subgroup are as follows:

- ON: When pressed, the output of the subgroup is sent to the Master bus. When

depressed, it is muted.

- INS: Turns the insert on. The insert send always have the signal present, whilst

pressing the INS switch activates the insert return input.

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- FADER: Attenuates the signal sent to the Master bus from unity to minus

infinity. The control has a stepped feel for easy recall of settings. Fader all

clockwise means unity gain, whilst 12 o’clock means an approximate 20 dB of

attenuation. (or -20dB of gain ).

Controls for the Master Aux send levels are as follows:

- Master AUX 1 and 2 send level on a dual concentric control ( inner for 1, outer

for 2 )

- Master AUX 3 send level on a Stereo control.

Right part of the unit is dedicated to the mixer’s Master section, as follows:

- VU Meters: Measuring the average level at the master outputs. They are

calibrated so 0VU = +8dBu.

- Master Fader: Attenuates the Mix’s output from unity to minus infinity. The

control has a stepped feel for easy recall of settings. Fader all clockwise means

unity gain, whilst 12 o’clock means an approximate 20dB of attenuation.

- ON: When pressed, the output of the Master is sent to the Output connectors.

When depressed, it is muted.

- INS: Turns the insert on. The insert send always have the signal present, whilst

pressing the INS switch activates the insert return input.

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BACK PANEL OVERVIEW

All the external connections are on the back panel, as follows:

- 5 pin XLR for the external HA-PSU02 power supply unit.

- XLRs for Mix Output L and R.

- XLRs for Monitor Output L and R

- XLRs (2) for Master Insert Send L and R

- XLRs (2) for Master Insert Return L and R

- DSUB 25 for Subgroup 1-4 Insert sends and Aux sends

- DSUB 25 for Subgroups 1-4 Insert Returns and Auxiliary inputs.

- DSUB 25 (2) for Channel Input 1-8, 9-16

- DSUB 25 (2) for Insert sends 1-8, 9-16

- DSUB 25 (2) for Insert Returns 1-8, 9-16

All XLRs are:

- Pin 1: GND

- Pin 2: Hot

- Pin 3: Cold

Preliminary User Guide v1.1