MC624 Pristine Monitor Controller 6in/4out - DIY Analog Pro Audio
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  • MC624 Pristine Monitor Controller 6in/4out - DIY Analog Pro Audio
  • MC624 Pristine Monitor Controller 6in/4out - DIY Analog Pro Audio

MC624 Monitor Controller

$799.00
$799.00 VAT incl.
$799.00 VAT excl.

The MC624 is similar to the monitor section of a mixing desk: it lets you select one out of six stereo audio sources, adjust the level and route it to one of four monitor outputs.

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MC624 Monitor controller


Bootstrap Image Preview


The MC624 is similar to the monitor section of a mixing desk: it lets you select one out of six stereo audio sources, adjust the level and route it to one of four monitor outputs.

The level can be set in very accurate 1dB increments.

The MC624 gives you the possibility to listen to normal stereo, right only, left only, left + right (mono), phase reversed right, left – right (difference), dimmed and mute.

Inputs can be configured for balanced or unbalanced (input 1 to 4), -10dBV or +4dBu level and an offset can be added if added to correct input level differences.

Outputs can be configured for balanced or unbalanced and an offset can be added to correct output level differences. Output 4 can be set as a Sub output (unfiltered).

An infra-red detector allows controlling the MC624 from an ordinary TV remote, with a learning function.

Several units can be linked together for surround. One unit is the master and controls the other units.


Highlights

    • 6 stereo sources: 2 XLR, 2 jacks, 1 RCA, 1 RCA/front mini-jack,
    • 4 stereo output or 3 output+sub: 2 XLR, 2 jacks,
    • Relay driven passive stepped level control, 64 x 1dB steps,
    • Buttons for Dim, Mute, Mute left/Mute right, Mono, left-right difference,
    • "Wire with gain" headphone amp with 2 gains,
    • Minimalistic audio path,
    • Fully differential throughout,
    • All switching done by relays,
    • Controllable by a TV remote, with a learning function,
    • Expandable to surround by stacking several units,
    • Available assembled or as a full kit (everything included).

Bootstrap Image Preview


Design considerations

The design objective has been to put as little electronics as possible between audio inputs and outputs. The total passive approach was ruled out because of the stress it puts on the audio sources, increasing distortion, when you want to achieve a low enough output impedance, necessary for the noise immunity. So we opted for a unity gain buffer, optionally switch-able to provide the 12dB of gain, necessary for the semi-pro -10dBV compatibility. The buffer used is one the best op-amps available today (spec'ed distortion at 0.00008%). This buffer is the sole active component in the signal path. The circuit is fully differential throughout and there is no capacitor in the signal path. All the switching is done by relays. The buffer feeds a passive precision logarithmic attenuator that is also switched by relays. The headphone amplifier is also a high end design with extremely low distortion, high bandwidth and high drive capability.


Bloc diagram

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Controls


INPUT SELECT Pressing one of the six push switches selects the corresponding input and sends it to the selected output and to the Meter Output. Inputs are mutually exclusive.

INPUT 6 Is a 3.5mm jack on the front panel duplicate of the back panel input 6.

OUTPUT SELECT Pressing one of the four push switches sends the selected input to the corresponding output. Outputs are exclusive except output 4 which can be set as a SUB output and activated in addition to one of the first three.

MUTE Turns off the monitor output signal (but not the Meter Output neither the headphone output).

L/R Mutes the left and right channels alternatively. Unmuting is done by pressing the MUTE switch.

MONO Sums the left and right channels

DIFF Inverts the phase of the right channel. When DIFF and MONO are both activated, the output is the difference left-right.

DIM attenuates the output by an amount of dB defined in "Functions Setup" (default: -20dB).

Infrared sensor Lets you control all the function from an ordinary TV remote.

3 Digits display Displays the current level in dB. It is possible to set "0"dB at the level of your choice. The display is also used to set-up some parameters.

LEVEL Sets the monitoring output level. It is also used to set-up parameters.

PHONES Phone level setting, independent of the monitoring level. There are two phone jacks, one on the front panel and one on the back panel.

O1 switch Power switch

Bootstrap Image Preview

Circuit


1 Input select relays

2 Quad buffer zone

3 Logarithmic ladder attenuator


4 Output select relays

5 Headphone amplifier

6 Microcontroller

7 PSU


What's in the kit?

Absolutely everything!

  • Passive components (resistors, capacitors, inductors),
  • Active components (diodes, IC's),
  • Front panel elements (switches, potentiometers, knobs),
  • Connectors, relays,
  • PCB's,
  • Case and all hardware

You bring the solder (use good quality solder, 1mm diameter max) and the Lunchbox.


Difficulty level

The MC624 kit is a medium difficulty kit. Nothing very difficult but a rather large number of components.

Setup is very simple but require a good quality DC millivoltmeter.

PK007

Specific References


Technical specifications

Measure Conditions Value
Input impedance Phase to ground 15 kΩ
Maximum input level on differential inputs +26.5 dBu
Maximum output level on differential outputs +26.5 dBu
Minimum gain   - 63 dB
Maximum gain   0 dB or +12dB
Frequency response Deviation < -1dB DC to 250 kHz
Total harmonic distortion (THD) + N f=1kHz too low for the HP8903A
Headphone amp frequency response Deviation < -1dB 1Hz to >250 kHz
Headphone amp output power R load = 33 ohms 1165 mW
Headphone amp output power R load = 66 ohms 950 mW
Headphone amp output power R load = 132 ohms 580 mW
Headphone amp THD + N f=1kHz too low for the HP8903A

Sound Skulptor MC624 high-end monitor controller - Part 1

 

Sound Skulptor MC624 high-end monitor controller - Part 2

 

Sound Skulptor MC624 high-end monitor controller - Documentation and tools

 

Sound Skulptor MC624 high-end monitor controller. Switcher 2 assembly

 

proaudio.de review of MC624 (German)

Reviews

Write your review
Grade 
Philippe Kuhn
 01/17/2023

Excellent

A fantastic device. Well thought out design and excellent sound quality. The stereo image is not affected and the integration of the remote control is very easy. Comparable devices cost at least 5 times more.

Grade 
Nathan Jaminon
 04/09/2020

Un must !!

Ce contrôleur de monitoring est tout simplement excellent: des composants de qualité, un assemblage robuste, des fonctions très utiles et un grand nombre d'entrées et sorties. Si vous n'avez pas besoin d'I/O numériques, c'est le contrôleur de monitoring dont vous avez besoin

Grade 
Philipp Wilfinger
 12/23/2019

Great Monitor Controller

I was looking at the options out there for monitor controllers with stepped relais. The only ones that would have been interesting would have been arround €3000+
The 624 is the perfect alternative if you like me dont need any digital I/O.
Have worked on mine for over 2 years now - very happy!

Grade 
Holger Classen
 10/18/2019

Excellent Controller

The monitor controller is excellent, much better than my old one. Pristine, clear, wonderful. Recommended.

Grade 
Robin Hunt
 01/11/2019

Wonderful Product

Im not a super experienced DIY electronics guy. I am really good though at soldering cables ;) so it says what over the quality of the kits and the manual describing building it. This is really top notch and if you have time to do it proper and are meticulous with the description its very do-able.

Then the quality of the finished controller. Just one word: Gorgeous: its as transparant as possible and I really can't detect any color which is good in a monitor controller :)

All the knobs and switches feel solid and great. I added some screws to make sure the top and bottom plate couldn't move anymore.

The quality is crazy for the price. Even if you would buy the completed version. Superb!

Write your review

MC624 Monitor Controller

The MC624 is similar to the monitor section of a mixing desk: it lets you select one out of six stereo audio sources, adjust the level and route it to one of four monitor outputs.

Write your review

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