Chapter 1: Introduction
The Drawmer MC2.1 Monitor Controller integrates clarity, fidelity, and transparency with a comprehensive set of mix checking features. It is designed for accuracy and faithful reproduction of recorded audio.
Features at a Glance:
- Ultra low noise and transparent circuit design with a linear power supply.
- Three stereo balanced speaker outputs and one dedicated mono speaker/sub-woofer output, each with individual left/right trims for level matching.
- Timed relay protection on all speaker outputs to prevent power up/down bangs.
- Comprehensive mix checking facilities including Left/Right Cut, Phase Reverse, Mono, and Dim.
- Paralleled custom quad potentiometers for precise channel matching and a smooth feel.
- Four inputs: balanced Neutrik XLR, balanced Neutrik XLR/JACK COMBI, and shared aux phono or 3.5mm jack.
- Two headphone amplifiers with individual level controls.
- Built-in talkback microphone with level control, mono output jack, and internal headphone routing.
- Rugged steel chassis with a stylish black brushed aluminium cover, stackable and rack-mountable (using a 2U kit).
- Dimensions: L 272mm x W 215mm x H 81mm. Weight: 2.5kg.
The MC2.1 aims to provide an audio experience equivalent to 'What You Record Is What You Get', ensuring the audio signal is not degraded or artificially improved.
Active vs. Passive Circuits
While passive monitor controllers are theorized to be superior due to fewer components, they suffer from disadvantages like output impedance variations affecting level matching and difficulty in achieving a reliable mono signal. Active designs, like the MC2.1, offer buffered attenuation and switching, providing better control over distortions, crosstalk, frequency response, and transient fidelity, and are less affected by cable lengths. The MC2.1 combines the transparency of passive circuits with the advantages of active ones.
Installation
The MC2.1 is a free-standing desktop unit with front-panel controls and rear inputs/outputs. It can be stacked or screwed into a standard 19" rack using a 2U mounting kit. Speaker trims on the base are inaccessible when mounted, so calibration should be performed before installation.
Screwing the MC2.1 to a Desk
To secure the unit to a desk, drill four 4mm diameter holes into the desk according to the provided dimensions. Use M3 screws (14mm plus panel thickness) to fasten the MC2.1, including its rubber feet, to the desk.
Power Connection
Use the supplied power cable suitable for your country's domestic outlets, ensuring it connects to the mains supply earth. The unit features an integral fuse drawer. If the unit needs to operate at a different mains input voltage, a technically competent person must follow a specific procedure involving disconnecting the unit, removing the top cover, sliding the voltage change-over switch (S14), and exchanging the fuse (160mA for 315mA or vice versa) as required. The top cover must then be replaced, and the unit reconnected to the mains.
Portable Appliance Testing
For Portable Appliance Testing (PAT), the screws holding the feet to the bottom of the unit can be used as an earthing point.
Audio Connections
The MC2.1 supports various audio connections including XLR (output/input), 1/4" Jack (balanced mono, talkback), RCA (phono) jack, and 3.5mm headphone jack.
Interference
In environments with high levels of disturbance (e.g., near TV or radio transmitters), it is advised to operate the unit in a balanced configuration. Connect signal cable screens to the chassis connection on the XLR connector rather than pin 1 to conform to EMC standards.
Ground Loops
To resolve ground loop issues, never disconnect the mains earth. Instead, try disconnecting the signal screen on one end of the cables connecting the MC2.1 outputs to the patchbay. Balanced operation is recommended.
Typical Connection Guide
A diagram illustrates the typical connection of sources like a Digital Audio Workstation (DAW), Mixing Console, or iPod/CD/DVD/MP3 player to the MC2.1's inputs (I/P1, I/P2, AUX). It shows the connection of speakers (A Left, A Right, B Left, B Right, C Left, C Right, and A Sub-Woofer) to the MC2.1's outputs (A, B, C, MONO). The diagram also indicates the routing of the Talkback signal to headphones and an external output.
Chapter 2: Control Description
The MC2.1 Monitor Controller offers a transparent signal path and numerous features valuable for sound engineers.
MC2.1 Controls
The unit features controls for Source selection, Speaker output selection, and Mix Checking functions, along with headphone outputs and talkback capabilities.
Source Selection (1)
Three switches select which of I/P1, I/P2, and AUX is heard. These can be operated individually or simultaneously, with simultaneous selection summing the signals into a single stereo signal. Note that the MC2.1 does not provide individual level trims for the inputs.
Speaker Selection (2)
Three switches select which of the three speaker outputs (A, B, or C, plus the additional mono output) are heard. Each can be operated individually or simultaneously, ideal for A/B comparisons. Precise monitor level matching is achieved via individual level trimming controls located on the underside of the unit.
Mix Checking (3)
This section covers Output controls (Phase Reverse, Mono, Dim) and Cut controls (Left Cut, Mute, Right Cut).
Output Controls
Phase Reverse: Inverts the polarity of the signal on the Left Channel to help identify phase problems like cancellation or unbalanced stereo signals.
Mono: Combines the Left and Right stereo signals into a single mono signal, essential for testing audio on non-standard applications or identifying mix issues.
Dim: Attenuates the output level by 20dB, allowing volume reduction without altering other settings.
Cut Controls
Left Cut: Mutes the Left channel signal, allowing only the Right signal to be heard.
Right Cut: Mutes the Right channel signal, allowing only the Left signal to be heard.
Mute: Cuts both channels. If Left Cut and Right Cut are active simultaneously, it functions identically to Mute.
Note that Cut/Mute controls affect headphones differently than speakers; headphones will continue to pass audio. Left/Right Cut on headphones is not a full 100% pan, allowing for a more natural sound.
Headphones (4)
Two dedicated 1/4" TRS headphone outputs are provided, each with an individual level control independent of the main monitor volume. Source and Output controls affect headphones similarly to speakers, but Mute and L/R Cut switches have a different effect. A warning advises unplugging headphones before powering the unit on/off and setting headphone levels down before inserting jacks to protect ears and drivers. Care should be taken when using consumer-grade headphones.
Talkback (5)
The MC2.1 features a dedicated talkback function with an inbuilt microphone and gain control. Activating the Talkback switch routes the operator's voice through the headphones and to the rear output jack. This function also automatically engages the Dim switch for headphones and speaker outputs. The switch is non-latching, requiring it to be held down to remain active.
Monitor Volume (6)
The Monitor Volume control adjusts the signal level for all speaker outputs (A, B, C, and Mono). Its active circuitry allows for signal level increase, helping to reveal subtle mix problems. The volume knob uses a parallelled custom quad potentiometer for excellent channel matching. Calibration is recommended for accurate level and balance control. A warning advises lowering the volume before powering off the unit to prevent hearing damage or speaker damage.
Power LED (7)
A lit LED indicates that the unit is switched on.
Rear Panel Controls
Inputs (8)
The MC2.1 offers four inputs: I/P1 (balanced Neutrik XLR), I/P2 (balanced Neutrik XLR/jack combi), and AUX (shared stereo RCAs and 3.5mm stereo jack). Inputs are activated by the Source switches. The AUX input sums signals if both are used simultaneously, requiring level matching prior to the MC2.1.
Outputs (9)
Three stereo balanced speaker outputs (A, B, C) and one dedicated mono speaker/sub-woofer output (MONO) are provided via Neutrik 3-pin XLRs. Each output has an individual Left/Right/Mono trim potentiometer on the underside for accurate monitor level/room matching. Outputs are activated by the Speaker switches.
Talkback Output (10)
A 1/4" mono talkback output jack on the rear panel allows the talkback signal to be routed to other devices, such as live-room monitor speakers, a mixing desk, or a DAW for overdubs. Specific cable wiring is provided for connecting to a Dual Mono jack.
Mains IEC and Power Switch (11)
The rear panel features the mains IEC inlet, which includes the internal mains fuse. The power switch is located above the IEC inlet and is a hard boot switch, meaning the unit draws no power when off. A timed relay protection circuit is incorporated to prevent issues during power up and down.
Speaker Calibration Trim Controls (12)
Seven rotary controls are located on the underside of the MC2.1 for individual speaker level calibration. Each speaker output, including the mono/sub, has a control. A small screwdriver is used to adjust speaker levels (counter-clockwise to decrease, clockwise to increase). Refer to the 'Monitor Calibration' section for the process. These trims should not be touched after calibration.
Chapter 3: Monitor Calibration
Calibrating your speaker system is crucial for centering the stereo image, ensuring consistent speaker levels, and achieving industry-standard listening levels. The MC2.1 facilitates this with its individual trim controls.
Requirements
You will need a Sound Pressure Level (SPL) Meter (preferably C-weighted, slow setting) and specific test files, such as pink noise files (40-80Hz bandwidth limited, 500Hz-2500Hz bandwidth limited, and full-bandwidth), recorded at -20dBFS. WAV files are preferred over MP3s.
Procedure
The calibration process involves the following steps:
- Turn off the monitoring system and ensure all inputs and speakers are correctly connected.
- Set all DAW/System controls to 0dB/unity gain and remove any EQ or dynamics processing.
- If active speakers or amplifiers have their own level controls, set them to maximum.
- On the underside of the MC2.1, set all speaker calibration trims to their full attenuation position (fully counter-clockwise).
- Set the large volume control on the front of the MC2.1 to 12 o'clock; this position will provide the 85dB listening level.
- Turn the system on and play the 500 Hz – 2.5 kHz bandwidth-limited pink noise at -20 dBFS. Select the required Source (I/P1, I/P2, or AUX). You should not hear it yet.
- Activate Speaker A by engaging only the Speaker A switch.
- To hear only the Left A speaker, activate the Right Cut switch and deactivate the Right Cut switch.
- Rotate the Left A trim control clockwise until the SPL meter reads 85dB.
- To hear only the Right A speaker, switch in Left Cut and deactivate the Right Cut.
- Rotate the Right A trim control clockwise until the SPL meter reads the desired level (85dB).
- To calibrate each speaker, repeat steps 7 to 11 for speakers B and C.
- To calibrate the sub-woofer, play the 40-80Hz signal with only Speaker A active. Use the Mono trim control to increase the sub volume until the desired SPL meter reading is reached.
- Repeat steps 7 to 12 while playing the full bandwidth pink noise for fine adjustment.
- The calibration process is now complete. Be mindful of the volume control's headroom and regularly check calibration.
Mix Checking Tips
The MC2.1's versatility allows for effective mix checking to improve balance, pinpoint stereo width, phase, and mono problems.
Not too loud...
Avoid monitoring at excessively high volumes (above 90dB) to prevent ear fatigue and maintain accurate perception of mix issues. Listening above 100dB can cause long-term hearing damage.
Shhhh...
Regularly listen to your mix at very low levels. This practice heightens the audibility of balance issues and prominent instruments. Adjust volume or EQ as needed. A mix that sounds good at low levels is likely to sound good at higher levels.
Using the DIM switch to lower volume is preferable to turning the main volume down, as it offers better control and maintains left/right channel matching.
Increase the Volume of Quiet Passages
The MC2.1's active circuitry allows for signal level increases, making subtle problems like low-level noise or unwanted harmonics more apparent, especially in quiet passages.
Here, There and Everywhere...
Listen to your mix on various playback systems (e.g., low-quality domestic systems, car speakers, portable radios) to identify issues that may not be apparent on high-fidelity monitors. Calibrate speakers to match output levels for best results.
Cut It Out...
Use the Left and Right Cut switches to check stereo balance, identify instrument bleed across channels, and make panning adjustments.
Phase Reverse...
Utilize the Phase Reverse switch to check polarity and improve instrument interaction by removing phase cancellation.
Monogising
Frequently check your mix in mono. This is crucial for live venues, dance clubs, broadcast, and mobile phone audio, as it ensures music sounds good across all systems and helps identify phase problems and comb-filtering effects. When a stereo mix is combined into mono, out-of-phase elements may drop in level or disappear.
What causes phase cancellation?
Phase cancellation can occur due to stereo widening effects, chorus, simultaneous direct box and microphone recording of a source, or using multiple microphones on a single source (like drum kits). Adjusting panning in mono can help resolve these issues.
True Mono
To achieve a true mono signal from a single speaker, activate the Mono switch along with either the Left Cut or Right Cut switch. This isolates the signal to one side, preventing the 'phantom' image and over-inflated bass that can occur when listening to mono through two speakers.
Listen to the ‘Stereo difference' or side signal
The 'stereo difference' or side signal, representing elements contributing to stereo width, can be heard by activating the Phase Reverse switch and then summing the left and right channels using the Mono switch (Left-Right). This is useful for judging ambience, reverberation, and identifying timing differences between channels for alignment.
Chapter 3: General Information
If a Fault Develops
For warranty service, contact Drawmer Electronics Ltd. or your nearest authorized service facility. Obtain a Returns Authorisation (RA) number before shipping. Ensure the product is packaged securely, preferably in its original container, to prevent damage during transit.
Contacting Drawmer
Drawmer Electronics Ltd. is available for application questions. Correspondence can be addressed to: Drawmer Electronics LTD, Coleman Street, Parkgate, Rotherham, South Yorkshire, S62 6EL, United Kingdom. Contact via Telephone: +44 (0) 1709 527574, Fax: +44 (0) 1709 526871, or Email: tech@drawmer.com. Further information is available on their website: www.drawmer.com.
Specification
Input
Maximum Input Level: 21dBu
Output
Maximum Output Level (before clipping): 27dBu
Dynamic Range
@ unity gain: 118dB
Crosstalk
L/R @ 1kHz: >85dB
Adjacent Input: >95dB
THD & Noise
unity gain 0dBu input: 0.0014%
Frequency Response
20Hz-20kHz: +/- 0.2dB
Phase Response
20Hz-20kHz: +/- 2degrees max
Power Requirements
115V or 230V at 50-60Hz, 20VA (Voltage set by internal voltage switch)
Fuse Rating
@115V: T315mA
@230V: T160mA (Conforming to IEC 127-2)
Fuse Type
20mm x 5mm, Class 3 Slo-Blo, 250Volt working
Case Size
Depth (with Controls & Sockets): 272mm
Width: 215mm
Height (with Feet): 81mm
Weight
2.5kg
Block Diagram
A block diagram illustrates the signal flow within the MC2.1, showing inputs (I/P1, I/P2, Phono, 3.5mm Jack), processing stages (including phase, dim, mono, volume, mute, left/right cut, and trim controls for each output), and outputs to speakers (O/P A, B, C, MONO) and headphones (HEADPHONE 1, HEADPHONE 2). It also shows the connection to the Talkback microphone and the power supply.
