BMC-2 JET CLOCK DAC & MONITOR CONTROL USER’S MANUAL
INTRODUCTION APPENDIX Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 BMC-2 and Jitter Rejection . . . . . . . . . . . . . . . . . . .14 BMC-2 Design Philosophy . . . . . . . . . . . . . . . . . . . .15 Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Calibrated Listening . . . . . . . . . . . . . . . . . . . . . . . . .18 Technical Specifications . . . . . . . . . . . . . . .
INTRODUCTION BMC-2 is a dedicated Digital-to-Analog Converter and high quality “hands-on” Monitor Control that’s an ideal solution for you, whatever your audio production or monitoring setup – be it digital or analog. We at TC Electronic realize that predictable speaker and headphone control is an important part of your production process, and with BMC-2 such luxury is always available to you – regardless of the state of the computer at the heart of your system.
EN SETUP EXAMPLE 5
OVERVIEW – REAR PANEL 6 Power In Analog Outputs SPDIF I/O Use the supplied 12V DC power supply. Balanced analog outputs for active monitors, amplifier or mixer. 24 Bit SPDIF/AES3-id input and output on RCA connectors. Phones TOS & ADAT 1/4" jack connection for headphones. Lightpipe inputs and outputs on standard TOSLINK connectors (TOS: Channels 1-2 – ADAT: Channels 1-4).
EN OVERVIEW – TOP 7
OPERATION 1 – Rotary Control The Rotary Knob is always active, unless Ref Level or Cut is enabled. The “Valid” LED and the dot in the knob itself are lit when it is active. The markings on the panel around the knob follow half hour readings on a clock.
OPERATION Note that input sample rates may well be identical without being synchronous. BMC-2 constantly monitors and indicates if inputs are synchronous to the one currently selected. When the LOCK LEDs are lit steadily, this indicates that the input signals are synchronous. When the LOCK LEDs blink, this means inputs are not synchronous. Any selected input format is passed bit-transparently to all digital outputs with the exception of the output that is assigned to ALT.
OPERATION Selecting ADAT Sample Rate: As ADAT double sample rate format is not detected automatically, you must select this manually if required. Press and hold the ADAT button for approximately 3 seconds to select double sample rate (88.2 or 96 kHz). When double sample rate is selected, the yellow “x2” LED is lit. 5 – CLOCK STATUS LEDs The CLOCK STATUS LEDs indicate the sample rate of the currently selected input. When the yellow “x2” LED (double sample rate) is lit, the “44.1” LED represents 88.
– Press and hold the REF button for five seconds until the meters blink. Do not release the REF button until the meters are lit steadily again. If you prefer, you can also program the DIM function to be activated once the REF button is pressed. Assigning ALT to a digital output of your choice: – First disengage ALT. ALT is disengaged when the ALT button’s LED is not lit.
OPERATION To calibrate levels for the ALT speakers: – Press the ALT button. - With REF disengaged (LED unlit), set the desired level using the Rotary knob and the headphone level control. – Press and hold the REF button for approximately five seconds until the meters flash. Once the meters are lit steady again, the new level has been set. 10 – PHONES Knob Please refer to section “6 – REF” for additional information on calibration. Pressing this button toggles between Stereo, Mono and Side monitoring.
12 – VALID LED When the VALID LED is lit, the big volume Rotary Control is in the signal path. When it is not lit, you are listening at REF level (see “6 – REF Button” for more information). 13 – METERS The Level Meters show the precise sample peak level of the input selected without any gain changes. If Mono or Side monitoring is selected, the left LED bar shows the Mono component, while the right LED bar shows the Side component.
APPENDIX BMC-2 Clock & Jitter Rejection A digital audio signal relies on only two components: level and time. We all know about levels (bits) – but timing is equally important to avoid noise and distortion. Jitter is unwanted variation of a digital audio signal’s timing. It is typically recognized by compromised dynamic range of AD, DA and sample rate converters; or by clicks and dropouts due to interface breakdown.
BMC-2 Design Philosophy In the design of BMC-2, it has been important to provide constant control of your speakers, regardless of the state of your computer or other signal sources. Another criterion was not to touch the signal unless necessary. Consequently, BMC-2 features a synchronous design with bit transparent handling, impressive jitter rejection and a sample rate generator with a memory lock function that is invoked should the clocking input fail.
APPENDIX – WIRING DIAGRAMS In setups where the BMC-2 balanced outputs are connected to unbalanced equipment, it is possible to suppress noise by using a cable wired as illustrated below. Wiring for connecting the BMC-2’s balanced XLR outputs to unbalanced equipment with 1/4" input jacks.
APPENDIX – WIRING DIAGRAMS EN When you are feeding an AES3 signal to the SPDIF/AES3 input of the BMC-2, or when you are feeding another device’s AES3 input from the SPDIF/AES3 output of the BMC-2, we recommend placing a small circuit between the units to ensure optimal cable length and signal integrity. These circuits are not supplied by TC Electronic – please contact a qualified technician for assistance.
APPENDIX – CALIBRATED LISTENING Correctly calibrated REF level is essential for mixing. Audio for different audiences requires different ranges in dynamics (please refer to the left-hand illustration below). Without calibrated listening in the studio, you won’t be able to judge the dynamic range of a program/track reliably.
APPENDIX – CALIBRATED LISTENING EN Some engineers apply “squeeze-box tactics” because of the popular wisdom that this will produce the loudest result. The red line in the right-hand illustration shows how material with a low dynamic range ends up loud when level control is based on peak level measuring (as it used to be). Now with loudness detection principles moving into consumer electronics (iTunes, Dolby etc.
TECHNICAL SPECIFICATIONS Digital Inputs and Outputs Connector (S/PDIF, AES3-id compatible): Formats (S/PDIF and TOSLINK): Connector (ADAT® or TOSLINK): Format (ADAT®): Digital IO Engine: RCA Phono, BNC adapter included, 75 Ohm, 1 Vpp (terminated) S/PDIF (24-bit), IEC 958, Pro-status bits Optical Pipe Ch. 1 to 4 @ 48 kHz, Ch.
TECHNICAL SPECIFICATIONS DAC D to A Conversion: D to A Delay: Headphones Output Connectors Impedance Max. Output Level: Digital gain: THD: Dynamic Range: Freq. Response: Power @ 40 Ohm Load: Power @ 600 Ohm Load: EMC Complies with: Safety Certified to: Environment Operating Temperature: Storage Temperature: Humidity: 24 bit, 128 x Oversampling Bitstream 0.40 ms / 0.20 ms @ 48 kHz / 96 kHz 1/4" Phone Jack (Stereo) 80 Ohm +20 dBu (no load) Off to +12 dB < -85 dB (0.
