B.M.C DAC1 Pre-Amplifier (HR)
The B.M.C. DAC 1 is not only a digital-to-analog converter, it serves as a preamplifier and the control center of a consistent B.M.C. chain.
AVAILABLE IN SILVER ONLY
B.M.C. applies exceptional concepts to their components to make technical innovation and perfection serve music reproduction.
For receiving digital audio signals besides the established SPDIF-compatible interfaces (AES/EBU 110 Ohm, coaxial 75 Ohm and optical Toslink) there is the exceptional and consequent â€śSuperlinkâ€ť. Unlike SPDIF transmission the different digital audio signals are not merged into one single signal stream and decoded to separate signals again after being received by the DAC. SPDIF surely makes sense from the commercial point of view, but Superlink is the solution without compromise, which requires 4 times the amount of interconnection cables but skips any coding process. Left/right-clock, bit-clock, digital audio music data are transmistted from the CD-transport to the DAC while the master-clock is generated inside the DAC and sent to the CD-transport. The transmission is done with 4 x 75-Ohm BNC cables with impedance matching.
Superlink results in a more intense link to the music, wider and more realistic sound-stage, more details and beautiful sound colours. Due to the consequent approach of Superlink just the shortest signal path is available and thus the sample-rate-converter (alias SRC, or up-sampler) is not available.
For standard SPDIF inputs the SRC may deliver a better result whenever the source signal includes a noticeable amount of jitter. But due to its digital signal proceeding an SRC adds a certain note to the music signal.
All other options are available for any digital input. Two different digital filters are available with either â€śFlatâ€ť frequency response optimisation or â€śPulseâ€ť for best dynamic response and with minimised pre- and post ringing. The pulse filter has a soft treble roll off, but avoids specifically the unnatural pre-ringing. In spite of its filter's soft treble roll off, it is generally considered as more transparent sounding.
Furthermore there is a â€śLowâ€ť ( 32fs) and a â€śHighâ€ť (128fs) oversampling rate available. Both options have their individual character and are suitable for decent sound tuning. â€śLowâ€ť has a more dynamic and detailed expression, while â€śHighâ€ť is softer and smoother.
The digital signal performance is further optimised by a clock synchronisation circuit right in front of the DAC-Chips. All digital signals are re-timed to the local master clock and thus the point of lowest jitter is at the DAC-Chip where the analogue music signal is made.
The conversion is made by two 24-Bit / 192kHz TI/Burr-Brown PCM1792 chips with current output.
The output current is filtered and converted to an output voltage by discrete, fully balanced I/V converters, which operate feedback free. Thanks to the special â€śCurrent Injectionâ€ť circuitry a maximum of sound quality is preserved, which is stabilised with the unmatched â€śLEFâ€ť driver circuit keeping all sonic details.
Originally those circuits were designed to put focus on the sound quality and leave the measurement specifications second, but the present standard is on a level that leaves no need for such a choice: Both are on top level and the sound in a class of its own.
Optional Volume Control
Optionally a pre-amplifier module with a multi-functional volume control is available.
A motor driven, remote-controllable potentiometer is acting as a position indicator using an A/D-converter and a volume value is calculated which is transmitted in two different ways:
â€˘ One set of 62 steps of digital potentiometer in a balanced configuration, buffered by a set of push/pull class-A output drivers, which can drive power amplifier inputs as well as headphones. Balanced XLR and standard RCA outputs are both available.
â€˘ An optical interface for a DIGM (digital intelligent gain management) control, for a lossless volume control of B.M.C.'s power amplifiers.
The second option does not require a preamp, so the fixed output can be connected directly to the power amplifiers. This signal is not divided inside the power amplifier, but always used untouched and the volume is set by 66 different power amplifier gain settings in 1dB steps. The usage is therefore not any different from a traditional volume control, but the impact of DIGM is remarkable:
â€˘ A: There is no excess gain in the amplifiers, and the signal path can be very short.
â€˘ B: Reducing the volume also reduces noise and distortions unlike a traditional volume control.
â€˘ C: DIGM reduces the final speaker voltage and there is no more gain afterwards, so noise is kept low.
â€˘ D: There is neither any traditional nor digital potentiometer inside the signal path.
â€˘ E: DIGM switches precise metal-film resistors in parallel to the signal current and thus is a native part of the amplifier's I/V conversion.
Any digital or analogue circuit has a sonic dependency on the power supply. Due to the fact that different power supplies have different influence on the music reproduction B.M.C. offers the DIY customer different power supply options.
The first available power supply is equipped with a bold selection of parts. A R-Core transformer represents a very good combination of AC power filtering and low magnetic noise. 10 double 10A Schottky-diodes used for rectification are extremely fast switching without overshooting. Due to the large dimensioning the voltage loss is minimised. 34 â€śBalanced-Currentâ€ť capacitors sum up to 75,000 ÎĽF of storage capacity which would be respectable for a power amplifier. Those capacitors are second-to-none concerning sonic performance. Due to their specific design, cleanness, precision, power-feeling and sonic colours are on an exciting performance level.
In front of each functional circuit group is an extensive voltage stabilising. Just as stable as a voltage regulator but without feedback loop. At these points â€śBalanced-Currentâ€ť capacitors again enhance the performance as well as induction free Polysterene capacitors.
The carefully selected solutions for lots of technical details for this DAC result in a music experience that lets you forget any digital origin. Opulent, rich in details and emotionally affecting.
Although specifying this component as a â€śdigital to analogue converterâ€ť is certainly correct in technical terms, we feel it is actually rather a true B.M.C. = â€śBinary to Music Converterâ€ť
20Hz - 20kHz
THD ~ DAC:
0.003% ~ 0.006%
THD ~ PRE:
0.004% ~ 0.0009%
(1) Balanced XLR Input
(2) Unbalanced RCA Inputs
(1) Balanced XLR Output (DIGM)
(1) Balanced XLR Output (Variable Level)
DAC Analogue Output:
Balanced XLR + Unbalanced RCA
Superlink, AES/EBU, Toslink, Hi-Res USB, Coax, BNC, DIGM
17.1 x 3.9 x 13.8â€ś (WxHxD)
Content of Packing:
- DAC1 PRE Unit
- Power Cord
- Remote Control w/Batteries
- Owners Manual