B.M.C. Belt Drive CD Player Display


Just measurement results don't really serve as a decision maker, but this was already true in analogue ages: In measurement the direct drive turntables outperformed the belt drive, just in terms of sound within the higher grade class of turntables belt drive types outperformed their direct driven counterpart clearly.

In the case of CD players the situation seems to be quite similar, but there is one major difference: While turntables rotate with a constant velocity a CD player constantly adjusts the speed depending on the play time position for a constant data stream. Sometimes this fact is regarded as an argument against belt driven CD players, but the speed changes are slow and continuous and thus a belt drive can technically manage this challenge. Rapid changes in speed just happen during title skip. Naturally a belt driven, flywheel-type CD player reacts somewhat slower here. But sacrificing a higher level of musical enjoyment for faster track access times? This might be too disadvantageous a sacrifice.
Belt Drive is More Than Just a Belt

1. Belt drive decouples the motor vibration from the CD
2. The CD turns on a precision bearing, analogue to a turntable bearing also regarding size.
3. A CD stabiliser removes vibrations and resonances from the CD and due to the inertia any rotation is quiet and smooth.
4. Quiet operation of the servo circuit instead of plenty small and harsh speed changes.

According to this short description it should be understandable that most mid and high frequency jitter won't ever happen.

Superlink & SPDIF Interfaces

For transmitting 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 “Superlink”. Unlike SPDIF transmission the different digital audio signals are not merged to 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 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.

Power Supply

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.'s CD transport uses an advanced switching power supply, with active primary voltage filtering and separate transformers for display, motor, logic and audio circuitry on digital and analogue domain. Additionally there is complex voltage stabilisation separately in front of each functional group.

Type: Sources

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