B.M.C. - Balanced Music Concept

Technology is constantly developing. Anyone who has ever bought a computer is aware of this problem. You have hardly left the shop before your piece of equipment is outdated. It is no different when speaking of High End equipment. What is today still state of the art can be totally antiquated tomorrow.

The BMC components are based on a completely different concept – that of modular construction. Each of our pieces of equipment can be individually assembled. And it is, of course, possible to make additions to any one of them at any time.

So we have the advantages of the most modern of digital technology – coupled with a sound pattern which is totally free of regulatory interference.

Excellent sound results do not have to be situated up in the highest price range.

 


B.M.C. Phono MCCI


B.M.C. applies exceptional concepts to their components to make technical innovation and perfection serve music reproduction.

B.M.C.'s Phono MCCI is a truly balanced, global feedback free, passively equalised moving coil phono pre-amplifier with the exceptional Current Injection input and LEF single ended class-A output stages.

 

Amplifier Features

1. Balanced Current Injection input
2. Common base circuit for highest bandwidth
3. Widely automatic gain adjustment
4. Feedback free circuit with very short signal path
5. Full balanced circuit
6. Balanced LEF single ended class-A output

EQ and Other Options

1. Passive equalisation with the I/V converter
2. Neumann corrected RIAA, or traditional RIAA
3. RIAA options for low end extension and warmth
4. 3 selectable gains
5. Subsonic filter selectable

High End Parts and Exteriors

1. Special ultra-low-noise transistors with very high Hfe, 10 in parallel
2. “Balanced Current” capacitors for precise and colourful sound
3. Induction-free Polystyrene capacitors
4. Metal-thin-film resistors with 0,5% tolerance
5. Fully gold plated 4-layer printed board
6. Copper plated iron shield cover

Amplifier Circuit

“Current Injection” (CI) means a current input, in which the pickup cartridge itself becomes part of the amplifier. The MC-cartridge is a generator injecting its current into a system of balanced DC-currents, directly creating an amplified output voltage. CI uses the original current of the cartridge and therefore the amplified voltage has a very precise analogy to the source signal. Actually this CI is rather an I/V converter than an amplifier in the traditional sense. Dynamic losses and distortions are remarkably lower compared to common voltage amplifiers.

 

 


The Current Injection input circuit is an unusual application of the common base circuit, which is known for widest bandwidth, lowest distortion, best dynamics and musical performance. In common applications the disadvantage would be a low input impedance, but fortunately this matches perfectly to our most important audiophile sources: MC-cartridges and current output digital/analogue converter. Already, for decades some, of the best phono MC amplifiers use common base circuitry, but just with the balanced CI input circuit such an idea can be applied without compromise.

The current for the CI-operation is determined by the cartridge's impedance and the phono amplifier's input impedance. This way the resulting gain in a wide range adjusts automatically to different MC-cartridges as a high-output MC may generate a higher voltage, but due to the higher impedance it reduces the current.

 

The whole signal proceeding is done in two short gain stages. Due to the fact of no feedback there is also no need for excess gain.

Generally there are many ways of designing low-distortion voltage amplifiers, but at lastly there is always a current driver required. Dynamically there are no alternatives to single-ended (opposite: push pull) designs, but those require a mandatory full class-A operation and also deliver higher grades of even-order distortions. LEF (Load Effect Free) applied to a single-ended class-A design avoids distortions by not moving the transistor through it's un-linear characteristic curve. Additionally the fully balanced design widely rejects even-order distortions.

A truly class-A balanced design is a constant non-moving load to the power supply. However much energy one signal requires, the balanced mirror signal requires less. In theory this way there would be no modulation of the power supply by the music signal at all any more and in our existing applications the power supply modulation is decades smaller compared to an un-balanced circuit.

Furthermore balanced designs have a natural rejection of common-mode power supply disturbances. This results in a remarkably improved “inner quietness” of the music reproduction. In consequence there is more space left for sound details, colours and 3-dimensional sound-stage.
RIAA and Other Options

Due to the absence of global feedback, the RIAA equalisation can not be an “active-type”, which usually would be inside the feedback loop. The precisely made RIAA filters are applied in two decoupled stages in a “quasi-passive” manner, which means a frequency dependent passive I/V converter. Excess gain, which is a traditional disadvantage of common passive RIAA solutions, is not required. B.M.C.'s Phono MCCI combines the dynamic neutrality of a passive equalisation while avoiding excess gain.

The common RIAA rolls off with endless damping for high frequencies. Logically a perfectly matched LP was cut with an infinitive gain before, which is obviously impossible. Consequently the common RIAA is never truly accurate. For the treble emphasis limitation in recording for decades there is a quasi-standard defined by the leading record-cutting-machine manufacturer Neumann. Applying a correction according to Neumann makes a small but very well audible difference in voltage. The correction of the phase shift is even more obvious. Optionally the Neumann-correction can be disabled so it is easy to check out the difference. There is simply more breath and transparency within the music.

For matching cartridges with low-level-extension problems or too less “body” it is possible to extend the lower bass or adding “body” plus lower bass.

Although the gain between different cartridges differs less than usual, according to the construction of the MC there might be level differences. Phono-MCCI allows the setting of 3 different gain levels.

Ideally the cartridge should match to the tonearm and the system is well damped. In other cases a subsonic-filter can be selected.

High End Parts

Phono-MCCI's very special transistors feature a super high Hfe and a super low typical noise figure of 0,3dB which is at the limit of today's possibilities. Each functional group uses 10 in parallel which reduces the statistical noise by 10dB. There should hardly be any more quiet solution for a phono amplifier.

The “Balanced Current” electrolytic capacitors have a balanced characteristic for charge and discharge. The important ESR-bandwidth is far beyond common electrolytic capacitors. This results in an improved musical performance, precision, detail and beauty, starting from the very low frequency, covering the whole spectrum.

Induction-free Polystyrene capacitors feature the lowest losses of all film capacitors and show no resonances. Used in audio circuits they deliver very open and pleasant treble.

Metal-thin-film resistors with 0,5% tolerance represent the highest part level within this group. SMD types do not have clamped contact wires and show lowest inductance.

The core part is build on a fully gold plated 4-layer PCB. The solder is lead-free and includes silver. The sensitive core module hat its own copper plated shielding box.

 

New Standards

The digital music reproduction over the years challenged the analogue technology to deliver better phono components. This improvement process should not be limited by old standards. In this sense an un-balanced phono input and circuitry is no longer state-of-the-art. With all the limits in noise and the related detail resolution it limits in-depth listening. All aspects of the circuitry should serve dynamic fine resolution all-over the whole frequency range for really unveiling the advantages of Vinyl-reproduction. Part of this philosophy is the abandonment of global feedback also for RIAA amplifiers and the related own dynamic actions. Then music can blossom and catch emotionally while being relaxing; leading us into a different world, touches and may seduce us...

 


 

B.M.C. - Digital / Analogue Converter


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 “Superlink”. 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 “Flat” frequency response optimisation or “Pulse” 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 “Low” ( 32fs) and a “High” (128fs) oversampling rate available. Both options have their individual character and are suitable for decent sound tuning. “Low” has a more dynamic and detailed expression, while “High” 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 “Current Injection” circuitry a maximum of sound quality is preserved, which is stabilised with the unmatched “LEF” 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.eine Klasse für sich.

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:

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.
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:

A: There is no excess gain in the amplifiers, and the signal path can be very short.
B: Reducing the volume also reduces noise and distortions unlike a traditional volume control.
C: DIGM reduces the final speaker voltage and there is no more gain afterwards, so noise is kept low.
D: There neither any traditional nor digital potentiometer inside the signal path.
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.
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. 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 “Balanced-Current” capacitors sum up to 75,000 μF 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 “Balanced-Current” 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 “digital to analogue converter” is certainly correct in technical terms, we feel it is actually rather a true
B.M.C. = “Binary to Music Converter”

 


 

B.M.C. Belt Drive CD Player / Transport

 

 


B.M.C. applies exceptional concepts to their components to make technical innovation and perfection serve music reproduction.

One truly uncommon concept is a CD transport with belt drive. Why should a belt drive be applied although almost all other CD player work with direct drive?
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.

 

 

Optional Upgrade to a CD Player

By adding the digital-to-analogue converter module the belt drive CD transport can turn into a complete CD player with analogue output.
The digital signal performance is 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 in to an output voltage by discrete, fully balanced I/V converters, which operate feedback free. Thanks to the special “Current Injection” circuitry a maximum of sound quality is preserved, which is stabilised with the unmatched “LEF” 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 choice: Both are on top level and the sound is class of their own.

The combination of a belt driven CD transport (belt-drive, precision bearing, CD stabiliser with flywheel effect) and consequent digital signal interconnection, as well as an optional DAC with advantageous technology concludes in a musical performance never revealing its digital origin.

 


 

 

 

B.M.C. Amplifier C1

 


A balanced amplifier? More exactly, a power amplifier with variable amplification and input choice.

In the consistent BMC amplifier concept, there is no place for a pre-amplifier whether separate or integrated. Only in this way can a short, permeable signal path be put into effect.
The AMP C1 is the all-rounder among the BMC amplifiers, as it fits in seamlessly with the classic concept of equipment.

All functions can be carried out with the aluminium remote control. Two pairs of balanced XLR and three pairs of unbalanced RCA inputs. Lossless volume control by the avoidance of unnecessary attenuation of signals as well as senseless high amplification.
Natural distortion-free circuit concept in consistent format. 2 x 200 watts on 8 Ohm, 2 x 350 watts on 4 Ohm.
Powerfully supplied by a fully stabilized network with 2 kW ring-core transformer.

 

 


 

B.M.C. Stereo Power Amplifier S1

 


Universally applicable as a classic 2 circuit final amplifier. With balanced XLR and unbalanced RCA input.

In a BMC chain a consistent short signal path using the lossless DIGM volume/ amplification adjustment is advisable, controlled by the DAC1, with the advantage that you do without both the signal attenuation and the senseless high amplification. Tonal and technical crème de la crème: The balanced CI (Current Injection) input which offers a further increase in the purity of the signal and thus the immediacy of the music reproduction by processing the original input current up to its arrival at the loudspeakers.

Natural distortion-free circuit concept in consistent format. 2 x 200 watts on 8 Ohm, 2 x 350 watts on 4 Ohm. Powerfully supplied by a fully stabilized network with 2 kW ring-core transformer.

 


B.M.C. Mono Power Amplifier M1

 

 

 

 


Universally applicable as a classic 1 circuit final amplifier. With balanced XLR and unbalanced RCA input.

In a B.M.C. chain a consistent short signal path using the DIGM volume/ amplification is advisable, controlled by DAC1, with the advantage that you do without both the signal attenuation and the senseless amplification. Through two unconnected mono final amplifiers the channel separation is unsurpassable.

Tonal and technical crème de la crème: The balanced CI (current Injection) input which offers a further increase in the purity of the signal and thus the immediacy of the music reproduction by processing the original input current up to its arrival at the loudspeakers.

Natural distortion-free circuit concept in consistent format. 200 watts on 8 Ohm, 380 watts on 4 Ohm. What he finds his strength? See next to.

All our amplifiers have one thing in common:
In each of them potters a gigantic power pack with a 2 KW ring-core transformer. We have also made no economies anywhere else – as can be clearly seen. There has already been a mention of it but we don’t wish to deny you a look into the inside. For the sight of this is a sure indication of the elemental force with which our equipment goes to work.

Power is, and remains, dependent on size. In order to make an impression on the Walls of Jericho, it takes something more than a soft humming.


 

We carry the entire line of BMC Products call us for details or a demo in our showroom!

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PHONE: (954) 558-6846

FAX: (954) 239-1531

Showroom / By appointment only

E-mail us: info@cruzefirstaudio.com

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