In the mid-seventies of the last millennium Backes&Müller presented its first loudspeaker and began its development of loudspeakers with a quantum leap. As one of the first manufacturers B&M focused on active technology that clearly enhanced the quality of acoustic conversion. In active technology every chassis (every path) is channelled to its own power amplifier, so that bass, middle and high frequencies are completely decoupled from each other. This was a prerequisite for implementing further leading-edge technology - Backes&Müller’s proprietary control technology (DMC). Here every membrane movement of each chassis is measured and controlled. This ensures that exactly what the input signal (Music signal) specifies is transformed into sound. Decaying oscillation or delayed transient oscillation from the existing membrane mass is thus prevented. Starting in 2006 Backes&Müller achieved the next quantum leap with the introduction of digital signal processing and FIRTEC technology. Now for the first time in multi-mode loudspeaker design correct phasing is feasible, guarantying that music reaches the listener’s ears time-aligned. Along with the other transmission technologies developed by B&M, this elevates the manufacturer’s products to a whole, new sound level!
“The cylindrical wave emitter reproduces music more exactly than any other loudspeaker. The BM35 is simply the best loudspeaker I have ever heard. Nostalgic excursions are alien to B&M head of development Johannes Siegler. One could almost think he is a revolutionary. His innovations, such as the line emitter, make other high-end developments look like baby steps. However, can one particular loudspeaker resolve the consistent prejudice against active and digital technology? It can.
Whereas the Focal (Focal Grand Utopia) only sketched the position of 400 musicians, the Backes placed each of them in their correct position: unbelievable! Even from less favorable seats it facilitated the musical listening experience. My colleague, Lothar Brandt, certified it as having: “the reproductive clarity of reading glasses, but with the width of a panorama painting. It’s tremendous that such a revolution has finally originated from Germany again.”
Malte Ruhnke (Editor-In-Chief Stereoplay)
On the basis of physical factors all drivers make mistakes, which one must accept in passive and uncontrolled systems. In contrast, all BM drivers are a part of active error correction systems.
Active loudspeakers know no conduction loss, no impedance issues; have faultless crossover performance, exact phasing, an optimal amplifier-chassis ratio, more actual output stage power at their disposal, quicker impulse processing and higher dynamics. All of this produces active regulatory intelligence. A sensor system continuously compares and corrects the membrane movements with the actual music signal.
B&M uses two types of negative feedback: inductive and capacitive. Intelligent electronic fuses ensure that the entire system is reliably shut down in the case of an impending overload. The BM electronic crossover splits the music signal into individual paths of respective frequency ranges and allocates these to their individual output stage. Every individual output stage drives to its respective driver, optimised for its frequency range.
All of these components necessary for optimal music playback are mounted in a large dimensioned cooling element, the electronic module. Control and monitoring of all device functions (i.e. turning on and off, differentiated error diagnosis, digital volume programming) are carried out by a micro-controller and shown on a matrix display.
Technologies for impulse fidelity: Firtec & DMC
BM-FIRTEC™ (FIR-Time fi lter technology): for correctly timed, linear phase and tonally correct reproduction. The programmed digital signal processor (DSP) in the FPGA works with a model of the physical characteristics of the loudspeaker including the type of chassis and cabinet. The parameters of the model can be then ascertained with real measurements of the loudspeaker setup. Accordingly, they consider all the tolerances of the components used including chassis, electronics or amplifi er, even the acoustic phenomena around the edges of the cabinet.
The main feature of the FIRTEC technology is that it linearizes not only the amplitude frequency response but also the phase progression.
In other words, the FIRTEC process reproduces the music tonally untainted, all frequency ranges unadulterated and even in their correct time structure, identical to the way they were recorded, with no frequency ranges playing catch-up. All Backes&Müller loudspeakers are equipped with FIRTEC and DMC2.0 which ensures a constant phase progression over the entire frequency range with no latency. An absolute first worldwide with conus loudspeakers.
Impulse response before and after Firtec:
The graphic shows how the B&M FIRTEC Technology recognizes and equalizes a complete loudspeaker system up front so that the loudspeakers with FIRTEC can reproduce music genuinely.
Nearfield Extension: Next
In the BMLine, the reproduction of mid- and high-tone ranges from 800Hz and upwards is handled b a newly designed element radiating cylindrical waves. In cooperation with the Fraunhofer Institute for Applied Mathematics in Kaiserslautern, Germany, a slit shaped emitter was designed with an extremely powerful driver. With a cylindrical wave, the acoustic energy reduces by 3dB when the distance is doubled; with a normal spherical wave, this reduction is 6dB.
This means that with the BMLine, even in larger rooms, your listening area is practically anywhere in front of the speakers. Effectively, this means the intensity of the sound in your ear is due to a much higher proportion of direct waves and the effects of indirect or reflected waves is thereby significantly reduced. The room characteristics therefore have a much lesser influence on the acoustics. The direction of the cylindrical waves also ensures that reflections from the ceiling or floor are further minimized. In this way, a completely different musical experience can be enjoyed with an exactly defined sound. For frequencies up to 800Hz, the linear arrangement of the bass and mid-tone cone speakers also emits a perfectly matched cylindrical wave.
DMC2.0 - Technology
BM-DMC2.0™ („Dynamic-Membran-Control“): As was the case in 2015 when the new BMLine Series speakers were introduced, the new BMPrime Series are fitted with improved DMC2.0 sensor regulators. A new construction of the sensor with the help of modern computer technology allows us to influence the exactness of the control process to improve it by Factor 4. This progress is so essential that we have applied to patent the new regulator (patent pending). Basically a sensor regulator functions by exactly measuring the movement of the membrane at every time and comparing it to the programmed path that results from the musical signal. In this way false membrane vibrations, provoked by mass inertia or the material characteristics of the membrane material are already stopped as they are created. If the music suddenly stops, for example when a bass player stops the strings, a loudspeaker without DMC2.0 regulation would continue to vibrate and generate a “pseudo-bass”. Our technology prevents this late reverberation as well as too late transient oscillation of the beginning of the first note. From a technical point of view the impulse from the musical signal is correctly transformed into sound without temporal distortions. Listeners often describe DMC2.0 regulated chassis as quick and accurate. This simple regulating principle means the very finest of attention to detail in its implementation while building the chassis by hand in our factory, as well as comprehensive know-how of the entire physics of sonic conversion. The effort is rewarded with neutral, unfalsified music reproduction, a linear amplitude and phase response down to the lowest cut-off frequency without latency periods!
Int. Pat. PCT/EP2016/053272
|Wortbreite||16 Bit bis 24 Bit|
|Samplefrequenz||20 bis 216 KHz|
|Ausgang||AES3 Format mit 24 Bit Wortbreite mit 96KHz FS|
|Elektrische Formate||SPDIF, optisch wie auch auf Cinch, AES3-Format|
B&M DvX - Technology
B&M DvX™ Technology. The concept of directional, virtual coax is implemented by 2 mid-range speakers, whose ransmission band is chosen so that both membranes of the mid-range speakers physically function as one integrated cone. The positioning of the tweeter in the exact centre of this virtual membrane area creates a coaxial loudspeaker that prohibits the time delays that would normally result from a change in listening position within the near field. In combination with the wave guide, a directional coax with directional radiation emerges, which minimizes reflections from the side walls of the listening area.