Speaker Backes & Muller BM line 25

Those who make music or has the inimitable homogeneity of live concerts in the ear, is with the Backes & Müller BM line 25 (39000 euro the couple) will quickly warm – and afterwards more want to have no conventional box.

  1. Speaker Backes & Müller BM line 25
  2. Data sheet

Behind the beautiful facade of its new BM line 25 of old Saarbrucken active boxing specialist has a complex Backes & Muller and, as we will see, highly interesting concept hidden, its deeper meaning not necessarily equal opens also connoisseurs of the loudspeaker scene right off the bat.

Only active speakers with electronic filters and built-in power amplifiers in the program, have the German from deepest conviction is all too familiar. But why is the new 25 so entirely different as the still available classic 18 BM and BM 30, in whose midst she numerically joins?

Before we leave this question to the bottom, a look at the specifications of the manufacturer is recommended each advanced audiophile. It says: “The BM 25 has a constant phase course” and a half-sentence continues: “At the same time, all frequencies reach the listener’s ear.”

If should turn this explosive for every audiologist and boxes developer statement as true, then the BM 25 would be one of the world’s rare transducers, whose bass time lags behind the remaining events not in any form.

But what is the speech? Most filters, analog and digital, creating phase-rotations in addition to the desired effect in the frequency domain (without which no more way box would work), say, delaying more than other parts of the spectrum. Noticeable this is indicated by a significant increase in the Group delay of the visually more descriptive first derivative of the phase history especially in the bass range.

If Word keeps Backes & Muller, the bass range of the BM 25 as also the sound should be a total of unprecedented precision, the box would have to sound like a cast.

Because even testers are sometimes impatient, was right after unpacking to the nitty-gritty. Johannes Siegler, his character of an electrical engineer and since 2001 was business leaders such as also lead developer in the House of the year B & M (see interview with Johannes Siegler) with (almost self explanatory) building his recent work to end, that was in the room really to the point.

From the same Thorens precursor fired, which was used also in the other subjects – needs the box way logical no external power amplifiers – was “Tuva Rap” first again on the program. The charismatic, enriched with all kinds of percussion, wind instruments and voices piece debunked imprecisely, washed out sounding boxes seconds.

Actually, the musicians compared to the already high-precision for Blumenhofer Horn seemed once again more clearly outlined in the background as highlighted by a magic hand and again a lot easier to understand the complex chants, although they were not all in relation to the rest.

What happened in the bass range, is hard to describe with words. It was less about the usual attributes volume or depth – of which was plentiful – as contrary to the whole thing. You had incorporated exactly where he belongs, perfect feel the bass and if required insanely powerful. The outstanding precision could irritate initially many years HiFi headphones, but who even makes music or has the inimitable homogeneity of live concerts in the ear, is to quickly warm with the Backes – and want to have no conventional box afterwards.

The remaining sound talents of BM 25 were obviously fascinating, but the preoccupation with building standing in front of their thorough consideration. The recent work of the 35 years of young specialists of boxes decorate four identical low-midrange driver with rugged carbon fiber membranes, which are paralleled in the keynote range from 80 to approximately 400 hertz.

Two are up to around 1500 Hertz in use, where the transfer to the tweeter takes place itself is to an air motion transformer from the professional sector which far surpasses simple lens systems durability and dynamic.

The linear order (which explains the name of the series) results in an approximately cylindrical beam pattern, which compared to a conventional design in the style of the Bremen town musicians (bass, tweeters above) brings many advantages: floor and ceiling are less intensely illuminated, which reduces room reflections and the direct sound component increases. At the same time, the box carries further because of the distance-related loss of level with 6 DB per doubling of distance, but only by about 3.

On the back of two 25-Kevlarbässe plug, top and bottom, which cover the range between 80 and 20 hertz. The difference in the way to the front of the chassis is compensated for by a corresponding delay.

Brings us to the heart of the BM 25, which is one of the most modern, that are currently on the market. The signal processing is largely digital. Conventionally, i.e. analog, only the (sensor-controlled) bass range as also the three MOSFET power amplifiers with a total output of 1 kilowatt, which would be connected with external amplifiers with rather bulky dimensions and not inconsiderable power loss in thick, passive filter components work.

The conversion assumes a conglomerate personally developed by Siegler of A/D and D/A converters with a computational dynamics of 160 decibels, so also in the small signal range no sound losses are to be feared. The separation of the branches using FIR filters (finite impulse response), allow an independent influence of time and frequency.

The BM 25 is also as thought-out as the concept. Three freely programmable Equalizer available which are either to control a small display on the back or a user-friendly PC software (see screenshot) are the user in addition to subsonic filter, bass and treble controls.

In this case, the boxes will receive commands via network cable directly from the computer, which makes things extremely comfortable. Users may enter even an asymmetric listening position and to compensate virtually push back the more box, by delaying the signal. A targeting of room modes is possible as well as corrections when close to a wall or a gentle high-frequency attenuation in reverberant rooms.

And what does offer the BM line 25 except physical correctness? It might be a half-baked testbed with the charm of a precocious engineering Kit? Such questions are justified, but older Backes models in audiophile circles not just considered quintessential of holistic musicality.

Of these reservations was, to make it short, nothing to feel, not when compared with less technically complex passive boxes like the well-known 800 D B & W or the Blumenhofer Horn at the BM 25. They both when it mattered, in the over all fidelity the Backes not really ranged up.

Who genuinely liked with F 1 in the package the Thorens Monos brutal shocks out even a little more coolly model, but also the Backes penetrated without visible effort into sound pressure areas could hardly use the vast majority of users. Friedemann of Witeckas with only three microphones captured Harp music (05/2007 said track 4 of the booklet CD from the output) was only an example for the game force of Backes. A spatial as carved in stone and the equally Slackless as highly sensitive sound imprint, which must the BM 25 once someone imitate. What, there should be stereoplay safe, extremely difficult.

Backes & Müller BM line 25

Manufacturer Backes & Müller
Price €39000.00
Test procedure 1.0

Technical data and test results

General data
Installation tip:
Measured values
Operating voltage for 90 dB SPL
Impedance minimum stp
Maximum volume upper value
Maximum volume lower value (> 45 Hz)
Lower cut-off frequency (-3dB)
Lower cut-off frequency (-6 dB)
Short conclusion
Fine resolution
Border dynamics
Bass quality
Sound points
Measured values
Overall rating
Price / performance
tested in output 1 / 09