The diaphragm movement: how does the diaphragm move?

The diaphragm does not move piston-like, as in cone loudspeakers, the flat diaphragm vibrates on its own axis. The bending waves move from the middle outwards, comparable to the wave movement on a water surface after throwing in a stone. Using Mother Nature as an example, the basilar diaphragm of the human inner ear functions along the same wave principle as the Manger sound transducer.

Star shape: why this star shape?

The star shaped absorber, nowadays a hallmark of the Manger sound transducer, is not a designer’s idea but has a necessary function. The outward moving waves must be dampened at the edge of the diaphragm. The star absorber acts like a reed belt along a riverbank, which prevents the waves being bounced back to add to the oncoming waves.

Crossover frequency: where is the crossover frequency between the Manger sound transducer and bass drivers?

The crossover frequency from the Manger sound transducer to the bass drivers lies between 140 - 170 Hz, depending on the choice of the bass drivers.

4 connecting wires: why does the Manger sound transducer have 4 connecting wires?

The Manger sound transducer works with 2 voice coils, which are electrically connected in parallel. These 2 coils lie adjacent to one another on a supporting frame. When one moves out of the air gap, an undesirable opposing force appears as a result of counter induction. This impairs the actual coil movement. However, as the second voice coil simultaneously moves into the magnetic field, the energy forces are neutralised and the opposing force is cancelled out. The voice coil is only moved time correctly by the music signal. Using the patented twin voice coil principle, the Manger sound transducer achieves an extremely fast rise time of 12µs. for lower frequencies i.e. with slower movements, these 2 adjacent coils act as one long voice coil and achieve a maximum excursion of +/- 3.5mm.

Burn-in time: does the Manger sound transducer have a burn-in time?

Yes, just like every other loudspeaker chassis, the Manger sound transducer has a
recommended burn-in time of 24 hours.

Pair-matching: are the Manger sound transducers selected in matched pairs?

No, due to the very strict mechanical tolerances of the Manger sound transducer the maximum permitted deviation in frequency range is 0.5dB. Stringent quality checks give each Manger sound transducer its own measurement protocol.

Repair: can the Manger sound transducer be repaired?

Yes, basically speaking the Manger sound transducer is repairable. Coil and diaphragm can be replaced, the basket and magnet reused.

Improvements: are there still any improvements possible to the Manger sound transducer?

The Manger sound transducer has reached a technical level that does not envisage any improvements in the foreseeable future. In the long term the Manger sound transducer can always be modified. In this respect all our clients are kept up to date on any developments.

Long term stability: how is the long-term stability of the Manger sound transducer?

After the burn-in phase of 24 hours, the Manger sound transducer does not alter. Our own positive, long term tests have been obtained from recording studios which have been using the Manger sound transducers since the mid 80s. There they are driven daily at high volume levels for 12-14 hours. After measuring, no deviations from the original test protocol could be detected.

TSP: how are the Thiele-Small parameters?

The Thiele-Small parameters are invalid for the Manger sound transducer. These are based on an equivalent circuit diagram of a piston loudspeaker with mass/spring characteristics. The Manger sound transducer works however, according to the bending wave principle and acts almost like a resistor.

Any future developments?

The Manger sound transducer is at a technical level where no more teething problems occur. Any Manger sound transducer from 1986 onwards can be modified, should future improvements through new materials be reached. This means you can always achieve the latest technical standard via modifications without investing in new equipment.

Room temperature: what is the optimal room temperature for the Manger sound transducer?

The Manger sound transducer functions optimally within a room temperature range of
15-35°C. other temperatures e.g. as in cars, alter the material properties and thereby impair the audio reproduction.

Amplifiers: which amplifiers are best for the Manger sound transducer?

Based on our experience, the most suitable amplifiers are those with a high bandwidth, in excess of 150kHz. The higher the upper value of the frequency range, the more precise the acoustic details will be reproduced by the Manger sound transducer.

Zerobox: are there any differences between the Zerobox models?

The major difference between our Zerobox models lies in the low frequency range having differing lowest frequency limits depending on the bass driver chassis used and cabinet volume.

Which Zerobox model is correct choice?

The correct choice depends on different factors: room size, placement in the room and listening habits. Direct contact with us on an individual basis is highly recommended.

Why are three Manger transducers the preferred choice in ZB models?

With only one transducer in the loudspeaker housing, a typical pressure drop
to one half of the original value occurs as soon as the acoustic wavelength
matches the housing width. With the two extra bending wave transducers mounted in either side of the cabinet the side-mounted drivers create an acoustic baffle, with no omnidirectional radiation. The front driver is still the main driver, and the side drivers are switched in serial with a coil, so that they just support the front driver's radiation like an infinite baffle. The side-mounted drivers are faded out above 1000 Hz with a gentle six-decibel filter. The result is that you can't recognise the cabinet

Can the MSW be used as a dipole tweeter? I.e. on an open baffle.

It can be used, but we don't recommend it. The Manger driver works more controlled in the low frequencies if the drivers is built in a sealed cabinet. The spring behaviour of the air controls the diaphragm movement at the low end. You can also drive the Manger with more power.

If I crossover @ 1500hZ from my Volt BM2500.4 bass mid driver, do I still connect both sets of voice coil leads?

Independent of the crossover frequency both voice coils are always switched in parallel. The two parallel-switched voice coils creates the fast rise time on one hand and on the other hand an excursion of +/- 3.5 mm.
We wouldn't recommend a crossover frequency which is that high, because localisation and image should be created only by the Manger not from both drivers. The highest fg should be around 600 - 800 Hz.
In the Zerobox speakers we use a crossover frequency of 150 - 180 Hz!

Is there any preferred arrangement with regard to the orientation of the transducer in the speaker cabinet? For example, is there a preferred position for each of the leads across the diaphragm in terms of, say, a clock face

There is no preferred arrangement, the driver’s work concentric and coplanar. We just use the symmetrical axis for aesthetic reason

For which kind of music is the Manger sound transducer best suited?

The Manger sound transducer is suitable for all music styles; it reveals the natural content of every sound medium. Unfortunately this can sometimes show up poor quality recordings. We gladly send you our reference CD as a comparison






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