TNT-Audio inter.views Daniela Manger [English]

Inter.view with Daniela Manger, of Manger Products

TNT-Audio >
Manger is somehow a new name in the HiFi scene, would you please introduce your Company to our readers?

Daniela >
Manger started in the 70s with the development of the Manger sound transducer, a bending wave driver. My father, Josef W. Manger - the inventor of the Manger sound transducer, figured out that conventional loudspeakers have their own sound.
By performing measurements in the time domain (like measuring step response), he realised that the incoming signal has been distorted by the mass spring action of conventional drivers.
Since then he has been active in transducer research. In 1982 he was presented with the Diesel medal, one of Germany's highest awards for engineering excellence. After nearly 30 years of R&D, the Manger sound transducer and a variety of finished speaker models, called Zeroboxes are now completely manufactured in our company.
I took over the business in 1991 after I'd finished my degree of electrical engineering, which currently employs 10 people. My father (72 years old) is still researching in the field of hearing physiology, and works with the many institutes around the world who are using our sound transducer.

TNT-Audio >
99% of the loudspeakers in the market use technology which is almost 1 century old (magnet + moving cone). Your Manger driver seems to break new ground in this field. Which was your source of inspiration for such a revolutionary and unconventional approach?

Daniela >
Our ability to instantly recognise the difference between someone playing a piano or just a loudspeaker - passing by an open window. Everybody here knows this from their own experience.
The starting of the development was quite a simple question "Why does a natural instrument sonically differ to its reproduction by a loudspeaker?"

TNT-Audio >
Your driver has a claimed frequency response ranging from 80 to 33,000 Hz. What are the technical limitations that prevent your driver from reproducing lower bass frequencies?

Daniela >
The diameter of the membrane stipulates the reproduceable frequency range. For the lowest frequencies it is also not necessary to work with a different driver system than the conventional piston driver. At these low frequencies a piston driver works well, and has no problem generating high sound pressure levels.

TNT-Audio >
If I understand well, your driver eliminates the transient problems conventional drivers have. According to your theory, this will make your driver "disappear" - acoustically, I mean - whilst conventional loudspeakers remain "visible" while they are playing, i.e. our ear always is able to perceive where the sound is coming from.
I've heard several loudspeakers that literally disappear into a listening room, despite the fact they use conventional speakers, so there should be some other reason....

Daniela >
Not only do the drivers disappear - the complete Zerobox disappears like the name says! When listening to stereo sound, you create an acoustic image... an acoustic scenery, if you will.
Naturally, if you listen just to a mono signal just with one box then you can recognise that the sounds come from the Zerobox, but even in this configuration it has no own sound... no finger print, because of the quite perfect time response.

TNT-Audio >
Single-membrane drivers/loudspeakers should (in some sense) have the same advantage: one single moving mass, more realistic transients. What is your opinion on these (typically high sensitivity) single-driver loudspeakers?

Daniela >
They are all the rage nowadays, especially when mated to SET amps. It is correct that the time response is better compared to a multi-way speaker, but it still has a piston-like action, which has an audible characteristic sound.

TNT-Audio >
It seems your driver doesn't make use of springs as conventional drivers do - apparently, it doesn't use air as a spring... could you please explain where the energy goes after an impluse is received by the driver? Is it transformed into heat by the dampers behind the membrane? Doesn't this cause any rebound?

Daniela >
Our driver works like a transmission line to bending waves. This means that no discrete mass or spring is working. It acts like a mechanical resistor, the center damper and the outer perimeter is matched with its impedance, so that any reflections are avoided.
After the incoming pulse moves the voice coil, the diaphragm starts to bend and move the air in front of the diaphragm. Take a look on the picture in the brochure "Acoustical Reality" - it shows a cutaway of the diaphragm with the air molecules in front.

TNT-Audio >
The step response graphs of your driver are impressive, to say the least. What about polar response performance?

Daniela >
If you measure the step response at different angles, you will see that the rise time decreases, but this is okay for our hearing sense. It is equivalent to changing position, like moving from in front of a singer to the side. The sound changes, but not the characteristics and not the local behaviour.
Pressure changes always give you information about the sound source and the size of the sound source. Every natural sound source, e.g. instrument, bird, a singer has its own "directivity" - this is where the sound starts travelling. This is the same with a speaker but if you add a finger print of the speaker to the reproduced signal then you will recognise it as a loudspeaker sound.

TNT-Audio >
Could you please briefly summarize the interesting concept behind the ZeroBox Manger cabinet? And what about increased room interactions caused by the use of lateral drivers?

Daniela >
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 result is that you can't recognise the cabinet.

TNT-Audio >
Are you planning further upgrades for your drivers? In which direction will the research go?

Daniela >
Regarding the new high bandwidth audio formats(SACD, DVD-Audio), we will work on a driver with a higher bandwidth. On the theoretical side, my fathers' research is on the importance of transient response for our hearing perception.

Courtesy by Daniela Manger for TNT.
HTML: Tom Browne