It is very easy to get a loudspeaker membrane to move, but this movement needs to be perfectly controlled. It needs to accelerate and stop as fast as possible without creating any unwanted vibrations.

A loudspeaker membrane is pushed and pulled by the coil in the magnet gap depending on the current that goes through it. The mechanical construction of a transducer represents a mass on a spring that naturally doesn’t behave the same way at all frequencies. It typically has a resonance frequency where it moves easier. Not only the transducer has resonance frequencies but also the material itself, the suspension, the spider, etc. It is important to know all these physical characteristics to be able to correct them with the electronics.

So whatever the material of the transducer (paper, fabric, polypropylene or any other) it has to be accounted for in order to avoid any coloration of the sound. The material of the membrane should not colour the sound, all materials should reproduce accurately and not “sound” different. We have chosen material for their weight, rigidity, durability as well as homogeneity in production.
In order to correct all of these physical characteristics we have implemented a feedback loop from the speed of the transducer and acting on the output impedance of the amplifier. Needless to say that this circuitry is impossible to function in real-time with any digital technology and only analogue circuitry will achieve a perfectly seamless result.

Our AOI technology ensures that there is no colouration of the sound from the transducers and that the transients can be perfectly reproduced.

A good illustration of the result of our CPR and AOI signal is introducing a square signal into the speaker and seeing what comes out.

In real life only sine waves exist. To create a perfectly square signal an infinite number of sine waves is necessary and all must be perfectly positioned in time. Imagine trying to fill the corner of the square signal with sine waves, you would need many sine waves, smaller and smaller, but all positioned accurately in time.

As shown in the illustration below, a standard loudspeaker response might reproduce the frequencies used in the square signal but the timing is not respected as the low frequencies are delayed by the filters (acoustic, mechanical and electronic). As a result, the loudspeaker will start reproducing the high frequencies and the low frequencies will follow, then the high frequencies will stop and the low frequencies will stop slightly later.
With our CPR phase compensation, all frequencies above 150 Hz are time aligned and it is possible to reproduce a square signal and sharp transients in any sound much more accurately.

Of course it would be possible to compensated phase down to 20 Hz. However, as we have seen, we are not sensitive to phase below about 300 Hz and furthermore this would mean adding delay and latency in the system. It is generally considered that a latency in the loudspeaker of 1 millisecond is the maximum acceptable. Of course, when listening to music at home, there is no issue with a slight delay between pressing the play button and the music coming out of the speaker. But the latency must be very low when monitoring recording, mixing or in postproduction. Our largest speaker has a latency of only 0.6 milliseconds, which suffices to align phase down to 150 Hz. This latency is the same as moving the listening position back by 20 cm as it will take sound 0.6 milliseconds to travel that distance.

The answer is simple: both.

There are details and parameters you can measure but not hear easily and there are details that are very difficult to measure but that can be heard.
A loudspeaker should not sound beautiful but simply reproduce accurately beautiful sounds by transforming and electric signal into an acoustic signal.

If you accept this and accept that the artist, instrument sound engineer, natural sound, or whatever you are listening to is what you want to hear, then you can measure many parameters on you loudspeaker such as frequency, phase, distortion, directivity, energy, impedance, etc.

All these parameters can be optimised objectively but then it is necessary to listen to the loudspeakers with different specialists and in different environments.

For each new development and improvement we have a panel of specialists who listen to our loudspeakers and work with them for a period of time in their environment. We like to include some classical musicians and producers, as they know exactly what their instrument should sound like. More subjective parameters are evaluated such as: transparency, dynamic behaviour, sound stage, colouring, comfort of listening as well as personal impressions.

Then process is lengthy but necessary to validate any development or change.

Once validated, we establish a reference that needs to be matched in production for every single loudspeaker, hence the individual calibration.

People ask us if we match our speakers in pairs. No, we match components in each loudspeaker so each loudspeaker matches the reference that is as close as possible to reality and subjectively validated by hundreds of ‘listenings’.

Class G/H amplifier

Amplification of the signal is necessary to drive the membrane and create loud enough sound.

There are numerous types of amplifiers that all have advantages and disadvantages. In general class AB is considered to be the most accurate but it has the disadvantage of not being very efficient producing lots of heat that needs to be evacuated and also crates thermal stress on the components.

We developed our own class AB amplifier that we use for the less energy intensive drivers such as tweeters. For most woofers we developed a class G/H amplifier that uses 2 different tensions and seamlessly travels from one to the other minimising energy used (and therefore heat).

Not many people used class G/H amplifiers, as they are complex and difficult to get right.
All our amplifiers also integrate our AOI system as a real time feedback loop.

Note that we have developed class G/H amplifiers for other industries, such as prestigious precision mechanical industry, when they cant achieve what they want with any other amplifier such as class AB or class D.

Our world-class competencies are used in several other industries.

We are proud that the competencies and know-how we have applied to electroacoustic are also world-class in other industries:

Building on our tweeter technology, we have manufactured high precision seismographs that measure vibrations on many European bridges.

Based our class G amplifier technology we have developed special amplifiers for the Swiss precision mechanical industry.

With our precision acoustic technology we developed small anechoic chambers used in the watch industry.