Interview with Rainer Weber of Kaiser Acoustics

Upon Rainer Weber (Kasier Acoustics) visit in Ljubljana we set for the interview. It took some time, but finally here is an elaborated look into his mind and the hearth of the Kaiser Acoustics. Enjoy the reading...

Tell us a bit about your background please.

I have a degree in electrical engineering and physics

How you got involved into the high-end audio scene?

I built my first speaker at the age of 10. Of course a that time it was a kit from Heco (a famous german manufacturer). I was fascinated about my speaker and wanted to learn more about it and of course build better speakers.

How and when Kaiser Acoustics was formed?

In 1998 (I was at time working for Siemens Automotive responsible for vibration testing and fatigue) I supervised a student which wrote his thesis in my department. 

We talked a lot about vibration and acoustics and I mentioned that I build speakers but I would need an excellent carpenter. The student mentioned that he went to school with Hans Jürgen Kaiser and so we got in contact. From the very first moment there was a common understanding and a high appraisal regarding the mutual skills.

Why the involvement with Kaiser Acoustics? 

See above

Is there a person or company in audio business that inspired you into audio business?

Yes there are a few:

Aleksandar Radisavljevic from RAAL
Steve Elford from Vertex AQ
Dietmar Bräuer from Trinity
Per Skaaning from Audio Technology
I highly appreciate the work of Kondo, Japan, Thomas Meyer (Vinylsavor), Vincent Brient from TotalDac, Lars Engström form TheLars in Sweden, Rumen Artarski from Thrax and Kerem Kücücaslan from Absolare.
Furthermore I admire the work of a german engineer but I will tell more in future.

Do you consider yourself an audiophile?

I think I am more a music lover than an audiophile, maybe a blend of both. I am more focused on music and sound and I see all the technical stuff just as a measure to reach the sound (music) target. Secondly I rate musicality and emotions above the sheer fascination for technical solutions

Do you feel there is certain aspect of your speaker designs that sets it apart from the traditional dynamic speakers ? 

First we want to produce a speaker which touches the soul of a music lover. There are a lot of specific solutions in the speaker to achieve this. We pay a lot of attention to just have sound where we want it so no unwanted vibration in the cabinet or whats ever. We name that perfect boundary conditions for our drivers.

That means we pay attention to use the best components, lowest vibration on the components and drivers and reduce RMI/EMI.

Second we thought about the right requirement for speaker design. A flat response in 1 m distance in an anechoic chamber is not the right requirement. You need to accept that the speaker is usually placed in a living room or dedicated listening room where it faces room acoustics (so no anechoic chamber and also no free field like an open air concert). You need to consider that in your design. Furthermore psychoacoustics are very important as we produce our speakers for human beings not machines.

All that points lead us to certain aspects that are not adressed in most designs of our competitors.

Why did you decide to use drivers on the back side? Some might argue that decision!?

The reason is psychoacoustics, especially the importance of the direct and diffuse field. The direct field (first wavefront) is important for spatial hearing (in the frequency range where phase information and interaural differences are important).

The diffuse field is very important regarding the tonal quality of a sound. See a human being needs at least 2 ms to distinguish a noise from a tone, events shorter than 2 ms just do not have a tonality importance. But in that range above 2 ms the first wavefront is almost gone, you have reflections (room interaction) and the diffuse field dominates.

So what are the challenges:

In our designs we try to have as much bandwith as possible to have fast response and speed.
The inverse bandwith (1/BW) is the time you need to excite a system. And that counts for every subsystem, i.e multiple ways. So we try to give all of our ways sufficient bandwith. In the Kawero the bass/midrange covers 60 Hz to 5500 Hz (thanks to Audio Technology).

Of course with a 7” driver we have a change in radiation over this frequency band, we have the baffle step (4 Pi radiation to 2 Pi radiation) and the driver will beam at higher frequencies.

That means we have a rising response (smaller radiation with the same energy leads to higher level), which we equalize in the crossover to have “flat” first wavefront. But we are robbing energy of the system in the midrange which we would love to have for a proper sound power response. Or in other words the before mentioned diffuse fields is lacking some midrange energy. So what to do. We add that energy to the diffuse field with the help of the rear firing units (woofer running high with low order low-pass design – and passive radiator of the midrange with same cone design as the front firing unit).

People that argue that decision “the bass goes to the rear” just have not realises that in that frequency range we have a 4 Pi (360°) omnidirectional response due to the long wave lengths.
It does not matter for the lowest frequencies whether you put them on the front or back.

Additionally with the overlapping in some frequencies of woofer, PR of bass/midrange and front firing bass/midrange we can achieve a very smart and specific radiation starting as monopole in the lowest frequencies to dipole and bipole, which is very interesting in coupling to room acoustics.

Kaiser Acoustics speakers are of stand out beauty. Kindly tell us more regarding the bespoke approach to the finishes.

We do every cabinet and the lacquering in house. This gives as perfect control over each process of the build up of the speakers.

We have rare and fancy veneers for more than 150000 Euro in stock. And we have excellent contacts to veneering factories. For example when a very seldom veneers comes in at the veneering company we get a call and mail with pictures asking wether we would like to have it for our speakers. We have 3 CNC machining centres in house, the biggest one can machine pieces 4 m by 1,5 m by 1,2 m.

We do VIP both for the automotive industry for the car shows in Geneva, Paris and Frankfurt. And we deliver interior design solutions for the most exclusive hotels. So crafting wood to perfection is nothing new to us.

I give you and example for the veneers. We are experts to the veneer job. Usually in carpeting you just apply glue on the backside, but we apply with a very special machine also glue to the edge where on sheet of veneer touches the next one. Therefore we have no risk that the veneer opens and the edge is protected against humidity.

For the inhouse piano lacquer (we use now the Fazioli after BASF) we need to keep a very accurate time table for the lacquering sanding and polishing of a layer. If we are to early the lacquer is not as hard as we want it, when we wait to long it is to hard to be perfect for a intermediate layer. So therefore do not be surprised when someone works at 2 am on the lacquering of the Kawero cabinets (if it is piano lacquer)

Are you building your speakers in house? What is the procedure? How are the standards?

We do everything in house. What we get from suppliers are crossover components, drivers and cables.

First we do calibrate the tankwood boards on special machines. We order them a big thicker as we would need them and to avoid the tolerances of the supplier we sand it down to the thickness we need ( a few mm).

After that we do the veneering. We apply two veneers on the tankwood – inside and outside. One so called blind veneer and then the nice top veneer. The reason is that tankwood and the top veneers have different properties in thermal expansion and humitidy expansion.

Therefore we have a “middle veneer” which can absorb this reaction forces – otherwise you get severe cracks in the top veneer.

Can you tell what is so distinctive Kawero Classic?

Kawero Classic:

Our first speaker and our current flagship. And it was our engineering mule where we learned a lot about the importance of cabinet design and materials and crossover components as well.

This speaker was requested by my friend Norbert Mundorf. We joined a booth at RMAF 2009 and he felt in love with the Kawero sound. He had the idea that I should make a smaller Kawero for him to promote his products in China. Therefore a Mundorf AMT and no RAAL ribbon (but the Mundorf is also exremely good) and no Duelund parts in Vivace I instead Mundord silver-gold-oil.

My latest creation and maybe the speaker where I have a big emotional connection to.

I went almost crazy with the crossover design and was about to cancel the project. But the other day I had a brilliant idea in the middle of the night, went in my pyjama to the lab and builded up the crossover prototyps. And it sounded awesome. When I got to bed again at 5 am my wife told me that I am totally nuts.

What is most important thing in building loudspeaker?

Two good ears and look over the fence. Trust your ears even if your engineering education tells you that this feature can not have an effect.

Lot of people might not know about your profound knowledge regarding the acoustics. Please elaborate on this..

I have a professional career in the automotive industry. I am the NVH director of Continental Automotive responsible for the acoustics of engine systems. I am in the advanced development and most of my time thinking of solutions for the cars which come to market in 2020 to 2025.

Additionally I was awarded as a senior technical expert. The great benefit of the this opportunity in a different industry (which much more sales as audio) is that I have tools like artificial heads, laser scanning vibrometers, sound intensity probes, acoustic holography camera and also simulation tools which are hard to find in the high end industry.

You implements quite some exotic materials for your speakers. What and why?

We use a material which is called Panzerholz in german, thus the wording “tank wood” which I am sure might not be the right English term, but I am not a native speaker.

So what is the benefit of tankwood?

Tankwood is very dense and stiff, it has almost the same Young modulus like aluminium (standard not air craft grade). And it is an inhomogeneous material. It starts a 1,4 mm beech veneers slices which are bonded together under enormous pressure and with some 2 component resin.  So there is a correlation to carbon panels, which are carbon fibres embedded in a resin. Here we have wood fibres embedded in a resin.

You can order different alignments between the layers which have different properties to address what kind of mechanical stress (push-pull, bending, torsion) you have in your panel. Most interesting feature compared to homogenous materials like MDF, HDF and aluminium is that the speed of sound in the material is different in each direction. Why? See, the speed of sound in a rigid  material is the square root of Young modulus divided by density.

The young modulus is different in the 3 directions but the density is constant. Therefore the speed of sound is different in each direction leading to a high dispersion of energy so that resonance can not build up so easily.

Please tell us more about your unique internal design? 

All internal braces and panels are designed to have different eigenfrequencies.

We use several approaches to do this, one is to design some dimensions according to the Devine ratio (“Golden ratio in nature”) the other is about modal spacing where we try to use Fibonaci algorithm. 
Furthermore we are implementing an acoustic labyrinth with a billion of possible transfer paths in the critical areas (crossover brackets, stands and some more). There the cancelation of unwanted vibration energy goes with some phase randomisation not with damping.

The math behind this is quite complex.

How do you see the connection of solid state and tube based equipment with Kaiser Acoustics speakers?

Well I am usually more tending towards the tube based equipment. We used different tube amplifiers during the long time development of the Kawero like low powered Yamamoto single ended triode with AD-1 tubes or higher power units like Mastersound 845 mono blocks.

So tube amps (whether single ended or PP) are a perfect match with the Kawero.

On the Chiara I prefer more power and prefer Thrax Heros or SPEC RSA-F33EX to drive it.

How do you achieve high end performance?

It is a bit like cooking. Choose the right recipe (that means the right design) and then use the best ingredients (that means, drivers, crossover components, cabinet and cable).
The integration to a (speaker-)system is the key and and art.

What product of yours you’re most proud of?

The Chiara. I always wanted to make an exceptional speaker with a 5” woofer since I was 18 years old.  A short story: When I got my driver´s license at 18 my first drive with my car was to a high end dealer in Nüremberg, 1 h away from Regensburg.

At that time the famous Apogee Duetta was highly claimed and the reference speaker in some magazines. It was not available in my hometown and therefore I decided to go there. 

I meet a very kind guy who demonstrated the speakers well despite the fact that at that age this speakers were far beyond my budget. After the demo the guy asked me whether I would like to here something else, something extraordinary good. Of course I wanted. And I listened to a speaker which was called Intonation Terzian, a 2 way with 5” woofer designed by a organ manufacturer from Hamburg. 

This speaker completely outperformed the Apogee. I did not understand why, I was shocked.Since that time I always had in mind to make something in that direction.

Chiara took also a very long time in developing the crossover and I learned a lot about the major structure borne vibration issues in stand mount speakers. Together with my friend Steve Elford from Vertex AQ we implemented some Vertex AQ acoustical labyrinth technologies in the stand and crossover and the performance is unbelievable for such a small speaker.

Do you think the ultimate transparency, dynamics and musicality can be jointed in ultimate perfomance?

Yes, I think so. When in reality at a music event the sound (or sound field) has this transparency, dynamics and musicality why should there be a reason to be not able to reproduce the same. It is still a long journey and a very difficult job.

I see most of the problems in dynamics (without distortion) and rise time.

And of course that boundary conditions of a big concert hall are completely differentness from a domestic listening room. As explained earlier the main task is to create a sound field coming close to the real event. So radiation and diffuse field together with room acoustics are very very important contributors to a magical perception in hifi.

What electronic do you use to drive you speaker in lab?

Thrax Heros
Mastersound 845 monoblock
We have also some Hypex Ncore modules

Every manufacturer strive for some certain sound outcome. How do Kaiser Acoustics voice their speakers?

Most important thing is that we voice our speakers in a way that touches your soul. And we voice it in a way that is works in a normal domestic environment

What would you say that sets Kaiser Acoustics above other manufacturers?

If you analyse our rationale and design and you come to the conclusion that we do not like to make compromises. Our motto is “Do it or do not do it – there is nothing in between”. So we try to make the very best and to not make design decisions based on money or margin.

As we have a solid income from the furniture business and from Continental there is no need to make a compromise just to hit a certain price point. We make the best speakers in each size an this tomes to a cost not the other way around.

And we try to combine appearance with performance; because at the end of the day the man are flabbergasted with the performance of our speakers but the appearance (which is important for their wife’s) is then the cause to purchase it.

Form follow function in Kaiser Acoustics? 

Yes it does. It is a functionality reason why our woofer is back at the Kawero/Vivace and the tweeter can be time aligned and rotated.

How important are room acoustics with the high-performance listening?

As I have mentioned before: You need to consider in your early requirement engineering that the speaker will be placed in a room. This comes not as a sudden.

Then you have to address this (with some psychoacoustic knowledge behind). 

So your speaker will face a room acoustic phenomena called room gain. It will have to face 4 Pi radiation to 2Pi radiation (baffle step) and it will face reflections on the side, ceiling and floor. Think about the effects on the sound perception, fix it and you are fine.

The problem is that you have a big variation for ie room acoustics at our clients. So you should smart try to find a solution which works in most of this environments.

Of course in a dedicated highly optimized room the performance will be even better

Is high end well constructed loudspeaker capable of top performance in moderate home, without expensive room treatment?

Yes you can. For instance the Kawero is available with 3 different woofer sensitivities based on the room acoustics of the client. When we start a Kawero project we do extensive room acoustic calculations of the client´s environment and propose a matching woofer solution. When the client should move and the woofer does not match the new situation we change the woofer without charge.

Do you think that real live experience is possible inside or our listening spaces? Yes, no? And why?

We can come close. First let us agree that of course the recording has to deliver the quality so that we would be in a position to create something like live experience. But it is very hard: See many instruments emit different spectra in different directions. Not an easy job for microphone positioning.

And we will have a challenge with rise time and dynamics of the real event. The problem is that we would need to create a dynamic sound field which is exactly the same as in the live event. And that implies that we have similar direct and diffuse field (and similar reflections – room size)

What is the definition of the ultimate audio system for you?

The ultimate audio system for me is a system where you can not distinguish a real sound from the sound of the system. We are still far away from the ultimate.

What kind of customers buys Kaiser Acoustics speakers? 

We have very different customers. Our typical client is a music lover first and an audiophile with a huge collection of music. Many of them play instruments.

Usually they have a long history with high end equipment and are very experienced listeners.

Our customer buy because of the musical performance of our speakers. 

They do not buy because of our brand image and because Kaiser Acoustics is the new kid on the block

Would you say that Kaiser Acoustics speakers share the same recognisable sound across the range? 

Yes, obviously the speaker have attributes in sound which they all share as they are designed by the same team. It tells also a lot about our priorities in sound. They can make very big and realistic sound stage with depth. They have a very good attack and they have a very natural tone and sound.

There is the high-end and ultra high-end. What is the difference in you view? 

Ultra High End is like going crazy and over the edge of the already established thinking and design. It is like paying extreme attention to every minute detail and solution.

As I am the technical director in the company I design without thinking about the costs.

The only parameter that counts is performance. 

I create speakers for myself, that means, would I like it in my listening room?

It is not about whether I can sell or make a big margin on them.

And Ultra High is about manufacturing, materials and long term stability.

Like Porsche in the Car Industry

Do you plan to expand to other products in future?

We are thinking of adding a new flagship loudspeaker to the line. It will contain 2 15” fieldcoil drivers and also a fielcoil compression driver. Something extraordinary good. Additional we consider to add something like a “floor-stander Chiara” which could be also very interesting. There is a lot of cost and effort in the sophisticated stand of the Chiara which we would not have with a floor-stander. 

Where does high-end audio morph into the luxury product market?

Have a look on our surface choices with a high degree of choices. We have a huge stock of fancy and rare veneers and can apply the finest piano lacquers.

You can even send us a tree and we make a nice veneer out of it – everything is possible

I think this touches luxury market because it is not really essential for the acoustical output of our speakers. 

What is your view of current high-end audio industry and society?

In my opinion the quality and performance of current high end equipment is significantly better than in the old days, especially speakers. Of course some very old technologies like field coil motors are still hard to beat.

Nowadays the high end market is a niche market and the average age of the high end customers is more the seniors. The problem is to find customers in the new generation which thinks compressed music over an Ipad is good enough.

Do you distinct between audiophiles and music lovers?

Well, yes and no.

If you think of an audiophile who has only 10 audiophile records and listens each day the same few tracks and his main target is to listen to the technical accuracy of the sound this is not our main customer.

A music lover who listens mainly to get emotionally involved by the sound and his main goal is the perception of the music; this describes our customers better.

But on the other hand, many music lovers can enjoy music even on a far inferior system like the Kawero, because it is about the music.

And hard but true, a lot of music lovers can not afford a ultra high end system.

Where does usual hi-fi stops and high end comes in for you? 

For me high end is defined by top performance and engineering solutions.

High End shall be able to play music as close as possible to reality and it shall deliver the emotional content of music.

Products without any compromise define for me the ultra high end.

What is the definitive goal of Kaiser Acoustics?

Our goal is to make speaker where you can dive deep into the music, where you get goosebumps (best indicator) and where the sound is having no fatigue.

The speaker shall deliver fun to listen to music. 

What are your musical references and how do you use them with the creation of the speakers?

I like everything from Classic to Jazz and Pop/Rock.

I do not like very much techno, to heavy experimental Jazz and 12 tone music.

Is classic music the top most test material for state of the art reproduction? 

Classical music is very demanding. I has a big range in dynamics and a lot of instruments.

On the other hand the boundary conditions of the real event, say a concert hall, and a living room differ significantly. In a living room there is just not the space to house a big orchester; so it will be sometimes a scaled down perspective on the event.

But on the other hand a good speaker system in an optimised room can deliver a very close perception to the real event.

Another note:

Many people are not experienced with classical live music, whereas a human voice is something we are very used to. Our complete human hearing mechanism is focused on human speech and communication.Therefore we do a lot of testing with human voice because we can easily address a good or bad reproduction there.

What are your plans for future?

We are just designing a new flagship speaker with two 15” field coil drivers and a field coil compression driver.

Furthermore we are thinking of adding a kind of “Chiara floor-stander” as a speaker between the Chiara and the Vivace.

Last as a dream, I would like to build a turntable. With our knowledge regarding material and vibration I think we could achieve something special.

Would you like to add something to our readers for the end? 

Enjoy more music! It enriches your life!

Thank you!