First interview in the loudspeaker guru's serie, Tony Gee van Humble Home made Hifi.

This is a continuation of the interviews Peter Smith did with: Siegfried Linkwitz, Ken Kantor, Darren Kuzma and many other interesting loudspeaker guru's. See www.helarc.com (click the Guru's speak for a overview ). Until we found a nice spot on this site for all the coming interviews, i will put them here in the review section. I hope to bring a new interview each month. As soon as we have a confirmation from a new Guru we will publice the name here.  

Scroll down for interviews with:
Jeroen D.
Marc Heijligers
Allan Isaksen



Bio
Tony Gee, founder and owner of tg-acoustics and Humble Homemade Hifi, has been into music and audio from a young age. At primary school he was already experimenting with full-range drivers and old valve amplifiers. At the age of fourteen he bought an electric bass-guitar and formed his first band. He first studied general art and later studied architectural design at the art academy. He took double-bass lessions from the well known danish bass-player Peter Björnild. In the meantime, with more than 25 years of experience in loudspeaker design and several publications in audio magazines, his name has become well established in the world of loudspeakers. *Most people here will know Tony from his extensive and ongoing capacitor reviews.* Added by Caps&Coils.

1-What was the first speaker you built? And how did you get involved in speakerdesign or the audiofield?
I built my first loudspeaker at the age of 10 using drivers salvaged from old radios mounted in a cardboard box. Being a musician got me seriously involved in loudspeaker design: the only way to build an affordable bass-rig was to build one meself. Since then I haven't stopped.

2-Can you tell us some more about your favorite music? Do you have special pieces of music you use to review loudspeakers?
I mostly listen to classical music and jazz but when tuning loudspeakers I also play some popular music and rock. A loudspeaker should be as neutral as possible, so it must be able to produce all types of music in a "natural" way. My favourite period in classical music is from about 1500 to 1650 but I can also realy enjoy Beethoven symphonies or string quartets. Anything after 1850 is too modern for me! Jazz-wize I like musicians like Brad Mehldau, Avishai Cohen, Keith Jarrett and many more. And of course being a bass-player I have a pile of Jaco Pastorius cd's. When voicing crossovers I prefer to use recordings that have a very natural tonal balance, natural room acoustics and dynamics. Most well recorded classical and jazz music from smaller labels comes standard like that. Classical music is always "un-plugged".

3-Without giving the standard “weakest link” answer, how important would you rate speakers as component?The loudspeaker crossover is the most important component. It can make or braek the loudspeaker and therefore the whole system.

4-How have speakers changed in the past ten years?
The basic design of a dynamic loudspeaker is still the same, but great improvement has been made in lowering distortion. Also the introduction of neodymium magnets has opened opportunities for building drivers with compact motors and therefore less reflections from the rear of the driver.

5-How about mechanical resistance in loudspeaker drivers. QMS and Rms. Important or overrated?
Very important, one of the first things I look at when choosing an appropriate woofer. It increase dynamics and low level detail. All tg-acoustics designs use drivers with extremely low mechanical resistance. For example, the large 15-inch woofer in our up-coming reference speaker has mechanical losses normaly only found in small midwoofers!

6-Do we have to spend a lot on woofers and tweeters to get good sound?
No, not at all. Spend a lot on the crossovers! Not only the crossover configuration but also the differences in crossover component sound quality is far more important than the drivers. As long as the drivers are low on distortion levels, it doesn't really matter.

7-Do we have to spend a lot on capacitors and coils in the crossover to get good sound?
It depends, choise of crossover components is like cooking. You have to find the correct mixture and balance of quality and sonic signature to get an end result that meets your personal taste and budget. Using the best and most expensive components doesn't guarentee to best result. Its all about combinations.

8-About loudspeaker cabinets. Any thought on the use of exotic materials other than mdf?
MDF is made from glue with a bit of saw-dust thrown in, is cost effective and easy to finish. But thats about all. Sonically speaking soild-wood and plywood is far superior in having a more natural tonal balance. In direct comparison MDF sounds lifeless, coloured and boring. All loudspeakers built under the tg-acoustics brand use a combination of real solid-wood and plywood, all FSC certified.

9-What are the top three design parameters you use? (or the top three things you worry about most)
Natural tonal balance, dynamics and coherency.

10-Do you design on measurement or sound?
Both. It's easy to design the same loudspeaker with many different crossover typologies that all measure with a flat frequency response. But they will all sound different. Which one sounds "the best"? Measuring is important, and makes life a lot easier but a computer doesn't have ears!

11-What do you think about dynamics? Must a speaker really be able to do 115 dB to be any good. Or is this overrated?
Dynamics is the difference between quiet and loud and how well a loudspeaker can follow sudden changes in output level without compression. To me it isn't about the maximum SPL, at least not under normal listening conditions. An acoustic guitar can be very dynamic although it isn't a loud instrument at all. Perceived dynamics are more about fast rise-times and short decay-times.

12-What do you think is that "special something" is that makes some speakers sound so good?
The designer has chosen a nice combination of ingredients and knows how to cook!

13-How many octaves does a speaker really need to sound right? Is the bottom octave required? What about above 20K?
It depends on the design. 40Hz from a 12" woofer sounds totally different to 40Hz from a 12cm woofer.

14-You have to choose: minimalist twoway monitor or a 4 way active loudspeaker. Which do you bring to the deserted Island?
A minimalist 2-way monitor, this wil last longer on solar energy than a large 4-way active system!

15-What one piece of advice you would like to give to every new speaker builder?
Don't try to build to best loudspeaker the first time round. Get a pair of cheap but good 18cm midwoofers and a pair of cheap but good tweeters, and build lots of different speakers and crossovers with just these four drivers. Also, before you do anything, read Vance Dickason's Loudspeaker Cookbook at least twice.

16-Will we ever find the Holy Grail in sound reproduction? And what keeps us away from reaching this goal?
No. As said earlier, it is all about combinations of many variables. There is still lots of progress in design and quality of components, so there will always woofers with even lower distortion than before, or even "quieter" capacitors, etc.

17-So which is it for you, tubes or Solid State?
Mostly Solid State for being more flexible. As a loudspeaker designer I need amplifiers that aren't bothered by varying impedances and can produce heaps of power when needed. Saying this, I do also own a little EL-84 push-pull tube amp.

18-Any thoughts on the audio industry's movement to the far east?
Shipping goods around the globe just to save a few bucks is rather futile and very bad for the enviroment. On the otherhand nearly all hifi-equipement today is produced in the far-east, even by high-end non mass market manufacturers, so it is nearly impossible not to be part of this. I know that today it is impossible to source everything from your home-town but at least all the components used in tg-acoustics loudspeakers are sourced and produced within a 1500km radius of Amsterdam. Also they are RoHS compliant.

19-What does the future hold for speaker design?
Hopefully the younger generation who only knows music from PC-speakers and telephones will learn to appreciate real sound and buy some decent speakers!

20-Will high end stereo be alive in twenty years?
Yes.

21-Can you name some loudspeaker designs you like? Commercial or DIY.
Sonics Arkadia, Lumen White Silver Flame, Audioplan Kontrast V, and many more..............

22-And the final question, can you tell me we are you are working on at the moment?
Many things, but one of them is a new reference model for tg-acoustics using a 15" woofer, an 8" midrange and a tweeter. A classic, no-compromize system.

Tony Gee
15-09-2006

Second  interview in the Speaker gurus series: Jeroen D.



Bio Jeroen D*.
I was raised in a musical family. My mother is a piano player and my brother plays the violin, both of them professionally. I myself started playing the piano when I was seven years old and changed to playing flute when I was twelve. So music is a very important part of my life and I have heard for years and years the real sound of piano, violin and flute. I did not go professionally in playing music, instead I became an electronic engineer.  This has helped me a lot in developing my own audio systems. From my audio systems I want the most realistic mid and highs. The bass has to be adequate and not disturbing. I have to compromize there because I want to play music in my living room, not in a heavily damped studio room. I have always lived in rooms with very hard walls. After discovering the website from Siegfried Linkwitz and studying all his material, I concluded that I should take his approach very seriously. In the meantime I did a lot of experiments with closed box midrange housings, thereby verifying the sphere/tube concept from B&W loudspeakers. Eventually all my experiments led me again to open baffle systems in the end. The few remaining low frequency room modes from an open baffle loudspeaker can be reasonably well controlled by EQ. The mid/highs benefit from a rather 'live' room. The end result of the open baffle system gives transparancy and tonal balance that is comparable with a good headphone, together with a large and deep soundstage which is what I like a lot. (*Jeroen D is known in the Netherlands. for his openbaffle designs, which were published in the Dutch Elektor Audio Special. Visit his home page to see some of his work added by caps&coils)

1-What was the first speaker you build? And how did you get involved in speakerdesign or the audiofield?
The first speaker, about 20 years ago, was a design (Vector II) from Speakerland, a very well known DIY loudspeaker shop in the Netherlands. The Vector II was a four way with a bandpass double chamber bass system (SEAS
CA25RE4XDC), a closed low/midrange (VIFA 17WP200), a dome 2" mid (ADR50S) and the Technics TH400C leaf tweeter. It sounded very well in the dampedlistening room at the shop but in my living room I had severe bass problems. Also, the sound of violins appeared not to meet my expectations. I started to dig into the techniques for bass room equalization and developing other crossovers for this system. I didn't buy new drivers, but in the end made several housings for these drivers and learned a lot while designing the first loudspeaker that came much closer to what I was searching for.

2-Can you tell us some more about your favorite music? Do you have special pieces of music you use to review loudspeakers?
Classical music is my favorite, from the earliest period up to the well know Russian composers of around 1900. Furthermore, I like (symphonic) rock, latin music and some jazz. I don't have special music to review loudspeakers, most of the time I use music to which I have listened the most during the last weeks.

3-Without giving the standard "weakest link" answer, how important would you rate speakers as component?
They are the most important component in your audio system. Especially the way a loudspeaker interacts with your listening room can make or break the listening experience. By that I mean that the on-axis response is of limited
importance. 80% of the sound you hear is coming from your room. So loudspeaker dispersion, the power response and placement are of paramount importance. The weakest link however, is that we cannot close the open loop of recording in the studio and playing in your listening room. Floyd E. Toole already has told us that we will have to face the fact that the recording engineer does not produce the record according to what is heard in your own listening
room. When a recording of a piano in a well damped studio is played through good loudspeakers in a real concert hall, the sound appears to be very realistic. You can hear the music in the real environment, while the recording engineer didn't not have to gamble for a nice reproduction in a living room. The other way round, recording in the concert hall and playing music through loudspeakers in an anechoïc room is considered to be a bad approach. Our brain is not used to process sound in a non reverberant space. So we have to deal with recording in a concert hall or studio with its own
acoustics and playing through speakers in another room with different acoustic properties.

4-How have speakers changed in the past ten years?
They have been optimized to produce less linear and non-linear distortion. Most progression has been made in improvement of non-linear distortion. Quite recently I found that non-linear distortion is not really of concern
anymore when using well known good drivers. Linear distortion (stored energy and resonances) in loudspeakers is more important. Progress in this respect has not been overwhelming, which is for me the explanation that 10 year old drivers can sound surprisingly well.

5-How about mechanical resistance in loudspeaker drivers. QMS and Rms.Important or overrated?
It depends. High Qms and low Rms are indications of low losses. Losses can be non-linear. As long as they are linear however, Qms and Rms don't really matter, just work with the driver to design a good system. So in the end, only a linear response, low non-linear distortion and dispersion of the driver matter to me. If these three parameters fall within my system design goals, the only thing that matters is to design an adequate housing and crossover to build a really good system.

6-Do we have to spend a lot on woofers and tweeters to get good sound?
No, but if you want to play loud with ease you have to use a large woofer surface (12" or two 8" drivers) and go at least three-way or use a tweeter with waveguide together with a really large woofer (like a studio monitor). I have never heard in a standard two-way (mostly bass reflex with a 6,5" midwoofer) the quiet sound of a larger system, with surprising dynamics once they suddenly appear in the music.

7-Do we have to spend a lot on capacitors and coils in the crossover to get good sound?
Not at all, the crossover topology and using the proper component values are the key to get good sound. This can only be achieved by carefully tuning after a lot of listening related to good measurements. Only then you know what you are doing when designing and making changes to the crossover.

8-About loudspeaker cabinets. Any thought on the use of exotic materials other than mdf?
Not really. You can use very stiff exotic materials for example, but what you may not overlook is the backwave that is re-radiated through the loudspeaker cone. The loudspeaker cone is very transparent when compared to the cabinet walls. This does not mean that you will have to minimize cabinet panel resonances, but braced and damped MDF is still adequate in my opinion.

9-What are the top three design parameters you use? (or the top three things you worry about most)
- smooth response of the drivers within the frequency band I will use them.
- negligible resonances in the panels of the baffle or the enclosure.
- dispersion of the system as a whole and tuning the crossover for deviations from the ideal (i.e. uniform and slightly decreasing power response).

10-Do you design on measurement or sound?
I design by carefully considering all system aspects, given the type of system and drivers chosen. The crossover is designed after measement. The sound is optimized by listening. By measurement of the disperion of the speaker I try to find spots were I should put more or less energy in some part of the frequency band. How much, is decided only after carefully listening to almost all of my music tracks.

11-What do you think about dynamics? Must a speaker really be able to do 115 dB to be any good. Or is this overrated?
Under normal circumstances, a nominal sound pressure of 85dB average and 105 dB peak is sufficient. If you want earthquaking home theatre sound, things will be different, then 115 dB peak pressure could be necessary.

12-What do you think is that "special something" is that makes some speakers sound so good?
The designer found the right balance between dispersion and on-axis response. Sometimes you are lucky and drivers appear to have a very good balance between a nice linear response and dispersion. I found this e.g. to
be the case with the Peerless HDS134 midwoofer together with the SEAS millennium tweeter. A very nice combination and not very sensitive to crossover faults. Another very nice combination appeared to be the Visaton
AL130 midwoofer together with the B&G NEO3PDR tweeter. I've worked with a lot of driver combinations, but these two I liked a lot.

13-How many octaves does a speaker really need to sound right? Is the bottom octave required? What about above 20K?
As long as anything above 40Hz is reproduced well, a speaker can sound already very very good. What about above 20kHz? I feel that 15kHz is already enough for very good sound, although I am still able to hear sounds up to and including 20kHz.

14-You have to choose: minimalist twoway monitor or a 4 way active loudspeaker. Which do you bring to the deserted Island?
If every thing else stays the same, I would choose the 4 way active. Ever heard a minimalist twoway monitor outside? The sound is very thin and weak.

15-What one piece of advice you would like to give to every new speaker builder?
Buy a good 5" midwoofer and 1" dome tweeter in the range of 40-60 euros each. Build a closed box monitor system and get acquainted with acoustic measurements. Combine the monitors with two compact active subwoofers (left
and right) that you buy at a DIY-shop. This way you can already achieve very good sound. The costs are low, the crossover is not too complicated and you can experiment easily with different crossover combinations. You can also
try different enclosures, different shapes and thickness of materials and methods of damping.

16-Will we ever find the Holy Grail in sound reproduction? And what keeps us away from reaching this goal?
We will never find the Holy Grail in sound reproduction, because listening in a different environment than that where the recording was made is fundamentally flawed.

17-So which is it for you, tubes or Solid State?
At the moment, UcD solid state, class A or SET are only better in theory. The latter two are expensive to buy or build, large and consume a lot of energy.

18-Any thoughts on the audio industry's movement to the far east?
It is a pity, the drivers are not made with the love and care they used to be.

19-What does the future hold for speaker design?
Implants in your head so you don't need speakers anymore.

20-Will high end stereo be alive in twenty years?
Yes, together with high end multichannel, just like vinyl is still very alive.

21-Can you name some loudspeaker designs you like? Commercial or DIY.
ESL (Quad), Orion (Linkwitz), Milestones (Marc Heijligers)

22-And the final question, can you tell me we are you are working on at the moment?
I have just finished MOB3W, which you can find on my homepage. In the meantime, I am busy helping friends which are developing there own open baffle systems. Also, in the near future I will design crossovers for some high end traditional 2,5 and 3-way SEAS excel and nextel based systems.

Bio: Marc Heijligers
I've devoted 40 years of my life to education and research (Master and  Ph.D. in Electronic Engineering, research scientist at Philips Research). I'm working in the area of IC-design, ranging from the design of digital hardware to of embedded software and CAD tools.

In my free time I'm designing audio equipment, although I spend most of my free time towards exploring music, and a little bit of my time generating noise out of a guitar. I've always been intrigued by the 
reproduction of music using audio equipment. The lively energy that is missing during the playback of records, but obviously present at live concerts, has initiated my curiosity to investigate and develop audio equipment by myself. (Click here to visit Marc's site)

1-What was the first speaker you build? And how did you get involved in speakerdesign or the audiofield?
The first speaker I've built in 1996 is the Maxim from Klang & Ton  2/94. It consists of a Podzus Gorlich 175/25VK woofer/midrange unit,  and a modified Scan Speak D2010 tweeter with no ferro fluid. The reason I started building this speaker was because I was impressed by the Ensemble PA-1, but this speaker was outside my budget as a student at that time (€3000), so I decided to build something myself.

2-Can you tell us some more about your favorite music? Do you have special pieces of music you use to review loudspeakers?
For reviewing speaker I use a wide range of music. From my own CDs I  create my own sampler CDs, containing pop, jazz and classical music. For me a loudspeaker has to be an all-arounder, being able to reproduce the delicacy of a tiny lute recorded in a big church, but  also to break down your house with rock music of for instance Rage Against the Machine.

3-Without giving the standard "weakest link" answer, how important would you rate speakers as component?
Together with the room acoustics, speakers are the most important component. A particular loudspeaker in a room defines a very specific signature to your audio chain and the reproduced music.

4-How have speakers changed in the past ten years?
Besides new materials, applied in magnets or cone materials, not so  much has changed in technological sense. Most theory is available and  well understood.

In the field of headphones, these technological advantages did contribute significantly to the improvement of their sound quality, at more affordable prices. In the field of speakers. we still find equally good examples of speakers over a wide range of decades. This  is because despite the technological advantages, a speaker remains a  trade-off between many of its intrinsic properties (flat on-axis response versus flat power response versus phase alignment versus flat electrical impedance versus ideal impulse response versus unit operational range versus polar radiation, versus interaction with room acoustics). In many cases design choices are based on personal  taste or specific environmental constraints. Although perfectly valid, this explains why we haven't converged to some sort of "ideal speaker".

What we do see however is that CAD tools provide designers with the  capability to create more predictable results, and hence we see more consistent results appearing on the market. There is a similarity to the car industry, where wind tunnels and simulation models make cars look more alike than 25 years ago.

5-How about mechanical resistance in loudspeaker drivers. QMS and Rms. Important or overrated?
The Qms characterizes just a small part of the whole speaker. One should look at the total characterization of a loudspeaker driver, and determine how one can design with that. In the future I expect a shift towards active control-loop-like filtering techniques (MFB, does history repeat itself?), where the exact driver properties will become less important. In that case, a loudspeaker driver and its enclosure can be optimized towards its radiation pattern.

6-Do we have to spend a lot on woofers and tweeters to get good sound?
No. I've seen speakers that sound lively and transparent, using relatively cheap units (25 euro). Just like with food and ingredients, it is the challenge of the designer to cook something nice. The other way around, expensive units are no guarantee for good sound (JK Acoustics Ultimate). Flawed units exist in all price ranges.

7-Do we have to spend a lot on capacitors and coils in the crossover  to get good sound?
No. Components are the icing on the top, and deliver you those "last 10%". If a speaker doesn't sound proper with bipolar elcos and chokes with cores, something is wrong with the crossover topology.

8-About loudspeaker cabinets. Any thought on the use of exotic materials other than mdf?
MDF is used because it can be easily handled. A good speaker consists  of a mix a materials and bracings, to spread resonances over a wider frequency range, preferably underneath an audible threshold.

9-What are the top three design parameters you use? (or the top three things you worry about most)
I take care that I don't create too large deviations in the frequency  response (on-axis as well as power response), align the group delays of the units, minimize stored energy (acoustic as well as electric).

10-Do you design on measurement or sound?
You can't design a proper speaker if you don't use both methods. You  first start with a rough design based on measurements and simulations,  then you listen, then you use your observations and measurements to create a next step in your design, and repeat that procedure until you are satisfied. Designing audio equipment is a challenging activity, as it bridges  human perception, art and science, where there is the danger to get trapped in personal preferences or beliefs.

11-What do you think about dynamics? Must a speaker really be able to  do 115dB to be any good. Or is this overrated?
There is a big difference between dynamic range and dynamic sound that  is full of energy. 115dB in a typical Dutch living room will blow your  ears. I think it is much more important to combine transparency with  energetic behaviour. This requires a system that is free of  resonances. When evaluating audio equipment, I very often listen to  the "silence between the notes". If it is not there, and there is  "constant sound" or "stress", you know that something is wrong.

12-What do you think is that "special something" is that makes some speakers sound so good?
A good designer, or somebody that has had a great amount of luck.  There are a wide range of good loudspeakers based on different technologies in the widest sense (paper or magnesium, monopole or  dipole, 1st ordered filtered or 4th order, etc. etc.). It's a matter of combining the right ingredients, but that requires decent 
craftsmanship.

13-How many octaves does a speaker really need to sound right? Is the bottom octave required? What about above 20K?
The necessity of the bottom octave very much depends on the music.  With blunt pop records, a full-scale bottom octave in an average  living room does imply fluffy or boomy bass. With classical orchestral music, it creates the sense of "being in the concert hall".

I think there is enough work to do to get the range up to 20kHz  correct, before worrying about anything above 20kHz. Especially with  tweeters, there is an immense difference in timbre from different cone  materials like soft domes, metal domes, ceramic, magnesium, beryllium, band tweeters, and Heil Air Transfomers to name a few.

14-You have to choose: minimalist twoway monitor or a 4 way active loudspeaker. Which do you bring to the deserted Island?
I would bring both. I will re-use the wooden cabinet of the 4-way  active loudspeaker to create a listening room, and the monitor speaker to enjoy its delicacy.

15-What one piece of advice you would like to give to every new speakerbuilder?
Be sure you have a good reference. This refers to live instruments as  well a good pair of headphones and a lot of different type of  (acoustic) music. Reading a good cooking book and only knowing how a domino pizza tastes like is not the right fundamental to become a top- star cook. If you want to become a top cook, you have to develop a  good sense for the basic ingredients first. Hence, you should take a step to go beyond the Pink Floyd and Norah Jones CDs in your collection, and train your ears everywhere.

You will realize that a cello has many different timbres. Listen at  the enclosed sample, with 5 musicians playing different cellos and the same piece (Bach Cello Suite No. 1, Courante), and see the corresponding differences in the spectrum (total scale is 80dB!).

Download Cello - Courante

1. The first cello sounds warm with a lot of body (growling), and a rich overtone

2. The second cello sounds thin in the low range, and resonant

3. The third cello sounds sounds nasal

4. The fourth cello sounds even more nasal

5. Sounds more homogeneous and harmonic rich

6. Sounds darker

What would that mean for your frequency response if you tune your  speaker? In hifi shows I see people entering a room where an instrument is reproduced, saying "this is not a cello/violin/guitar". How can they be so sure?

Training yourself, and auditioning your records on a rather neutral  headphone will prevent many CDs to be blamed for "recorded badly", and  will challenge the designer not to make all records sound "open and  brilliant", but more realistic and acceptable.

16-Will we ever find the Holy Grail in sound reproduction? And what keeps us away from reaching this goal?
Audio is a projection of reality. Practical limits keep us from  getting "the real thing" in the living room. Hence, we have to make  trade-offs in the design, and therefore the partial "Holy Grail" chosen will depend on people's taste.

17-So which is it for you, tubes or Solid State?
A properly designed amplifier in any of those technologies is fine. If  it requires a steam machine operated by dwarfs, that's fine as well. :-)

18-Any thoughts on the audio industry's movement to the far east?
Inevitable. Asians have proven themselves many times to be very good fabricators. I expect their innovative role to increase over time, and audio to become a more world-wide competence.

19-What does the future hold for speaker design?
I would expect more active filtering, on-the-spot measurement and 
adjustment capabilities, and more "big sound from small boxes".

20-Will high end stereo be alive in twenty years?
As long as there will be music lovers, there will be high-end stereo.

21-Can you name some loudspeaker designs you like? Commercial or DIY.
I like certain speaker designs because of particular properties. There is not a single speaker that would meet all criteria:

- Ensemble PA-1: smooth timbre from a small box.
- Totem Arro: transparency.
- Audio Note J or E: timbre of voices.
- Apogee Scintilla: homogeneous timbre.
- Sonore: correct projection of size of instruments.
- DIY of Herbert Rutgers: superb 3D imaging
- DIY of Nico v.d. Sande: very energetic speaker and delicate mid-treble

But this list is far from complete as I "need" to listen to many other  designs as well (e.g. Jeroen D's dipoles, Magico Mini, Quad ESL 2905,  Linkwitz Orion, Avalon Isis and Indra, Lumen White).

22-And the final question, can you tell me we are you are working on  at the moment?
Still tweaking the Milestones, developing two monitor speaker designs, 
and so now and then helping other designers.

Bio: Allan Isaksen started his career at Vifa A/S, Denmark in early 1983 as a newly graduated acoustics engineer. After having designed numerous famed Vifa drivers he was appointed as Engineering Manager at Vifa in 1987. In 1990 Vifa appointed Allan Isaksen as their Director of Sales and Engineering with responsibility for all Marketing, Sales and Engineering activities. In 1999 Allan Isaksen relocated from Denmark to the GuangDong Province of China, where he established the Chinese production base for Vifa/Scan-Speak, Vifa Loudspeakers (PanYu) Ltd. After Vifa and Peerless merged into dst (danish sound technology), the China production company was renamed DST Loudspeakers (PanYu) Ltd., which Allan Isaksen lead as General Manager until he in 2005 founded Wavecor Ltd.

1. Do we know any of your driver work?
Most likely. I still assist designing drivers at Wavecor but I was behind many of the classic designs for Vifa back in the 80’s and earlier 90’s.

2. Do we have to spend a lot on woofers and tweeters to get good sound?
Not necessarily. At Wavecor we design really good sounding drivers while still keeping prices reasonable. The sound of a driver mainly depends on the guy who engineered it – his knowledge and experience and how high he prioritizes the sound. In principle a good sounding driver does not have to be more expensive than a bad sounding driver. With the right knowledge and intentions you might as well design a good sounding driver for the same money.

3. I mean really, there are like, ten parts in a woofer. How hard can this be?
It seems simple and it is relatively simple if you know how to do. Having said that it does require a rather broad set of skills to really understand and design good drivers. You have to know about acoustics, mechanics, electronics, and materials. It’s very easy to design and build a driver that makes sound. Anybody can do that. This is proven by the vast number of driver manufacturers you will find, especially in China. But only a good handful of manufacturers make good sounding drivers so it might be that not too many can do a good job – or maybe they just have no motivation to do so.
 
4. What are the three main differences between a $5.00 and a $100 woofer?
Well, honestly, the main reason for the difference might be profits. Not only the manufacturer’s profit but profits through the entire distribution chain. If you talk about manufacturing cost a significant difference could relate to where the driver is made. Obviously it adds to manufacture in a high cost country. Building small lots usually make things more expensive as well. If you buy a $100 woofer you usually get a die cast frame and probably a larger voice coil and larger magnet. On the $100 woofer the manufacturer has to spend money on looks, so it looks like a $100 woofer. On a $5 woofer you probably cannot afford anything but the basics. However, I have seen examples where I would say that the $5 woofer sounded better that the $100 ditto.

5. Are parts mass-produced and you pick them from a secret catalog?
Especially in China there are a vast number of parts suppliers that all have their “standard” parts to offer. They might even have a catalogue (but not a secret catalogue).At Wavecor we use these “standard” parts from time to time if we find any that meets our requirements and matches our design philosophy. However, more than 95% of our parts are designed by ourselves and made by tooling owned and paid for by us.

6. Are all good drivers made in Scandinavia?
Having set up Wavecor in China you might guess what my answer is? Obviously it is not important where a product is made. What is important is who is making it and how, and maybe even why.

7. A lot of speaker manufacturers say they use custom designs from Vifa or Seas. Are they really custom or just small changes made to stock drivers?
You should probably ask Tymphany and Seas that question. At Wavecor we do make custom designs as well and span the entire range from making completely new designs to just changing the colour of the dust cap.

8. Besides stiffness, what do you have to say about cone material?
The cone material is important. Besides stiffness it’s also about internal damping and the speed by which the sound travels through the material. However, the shape of the cone is at least as important as the material itself.

9. Tweeters: metal, fabric, ribbon, amt?
I have never really worked with other tweeter types than domes. I prefer the sound of a good soft dome tweeter. However, hard-dome tweeters do have advantages in the lower frequency region, say below 5 or 10kHz.

10. What to think of Qms and Rms. Mechanical resistance, overrated?
Yes and no. I don’t think the mechanical resistance in itself is very important. The importance lies in other phenomenons that are mainly related to the suspensions and the mechanical losses. This is something that, to my knowledge, nobody yet has taken into account when developing the various equivalent circuits of a driver. And yet very important for the sound. It’s non-linear phenomenons that seem always to go hand-in-hand with the mechanical resistance. So far I have not come across one driver with high mechanical losses that did not suffer from reduced dynamics and details and less natural sound.

At Wavecor we strongly believe this is the right direction and you will usually see that Wavecor drivers have higher Qm than most. We can easily hear the difference but it’s a little frustrating that we can’t easily prove our point in terms of measurements – at the same time as most reviewers and “experts” mainly rely on measurements like the conventional frequency response curve.

11. Why do expensive woofers seem harder to tame in the XO?
I don’t think this is always the case. You can say that in most cases good sounding woofers are harder to tame. This relates to what we just discussed before about mechanical losses. Once you remove most of the mechanical damping in the suspensions and maybe the cone, you are left with the “naked truth”. This means that you are left without mechanical damping to reduce and hide the various resonance phenomenons. So you are likely to have for instance a more uneven frequency response that you would have if you had a lot of mechanical loss.

12. Any tips to know if a driver is good or bad on paper?
For a tweeter you do have to look at the frequency response curve. Here the mechanical losses are less variable than on cone drivers. Try to avoid tweeters where the resonance frequency is close to the frequency range, where you want to use it. For a woofer I would look for the T/S parameters to make sure it fits my application in terms of cabinet volume and –principle. Check the frequency response as well to make sure it’s not impossible to work with. Other than that, of course, look for woofers with low mechanical loss.  At the end of the day, as we try to promote at Wavecor: The sound, judged by your own ear, is really what should make the final decision.

13. So which is it, tubes or Solid State?
Depends on the purpose and on the speakers. I listen to both and enjoy both. For relaxing listening I prefer my Zanden tube amp but for critical listening, especially if the speakers are not very efficient, a solid state amp works better for me.

14. What does the future hold for driver design?
The future will probably hold the same kind of gradual evolution we have seen so far, for almost a century. As new materials become available and as new manufacturing processes become common, drivers will likely benefit by improvements in small steps. The increased availability of simulation software will continue to make further optimizations possible. When there will be a big major breakthrough? Couldn’t tell. We haven’t seen anything like that yet but I most certainly hope that you will see it coming from Wavecor.