A technical discussion of the Borresen ironless woofer.

[smowry]

That image just has different colours for the different material regions. The contour plot looks like this:
View attachment 442965

That's nonlinear analysis. Why are you not labeling your contour plots? Why are there no units?

Then this must be a contour plot of the DC permeability. If not what is the plot?

 

[Heinrich]

Hi Mark,

Really glad you stopped by. Please create a FEMM model if you could be so kind.

First I reiterate my question: what are you trying to gain with the invention? The iron in the motor is a widely solved problem. Please solve Doppler!

And I saw this (https://pt.audio/2023/06/29/borresen-m6-loudspeakers-paf-2023/):

Before I talk about the Børresen M6 loudspeakers and how they sounded, I wanted give a quick rundown of the system:

1 Børresen M6 Loudspeakers, Pair $ 550,000.00
1 Aavik C-880 $ 70,000.00
1 Aavik P-880 $ 70,000.00
1 Aavik D-580 $ 25,200.00
1 Aavik S-580 $ 25,200.00
1 Ansuz Gold SignatureMainz8 Power Distributor $ 64,000.00

Do you really compete with such people?

 

[Snickers-is]

Can you give me a hint? I reviewed you posts again and searched (ctrl +f) BH and resistance and I still cannot find the answers to either question.

Can I ask you to post the magnet BH curve? I used to export FEM magnet BH curve (text) files into VF OPERA. Is your FEM model at room temperature, typically 25C?

I did write that I did not know the type of magnet and the wire and number of windings used, so I had to guess, but it does not affect the simulation other than offseting the Bl value.

I believe I used an N42 or something. Nothing fancy. Magnets configured this way are really stable so you will not really challenge them. The BH curve for neo magnets are not that different, and changing the temperature does not change much either. In a driver like this you will never run into any significant heat. I have tested heat emission from motors on several occations. One was a tiny subwoofer for a BT speaker that I developed years ago. It needed cooling to survive. I also tested the 21IPAL from B&C. I did run it as hard as I could for a while. I was able to make the magnet system temperature to increase by 2-3 degrees, while I measured in excess of 350 degrees C on the coil. I am pretty sure this driver will fall something in between, it can not take that much power, but it has an 1,5 inch coil or something, so it should not do anything besides maybe lowering the Bl temporarily.

 

[Snickers-is]

Now I have become confused. Your model geometry does not seem to match picture from the Borresen website nor the patent images.

View attachment 442926

View attachment 442933
Note that the picture seems to match the patent immage which was created from a 2D mechanical drawing. Your model shows what appear to be much taller magnets, which I would have expected but did not see before. So could you please confirm if your model is different from the picture from the Borresen website shown above. Otherwise the model look great, just different from the picture.

View attachment 442927

This looks very much like radial magnets, but I am pretty sure Børresen only uses axial magnets. You know, they've got to save money somewhere...

 

[smowry]

6X 4.5inch ironless drivers + a tweeter
View attachment 442989

Mark,

What is your cost estimated to manufacture those 4.5 in woofers in China? My guess is about $100. Borresen is also a price gouger.

 

[NTK]

Do you really compete with such people?

No. That's not the issue. The issue is that, assuming the current narrative is true, an original idea was published in a magazine article, and someone stole it and applied a patent for it. This can mean if the original inventor implements his/her idea, he/she can be sued for patent infringement. The original (real) inventor has every right to get really, really pissed.

 

[howard416]

Why not put the magnets on the moving assembly and put the voice coil in the static portion of the motor?

Not going to happen with a tweeter, obviously, but...

EDIT: Oops, forgot this was already done: https://www.powersoft.com/wp-content/uploads/datasheet/PS_MFORCE301P02_DS.pdf

 

[Snickers-is]

Mark,

What is your cost estimated to manufacture those 4.5 in woofers in China? My guess is about $100. Borresen is also a price gouger.

I believe the 4,5 inch does not have a core. I calculated that driver as a 6,5 inch with 140sqcm Sd, and I got almost 950g of neodymium. That would probably bring it a little bit past 100USD. If it is a 4,5 inch, the magnet mass would be about 1/3 of that, so it should be easy to get them well under 100 USD.

 

[Snickers-is]

Why not put the magnets on the moving assembly and put the voice coil in the static portion of the motor?

Not going to happen with a tweeter, obviously, but...

EDIT: Oops, forgot this was already done: https://www.powersoft.com/wp-content/uploads/datasheet/PS_MFORCE301P02_DS.pdf

To get sufficient force factor you would need a bit of magnet mass, meaning you place quite a high percentage of the moving mass in the motor. This is not good for anything besides very low frequencies. You will also get very high inductance, meaning it is hard to push higher frequencies.

 

[Snickers-is]

The iron in the motor is a widely solved problem.

Please solve Doppler!

Iron in the motor is not a widely solved problem. There are simplified views that might suggest so, but it is not actually true.

Why do you worry about Doppler? If you stay below 1m/s it is really below the pitch treshold of human hearing.

 

[Heinrich]

... someone stole it and applied a patent for it.

A patent can be scrutinized.

Iron in the motor is not a widely solved problem. There are simplified views ..
Why do you worry about Doppler? ...

It may not be solved in principle, but practically. We are talking about amplitude intermodulation distortion. Doppler generates the same spectrum, but with different phase relations. Still it is IM, basically.

I question the vast amount of material used with "ironless". It reminds me of AMT and other wasteful misuse of resources for no good.

A part in every patent application is the section on benefits. You may want to explicate on this - in numbers?

ps on "pissed": I understand this perfectly, as Borreson's speaker are, according to Erin, just a waste of time, and that's nothing an inventor wants to see done to his baby

 

[smowry]

No. That's not the issue. The issue is that, assuming the current narrative is true, an original idea was published in a magazine article, and someone stole it and applied a patent for it. This can mean if the original inventor implements his/her idea, he/she can be sued for patent infringement. The original (real) inventor has every right to get really, really pissed.

Thanks NTK. This patent thing is mostly an insult and a sign of disrespect to me but more importantly this guy is an embarrassment to the loudspeaker industry. I view Borresen as a "Low Life" disguised as a technical entrepreneur. I referred to him as a POS in a conversation with Amir (another giant).

There have been and there still are great people within the industry that have earned respect. For example, I have interviewed and thus associated with the following giants.

1. Neville Thiele in Malaysia. Neville Thiele and Kees Immink bought me diner one exciting evening in KL Malaysia at our hotel when I joined them to present at an AES mini-convention. FYI: Kees invented the CD while he was at Philips.

2. Dick Small (no pun intended) One of the nicest and kindest man I have ever met.

3. Roy Allison A real down to earth guy that was a pioneer in the loudspeaker industry and he had a passion for loudspeakers.

4. Wolfgang Klippel We all know Dr. Klippel. The guy is a genius but a bit too serious at times.

I have worked closely with and on a one to one basis with Ilpo Martikainen, the founder of GENELEC. He came to my home in Phuket and my wife cooked baked stuffed shrimp (called tiger prawn in Thailand). I can still remember the joy on his face when he told me about his grandson riding on Ilpo's tractor on his farm in Finland. I worked closely and one on one with Charlie Hansen, the founder of Ayre Acoustics. Charlie was a great guy that funded some of my ironless motor R&D.

The men listed above are all giants, while some are legends, whereas Elizabeth Michael Borresen is a POS! He is a disgrace to the industry and a small man in my eyes. He has earned my disrespect.

 

[Snickers-is]

Use of steel in motors require some really serious efforts into design work. We normally do not test the effect of excursion and current simultaneously, and we rarely add polarity to this equation meaning we hide DC factors occuring in certain situation.

Here is an example, using a so called Lambda motor (an old design that by some is regarded as very high quality).

We can clearly see that at high peak currents, things get really rough in one direction of current, while in the other direction, things are more stable. We often see this combined with asymmetry that increases significantly as current increases.

If we look at the conversion between voltage and force, we include inductance in the equation. Sorry for the missing frequency axis values. I believe this was run from 10 to 1000Hz.

We can look at the coupling inductance as well. This is the magnetic coupling between the coil and the surrounding metals at DC. While inductance is normally only measured at high frequencies (1 or 10k) we do not see what this looks like when we get to low frequencies and any shorting ring effect stops doing anything meaningful:

These things become quite easy with no steel in the motor. But one can also get really great results with a super well designed motor. The problem is that they almost does not exist in the market.

If we compare the IMD induced by the motor and the IMD induced by doppler, it is quite easy to see that in a typical high quality loudspeaker the motor induced IMD is 10 to the power of something higher than doppler. If we introduce a doppler hearing treshold to the treshold of hearing differences in pitch, normally around 100 points per octave, we can just simply keep excursion as a function of frequency below a given level and never have to worry about it. We can not do the same with AM IMD as it is so much higher to begin with.

 

[Heinrich]

If we compare the IMD induced by the motor and the IMD induced by doppler, it is quite easy to see that ...

Who am I to dismiss your explications? My point is, that subjectively the AIC motor of 18sound sounded pretty good. No issues other that the useful excursion was limited to below 1mm, despite the spec sheet saying it was 5mm or so 8-( Within its limits, though, it was a perfectly transparent delight. Same with the way older JBL 2020. I score at -56dB with the Klippel self-test, sigh. Seems I hate speakers.

The Doppler induced distortion does not correlate to pitch. It is IM. Whatever, it is avoided by (a) huge cone areas, or (b) multiple drivers used in different frequency bands. Both attempts are getting quite cumbersome with an ironless design, as far as I understand it, due to high losses in the magnetic circuit. To replace amplitude modulation with Doppler doesn't appear to me as a good deal.

That's why I asked for numbers on outcome regarding the benefit.

 

[smowry]

I believe the 4,5 inch does not have a core. I calculated that driver as a 6,5 inch with 140sqcm Sd, and I got almost 950g of neodymium. That would probably bring it a little bit past 100USD. If it is a 4,5 inch, the magnet mass would be about 1/3 of that, so it should be easy to get them well under 100 USD.

In my experience even companies like Ayre Acoustics are selling their product at about 10x cost. At 500,000 Euro Borresen is at least an order of magnitude above 10x. That's price gouging. His transducer R&D includes copying concepts out of an industry periodical. Why? Is it related to ignorance or is it extreme cost cutting or is it both?

 

[smowry]

What about using a transducer array to reduce Doppler? What I call the Flower Array.

 

[racingpht]

Could the "iron-less woofer" result in this sort of FR performance?

.

No, they are NOT ironless.

X series magnet system – Bass/midrange​

Børresen DCC5 driver

In the X-series magnet motor system, we use double copper caps on the pole rings to achieve high flux and low inductance. The use of copper caps has been adopted from the Børresen Z-series. Copper produces a response to flux changes – the better the counter-effect of these copper rings, the flatter the inductance curve, and the lower the electro-magnetic resonance. In addition, lower inductance also means fewer spikes in the impedance curve. Both result in a lower load on the amplifier. To ensure high efficiency, the X-series has two pole rings. This causes the loss of some flux, which reduces efficiency, but this is compensated for by a larger magnet.

 

[racingpht]

Ironless measurements. Not sure if they has been posted before.

What look like to me is weak BL compare to traditional iron motors. Peak impedance does not exceed 20ohm for a ~6ohm DCR woofer is low, resulting underdamped bass above tuning point(maybe on purpose for the designer). Assuming the designer uses low loss voice coil formers(probably titanium), the impedance peak will be even lower if the voice coil former is more conductive like aluminum.

Other than that, I would love to hear the speaker myself.

BØRRESEN M1

Børresen to duńska marka należąca do Audio Group Denmark, firmy skupiającej kilka brandów wyspecjalizowanych w różnych dziedzinach audio. ...

audio.com.pl

 

[Snickers-is]

The Doppler induced distortion does not correlate to pitch. It is IM. Whatever, it is avoided by (a) huge cone areas, or (b) multiple drivers used in different frequency bands. Both attempts are getting quite cumbersome with an ironless design, as far as I understand it, due to high losses in the magnetic circuit. To replace amplitude modulation with Doppler doesn't appear to me as a good deal.

That's why I asked for numbers on outcome regarding the benefit.

The Doppler effect is changing pitch. It is like when a car passes you and it sounds like the revs go down. It is what we normally refer to as FM IMD. Purifi has written a bit about this in their own blog on their website:

Doppler distortion vs IMD?

purifi-audio.com

So, as you can hear, it is quite audible at 43Hz/12,5mm. That corresponds to about 3m/s if I am not completely messing things up here... But a 12,5mm x-max driver would typically have low distortion to some 6-8mm maybe, and if you keep this peak excursion point at a lower frequency, you suddenly stay below 1m/s, and it becomes really hard to hear FM IMD. This can simply be viewed as a fraction of the speed of sound. 3,4m/s is 1/100 of the speed of sound. This means we will have a 1% change in pitch for the secondary tone. The treshold goes just below 1/3 of this. You can test yourself, just fire up a tone generator, start a tone and change it by 0,3%. You may hear a very small change, but if you change it by 1% it is very easy to hear.

 

[smowry]

I have asked Lars Risbo from Purifi to join us. Lars is in Denmark too but he's on a different level than Borresen.

To bash or not to bash, that is the question.