To Sub Or Not To Sub, That Is The Question

[Musical Bass]

Let me put it this way, I find your claims very hard to believe.

That’s good otherwise it would just be more discussion! Turbulence is a term rarely referenced in loudspeaker design. Discovering the physics relating to 2 dimensional turbulence and its potential role in managing the enclosure pressure is a good thing.

 

[Musical Bass]

On the bright side, if your claim is indeed truthful, it is very easy to prove, unlike those who claim night and day differences in cables, internet routers etc.

The only way to evaluate is to listen to a system with the subwoofer properly integrated. This is easily done by ear in this case.

 

[DonH50]

That’s good otherwise it would just be more discussion! Turbulence is a term rarely referenced in loudspeaker design. Discovering the physics relating to 2 dimensional turbulence and its potential role in managing the enclosure pressure is a good thing.

When I went to school turbulence for acoustic waves was an x,y,z,t thing, not two-dimensional. Turbulence within the enclosure is one of many parameters used as part of any modern speaker (or subwoofer) design.

The only way to evaluate is to listen to a system with the subwoofer properly integrated. This is easily done by ear in this case.

Measuring the response is another way, and less subject to both listener bias and the limitations (lack of sensitivity) of our hearing at subwoofer frequencies. The question is not really of integration, which is usually determined around the crossover frequency, but the ability to cancel reflections (modes) all around the room over a broad band.

You are asking us to believe your claims without proof, buy your subwoofer, then see if we can hear the difference. Great marketing, especially when perceptual bias is considered, but I was hoping for actual proof of your technical claims. That is also easily done. This is not something for which you need a $30,000+ analyzer system; a $100 microphone and free software (REW) can be used to measure the in-room response. You mentioned previously that you could show graphs at several points in the room; a set of unsmoothed graphs taken at several places in the room, along with the locations and room dimensions defined, and the test system used, would be helpful.

Innovation is great but extraordinary claims should be rigorously proven.

 

[Musical Bass]

When I went to school turbulence for acoustic waves was an x,y,z,t thing, not two-dimensional. Turbulence within the enclosure is one of many parameters used as part of any modern speaker (or subwoofer) design.


Measuring the response is another way, and less subject to both listener bias and the limitations (lack of sensitivity) of our hearing at subwoofer frequencies. The question is not really of integration, which is usually determined around the crossover frequency, but the ability to cancel reflections (modes) all around the room over a broad band.

You are asking us to believe your claims without proof, buy your subwoofer, then see if we can hear the difference. Great marketing, especially when perceptual bias is considered, but I was hoping for actual proof of your technical claims. That is also easily done. This is not something for which you need a $30,000+ analyzer system; a $100 microphone and free software (REW) can be used to measure the in-room response. You mentioned previously that you could show graphs at several points in the room; a set of unsmoothed graphs taken at several places in the room, along with the locations and room dimensions defined, and the test system used, would be helpful.

Innovation is great but extraordinary claims should be rigorously proven.

Turbulence can be 3 dimensional as in x,y,z and that is the normal condition for most turbulence. Look up 2 dimensional turbulence for more information on this physics gem. It’s hard to explain really unless there is interest!

 

[Musical Bass]

Turbulence can be 3 dimensional as in x,y,z and that is the normal condition for most turbulence. Look up 2 dimensional turbulence for more information on this physics gem. It’s hard to explain really unless there is interest!

Extraordinary proof for loudspeaker evaluation is the percentage of customers that are satisfied. Not sure where you got your information for ear sensitivity but it bests the eye a million fold. I once read in a technical publication referencing the ear and eye sensitivities and it goes like this, if the eye could see with the same resolution that a healthy ear could hear it could detect the moon moving 1inch from the earth! Check it out as no listening machine is more sensitive. In that we all have independent environments and imperfect hearing conditions a proof of concept would require a consensus. My reason for posting here is because there is no consensus in the forum to use or not to use a subwoofer when all want to use one if improves the sound for them.

 

[DonH50]

Satisfied customers is sufficient for marketing and sales but do not represent technical proof.

I am not sure why you are introducing sight, and measuring instruments are far more accurate with much greater dynamic range than we can hear, particularly in a typical consumer environment, and in the bass region. Look up "equal loudness contours" (Fletcher-Munson, updated by Robinson and Dadson then ISO 226) to see how our hearing sensitivity falls off at low frequencies. Frequency resolution of our hearing can be expressed in relatively small fractions of an octave, thus the pushback on 1/3-octave smoothed charts which could easily mask details such as nulls due to reflections (modes) in the room.

But again the question is to prove the claim that room modes are eliminated, or at least greatly reduced, throughout the room using your subwoofer. That does not require a great deal of instrumentation with much in the way of precision or dynamic range; a $100 microphone and free software will suffice.

 

[Musical Bass]

Satisfied customers is sufficient for marketing and sales but do not represent technical proof.

I am not sure why you are introducing sight, and measuring instruments are far more accurate with much greater dynamic range than we can hear, particularly in a typical consumer environment, and in the bass region. Look up "equal loudness contours" (Fletcher-Munson, updated by Robinson and Dadson then ISO 226) to see how our hearing sensitivity falls off at low frequencies. Frequency resolution of our hearing can be expressed in relatively small fractions of an octave, thus the pushback on 1/3-octave smoothed charts which could easily mask details such as nulls due to reflections (modes) in the room.

But again the question is to prove the claim that room modes are eliminated, or at least greatly reduced, throughout the room using your subwoofer. That does not require a great deal of instrumentation with much in the way of precision or dynamic range; a $100 microphone and free software will suffice.

It’s not the route that we will pursue! You will be challenged on any measurement and levels really will vary slightly but no sharp nulls. You will eventually hear more as we get this on the market! I’m letting folks on this forum know why they are having subwoofer issues and that somebody is paying attention.

 

[DonH50]

It’s not the route that we will pursue! You will be challenged on any measurement and levels really will vary slightly but no sharp nulls. You will eventually hear more as we get this on the market! I’m letting folks on this forum know why they are having subwoofer issues and that somebody is paying attention.

So, no measurements, buyer beware... Verifying the elimination of, or at least great reduction in, the effect of room modes will not challenge anyone with basic measuring equipment. At this point I would not trust unsupported data, however, but would want documented third-party comparisons to ensure a proper test and not a one-shot result inapplicable to the general case (room).

People like Olive, Toole, and Welti have been paying attention and providing theory and test results for decades resulting in proven guidance for subwoofer integration.

 

[Holmz]

It’s not the route that we will pursue! You will be challenged on any measurement and levels really will vary slightly but no sharp nulls. You will eventually hear more as we get this on the market! I’m letting folks on this forum know why they are having subwoofer issues and that somebody is paying attention.

It would be easier to pay attention with some data and plots.

 

[Holmz]

The driver is critically broadband critically damped! I mentioned earlier that a loudspeaker diaphragm is also a microphone. The resonant state is high impedance therefore easy to modulate from external pressures like room modes. At higher frequencies it’s audible feedback. Subwoofers and turntables can have feedback occurring due to this sensitivity. Any questions on how this works after reading the patent? It’s how the driver is loaded so the compression is modulated by an attached 2-D turbulent volume that dissipates energy as heat due to viscous dissipation at its boundary layer. It’s akin to a virtual 3-D volume behind the driver that allows it to operate to lower frequencies avoiding resonance. The enclosure vibration is much less with this process. Free air for the driver is 40 Hz not the typical subwoofer Fa. It would be impossible to output 20 Hz without this modulation in a tiny enclosure! You wouldn’t use this 6.5” diameter in a large enclosure. It goes beyond just preventing feedback because this critical damping/loading affects the full range of the driver. Google the basic physics involved “Two Dimensional Turbulence” for a better understanding how it increases the entropy of a system. This action is that of keeping work done on a previous cycle from affecting a current work cycle. It is a universal concept!

^This^ sounds like it harkens back to Bob Carver designs, where the amplifier is getting some magic happening where the speaker is driving the amp.
The amp seems like it would need a low damping factor to achieve that?

 

[sigbergaudio]

Frontiers

Most of us are familiar with the Siegfried Linkwitz that developed the filters by the same name. The link above is to a page on his site titled issues with loudspeakers where he was (he passed) seeking a discovery for an acoustic termination for the inside of the enclosure. He hypothesized an internal acoustic resistor that would dissipate the excess energy without regard to level and frequency. It remains a challenge to do it is the culmination of the page! We are focusing on the difficult issues as you can see.

So are you saying you have created a cardioid sub? Perhaps our cardioid speakers are of interest to you: https://www.sigbergaudio.no/products/sigberg-audio-manta-1-active-speakers

A cardioid subwoofer can certainly improve the frequency response at the listening position, but it has little to do with the driver being affected by the room modes (my understanding of what you said), and will also not be as effective as you are claiming. Looking at your subwoofer I am also still ..doubtful. That you are claiming that people need to listen to understand and that you will not provide measurements proving the effect makes me even more doubtful.

 

[Musical Bass]

So, no measurements, buyer beware... Verifying the elimination of, or at least great reduction in, the effect of room modes will not challenge anyone with basic measuring equipment. At this point I would not trust unsupported data, however, but would want documented third-party comparisons to ensure a proper test and not a one-shot result inapplicable to the general case (room).

People like Olive, Toole, and Welti have been paying attention and providing theory and test results for decades resulting in proven guidance for subwoofer integration.

Decades of 1950’s tech! Loudspeaker subwoofer tech is based on resonance brought on by added moving mass! This resonance becomes a part of all of your music. If you are satisfied with this compromise then you do not need to concern yourself with what is being discussed.

 

[sigbergaudio]

Decades of 1950’s tech! Loudspeaker subwoofer tech is based on resonance brought on by added moving mass! This resonance becomes a part of all of your music. If you are satisfied with this compromise then you do not need to concern yourself with what is being discussed.

This is not true.

 

[Robh3606]

Decades of 1950’s tech! Loudspeaker subwoofer tech is based on resonance brought on by added moving mass! This resonance becomes a part of all of your music. If you are satisfied with this compromise then you do not need to concern yourself with what is being discussed.

I guess you just ignore the fact that any structure/object be it a hair pin to a room will have natural resonances mechanically or dimensionally. It's unavoidable. Your cabinet will have resonances as will your cone. You can't deny the undeniable.

Loudspeaker measurements are well understood why don't you post an impedance curve. As far as combating room resonance's passive loudspeakers excite them not damp them. Even the best DSP can't damp them they just adjust the speaker response to help minimize them by reducing output where they occur.

Low mass 6'5 drivers in a sub? Ignores Hoffmans Iron Law? Fixes room resonance's?

I don't think so?

Rob

 

[DonH50]

Decades of 1950’s tech!

You are ignoring a lot of advancement and innovations from that time, in electromechanical design and materials of the drivers, understanding of small-room acoustics and subwoofer integration, signal processing techniques, and so forth.

Loudspeaker subwoofer tech is based on resonance brought on by added moving mass! This resonance becomes a part of all of your music.

Your definition of resonance apparently differs from how the rest of us are using the term. A "resonance" creating sufficient distortion to corrupt all of our music should be very easily measured.

If you are satisfied with this compromise then you do not need to concern yourself with what is being discussed.

It is still unclear exactly what compromise you are describing since you go back and forth between subwoofer distortion and somehow improving in-room response. But attempt to tie it together by claiming "acoustically grounding" the subwoofer eliminates room resonances without providing any sort of measurements to back your claim.

My concern is for others who might not understand why marketing claims that seemingly defy physics should be questioned.

 

[Kal Rubinson]

I once read in a technical publication referencing the ear and eye sensitivities and it goes like this, if the eye could see with the same resolution that a healthy ear could hear it could detect the moon moving 1inch from the earth!

Do you have that reference? It is a topic of interest to me.

 

[Holmz]

Do you have that reference? It is a topic of interest to me.

The eyes run on amplitude, where as the ears also can process relative phase.

But there is no way to measure the moon’s movement with relative phase… it would need to be absolute phase, which the ears are NOT doing.

We can still howl at the moon though.

 

[Kal Rubinson]

The eyes run on amplitude, where as the ears also can process relative phase.

But there is no way to measure the moon’s movement with relative phase… it would need to be absolute phase, which the ears are NOT doing.

We can still howl at the moon though.

Thanks but I was asking for the reference as I find it hard to relate your description to what I know of sensory biology.

 

[Holmz]

Thanks but I was asking for the reference as I find it hard to relate your description to what I know of sensory biology.

I believe that we use LASERs (LASER ranging) for the moon.
The astronauts put a retroreflector there back in the day.
https://en.wikipedia.org/wiki/List_of_retroreflectors_on_the_Moon

Probably they use time domain, to measure distance.
However one could run the return signal back and beat it against the outgoing signal, to get an interference pattern and measure velocity.
This would be similar to how a ring laser gyro works.
https://en.wikipedia.org/wiki/Ring_laser_gyroscope

Both of ^these^ ttechy things are explainable, measurable and documented.
Which differs significantly rom the subwoofer that is described with hand waving ‘science’.

Thanks but I was asking for the reference as I find it hard to relate your description to what I know of sensory biology.

Correct, it has nothing to do with our current biology, and again nothing to do with the subwoofer.

It is fact that SONAR, and whales, dolphins, etc use signal… as well as bats.
And they arrays of receivers (or ears), and can use phase to show the direction of the enemy, fish or insect respectively.

 

[Kal Rubinson]

I believe that we use LASERs (LASER ranging) for the moon.
The astronauts put a retroreflector there back in the day.
https://en.wikipedia.org/wiki/List_of_retroreflectors_on_the_Moon

Probably they use time domain, to measure distance.
However one could run the return signal back and beat it against the outgoing signal, to get an interference pattern and measure velocity.
This would be similar to how a ring laser gyro works.
https://en.wikipedia.org/wiki/Ring_laser_gyroscope

Both of ^these^ ttechy things are explainable, measurable and documented.
Which differs significantly rom the subwoofer that is described with hand waving ‘science’.


Correct, it has nothing to do with our current biology, and again nothing to do with the subwoofer.

It is fact that SONAR, and whales, dolphins, etc use signal… as well as bats.
And they arrays of receivers (or ears), and can use phase to show the direction of the enemy, fish or insect respectively.

Thanks for the interesting diversion.