EnABL Processes

[planet10]

Does anyone have access to laser inferometry , or laser interferometry, equipment? This was suggested as a possible measurement technique when I first informed a speaker manufacturer of the EnABL process, who was previously unaware of it. I'm not even sure of what it is. Just 'putting it out there'.

One of the fellows i'll be doing up a comp set of drivers for is putting together just such a jig. He knows a huge amount about test/measurement and i've challenged him.

dave

 

[dlr]

One of the fellows i'll be doing up a comp set of drivers for is putting together just such a jig. He knows a huge amount about test/measurement and i've challenged him.

dave

This is the kind of testing that will show what is happening better than any other, I believe. I'd be extremely interested in seeing the results. It won't show the acoustic output, but it will show what effects there may be on any of the resonance modes in the driver.

Dave

 

[dlr]

dlr - you have the gear to perform test on treated speakers and seem to strive to do what we all are trying to do - make speakers perform better. I invite you to slap up a EnABL pattern and run some test. We would all be very grateful for your efforts, your listening impressions and your results.

Thanks, but I think that the best testing would be a set of distortion tests and I would recommend others over me for that. I have not (yet) moved into that area of testing, I rely on zaph and Mark K's experience. I say this because most decent drivers can be equalized in the crossover for the FR deviations and/or suppressed into the stop-band, but the contribution to distortion, especially motor non-linear distortion amplification, may be more responsible for perceived changes.

This doesn't address full-range drivers that usually aren't used with a crossover. I am not a full-range aficionado by any means. I can see how applying anything to a full-range would alter the sound and be a perceived improvement, especially since there won't be any re-working of a crossover.

Dave

 

[t-head]

dlr,

Please read some of the past posts on this thread. Bud has only recently dealt with 'full range drivers'. Before bravely posting on this forum, he dealt with his own multi-way system. The fact that SET and FR types were the first to respond is incidental. The cone distortions that the EnABL was conceived to address, is inherent to all cone drivers. Manufacturers of aforementioned drivers (transducers, for the scientificos among us) are well aware of the distortions inherent in their creations. Some have addressed the issue to varying degrees of success. Please stop whining for 'proof' and get to work...if anyone could have produced the desired 'proof', rest assured that it would have been posted long ago, if for no other reason than to get lazy naysayers off our backs...

Back OT - please do something constructive or go spread your unhelpful nonsense elsewhere. We all await your efforts with anticipation...Unfortunately, it seems you are as unsuited to the task as many here...if you cannot contribute, what do you hope to accomplish with your impotence? Please find a way to listen to EnABLed transducers and go from there, or lurk and desist from your negativity...it is not helpful or contributing to anything but you own egotistical self-promotion. Thank you.

t

 

[soongsc]

Here is some interesting reading for those that care to take the time and discover that Dave (dlr) is in fact an experimenter and quite fond of speaker cone "tweaks". In fact he has done work that in some ways resembles a crude form of EnABL with the treatment of a speaker surround - and he very much liked the results: "Was it worth the effort? Without doubt, this is one of the most successful and useful tweak results I've obtained. The benefit cannot be had any other way, short of digital equalization and has little in the way of negative consequences. The final results are shown below for the pair that I modified after I exhausted all experimentation on the guinea pig driver." http://www.speakerdesign.net/midrange_tweaks/insignia/insignia_woofer.html

dlr - you have the gear to perform test on treated speakers and seem to strive to do what we all are trying to do - make speakers perform better. I invite you to slap up a EnABL pattern and run some test. We would all be very grateful for your efforts, your listening impressions and your results.

This part of surround tweaking has been explored in many occasions. If you look at some of TB's speakers, they have similar tweaks that are in production. Technically speaking these are ways to more effectively transfer energy from the cone to the surround. The wider band you can do that with, the better. Altimately surrounds should be designed for specific drivers, which is not economical for mass production and parts control.

 

[soongsc]

Thanks, but I think that the best testing would be a set of distortion tests and I would recommend others over me for that. I have not (yet) moved into that area of testing, I rely on zaph and Mark K's experience. I say this because most decent drivers can be equalized in the crossover for the FR deviations and/or suppressed into the stop-band, but the contribution to distortion, especially motor non-linear distortion amplification, may be more responsible for perceived changes.

This doesn't address full-range drivers that usually aren't used with a crossover. I am not a full-range aficionado by any means. I can see how applying anything to a full-range would alter the sound and be a perceived improvement, especially since there won't be any re-working of a crossover.

Dave

My own experience is that the cone treatments are most effective in the range from 1KHz and above. This might vary with drivers of different sizes. But I don't think we are out here to convince anyone. The distortion tests that I have used only deal with sine waves. Much information is still hidden with this type of test. If there are any distortion tests that can use music signal as the source, I would like to know what tool can do that, and get my hands on it.

Surround tweaks, tend to be more in the frequency region below 1KHz unless it was originally specifically designed for a specific cone shape. To make things more complicated, spiders also contribute to some sonic signatures. The wider the bandwidth of the driver, the more complicated the issue.

When dealing with audio, I think it's best to look at data from various aspects rather than just let one type of test dominate. Of course for certain situations, certain types of tests will reveal differences more clearly than others.

 

[rjb]

Hi Soonqsc,
From memory I think you are the only one that has played with enabling aluminium cone drivers, and from memory I think you did not find it as effective as for paper cones. Am I right?
Has anybody else tried AL drivers?
Ross

 

[soongsc]

Hi Soonqsc,
From memory I think you are the only one that has played with enabling aluminium cone drivers, and from memory I think you did not find it as effective as for paper cones. Am I right?
Has anybody else tried AL drivers?
Ross

I have with the aluminum drivers because I don't have paper drivers, and that those were the only commercially available driver at hand. And I just wanted to see whether the pattern made a difference or not and show it.

I am working on something that seems to be more effect on metal drivers. It is more difficult because metal has less damping that paper, and that since the pattern needs to be stiffer than the cone material, as Bud mentioned the speed of sound in the pattern material should be higer than the cone material, it is further more hard to find material for pattern on metal cones. If you put pattern with some damping capability on metal cones, it will improve the performance somewhat as I have shown with the JX92S, but much more improvement should be possible if both right material pattern and some damping material is used.
Other aluminum cone drivers that use stiffer alluminum alloy will not benefit as much from soft patterns like I demonstrated with the JX92S.

 

[BudP]

dlr,

Welcome to the thread Dave.

You may find an interesting tweak here, scroll down to the first post by Mamaboni.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=100390&perpage=25&pagenumber=1

He shows pictures of his modifications in further postings. His work may be more in line with what you can accept as a relevant technique, for controlling driver surface, same frequency, resonance, created by unconstrained standing wave activity.

Your arguments do not fall on deaf ears, however the assumption that distortion tests will show the results of the EnABL process is incorrect. I have made a number of tests over the years of distortion, with all harmonics broken out for display. To my dismay there is no observable difference in their % of spl and only the slightest difference in amounts distributed in discrete orders, from treated to untreated.

We aren't affecting frequency response with the typical pattern application, but we do affect phase lag. This does make sense if the boundary layer transform, from transverse to longitudinal wave, has been lofted out of the laminar portion of the boundary layer. These tests can be found here.

The first four explore the phase change without frequency response change.
http://www.diyaudio.com/forums/showthread.php?postid=1206356#post1206356
http://www.diyaudio.com/forums/showthread.php?postid=1221791#post1221791
http://www.diyaudio.com/forums/showthread.php?postid=1226268#post1226268
http://www.diyaudio.com/forums/showthread.php?postid=1227789#post1227789

This last one shows the dispersal of the main resonance node, one very similar to the 1kHz node you were working on in your presentation.
http://www.diyaudio.com/forums/showthread.php?postid=1231568#post1231568

There is an introductory paper, without any "scientific" language that shows some early realizations of the problems I try to deal with and a break out from an early CSD plot, that shows the results of treating just a tweeter. You may be able to tame the tweeter giving you trouble with EnABL. However, you would have to invest about $10 to try.
http://www.positive-feedback.com/Issue21/standingwaves.htm

Here is a series from Jon Ver Halen of Lowther America. He posts a number of times and then sums up his findings.
http://www.diyaudio.com/forums/showthread.php?postid=1275431#post1275431

If you have access to interferometry I would be happy to provide some suspects for investigation. The only exposure has been at the hands of Dave Bei, when he worked at Mackie Designs, many years ago. The results we got were intriguing, but the machine, Dave and test results left for Italy quite suddenly and I have no data to show.

I am going to be treating a number of inexpensive oval drivers with whizzer cones to a number of interesting procedures, and intend to leave a pair untreated. Would you be interested in testing them? I no longer have a reliable test set up and have not been able to afford to bring it up to current standards. Perhaps if manufacturing returns to the USA, that lack of funds will be taken care of.

In any event thanks for your critique. Your words don't affect the EnABL process and it's removal of noise from sound reproduction drivers, but it does highlight the lack of relevant test regimens.


Bud

 

[Graham Maynard]

Hi All,

I have been following this thread for yunks. There have been those who trust the reports of improved reproduction (myself included because folks don't put their reputation on the line without very good reason) and those who doubt it, or worse, attempt to ridicule it as an unproven pseudo science using theory as a 'weapon' by which they can browbeat individuals forwarding the new ideas which they know known theory cannot establish.

It is not the theory which is wrong - but a lack of understanding relating to the usefulness of its application.

For anyone to prove that the unusual EnABL blocks do have or cannot have an effect, they will need to 'imagineer' some unusual test procedures.

Harmonic distortion measurements of steady sine output from amplifiers does not prove that a 0.0001% SS amplifier will 'reproduce' better than a 0.1% tube one because the most import aspects lie elsewhere, so where can harmonic distortion measurements, or indeed lasers looking at sine driven cones, lead us ?? Did those who spent maybe a decade or more developing the ultimate 'measured' amplifier produce something which is best for reproding audio ?

Sine waves measured in time isolation simply CANNOT reveal what will happen with complex and ever changing 'splashy' music streams in real music time.

Do all the dissonances we hear really occur in the cone itself, or are we also hearing trapped surface waves beating, interfering and creating new music driven surface pressure waves in music time ?

We need a free launch of continuously changing sound wave pressures, free of turbulent/diffracting layers/baffle effects at driver and cabinet -
at driver and cabinet -
so are not the driver and the cabinet where we should be searching for our interfering, trapped, reflected and standind wave effects - with tiny mikes listening beside the driver etc. - not 1 or 2 metres away where effects become masked by more substantial energies in a manner that defies separation ?
Sine sweep examinations here might indicate peaks/troughs etc., but only different types of music will define how significant such anomalies could be for reproduction.


Cheers ........... Graham.


(Keep up the good work Bud.)

 

[t-head]

Graham,

Thanks for popping in. Pertinent, on topic, well-considered posts, from a well-respected person such as yourself are always welcome and constitute 'water in the desert' of audio theory and practice.

dlr and all,

Please excuse my mini-rant with bad tone/manners...

soongsc,

I look forward to further posts concerning metal-cone drivers...you are a pioneer...

t (Richard)

 

[soongsc]

Hi Bud.

Thanks for sharing your treatment.
It works for me.

Yesterday I enabled a cheap speaker using your pattern.
Method and brand are not as you recommend, not as regulier as it would be, but, yes... it works.
Instruments are more separated, timbre is more correct and more dynamic.

An idea comes to me to use a pattern which have more random characteristic. That pattern is MLS (maximum length sequence).

So, I used base-4 MLS which give me 111100010011010 (1=6degrees painted, 0=6degrees non painted).

Your pattern looks like 1101100000 (1=2degrees painted, 0=2degrees non painted).

To my ear, on that cheap nude speaker, MLS is better than yours.
Especially on violin.
I was really surprised, how a poor nude speaker can sound like that.

Now, I'll try to find my time to treat my Fostex properly.

Again, thank you Bud.

Regards,
Atok

PS: There is another pseudo random sequence known as Baker Codes.

This is really quite interesting. I wonder what before and after measurements look like. Also wonder what the possibilities would be if random sequence of different kinds were used on the same driver at different locations.

 

[dlr]

dlr,

Please read some of the past posts on this thread. Bud has only recently dealt with 'full range drivers'. Before bravely posting on this forum, he dealt with his own multi-way system. The fact that SET and FR types were the first to respond is incidental. The cone distortions that the EnABL was conceived to address, is inherent to all cone drivers. Manufacturers of aforementioned drivers (transducers, for the scientificos among us) are well aware of the distortions inherent in their creations. Some have addressed the issue to varying degrees of success. Please stop whining for 'proof' and get to work...if anyone could have produced the desired 'proof', rest assured that it would have been posted long ago, if for no other reason than to get lazy naysayers off our backs...

Back OT - please do something constructive or go spread your unhelpful nonsense elsewhere. We all await your efforts with anticipation...Unfortunately, it seems you are as unsuited to the task as many here...if you cannot contribute, what do you hope to accomplish with your impotence? Please find a way to listen to EnABLed transducers and go from there, or lurk and desist from your negativity...it is not helpful or contributing to anything but you own egotistical self-promotion. Thank you.

t

This is precisely the type of post many would expect to get in reply on a thread such as this. Non-believers are not welcomed.

Dave

 

[dlr]

This part of surround tweaking has been explored in many occasions. If you look at some of TB's speakers, they have similar tweaks that are in production. Technically speaking these are ways to more effectively transfer energy from the cone to the surround. The wider band you can do that with, the better. Altimately surrounds should be designed for specific drivers, which is not economical for mass production and parts control.

Correct, TB did what I did, observed what others such as Scan-Speak and others have done for years and copied it. Two prime examples are the 13m/8640 and 12m/4631.

The issue addressed is specifically to address the cone/surround mechanical impedance mismatch that is frequency dependent. Were that not an issue, this EnABL treatment attempt would also be moot. The problem is that there is not perfect termination at all frequencies in the usable passband with some combinations of cone/surround materials. Some don't have much of an issue in that range, some have significant issues. It's been known for many, many years.

Even if a surround is designed for a particular driver, it may not be possible to fully compensate for all frequencies or, as you point out, it may not be economical.

Dave

 

[dlr]

When dealing with audio, I think it's best to look at data from various aspects rather than just let one type of test dominate. Of course for certain situations, certain types of tests will reveal differences more clearly than others.

Yes, that's why it takes a fairly extensive set of distortion measurements to cover the range involved. Multi-tone testing selected properly will highlight problem areas. Before/after of the same set of tests will show the alteration made. It's not rocket science, as the saying goes.

Dave

 

[Magnetar]

Have you used these dots on the phase plug of a compression driver?

An externally hosted image should be here but it was not working when we last tested it.

Would it matter even though the phase plug is metal? Where do the dots go and how would you do it?

What about the diaphragm? Any success stories?

These are not 'cheap' to experiment with.

 

[AJinFLA]

dlr,
Unfortunately, it seems you are as unsuited to the task as many here

This is precisely the type of post many would expect to get in reply on a thread such as this. Non-believers are not welcomed.

I am going to have to side with T on this one Dave. You are obviously not a psychiatrist. Being a physical science type, i.e. Engineer, you may well possess expertise in measurements of the soundwave that impinges upon the ear. What happens after that is clearly outside of your domain. This heavily laden train is steaming downhill. I would not throw science in it's way at this point. The view from off the track is more fascinating that way. Alice or any episode of the Twilight Zone has nothing on this one 😉.
Please let it continue unabated without further distractions.

cheers,

AJ

 

[t-head]

This is precisely the type of post many would expect to get in reply on a thread such as this. Non-believers are not welcomed.

Dave

Dave,

1. I apologized...to you in post and Bud by e-mail...my poor tone was not justified by yours...you are assuming much about me...

2. I never said you were not welcome. But assuming we are some kind of cult where other viewpoints are not wanted is false. We need people testing treated drivers...not simply dismissing out of hand what they do not understand and have no actual experience with (ie. EnABLed drivers). Listen yourself and then get back...your feedback about actual experience is very welcome.

3. read Grahams post...think out of the box...what can you offer other than scepticism? I was very sceptical at first as most were (are). After listening to treated drivers, it was clear that something was hapening that could not be explained by previous theory. So here we are...trying to discover at what level these changes are occuring...contribution is welcome...

Richard

 

[dlr]

dlr,

Welcome to the thread Dave.

You may find an interesting tweak here, scroll down to the first post by Mamaboni.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=100390&perpage=25&pagenumber=1

The felt treatment is certainly going to benefit if done carefully. Dunlavy used this technique many years ago, though in a different pattern. The lowpass usually keeps the problem area in the stop-band. Any addition of any material to the surface of a driver diaphragm is going to alter it, some to advantage, some to disadvantage. That is not in question.

He shows pictures of his modifications in further postings. His work may be more in line with what you can accept as a relevant technique, for controlling driver surface, same frequency, resonance, created by unconstrained standing wave activity.

Your arguments do not fall on deaf ears, however the assumption that distortion tests will show the results of the EnABL process is incorrect. I have made a number of tests over the years of distortion, with all harmonics broken out for display. To my dismay there is no observable difference in their % of spl and only the slightest difference in amounts distributed in discrete orders, from treated to untreated.

I have to say that this statement alone implies that the process is not making significant change. We're not in the area of things such as crossovers with phase issues, multiple drivers nor amps with feedback loops. The sound from a driver is the integrated response of all points that emit and form the wave. Measurement mics sense the coalesced wave, not what occurs at a boundary layer.

We aren't affecting frequency response with the typical pattern application, but we do affect phase lag. This does make sense if the boundary layer transform, from transverse to longitudinal wave, has been lofted out of the laminar portion of the boundary layer. These tests can be found here.

There is much contradiction in this thread. First, some say the FR is not altered, as you say. However, supporting links are to measurements specifically of FR and the CSD generated from an MLS impulse (as opposed to, say, any form of sine-wave test that is eschewed here).

The statement that stands out is yours that says that FR with the typiccal pattern is not affected, but the phase is. Either you have managed to find an exception to the universally accepted theorem embodied in the Hilbert-Bode Transform or there is some creative writing being taken in attempts to describe what is happening.

I went back to an earlier thread of yours
EnABL Thread in which you wrote this paragraph:

I will not be making any before and after Quantitative measurements. I am going to leave that to you folks who really do know what you are doing in that realm. Of course that means you will have to treat a set of drivers, or two, but I will not be upset about this. I will suggest that very little, of what is a profound qualitative improvement, is going to show up in the usual tests. At least that has been my experience, but, I am not qualified to do these tests anyway. You who must, should probably start qualifying the results of this process with a CSD plot.

If this is so, then I would ask how one can make the claim that is not possible to measure the effects with the widely used and well known set of measurements that are the industry standard? One must be well-versed in a measurement system to be able to disavow its abilities in any area.

The first four explore the phase change without frequency response change.
http://www.diyaudio.com/forums/showthread.php?postid=1206356#post1206356
http://www.diyaudio.com/forums/showthread.php?postid=1221791#post1221791
http://www.diyaudio.com/forums/showthread.php?postid=1226268#post1226268
http://www.diyaudio.com/forums/showthread.php?postid=1227789#post1227789

The above measurements are all specifically FR related. All phase can be re-created using the Hilbert-Bode transform due to the known relation between FR and phase of minimum-phase devices as is the case for raw drivers. For those not aware of this implication, no CAD software used today would be effective were this not the case. They rely specifically on drivers being minimum-phase and subject to the Hilbert-Bode transform being capable of generating phase from frequency response.

This last one shows the dispersal of the main resonance node, one very similar to the 1kHz node you were working on in your presentation.
http://www.diyaudio.com/forums/showthread.php?postid=1231568#post1231568

This is the first good evidence of benefit, though it is strictly frequency domain (though we're told that typically it's not being modified). The one thing we don't know is what the effect would be of applying an application of the "conformal coating" material without the patterned layer. There will without doubt be a change. At this point no conclusion could be made for that case. It would be an interesting contrast and go a long way to actually quantifying the change with the patterned approach.

There is an introductory paper, without any "scientific" language that shows some early realizations of the problems I try to deal with and a break out from an early CSD plot, that shows the results of treating just a tweeter. You may be able to tame the tweeter giving you trouble with EnABL. However, you would have to invest about $10 to try.
http://www.positive-feedback.com/Issue21/standingwaves.htm

I would not recommend tweeter mods to anyone unless they addressed the full 2-pi area of response. Larger drivers with improved on-axis response are likely to show improved off-axis response, though not always, but tweeters are a special breed, being domes. They are in most cases designed with highly optimized, damped responses that provide the desired on- and off-axis response. If one treats the on-axis only, the off-axis will likely degrade significantly. The sensitivity will likely also suffer due to the low mass nature of most tweeter domes.

Here is a series from Jon Ver Halen of Lowther America. He posts a number of times and then sums up his findings.
http://www.diyaudio.com/forums/showthread.php?postid=1275431#post1275431

There are two significant issues with the above. First, we're looking again at full range drivers that always have resonance problems and the his own recommendation is to listen off-axis. Any damping material applied is going to alter the response, not unexpected. But he starts off saying:

CLIO was used to measure both treated and untreated units. Interestingly, there was little difference in the measurements. Frequency response, phase response, and waterfall showed little difference between the two.

Second, his two measurements are not with the same setting. The window is evidently not set to start at the same time mark. Anyone with experience with a window MLS system would tell you that this can signficantly alter the resultant FFT calculation that is used to generate both the FR and the CSD. Valid comparisons must be made using identical conditions. I have seen similar changes in measured response output using the same impulse, but with different window settings.

On reviewing again just now, I see that planet10 made the same observation, noted different scale settings, then made this comment:

On the whole the EnABLEd cone doesn't look as good in these waterfalls as the stock one -- particularily above 1k.

In the end, everyone presenting any supporting evidence is using the industry standard MLS test scheme. The one truly strong case is the set of measurements made by soongsc. That is the kind of information that is needed to adequately support the case. I would qualify any statement about the efficacy, though, by presenting the same test data with a treatment of the conformal coating alone. An application of that is guaranteed to have an impact, the magnitude is unknown until tested.

(Cutting post data, the board software says it's too long). My position is that the only valid data is before/after measurements. A baseline must exist against which one can contrast. Without that, it's simply not valid.

In any event thanks for your critique. Your words don't affect the EnABL process and it's removal of noise from sound reproduction drivers, but it does highlight the lack of relevant test regimens.

Bud

No words change it, agreed, my involvement is as a skeptic to try to ferret out details and/or comment on areas that either make assumptions only or can be shown to be in error. Quantifying the change is possible, the specifics as to the mechanism for whatever magnitude it has, is not clear. But there are certain principles (such as the relationship between FR and phase) that can't be altered.

I hope to see results posted by planet10 using interferometry.

Dave

 

[soongsc]

This driver tweaking thing is really becoming addictive.😀 I thought I'd share some process I go through, inspired by the founder of Audio Refinement. Tweak somthing until you find it's better, then use that and try to beat it.

Mostly if I get an idea, and am not in the lab, I just try it in one channel, then I listen with one channel using the previous tweak and one with the new tweak. Normally if one sounds cleaner than the other, then I know I'm in the right direction. Then I take time in the lab to look at measurements and figure out the differences. If I notice a trend that seems to improve sound, then I tweak the driver in the lab until I get the best results I can during that session, do a second driver, then go back to listening. This goes on and on until I run out of ideas to get it better, then I go to a different driver that is on the plan. Normally the tweak methods I use can be undone, so I normally need 4 of the same drivers to cycle through. Currently I'm dealing with wide range drivers, and frequencies above 1KHz, sometimes I try to see how 500Hz~1KHz changes as well. This sets the way for two way designs where one driver is already a standard, and we start working on the other driver going though the same process. Only now for two way systems, it will become more tricky. I will share some of that when I go through some cycles of two way systems.

One thing to make sure is to get the flattest impedance curve you can on your listening system. Here is what one of my listening setup impedance looks like.

An externally hosted image should be here but it was not working when we last tested it.