It's all in the shaping. If you're only making foam for one pair, people will be willing to take the time to get it right, methinks. It doesn't compress much when cut right.
Any of these temporal effects are secondary to the on axis frequency response. The change in frequency response is going to be quite audible and more so than any temporal changes due to the foam. Without doing the EQ I don't see how you could even begin to evaluate the differences with and without the foam. It's apples and oranges if the FR is different.
Rob
No, I don't think I need that. One must EQ if there are any FR changes, period. Matched FR is a must or are you claiming it is not required for serious research, even if at a DIY level as we do? Is DIY excluded from such requirements to be considered adequate?
This is even more important if the claim is that it is not apparent in the FR directly as you claim, hence my query, unanswered, regarding the anecdotal evidence that is "overwhelming". If you provide direct evidence to support your claims (that you state are actually only anecdotal), but you cannot show that there was some method to control the FR changes via EQ, then your claims are nothing but conjecture and thus are flawed and not valid without some other supporting evidence. You must also prove that the EQ is the same on all axes, otherwise the polar response becomes an issue. The argument that it's the not same "*even if* it looks comparable on a FR plot" with/without has to be proven. So far there's no evidence that with EQ there is not a small change in the polar response (seems quite apparent), so I don't see empirical proof on either side. However, I do see theoretical evidence on one side along with some support from actual studies. The other side has anecdotes.
This change in the time domain must be in the frequency domain in one form or another in any case if it is as you say. It may be that the changes are at the level of distortion as it typically exists. If that's the case, then it must still be possible to obtain supporting evidence that the change is not reflected in the FR plots, yet is measurable and measured in the frequency domain through means such as comparative distortion measurements. If the FR is not EQed, then it is not possible to separate FR variances from other factors being considered. That, however, does not appear to be the case. From everything I've seen, use of damping materials in all cases changes the FR on all axes and somewhat differently, even if only slightly, not surprising. One must still EQ and measure again if one is to say that there is no impact in areas not subject to easy distinction in the FR, if that even were the case.
It is actually rather easy today to EQ nearly perfectly on any given axis, though it's probably not been done for this case. Changes on other axes would then easily be compared to determine any polar response changes. However, it does appear that it may not be possible to adequately EQ for the FR to a case of "all else being equal" since there does appear to be something of a difference in the FR alteration from damping depending on axis. Thus if one EQs flat on any given axis before/after, the polar response FR differences alone may contaminate any perception tests of an absolute nature. Claims regarding the impulse response are moot in this case. The test must control all variables or be able to account for those not controlled.
Ultimately the problem comes down to whether or not there is any absolute method to adequately control all possible variables, whether time domain or frequency domain. It would appear not. This applies to those making negative claims as much as it does positive claims. All of those anecdotes that you say are on your side appear to be fatally flawed.
Dave
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_Wim_
I used 12" WG - it's the one Autotech.pl is selling, only with somewhat refined throat by myself) - maybe it's a bit denser than the original. You can see some more photos on my web. It was a lot of work, but I would do it again anytime as the result is simply fabulous, whatever the foam does and despite I'm sure I've still made some errors. It was measured with the woofer in place, BTW.
gedlee
Sure, I'll send you an E-mail.
At this point I would like to thank Dr. Geddes for publicating all this work as it totally changed my view on loudspeakers and home reproduction once for all. Earl, thank you.
Hello Marcel,
Verynice speakers! The design looks familiar J
I am also using a 12” waveguide with foam plug, but I bought my waveguides from Earl. So far I have been very satisfied by these (now listening to these speakers almost 8 months).
I did not experiment without foam, I immediately glued the foam plug in (it is already time consuming to optimize the cross-over for 1 configuration, I did not want to do it twice…)
So far these have been the best speakers I have ever had, and there is still room for improvement in my cross-over. Currently I am building an automated rotary table to make the polar plots less time-consuming.
I am aware the subs are not in the ideal location (especially because I have only 2 subs), but they are so big there is no other suitable location in the room (both subs contain 2 x 18” speakers in a W-baffle) In the future I will probably build some additional small subs, but for now I am already very satisfied with the results.
At this point I also want to thank Earl for all his time he spent trying to educate us, even if some students just do not want to listen… I hope he can keep up this good work and make lots of new developments (I am still hoping for a CD with an optimized phase plug for the waveguide…)
Attachments
Hi Wim,
once you have data measured, you can easily simulate crossovers for all the polars at once - just use my software. You can even display real-time polar map as you manually shift components values - see my web for free download. I'm currently working on much upgraded and more user-friendly version supporting biquads directly for advanced plugins for miniDSP platform, for example (which is what I have), power response, etc. If anyone is interested, please let me know, I will send you some basic user guide for this (old) version. It can't be much simpler than that once you know what you are doing. Now I can't imagine designing crossover for this kind of loudspeaker without such a tool.
Marcel
Attachments
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Do you have a thread somewhere on this product so I can bookmark it?
Im very interested the Plugins you will have for MiniDSP.
Gentlemen,
I don't feel comfortable discussing this in Earl's thread, just wanted to let know that it is available when Wim wrote about his crossover. Please feel free to register at LoudspeakerSoft Forum where I've prepared dedicated sections to support my software and some related topics. The truth is that I didn't mean to promote this so soon. I still have to complete the new version, documentation, web, etc. It will have much more features and be more stable I hope. Anyway this version can be used freely by whoever wants to.
Power response, or something similar from the data provided, will be calculated in a new version (it won't be free). It won't be miniDSP plugin - just the biquad coeficients that can be entered directly to the standard ("Advanced") miniDSP plugin - in expected text format.
That's all about my stuff for now. Please continue about it at loudspeakers.com. More to come...
Thanks,
Marcel
I don't feel comfortable discussing this in Earl's thread, just wanted to let know that it is available when Wim wrote about his crossover. Please feel free to register at LoudspeakerSoft Forum where I've prepared dedicated sections to support my software and some related topics. The truth is that I didn't mean to promote this so soon. I still have to complete the new version, documentation, web, etc. It will have much more features and be more stable I hope. Anyway this version can be used freely by whoever wants to.
Power response, or something similar from the data provided, will be calculated in a new version (it won't be free). It won't be miniDSP plugin - just the biquad coeficients that can be entered directly to the standard ("Advanced") miniDSP plugin - in expected text format.
That's all about my stuff for now. Please continue about it at loudspeakers.com. More to come...
Thanks,
Marcel
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Hey, its far more interesting and relavent than the nonesense about "CMP".
But if it is going to be commercial software then it probably is not appropriate here.
I have been writting software that is virtually identical to what you have. Mine does everything that yours appears to do except the real time change of the polar plots with a change in value of a component. I just have not gotten arround to that as yet.
Mine does do a polar model to the data which allows me to look at the extreme nearfield as well as the far field from data at any field distance. The extreme nearfield can be used to diagnose where problems are occuring at the source such as diffraction. Its a pretty slick technique, but massively computationally intensive.
What language is the software written in?
Hello Marcel,
I will definitely give it a try. I do not equalize for the total power responce, but do something like this (my listening axis is 22,5°, and I have measurement every 7.5°):
In Arta I open my 22.5° impulse measurement and goto smoothed frequency responce (1/6oct). I press "CTRL+A" 3 times, which adds this measurement 3 times into the overlay manager.
Next I open the 15° measurement and press 2 times "CTRL+A". I do the same for the 30° measurement.
Next I open the 7.5° measurement and press 1 time "CTRL+A".
This now means the overlay manager contains the following measurements:
2 x 30 °
3 x 22.5°
2 x 15 °
1 x 7.5°
Next I open the 37.5 meauserment and averge this measument with all the overlays in the overlay manager (edit menu => power average with overlays)
Now I have a power average with more focus on the listening axis, which work better IMO. This average is exported to a txt file, and imported in REW (V5). With REW I calculate the parametric filters for my DCX2496 to make the average as flat as possible.
Off course REW cannot calculate the crossover, so this is what has been causing my delay, but your software looks fantastic for that!
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Marcel - nice work!
Some of the capabilities you are offering for free are very similar to what Fine X-Over offers for those that can afford it - please check Loudsoft.com
(Webinar: Audio Test and Measurement Webinars page)
I will keep on checking your site to follow the development of such nice and useful tool.
Cheers!
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Hi foks, in continuation where I was stoped in presenting facts proving Earl to be wrong ... again
back to topic:
Earls claim:
HOM is „Kolumbus egg“
My claim:
ASAR Pattern / CMP behaviour is „Kolumbus egg“
My further claim :
Each and any 3-D effect does have its equivalent in ASAR pattern / CMP concept
My further claim :
ASAR pattern / CMP concept provides the 100% description to any spatial related effects (for complete 3D definition, it would need to be boosted to tetrahedron reception or using some tricks though)
My further claim :
Seen as from a systemic ansatz, ASAR pattern / CMP concept is the acoustic complement to the concept of holography (especially helpful for analysing/ describing / understanding rather than for recording / reproducing of sound though).
My further claim :
HOM (as put by Earl) is a subset of ASAR pattern / CMP behaviour / diffraction effects
My further claim :
HOM (as put by Earl) - are not any relevant in the sense that quite any diffraction causes spatial effects, thus HOM (as put by Earl) aint any „special“
My further claim :
There is no prove whatsoever and only veeeery little anectotal evidence with respect to sonic impacts of HOM (as put by Earl) - as was clearly conceded by himself :
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-520.html#post2561338
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-519.html#post2561114
My further claim:
presence or absence of CMP behaviour / ASAR pattern makes all the differnce in audio perception – be it of whatever (welcome or distracting) outcome – right on eye level with tonal balance.
HOM (as put by Earl) isnt any „special“ in this as its a subset of CMP concept / ASAR pattern. Over the years there was no prove whatsoever brought foreward by Earl that „his HOM“ - and not mere CMP behaviour / ASAR pattern - is the root cause to any perceptional differnce
My further claim:
quite anything happening to make a horn / waveguide / diffraction alignment device working as it does is related to diffraction and reflection
My further claim:
diffraction – as causing a „second source“ effect - is inseperable from CMP concept / ASAR patterns – reflection – as causing a „virtual second source“ is another main root cause to CMP behaviour / ASAR patterns from any „real“ single acoustic source.
Earls claim:
stuffing foam into a wave guide improves sonics by removing / reducing coloration by removing / reducing HOM (as put by Earl)
My claim:
any dampening material adds a sonic pattern of its own in the vast majority of applications and especially in the application at hand (stuffing foam into a horn).
There is overwhelming anectotal evidence to this sonic coloration of dampening materials – though not sorted as such.
Simple mind experiment : if dampening materials soley remove „ill effects“ (in closed boxes for example), as to why can there be too much of removal ???
My further claim:
HOM (as put by Earl) is of course affected by applying dampening materials – but as said – not in any „special“ way
My further claim:
sonic coloration of OSWG is altered but not removed by stuffing with foam. ASAR patterns can be smoothed out by application of dampening materials but the underlying physical mechanisms of how dampening is actually happening in the time/ frequency matrix imposes an unavoidable sonic coloration
My further claim:
the altering of the sonic coloation achieved by stuffing OSWG's may well be perceived as „improvement“ by a vast majority of users - whatever *that* may tell us
My further claim:
the specific sonic coloration of dampening materials is widely known but not recognized as to be caused by the specific change of ASAR patterns in the presence of dampening materials (plus some additional effects).
My further claim:
„simple“ EQing never can make up for changes that result from stuffing with foam
My further claim:
comparing a „simple“ EQed (OSWG) horn without foam to a „simple“ EQed (OSWG) horn with foam of roughly the same FR is comparing apples with oranges.
My further claim:
ASAR patterns and especially „part spectrum“ versus „congrunent“ CMP behavior has to be understood – at least - to „understand“ why this is the case .
My further claim:
foam – as any other dampening material – provides a „distributed“ effect not to be well seen in FR plots (or put differently – the main effects seen in FR plots are by no means „the full story“)
Earls claim:
wavelet analysis is an useless method as each and everything of interest is also seen in common IR and FR plots
My claim:
wavlet analysis is the most versitale tool to most clearly visualize time domain effects (not any clearly represented in IR nor FR plots).
PBW analysis IMO is best suited to show how sound / tones develop over time, by its extraordinary high resolution with respect to the time / frequency matrix, thus allowing for unmatched insight into the hologram like pattern of spatial acoustics by adjusting its parameters to the time slots of interest.
My further claim:
FR plots are misleading and void when it comes to CMP behaviour / ASAR patterns – FR plots may give guidance for some tonal balancing and have proven to do *that* job pretty well – though, without giving clear insight as to why pretty comparable looking FR plots actually can provide significant perceptional differencies
My further claim:
well thought utilization of wavlet analysis provides exceptional high resolution in the time and frequency domain and hence aid greatly to easily understand and deal with time domain effects
Earls statment about facing dead ends in his HOM research:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-521.html#post2561516
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-428.html#post2213078
My statement with respect to a complete and stringet concept of ASAR patterns / CMP behaviour : http://www.diyaudio.com/forums/ever...teps-man-one-giant-leap-maturizing-audio.html
No big deal – but from time to time the most obvious has to be stated
Michael
PS:
To not be forgotten by later history (LOL), it may only be fair to note that also Siegfried Linkwitz claimed having found „Kolumbus egg“ which *he* called „Stored Energy“
But just like is the case with „Kolumbus egg“ Earl has found, this one also didn't result in a complete and stringent concept.
back to topic:
first not clear - second not true..
wide parts of the rest of the post could have been almost "copy and paste" from my CMP paper
LOL
The "real" crux you are facing with establishing a "specific" behaviour of HOM versus any other diffraction caused CMP effects is that you are trying to state that a subgroup of specific spatial orientation should have a significant different perceptability (as to your ideas).
Quite a task I'd say...
Michael
well depends - that part of your work that does not make any sense definitely is that old...
Michael
Earls claim:
HOM is „Kolumbus egg“
My claim:
ASAR Pattern / CMP behaviour is „Kolumbus egg“
My further claim :
Each and any 3-D effect does have its equivalent in ASAR pattern / CMP concept
My further claim :
ASAR pattern / CMP concept provides the 100% description to any spatial related effects (for complete 3D definition, it would need to be boosted to tetrahedron reception or using some tricks though)
My further claim :
Seen as from a systemic ansatz, ASAR pattern / CMP concept is the acoustic complement to the concept of holography (especially helpful for analysing/ describing / understanding rather than for recording / reproducing of sound though).
My further claim :
HOM (as put by Earl) is a subset of ASAR pattern / CMP behaviour / diffraction effects
My further claim :
HOM (as put by Earl) - are not any relevant in the sense that quite any diffraction causes spatial effects, thus HOM (as put by Earl) aint any „special“
My further claim :
There is no prove whatsoever and only veeeery little anectotal evidence with respect to sonic impacts of HOM (as put by Earl) - as was clearly conceded by himself :
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-520.html#post2561338
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-519.html#post2561114
My further claim:
presence or absence of CMP behaviour / ASAR pattern makes all the differnce in audio perception – be it of whatever (welcome or distracting) outcome – right on eye level with tonal balance.
HOM (as put by Earl) isnt any „special“ in this as its a subset of CMP concept / ASAR pattern. Over the years there was no prove whatsoever brought foreward by Earl that „his HOM“ - and not mere CMP behaviour / ASAR pattern - is the root cause to any perceptional differnce
My further claim:
quite anything happening to make a horn / waveguide / diffraction alignment device working as it does is related to diffraction and reflection
My further claim:
diffraction – as causing a „second source“ effect - is inseperable from CMP concept / ASAR patterns – reflection – as causing a „virtual second source“ is another main root cause to CMP behaviour / ASAR patterns from any „real“ single acoustic source.
Earls claim:
stuffing foam into a wave guide improves sonics by removing / reducing coloration by removing / reducing HOM (as put by Earl)
My claim:
any dampening material adds a sonic pattern of its own in the vast majority of applications and especially in the application at hand (stuffing foam into a horn).
There is overwhelming anectotal evidence to this sonic coloration of dampening materials – though not sorted as such.
Simple mind experiment : if dampening materials soley remove „ill effects“ (in closed boxes for example), as to why can there be too much of removal ???
My further claim:
HOM (as put by Earl) is of course affected by applying dampening materials – but as said – not in any „special“ way
My further claim:
sonic coloration of OSWG is altered but not removed by stuffing with foam. ASAR patterns can be smoothed out by application of dampening materials but the underlying physical mechanisms of how dampening is actually happening in the time/ frequency matrix imposes an unavoidable sonic coloration
My further claim:
the altering of the sonic coloation achieved by stuffing OSWG's may well be perceived as „improvement“ by a vast majority of users - whatever *that* may tell us
My further claim:
the specific sonic coloration of dampening materials is widely known but not recognized as to be caused by the specific change of ASAR patterns in the presence of dampening materials (plus some additional effects).
My further claim:
„simple“ EQing never can make up for changes that result from stuffing with foam
My further claim:
comparing a „simple“ EQed (OSWG) horn without foam to a „simple“ EQed (OSWG) horn with foam of roughly the same FR is comparing apples with oranges.
My further claim:
ASAR patterns and especially „part spectrum“ versus „congrunent“ CMP behavior has to be understood – at least - to „understand“ why this is the case .
My further claim:
foam – as any other dampening material – provides a „distributed“ effect not to be well seen in FR plots (or put differently – the main effects seen in FR plots are by no means „the full story“)
Earls claim:
wavelet analysis is an useless method as each and everything of interest is also seen in common IR and FR plots
My claim:
wavlet analysis is the most versitale tool to most clearly visualize time domain effects (not any clearly represented in IR nor FR plots).
PBW analysis IMO is best suited to show how sound / tones develop over time, by its extraordinary high resolution with respect to the time / frequency matrix, thus allowing for unmatched insight into the hologram like pattern of spatial acoustics by adjusting its parameters to the time slots of interest.
My further claim:
FR plots are misleading and void when it comes to CMP behaviour / ASAR patterns – FR plots may give guidance for some tonal balancing and have proven to do *that* job pretty well – though, without giving clear insight as to why pretty comparable looking FR plots actually can provide significant perceptional differencies
My further claim:
well thought utilization of wavlet analysis provides exceptional high resolution in the time and frequency domain and hence aid greatly to easily understand and deal with time domain effects
Earls statment about facing dead ends in his HOM research:
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-521.html#post2561516
http://www.diyaudio.com/forums/multi-way/103872-geddes-waveguides-428.html#post2213078
My statement with respect to a complete and stringet concept of ASAR patterns / CMP behaviour : http://www.diyaudio.com/forums/ever...teps-man-one-giant-leap-maturizing-audio.html
No big deal – but from time to time the most obvious has to be stated
Michael
PS:
To not be forgotten by later history (LOL), it may only be fair to note that also Siegfried Linkwitz claimed having found „Kolumbus egg“ which *he* called „Stored Energy“
But just like is the case with „Kolumbus egg“ Earl has found, this one also didn't result in a complete and stringent concept.
I am of the opinion that its long overdue that the whole thread „Geddes on waveguides“ should be moved to the commercial sector – out of following reasons:
1.) the core topic is of great commercial interest for Earl (which by not a small amount is the root cause of quite some emotion and friction happening here and is also turning my own tone somtimes a little more sarcastic as is appreciated by some)
2.) a lot of this core topic is covered by patentes in the commercial interest of Earl (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
3.) As clearly stated by Earl, he is seeing the DIY community as a core target for his products, thus, any pro and con statment posted here being of high commercial interest to him (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
4.) IMO more often than not, Earls statments in this thread boil down to supporting his commercial interests and thus have to be seen as advertizing in its core intention. (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
All above is way less to no issue at all, if done at the right place - the place where involved commercial interest is clearly stated – right from the beginnning - for anybody enterening the „discussion“ e.g. for all the less experienced people comming here to „learn“ from Earl.
Any„real“ discussion actually is never going to happen here for mentioned reasons.
For those not having followed this thread closely enough (and / or have not enought „in depth understanding“ about diffraction/ sound field/ dampening behaviour neccesary to judge whats actually going on here) it may be recalled that:
5.) over the years „wave guide“ contour - as coined by Earl - has been proven to not be any special (in the context of horns / wave guides / diffraction alignment device)
6.) over the years „HOM“ - as coined by Earl - has been proven to not be any special (in the context of diffraction/ reflection related effects elsewhere)
7.) over the years the „foam plug“ - as coined by Earl - has been proven to not be any special (in the context to how dampenings materials work elsewhere)
Or to say it in other words :
8.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „OSWG being „special“ as being the horn of providing least diffraction“
9.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „HOM is „special“ as to having specific „sonic impact“
10.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „the foam plug is a „special dampening measure specifically affecting HOM“
So guys, may I ask you to take action – according to what is stated to be the rules of this board...
Michael
1.) the core topic is of great commercial interest for Earl (which by not a small amount is the root cause of quite some emotion and friction happening here and is also turning my own tone somtimes a little more sarcastic as is appreciated by some)
2.) a lot of this core topic is covered by patentes in the commercial interest of Earl (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
3.) As clearly stated by Earl, he is seeing the DIY community as a core target for his products, thus, any pro and con statment posted here being of high commercial interest to him (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
4.) IMO more often than not, Earls statments in this thread boil down to supporting his commercial interests and thus have to be seen as advertizing in its core intention. (which by not a small amount is the root cause of quite some emotion and friction happening here and also is turning my own tone somtimes a little more sarcastic as is appreciated by some)
All above is way less to no issue at all, if done at the right place - the place where involved commercial interest is clearly stated – right from the beginnning - for anybody enterening the „discussion“ e.g. for all the less experienced people comming here to „learn“ from Earl.
Any„real“ discussion actually is never going to happen here for mentioned reasons.
For those not having followed this thread closely enough (and / or have not enought „in depth understanding“ about diffraction/ sound field/ dampening behaviour neccesary to judge whats actually going on here) it may be recalled that:
5.) over the years „wave guide“ contour - as coined by Earl - has been proven to not be any special (in the context of horns / wave guides / diffraction alignment device)
6.) over the years „HOM“ - as coined by Earl - has been proven to not be any special (in the context of diffraction/ reflection related effects elsewhere)
7.) over the years the „foam plug“ - as coined by Earl - has been proven to not be any special (in the context to how dampenings materials work elsewhere)
Or to say it in other words :
8.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „OSWG being „special“ as being the horn of providing least diffraction“
9.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „HOM is „special“ as to having specific „sonic impact“
10.) over all that years there was not a single prove (that did hold) brought forward to Earls claim „the foam plug is a „special dampening measure specifically affecting HOM“
So guys, may I ask you to take action – according to what is stated to be the rules of this board...
Michael