Beyond the Ariel

mige0 said:
Courtesy Earl

OS wave guide at 0 deg:

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48kHz Files provided by Earl I converted in CoolEdit and processed by ARTA to get CSD.
Looks pretty much excellent for me with respect to decay time
:)

Michael
Hi Michael,

Is it possible to reduce the time scale range to simething like 1ms or less (preferably something like 0.5ms)? No smoothing?
 
xpert said:



...

CSD is quite useless. One would have to know which deviation from ideal is critical or not. The threshold of perception, related to the graphs is where? CSD is nothing but the impulse response. To estimate the impact on audio reproduction the better way is to look at (1) amplitude over frequency and (2) group delay. CSD is nothing else, really. It's apperance leaves room for some free style interpretations. But that means nothing but confusion. Every technical info on audio transducers should be related to psychoacoustics. But it can't be done - honestly - with CSD pictures. CSDs can be compared to each other. But what does a difference tell about sound quality?

have fun
Based on my experience, CSD is very much related with reproduction fidelity and sound coloration. Non-balanced decay vs. balanced decay, rate of decay in various time ranges, etc. each show different sound quality.
 
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Joined 2009
soongsc said:

Based on my experience, CSD is very much related with reproduction fidelity and sound coloration. Non-balanced decay vs. balanced decay, rate of decay in various time ranges, etc. each show different sound quality.

Hi,

is there any validated relation to aural cognition? In other words, does anybody feel about it as You do? CSD is about NUMBERS. How do these express You aural sensation, can they be compared to others of an other driver/box and/ort person? And if, how?

In short, what is the meaning of that numbers the CSD presents to the DIYer?

Thank You

ps: the data above is obviously smoothed by windowing ..., the representation lacks info due to the falling characteristics towards the high end, especially that data is of less use than one might project into it ... pps: and so it is for nearly any CSD I've seen yet, big sunny picture of AYERS ROCK, myths, no essence ...
 
xpert said:


Hi,

is there any validated relation to aural cognition? In other words, does anybody feel about it as You do? CSD is about NUMBERS. How do these express You aural sensation, can they be compared to others of an other driver/box and/ort person? And if, how?

In short, what is the meaning of that numbers the CSD presents to the DIYer?

Thank You

ps: the data above is obviously smoothed by windowing ..., the representation lacks info due to the falling characteristics towards the high end, especially that data is of less use than one might project into it ... pps: and so it is for nearly any CSD I've seen yet, big sunny picture of AYERS ROCK, myths, no essence ...
Hi,

Generally, each designer should develope his/her own feel for relating the CSD (and any other data) with his/her own listening experience. I'm sure proffesionals will have a small group of people that help in the listening process, normally consists of people in the same target customer category.

Most DIYers are looking for some canned standards and methods. If this actually existed with exceptional quality results, audio would not be as fun. Basically, one needs to look at various decay patterns and listen to them to get a feel for how to interprete the data. The only thing I would strongly recommend is to start with full range driver designs. Once one have developed the feel, it's easier to determine the effects in multiway systems design.
 
Disabled Account
Joined 2009
soongsc said:

Hi, ... Most DIYers are looking for some canned standards and methods. If this actually existed with exceptional quality results, audio would not be as fun. ... Once one have developed the feel, it's easier to determine the effects in multiway systems design.

Hi,

I won't discuss that to the end. The feel of something ain't a good guideline whilst constructing an engine. Looks ain't either. A CSD is in the first place some data expressed in numbers, generated by sophisticated mathematics and in the end represented as some kind of fancy graphics.

The graphics gives a sketch on what is going on with driver/radiation/filtering etc. On the other hand it makes it a hard job to differenciate between situations. Comparison is made much simpler with 2-dimensional data: (1) amplitude over frequency, (2) group delay. Which both are totally equivalent to the CSD. No difference but that CSD is much harder to read, if numbers are of interest. To have a grip on a problem, I would of course prefer the data that I can know instead of looks, feels and the like.

so long
 
Numbers & such

Being an electrochemical engineer myself, I'd be the last person to dispute the engineering validity of quality data for designs...

However, that said, I've been chastised by certain parties when presenting data looking at least as good as much presented here alledgedly supporting the superiority of whatever speaker/technology is being discussed, usually with a tone intended to discredit any validity to what I asked, often with an implied patronizing "how could you present such useless data in a public forum" dimissive demeanor.

I can only chuckle when I see subsequent data presented by others supporting the very situation I pointed out; only difference is now it's their system, not mine. :D

Since so much of this "data" lacks any mention of conditions used to generate it (it seems to be implied that the pros have already made sure the experimental conditions are valid and the data interpretations and presentations beyond reproach) I don't give much credence to much of the content other than as entertainment value and testosterone strutting. as always, ymmv

If all this technical stuff were truly beyond question, folks would give the experimental conditions, assumptions made, error analysis, and limits on validity, rather than just put up some fancy graph and say "look how this supports <whatever> my position on <whatever>"

just my 2 cents...

John L
 
xpert said:


Hi,

I won't discuss that to the end. The feel of something ain't a good guideline whilst constructing an engine. Looks ain't either. A CSD is in the first place some data expressed in numbers, generated by sophisticated mathematics and in the end represented as some kind of fancy graphics.

The graphics gives a sketch on what is going on with driver/radiation/filtering etc. On the other hand it makes it a hard job to differenciate between situations. Comparison is made much simpler with 2-dimensional data: (1) amplitude over frequency, (2) group delay. Which both are totally equivalent to the CSD. No difference but that CSD is much harder to read, if numbers are of interest. To have a grip on a problem, I would of course prefer the data that I can know instead of looks, feels and the like.

so long
Each person have their own way and capabilities. This is nothing new. Amplitude and group delay are the basics. I agree.
When looking at CSD data, it's necessary to look at various time resolutions and the amplitude of each curve in time. This is more complicated. CSD is basically a series of SPL curves at different times.
 
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Joined 2009
soongsc said:
CSD is basically a series of SPL curves at different times.

Hi,

that is exactly the common misconception about CSD. From that all that insane overemphasized interpretations follow. CSD -is- group delay and amplitude over frequency and absolutely nothing more. Mathematics simply doesn't has space left for any other. You might hold me as a fool. CSD is -nothing- else than that.

This for CSD can merely be replaced with more handsome group delay and amplitude values. From these one knows which values might be critical and which not. That simple, take it for granted.

by
 
xpert said:


Hi,

that is exactly the common misconception about CSD. From that all that insane overemphasized interpretations follow. CSD -is- group delay and amplitude over frequency and absolutely nothing more. Mathematics simply doesn't has space left for any other. You might hold me as a fool. CSD is -nothing- else than that.

This for CSD can merely be replaced with more handsome group delay and amplitude values. From these one knows which values might be critical and which not. That simple, take it for granted.

by

Your statement fails here.

The problem is that you saying something is "Y" instead of "X", but haven't sufficiently described "Y" nor how "Y" is different than "X".

More specifically: what is "group delay", and there after "group delay and amplitude over frequency", and how is it different than "CSD is basically a series of SPL curves at different times".
 
xpert said:


Hi,

that is exactly the common misconception about CSD. From that all that insane overemphasized interpretations follow. CSD -is- group delay and amplitude over frequency and absolutely nothing more. Mathematics simply doesn't has space left for any other. You might hold me as a fool. CSD is -nothing- else than that.

This for CSD can merely be replaced with more handsome group delay and amplitude values. From these one knows which values might be critical and which not. That simple, take it for granted.

by
This is just looking at data from different viewpoints. I'm with ScottG on his question.:D
 
soongsc said:

This is just looking at data from different viewpoints. I'm with ScottG on his question.:D

CSD is not "basically a series of SPL curves at different times"...

this is an erroneous interpretation in my opinion.

What it does seem to show is how an original impulse at time zero decays over a set time interval over the bandwidth allowable under testing constraints.

To state that it's a bunch of spl curves at different times implies that the time > 0 curves can be generated independent of the time = 0 curve, which is not the case.

John L
 
"CSDs can be compared to each other. But what does a difference tell about sound quality?"

This is exactly right. As an engineer, the CSD plots are great summaries of data, but what do they mean?

I recall that Jon Ver Halen posted CSD plots of the Lowther DX4 drivers with and without Bud Purvine's enABL treatment. The CSD plots showed more stored energy in the enABL-treated driver which suggests poorer audio behavior and sound. But those who have heard the enABL treated DX4 drivers prefer them to those who have not heard them - and not by a little bit.

Perhaps there is information that speaker designers can glean from such plots, but I am in the same camp as yourself. I look at them but I am not willing to make any conclusions about sound quality based on those plots.

Retsel
 
Retsel said:
"CSDs can be compared to each other. But what does a difference tell about sound quality?"

This is exactly right. As an engineer, the CSD plots are great summaries of data, but what do they mean?

I recall that Jon Ver Halen posted CSD plots of the Lowther DX4 drivers with and without Bud Purvine's enABL treatment. The CSD plots showed more stored energy in the enABL-treated driver which suggests poorer audio behavior and sound. But those who have heard the enABL treated DX4 drivers prefer them to those who have not heard them - and not by a little bit.

Perhaps there is information that speaker designers can glean from such plots, but I am in the same camp as yourself. I look at them but I am not willing to make any conclusions about sound quality based on those plots.

Retsel

These issues are common in audiophilia, and I would argue that it represents a disconnect between what we measure and what we hear. However, do need to assume that what people heard was real. It's possible that the claimed superiority is nothing more than, I spent all that time or and/or money, I want it to sound better, so it does. The other issue, the disconnect issue, has to do with interpretation of measurements. The assumption is that lower stored energy, as shown in a CSD, will equate to better sound. However, is this true? It completely possible that, as has been shown in numerous distortion audibility tests, the ENABL process creates a sort of distortion we find desirable.

An additional and related issue is, what sounds better? We can argue that better is some concrete measurable variable. We can even argue that "sounds better" is something concrete and measurable, this might be something like the results for the average person (DBT's with a statistically diverse and representative sample), but none of this means that for every individual, "sounds better" is always the same thing. I might feel that large amounts of odd order distortion is desirable, the average person may disagree, but if I prefer it, then it sounds better to me. This makes equating something like a CSD plot against qualitative terms like, "Sounds better" very difficult, if not impossible, for all individuals. I like the way Dr. Geddes has described this issue before. We can't talk about all individuals, but we can talk about the average person (this is essentially the definition of the statistical models we use, we talk in terms of means comparisons). I think that those who like Lowther drivers and/or techniques like the ENABL treatment, are not the "average" person discussed. They are a very unique sample of people, who often also like things like singled ended triode tube amps, again, not average and not mainstream. I would guess that a large scale blind listening test session with a representative sample would indicate that the average person doesn't find those better, but that a select sample does.
 
Uhh ... so many comments - maybe next time I shouldn't complain (hugh)

xpert said:



CSD is quite useless. ...It's apperance leaves room for some free style interpretations. But that means nothing but confusion. ....

have fun


xpert said:


... CSD is about NUMBERS. ...In short, what is the meaning of that numbers the CSD presents to the DIYer?

... the representation lacks info due to the falling characteristics towards the high end, especially that data is of less use than one might project into it ... pps: and so it is for nearly any CSD I've seen yet, big sunny picture of AYERS ROCK, myths, no essence ...


xpert said:


I won't discuss that to the end...

A CSD is in the first place some data expressed in numbers, generated by sophisticated mathematics and in the end represented as some kind of fancy graphics.
... To have a grip on a problem, I would of course prefer the data that I can know instead of looks, feels and the like.



Below the data - consisting of mere numbers - you'r asking for.
Will be looking forward to your interpretation - Mr. Xpert - *without* the use of any processing or visualisation of course.
;)

Have fun!
:)

Impulse reponse
Numpoints = 65535
SamplingRate = 44100 Hz
Time(s) Amplitude(V)
0.000000E+000 4.978819E-005
2.267574E-005 8.200338E-005
4.535147E-005 1.155576E-004
6.802721E-005 1.411281E-004
9.070295E-005 1.541958E-004
1.133787E-004 1.608117E-004
1.360544E-004 1.666615E-004
1.587302E-004 1.560761E-004
1.814059E-004 1.415217E-004
2.040816E-004 1.312348E-004
2.267574E-004 1.224472E-004
2.494331E-004 1.151417E-004
2.721088E-004 1.091725E-004
2.947846E-004 1.108898E-004
3.174603E-004 1.055525E-004
3.401361E-004 9.352512E-005
3.628118E-004 7.463079E-005
3.854875E-004 5.536318E-005
4.081633E-004 2.999350E-005
4.308390E-004 3.761063E-006
4.535147E-004 -1.973561E-005
4.761905E-004 -3.686181E-005
4.988662E-004 -5.279817E-005
5.215420E-004 -5.776405E-005
5.442177E-004 -6.138336E-005
5.668934E-004 -5.032311E-005
5.895692E-004 -2.638847E-005
6.122449E-004 -1.251786E-005
6.349206E-004 8.793495E-006
6.575964E-004 1.746080E-005
6.802721E-004 2.808169E-005
7.029478E-004 2.962167E-005
7.256236E-004 3.607315E-005
7.482993E-004 3.958962E-005
7.709751E-004 4.673347E-005
7.936508E-004 5.603916E-005
8.163265E-004 7.176112E-005
8.390023E-004 8.202020E-005
8.616780E-004 8.945186E-005
8.843537E-004 9.264094E-005
9.070295E-004 9.349603E-005
9.297052E-004 8.714029E-005
9.523810E-004 6.733047E-005
9.750567E-004 5.382451E-005
9.977324E-004 2.838038E-005
1.020408E-003 -1.612971E-006
1.043084E-003 -2.545841E-005
1.065760E-003 -5.232329E-005
1.088435E-003 -7.512701E-005
1.111111E-003 -8.971974E-005
1.133787E-003 -1.150971E-004
1.156463E-003 -1.343715E-004
1.179138E-003 -1.644310E-004
1.201814E-003 -1.827846E-004
1.224490E-003 -1.854525E-004
1.247166E-003 -1.770450E-004
1.269841E-003 -1.694493E-004
1.292517E-003 -1.565076E-004
1.315193E-003 -1.550580E-004
1.337868E-003 -1.566784E-004
1.360544E-003 -1.641269E-004
1.383220E-003 -1.675687E-004
1.405896E-003 -1.716496E-004
1.428571E-003 -1.902323E-004
1.451247E-003 -1.982230E-004
1.473923E-003 -2.030993E-004
1.496599E-003 -2.062584E-004
1.519274E-003 -1.999993E-004
1.541950E-003 -1.903806E-004
1.564626E-003 -1.857201E-004
1.587302E-003 -1.628930E-004
1.609977E-003 -1.546867E-004
1.632653E-003 -1.406611E-004
1.655329E-003 -1.287366E-004
1.678005E-003 -1.277409E-004
1.700680E-003 -1.166425E-004
1.723356E-003 -1.035604E-004
1.746032E-003 -8.462804E-005
1.768707E-003 -7.016260E-005
1.791383E-003 -5.838831E-005
1.814059E-003 -4.670287E-005
1.836735E-003 -4.946134E-005
1.859410E-003 -5.204065E-005
1.882086E-003 -5.341549E-005
1.904762E-003 -5.679822E-005
1.927438E-003 -5.736984E-005
1.950113E-003 -6.384457E-005
1.972789E-003 -6.850538E-005
1.995465E-003 -7.404288E-005
2.018141E-003 -7.073495E-005
2.040816E-003 -5.690942E-005
2.063492E-003 -3.756748E-005
2.086168E-003 -1.702972E-005
2.108844E-003 4.014330E-006
2.131519E-003 1.728948E-005
2.154195E-003 2.356351E-005
2.176871E-003 3.670547E-005
2.199546E-003 4.248914E-005
2.222222E-003 4.094214E-005
2.244898E-003 4.277102E-005
2.267574E-003 3.770122E-005
2.290249E-003 3.295886E-005
2.312925E-003 1.529059E-005
2.335601E-003 1.077327E-006
2.358277E-003 -2.032949E-005
2.380952E-003 -3.987244E-005
2.403628E-003 -6.032026E-005
2.426304E-003 -8.210728E-005
2.448980E-003 -9.386011E-005
2.471655E-003 -1.058793E-004
2.494331E-003 -1.126294E-004
2.517007E-003 -1.185533E-004
2.539683E-003 -1.198617E-004
2.562358E-003 -1.133495E-004
2.585034E-003 -9.533159E-005
2.607710E-003 -6.579189E-005
2.630385E-003 -3.397748E-005
2.653061E-003 -9.395209E-006
2.675737E-003 2.186144E-005
2.698413E-003 5.342256E-005
2.721088E-003 7.023686E-005
2.743764E-003 7.888185E-005
2.766440E-003 8.789096E-005
2.789116E-003 8.680589E-005
2.811791E-003 8.909500E-005
2.834467E-003 7.853291E-005
2.857143E-003 7.327774E-005
2.879819E-003 7.086909E-005
2.902494E-003 5.427035E-005
2.925170E-003 4.465881E-005
2.947846E-003 3.963392E-005
2.970522E-003 3.213442E-005
2.993197E-003 2.684135E-005
3.015873E-003 1.636058E-005
3.038549E-003 1.059276E-005
3.061224E-003 1.597342E-005
3.083900E-003 3.706929E-005
3.106576E-003 6.968741E-005
3.129252E-003 1.036784E-004
3.151927E-003 1.394112E-004
3.174603E-003 1.721324E-004
3.197279E-003 2.059761E-004
3.219955E-003 2.394627E-004
3.242630E-003 2.724809E-004
3.265306E-003 3.096776E-004
3.287982E-003 3.481819E-004
3.310658E-003 3.853184E-004
3.333333E-003 4.158767E-004
3.356009E-003 4.376785E-004
3.378685E-003 4.548866E-004
3.401361E-003 4.732991E-004
3.424036E-003 4.882468E-004
3.446712E-003 4.847987E-004
3.469388E-003 4.808728E-004
3.492063E-003 4.711728E-004
3.514739E-003 4.554593E-004
3.537415E-003 4.363849E-004
3.560091E-003 4.344968E-004
3.582766E-003 4.343704E-004
3.605442E-003 4.342516E-004
3.628118E-003 4.346456E-004
3.650794E-003 4.426065E-004
3.673469E-003 4.421764E-004
3.696145E-003 4.535863E-004
3.718821E-003 4.616954E-004
3.741497E-003 4.722354E-004
3.764172E-003 4.730160E-004
3.786848E-003 4.732915E-004
3.809524E-003 4.628926E-004
3.832200E-003 4.566626E-004
3.854875E-003 4.621565E-004
3.877551E-003 4.614130E-004
3.900227E-003 4.653154E-004
3.922902E-003 4.602826E-004
3.945578E-003 4.647135E-004
3.968254E-003 4.608776E-004
3.990930E-003 4.713660E-004
4.013605E-003 4.858016E-004
4.036281E-003 4.967210E-004
4.058957E-003 5.140108E-004
4.081633E-003 5.314787E-004
4.104308E-003 5.396187E-004
4.126984E-003 5.455728E-004
4.149660E-003 5.469846E-004
4.172336E-003 5.567462E-004
4.195011E-003 5.656570E-004
4.217687E-003 5.713064E-004
4.240363E-003 5.705704E-004
4.263039E-003 5.726222E-004
4.285714E-003 5.666830E-004
4.308390E-003 5.644757E-004
4.331066E-003 5.591016E-004
4.353741E-003 5.523742E-004
4.376417E-003 5.381099E-004
4.399093E-003 5.316719E-004
4.421769E-003 5.157728E-004
4.444444E-003 5.039459E-004
4.467120E-003 4.841660E-004
4.489796E-003 4.623049E-004
4.512472E-003 4.379607E-004
4.535147E-003 4.264317E-004
4.557823E-003 4.102869E-004
4.580499E-003 3.901879E-004
4.603175E-003 3.648174E-004
4.625850E-003 3.203221E-004
4.648526E-003 2.813121E-004
4.671202E-003 2.323559E-004
4.693878E-003 1.769494E-004
4.716553E-003 1.281274E-004
4.739229E-003 7.188765E-005
4.761905E-003 1.688794E-005
4.784580E-003 -3.127137E-005
4.807256E-003 -6.956058E-005
4.829932E-003 -1.052631E-004
4.852608E-003 -1.405042E-004
4.875283E-003 -1.673679E-004
4.897959E-003 -2.061543E-004
4.920635E-003 -2.521440E-004
4.943311E-003 -2.997394E-004
4.965986E-003 -3.482784E-004
4.988662E-003 -4.078855E-004
5.011338E-003 -4.593985E-004
5.034014E-003 -5.184414E-004
5.056689E-003 -5.729494E-004
5.079365E-003 -6.281788E-004
5.102041E-003 -6.819656E-004
5.124717E-003 -7.400267E-004
5.147392E-003 -7.907668E-004
5.170068E-003 -8.480542E-004
5.192744E-003 -9.078326E-004
5.215420E-003 -9.675220E-004
5.238095E-003 -1.019161E-003
5.260771E-003 -1.081883E-003
5.283447E-003 -1.142441E-003
5.306122E-003 -1.211244E-003
5.328798E-003 -1.279667E-003
5.351474E-003 -1.360891E-003
5.374150E-003 -1.448537E-003
5.396825E-003 -1.563946E-003
5.419501E-003 -1.687978E-003
5.442177E-003 -1.826177E-003
5.464853E-003 -1.976581E-003
5.487528E-003 -2.121865E-003
5.510204E-003 -2.271140E-003
5.532880E-003 -2.413033E-003
5.555556E-003 -2.554629E-003
5.578231E-003 -2.689729E-003
5.600907E-003 -2.813375E-003
5.623583E-003 -2.930984E-003
5.646259E-003 -3.043323E-003
5.668934E-003 -3.154562E-003
5.691610E-003 -3.261334E-003
5.714286E-003 -3.366707E-003
 
Michael - that list of numbers sounds great!;)

Just to add to what Matt said, we have to be clear on the difference between "preference" and "accuracy" - they can be dramatically different things. I only ever deal in accuracy, not preference for the simple reason that preference has no answer, but accuracy does. So figure out which camp you are in first and then you can begin to understand how one could "prefer" ENable while its is clearly less "accurate" if the CSD has large decay ridges.

CSD is not meaningless, its just not everything either. Its shows nothing that the impulse response itself doesn't show.
 
One interpretation problem I have with CSD is that people sometimes make big deals out of very small changes. For instance, using CSD to look at room dampening. Let's say you have two graphs, one with and one without XYZ room dampening, and you show that, at the 0 time point, there is an average smoothing of 1db. In other words, if there was a peak or null, it's now reduced by 1db in severity, on average. However, as 10ms out, you see that what was once a visible decay ridge, had now been reduced to non-visible or much less visible, what does that mean. Common interpretation is that this room dampening has created a massive audible difference. In reality, I would argue it's minute, and probably not audible. The decay ridge needs to be looked at in absolute db terms as well, no? If it's already down 30 or 40db's, what will this delayed sound do to the audible signal, I would think probably very little or nothing. If the signal, which is 40db's down, is then reduced to 45db's down, is that audible? Have we really reduced the "ringing" in the room in some important or significant way?
 
auplater said:


CSD is not "basically a series of SPL curves at different times"...

this is an erroneous interpretation in my opinion.

What it does seem to show is how an original impulse at time zero decays over a set time interval over the bandwidth allowable under testing constraints.

To state that it's a bunch of spl curves at different times implies that the time > 0 curves can be generated independent of the time = 0 curve, which is not the case.

John L


As a statement, that is a LOT better.

However,

"..a bunch of spl curves at different times *implies*" (emphasis on "implies")

..that soongsc's statement "implies" this - is a matter of perspective. Note the word "basically" in his statement, it's a caveat in relation to the context of the discussion.
 
Jmmlc said:
Hello mige0,

It seems that the window rise time of the CSD you obtained using Arta on Earl's pulses is not the same that you used previously for the CDS in your message:

http://www.diyaudio.com/forums/showthread.php?postid=1818279#post1818279

Could you indicate the parameters used to obtain those CSD:

FFT size
Window rise time
Slice shift
Smoothing

(you said in your CSD comments that the decay was excellent, could you specify the frequency above which you consider the decay being excellent...)

Best regards from Paris, France

Jean-Michel Le Cléac'h




Sharp observer you are.
Yes its been my mistake (1/3 octave smoothing at CSD processing) as I did processing of Ears IR fils at a different PC – hence not the same settings for the CSD .



Settings used now (1/12 octave smoothing at CSD processing) - same as done for Earls OS CSD plots:

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same pix form same JA8008 twin in OB as before

acoustic target:

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on axis

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15 deg

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30deg

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45 deg

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Conclusions remain the same – pretty good at the point of equalisation getting worse towards wider angles.

The point here is that we *add decay* at other than 0deg – as of the optimised filter used for close to ideal on axis response.

Thinking about it – its not exactly the same as comb filtering out of that very reason. Comb filtering would not have a (PC-XO) filter behind that "stores energy" with the intent to release it at exactly that moment where it is necessary to get close to ideal impulse shaping on axis.

Regarding Earl decay time I think about roughly 2kHz its excellent.
At least to me anything below 1msec for the 25dB shown is OK – no need to be picky about another 1/10 of a msec.

I admit that the falling FR is in favour to Earl – but I didn't want to be unfair in my comparison OB versus OS.
I – of course - had a look way down the dB scale and it looks as expected - nothing strange happening there...

The main difference is that Earls CSD are made from an (small) compression driver where as the twin Jantzen OB is a 8" – so not exactly comparable anyway – but good enough for me to get a handle on the subject as I especially was interested if we could see any mouth reflections that translate to CSD decay.


Michael