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Multi-Way Conventional loudspeakers with crossovers

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Old 7th May 2009, 11:00 AM   #5401
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by mige0
Courtesy Earl

OS wave guide at 0 deg:

Click the image to open in full size.


OS wave guide at 15 deg:


Click the image to open in full size.


OS wave guide at 30 deg:


Click the image to open in full size.


OS wave guide at 45 deg:


Click the image to open in full size.



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?
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Old 7th May 2009, 11:06 AM   #5402
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by xpert



...

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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Old 7th May 2009, 11:33 AM   #5403
xpert is offline xpert  Afghanistan
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Quote:
Originally posted by soongsc

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 ...
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Old 7th May 2009, 12:19 PM   #5404
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by xpert


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.
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Old 7th May 2009, 12:44 PM   #5405
xpert is offline xpert  Afghanistan
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Quote:
Originally posted by soongsc

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
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Old 7th May 2009, 01:41 PM   #5406
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Default 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.

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
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Old 7th May 2009, 03:41 PM   #5407
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by xpert


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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Old 7th May 2009, 05:14 PM   #5408
xpert is offline xpert  Afghanistan
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Quote:
Originally posted by soongsc
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
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Old 7th May 2009, 05:33 PM   #5409
ScottG is offline ScottG  United States
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Quote:
Originally posted by xpert


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".
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Old 7th May 2009, 05:40 PM   #5410
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by xpert


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.
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