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Old 24th March 2008, 01:18 PM   #121
dlr is offline dlr  United States
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Quote:
Originally posted by Carlp


Here, here. And since we can't speculate on whether or not there is even anything to measure, and theory says virtually nothing will happen, and data we've seen so far says almost nothing happens, this thread will now be closed for lack of anything to talk about...



Carl
No skeptic of the mechanism, not one, has ever said nothing will happen. You're being disingenuous. But your suggestion of what to do is actually closer to the truth than anything else in any of the threads.

In any case, why was it even necessary to split the thread? If this is simply going to be "EnABL 2" with any and all aspects allowed (as long as it "might" do something), of what use is it if any and all aspects are to be allowed? Minor points, fine. Extensive posts that are primarily on "technique" have a thread dedicated to them. Add a link to posts in the other thread, that was how it was suggested it be done (by the moderators, I believe) before the split occurred.

So how about a comment on john's post? Why is it that a post with such significant implications is left without response by most? Someone, anyone, provide your analysis of the hard data. Hard data gets short shrift here. Is it because it's all been contradictory?

Dave
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Old 24th March 2008, 01:28 PM   #122
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Quote:
Originally posted by dlr

Alex, most of your posts should be made in the other thread. That thread is on technique and you can say whatever you care to there. That was the reason for the split in the first place, was it not? All "testing" you have made has been nothing but unsupported subjective listening.
dlr,

1) None of my posts in this technical thread have been subjective.
2) You had the opportunity to put my claims re baffle and ports to the test - you declined and made excuses.

Daygloworange has decided to put EnABL on baffles and ports to the test.
Personally, I'm delighted to have my 'unsupported subjective listening' put to the test by objective measurement.
It will be very interesting to see how this 'hard data' is interpreted.

Cheers,

Alex
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Old 24th March 2008, 01:36 PM   #123
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Default Baffle diffraction

I have looked at whether an obstacle of the order of an Enable patch could alter diffraction.

Description of the test set up:

Vifa MG10 flush mounted on large 23" x 25" baffle.

A single ring of "pin strip" tape was applies in a circular pattern 8 1/2" in diameter centered around the driver. Tap is 1/8" wide, 0.0035" thick (height off the baffle).

Mic positioned 5 1/2" from driver dust cap on axis.

This yielded a propagation delay of about 0.423 msec from driver AC to mic, and about a 1 msec delay before any diffraction form the tap pattern would reach the mic.

A circular pattern was chosen because it maximized the effect of diffraction from the tape.

The pattern was applied and the measurement made. Without moving anything the tap was removed from the baffle and a second measurement made.

The following figures speak for them selves.

Upper: Impulse response for no ring, white, and with ring, brown.

Lower: over lay of the two plots above.

Click the image to open in full size.


Next plot, same as above but vertical scale magnified 5 times.

Click the image to open in full size.

Next plot, same as first but vertical scale magnified 50 times. Only overlay shown.

Click the image to open in full size.


This last plot is an attempt to quantify the errors in repeated measurements. This is an overlay of two successive measurements made without the rings with the vertical scale magnified 50 time. Since full scale is -34dB it is apparent that any differences are at lease another factor of ten below that or better that -54dB.

Click the image to open in full size.

In case you miss the point, there aren't any differences due to the diffraction ring. Painting little dashes on you baffle will do nothing.

There is one another conclusion which can be drawn form this test. Enable patches applied to any surface, driver, port.... are too small to result in any significant disruption of acoustic wave propagation across a surface. This is more evidence to support the idea that application of enable paint results only is altered cone vibration due to a change in cone properties after application. It also sort of puts to rest the idea that there is something different happening in some kind of BL (which has never been defined).
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Old 24th March 2008, 01:52 PM   #124
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Default Re: Baffle diffraction

Quote:
Originally posted by john k...
[B]I have looked at whether an obstacle of the order of an Enable patch could alter diffraction.

Description of the test set up:

Vifa MG10 flush mounted on large 23" x 25" baffle.

A single ring of "pin strip" tape was applies in a circular pattern 8 1/2" in diameter centered around the driver. Tap is 1/8" wide, 0.0035" thick (height off the baffle).

Mic positioned 5 1/2" from driver dust cap on axis.
What does the diffraction impulse look like? I don't see it in the scale?
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Old 24th March 2008, 02:04 PM   #125
dlr is offline dlr  United States
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Default Re: Re: Baffle diffraction

Quote:
Originally posted by soongsc

What does the diffraction impulse look like? I don't see it in the scale?
That is the point. If there were any changes due to diffraction, they would appear as changes in the impulse response at the vertical line labeled "path length delay for diffraction ring". As is evident, there is no change in the impulse response.

Dave
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Old 24th March 2008, 02:16 PM   #126
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Default Re: Re: Re: Baffle diffraction

Quote:
Originally posted by dlr


That is the point. If there were any changes due to diffraction, they would appear as changes in the impulse response at the vertical line labeled "path length delay for diffraction ring". As is evident, there is no change in the impulse response.

Dave
I mean I don't see the baffle edge diffraction inpulse. That is what we really want to change. I don't think the pattern should create new diffraction impulses that are obviously measurable, and thus the data is data presented by John K is what I would expect. But we should look at the changes in the baffle edge diffraction impulse.
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Old 24th March 2008, 02:23 PM   #127
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Default Re: Re: Baffle diffraction

Quote:
Originally posted by soongsc

What does the diffraction impulse look like? I don't see it in the scale?


George, you really make me wonder what you are looking at. You can see the effect of the diffraction from the diffraction ring in the plots because there isn't any effect that is greater than maybe -60dB. I can't show you something that doesn't exist. There is no edge diffraction because the baffle is large the edge diffraction would be at a much later time. I'm sure that may not sit well with some. They will ask, how can this show that edge diffraction isn't changed by enable patches. In response I would say if you don't understand, then you don't understand acoustics. Acoustic waves don't take evasive action. They don't see a change in a surface (enable patch or baffle edge) until they get there. So if a ring about the dimensions of an enable patch is place away from the baffle edge and has no effect was so ever (to -60dB or more) on the resulting impulse response, thus no effect on the wave propagation, then it won't have an effect if placed nearer the edge either. There is no room for argument. The intent of this experiment is precisely to remove the effect of the edge so that the effect (or lack thereof) of the patches can be observed independently. The conclusion is irrevocable. A 1/8 wide, 0.0035 high bump on a surface is invisible to an acoustic wave in the audible frequency range. It won't alter the wave that reaches the edge and it won't alter any wave generated by the edge that propagated back across the patch.

No need to discuss it further.
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Old 24th March 2008, 02:27 PM   #128
soongsc is offline soongsc  Taiwan
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Default Re: Re: Re: Baffle diffraction

Quote:
Originally posted by john k...




George, you really make me wonder what you are looking at. You can see the effect of the diffraction from the diffraction ring in the plots because there isn't any effect that is greater than maybe -60dB. I can't show you something that doesn't exist. There is no edge diffraction because the baffle is large the edge diffraction would be at a much later time. I'm sure that may not sit well with some. They will ask, how can this show that edge diffraction isn't changed by enable patches. In response I would say if you don't understand, then you don't understand acoustics. Acoustic waves don't take evasive action. They don't see a change in a surface (enable patch or baffle edge) until they get there. So if a ring about the dimensions of an enable patch is place away from the baffle edge and has no effect was so ever (to -60dB or more) on the resulting impulse response, thus no effect on the wave propagation, then it won't have an effect if placed nearer the edge either. There is no room for argument. The intent of this experiment is precisely to remove the effect of the edge so that the effect (or lack thereof) of the patches can be observed independently. The conclusion is irrevocable. A 1/8?wide, 0.0035?high bump on a surface is invisible to an acoustic wave in the audible frequency range.

No need to discuss it further.
If the ring causes diffraction waves that are significantly high, then it just makes things worse rather than than improve the situation.
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Old 24th March 2008, 02:30 PM   #129
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The rings don't do S*%$, nada, nothing, zero, squat, good or bad.
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Old 24th March 2008, 02:32 PM   #130
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Default Re: Baffle diffraction

G'day john k,

There are a couple of points of difference with what you have tested and my application of EnABL to baffles:
- for a baffle of 23" x 25" I would be using a block size of 1" x 1/2"
- the EnABL pattern would be applied 1/2" in from the edge of the baffle
- I always use two pattern rings, not a single ring
- the differences as heard are at the listening position, not close to the driver.

I don't question your results, but the method used to test in this instance doesn't seem (to me) to correspond with how I am applying EnABL.
The measurement shows the impact of the tape in the middle the baffle, not at the edge of the baffle.

I have found that laying a plain strip of Scotch magic tape on a baffle edge makes no audible change.
Yet when I apply magic tape with the EnABL blocks stuck on top, there is an audible change.

Cheers,

Alex
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