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Old 14th October 2012, 07:58 PM   #381
Elias is offline Elias  Finland
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John,

Would you provide us some more information to make useful conclusions.

Room size ?
Speaker position ?
Mic position ?
Wall (celing, floor) materials ?
Acoustic treatments ?


It strongly looks like you are not living in a stone house


- Elias
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Old 14th October 2012, 08:22 PM   #382
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John ... my only gripe ... your choice of blue and violet. I can't tell which is which. Maybe a nice orange for either next time?

:P
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Old 14th October 2012, 08:38 PM   #383
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Originally Posted by gedlee View Post
I am sure people will see huge differences where I see little, but in these last few weeks before the election that's pretty common place.
Yes, with the peaks and dips in the frequency responses they're difficult to compare. I don't know what to make of it all. I couldn't see how one could draw useful conclusions from this, except that the monopole is much more efficient below 60 Hz.

Might it be interesting to add EQ based on a spatial average and then compare again?
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Old 14th October 2012, 09:09 PM   #384
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Originally Posted by Elias View Post
John,

Would you provide us some more information to make useful conclusions.

Room size ?
Speaker position ?
Mic position ?
Wall (ceiling, floor) materials ?
Acoustic treatments ?


It strongly looks like you are not living in a stone house


- Elias
This is a dedicated listening room build in the basement of my home. The room is approximately 16' wide by 20' long. The ceiling height is nominally 7' 2" but is stepped by about 3' in one area and has an 8" drop down across the length about 3' wide (to cover AC duct work). There is a sub floor over the concrete which is fully carpeted. The back wall is studs build against the concrete basement wall. The side walls are 2x4 studs with sheet rock on both sides. These walls are not against the concrete basements wall as there are other areas to each side of the listening room. The front wall (behind the speakers is also 2x4 studs and there is an air space about 2' wide between this wall and the concrete basement wall. The ceiling is also sheet rock on the 8" floor joists above. All walls and ceiling is insulated with fiberglass. There is also an alcove along one side wall that extends to the back (listening end) and also leads to the staircase up. So the room has a "stubby L" shape.

There are medium weight drapes behind the speakers. Side walls and back wall have no acoustic treatment other that a scattering of pictured in frames. My listening chair and a TV on one side wall are the only furniture but there are several other speaker system stored in one corner and there is an equipment cabinet between the speaker positions.

The acoustic center of the woofer was 3' 3" from a side wall, 4'3" from the front wall. This is the nominal position of my speakers as well. The mic was 5' 8" from the back wall, 3' high and centered left to right, at the listening position. Over all, above 100 or 200 Hz, RT60 is about 300 to 350 msec, which is in line with BBC type rooms, which is what I prefer.
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Old 14th October 2012, 09:11 PM   #385
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John ... my only gripe ... your choice of blue and violet. I can't tell which is which. Maybe a nice orange for either next time?

:P
The violet trace is the middle one at low frequency. It acrually look more black than violet.
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Old 14th October 2012, 10:15 PM   #386
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At what distance are those CSD taken?
About 10' or a little over 3M.
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Old 14th October 2012, 10:25 PM   #387
Elias is offline Elias  Finland
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Although we don't have modulation analysis results from John's system so the comparison is not possible, based on CSD it looks like in a purpose built dedicated listening room the differences between sources seem to be moderate.

Now try the same in a small shoebox living room in a concrete condominium. A different story alltogether.


- Elias
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Old 14th October 2012, 10:45 PM   #388
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Originally Posted by Elias View Post
Although we don't have modulation analysis results from John's system so the comparison is not possible, based on CSD it looks like in a purpose built dedicated listening room the differences between sources seem to be moderate.

Now try the same in a small shoebox living room in a concrete condominium. A different story alltogether.


- Elias
I have to admit that I am still struggling to understand the difference between the wavelet analysis and the raised cosine burst response. For clarity let me strees that the CSD is not a typical CSD. It is the burst response plotted as a waterfall. The sonogram is the same data, just plotted differently.
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Old 14th October 2012, 11:13 PM   #389
Elias is offline Elias  Finland
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Originally Posted by john k... View Post
I have to admit that I am still struggling to understand the difference between the wavelet analysis and the raised cosine burst response. For clarity let me strees that the CSD is not a typical CSD. It is the burst response plotted as a waterfall. The sonogram is the same data, just plotted differently.

If the 'wavelet' is formulated having a raised cosine envelope then there is no difference with this 'non typical CSD', except slight mathematical issues like no imaginary part in a tone 'burst'. There are also different methods to calculate envelope. Overall it may also depend on how strick sense we need to define a 'wavelet'.

Still, one would hope to derive some modulation related parameters out from the measurements as it would give more relation of perception of music signals.

- Elias
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Old 15th October 2012, 04:59 AM   #390
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Thanks John for posting the measurements.

Just wanted a few clarifications:
1) Were the three bass units equalised to have a similar bass extension.
2)What was the BW tested.
3)Was the same driver used in the three units...or is it the same cabinet that was interchangeable into a monopole/cardioid/dipole.
4)Since the measurements look very similar above 50 Hz, what was your subjective perception comparing the three. Even as per Dr. Geddes from 125 to 500 Hz, dipoles may have benefits over other units, perhaps due to directivity (if I understood him correctly).

Thanks again for your measurements.
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