Measured monopole and dipole room responses
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diyAudio Member

Join Date: May 2003
Location: Where you live
Hello,

Here comes more measurement results Again the purpose is to study the room response of speakers having different radiation patterns.

I did several measurements in four locations A, B, C and D in the room. See the pic for positions.

I measured the following speakers:

- Monopole bass. One 12" element in a 100 litres closed box.

- Dipole bass. Two 12" elements in a H frame.

- Monopole bass-midrange. One 6.5" element in a 12 litres closed box.

- Dipole bass-midrange. One 8" element in a small open baffle.

- Dipole line array. Eight 6.5" elements in a vertical narrow baffle having height of 1.5 m.

The measurement signal is the same as before. It is a 5 cycle sinusoidal burst having Hanning envelope. Burst frequencies are spaced at 1/12 octave.

- Elias
Attached Images
 paikat_geometria_a-b-c-d_da.png (12.2 KB, 559 views)
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diyAudio Member

Join Date: May 2003
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At first, let's examine the frequency range of 20Hz-100Hz.

Here's the monopole bass room response:
Attached Images
 monopolebass_a-b-c-d_spektrogram_20-100hz_da_resize_90.jpg (79.7 KB, 586 views)
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diyAudio Member

Join Date: May 2003
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And here's the dipole bass:
Attached Images
 h-dipolebass_a-b-c-d_spektrogram_20-100hz_da_resize.png (97.5 KB, 569 views)
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diyAudio Member

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Here's the monopole bass envelope magnitude and envelope delay frequency responses.

The envelope magnitude is the maximum value of the envelope at the given frequency. The envelope delay is the delay the maximum value of the envelope occurs from the time point it should occur ideally. Zero envelope delay means envelope maximum is in the correct position with no additional delay.
Attached Images
 monopolebass_a-b-c-d_taajuusvasteet_20hz-200hz_da_resize_90.jpg (95.9 KB, 559 views)
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And here's the dipole bass envelope magnitude and envelope delay frequency responses:
Attached Images
 h-dipolebass_a-b-c-d_taajuusvasteet_20hz-200hz_da_resize_90.jpg (93.1 KB, 552 views)
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 14th July 2009, 08:20 PM #46 diyAudio Member     Join Date: May 2006 Location: City of Angles Nice work, thanks for sharing! __________________ double complete rainbow all the way!!
 14th July 2009, 09:08 PM #47 diyAudio Member     Join Date: Dec 2007 Location: Melbourne the sunny city! Thank you ! Would you care to provide some explanations, which area to look for and if there's any conclusions ? Cheers! __________________ http://gainphile.blogspot.com
 14th July 2009, 11:56 PM #48 diyAudio Member     Join Date: Aug 2004 Location: US Are the dip[oles and monopoles equaized to have the same anechoic, on axis response? __________________ John k.... Music and Design NaO Dipole Loudspeakers. "We have no right to assume that any physical laws exist, or if they have existed up to now, that will continue to exist in a similar manner in the future." Max Planck
diyAudio Member

Join Date: May 2003
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Hello,

Quote:
 Originally posted by gainphile Would you care to provide some explanations, which area to look for and if there's any conclusions ?
Yes, I'm planning to draw some conclusions some of which I think can be quite interesting, but first I have more data to present

Quote:
 Originally posted by john k... Are the dip[oles and monopoles equaized to have the same anechoic, on axis response?
The Envelope Mag frequency response curves ARE NOT equalised to be the same for different speakers. For the dipoles I use some slight 6dB/oct dipole correction only, but that is mainly to increase the dynamic range of the measurement.

The spectrograms ARE equalised mathematically so that at each frequency the maximum value of the envelope is referenced to 0 dB. That can be seen in the spectrogram pics where the max value has allways the same colour. I think this equalisation gives better view of the room temporal response since one can directly compare different speakers at different frequencies one to one.

- Elias
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diyAudio Member

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To continue, let's move higher in frequency and look at the range of 20Hz to 2kHz.

First here's the monopole bass-midrange room response at different locations A, B, C and D:
Attached Images
 monopolemid_a-b-c-d_spektrogram_20-2khz_da_resize_80.jpg (83.8 KB, 390 views)
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