Measured monopole and dipole room responses

[Elias]

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

 

[Elias]

At first, let's examine the frequency range of 20Hz-100Hz.

Here's the monopole bass room response:

 

[Elias]

And here's the dipole bass:

 

[Elias]

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.

 

[Elias]

And here's the dipole bass envelope magnitude and envelope delay frequency responses:

 

[cuibono]

Nice work, thanks for sharing!

 

[gainphile]

Thank you ! 🙂

Would you care to provide some explanations, which area to look for and if there's any conclusions ?

Cheers!

 

[john k...]

Are the dip[oles and monopoles equaized to have the same anechoic, on axis response?

 

[Elias]

Hello,

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 🙂

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

 

[Elias]

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:

 

[Elias]

And here's the dipole bass-midrange room response in 20Hz - 2kHz at locations A - D:

 

[Elias]

And here's the dipole line array room response in 20Hz - 2kHz at locations A - D:

 

[Elias]

And then the envelope magnitude and delay frequency response for the monopole bass-midrange in 20Hz - 2kHz at locations A - D:

 

[Elias]

The envelope magnitude and delay frequency response for the dipole bass-midrange in 20Hz - 2kHz at locations A - D:

 

[Elias]

And here's the envelope magnitude and delay frequency response for the dipole line array in 20Hz - 2kHz at locations A - D:

- Elias

 

[CLS]

Please tolerate my ignorance.
How to read those charts and what do they mean?

 

[sendler]

Line array superiority

Fascinating work with an excellent test signal/ analysis method. Were you surprised by the substantial superiority of the dipole line array? I had often thought to try that as it would seem a good solution to the increased volume displacement demands of open baffle.

 

[brianpowers27]

Great test-

THank you for posting your test results. I would like to raise a concern I have regarding the comparison between the various tests. I am concerned that by using different drivers and baffle widths you are ignoring the baffle's role in the equation.

I would not consider the comparison between dipole and dipole line array to be complete until you are using the same drivers on the same shape baffle.

 

[sendler]

dipole line array

I would not consider the comparison between dipole and dipole line array to be complete until you are using the same drivers on the same shape baffle.

.
Yes, the advantage of the line array could be even bigger with better drivers.

 

[sendler]

OB line array vs. sealed

Now that I see the OB line array results look so good, it would be intersting to throw a box over the back to see the same set up running sealed.