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Old 26th August 2010, 07:45 AM   #1401
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Join Date: Jun 2007
Quote:
Originally Posted by witasso View Post
It seems there is another bug in the Compound Horn feature.
Hi witasso,

Many thanks for the feedback - for a change, this one is not a bug :-).

By way of explanation - for the given example, two equal outputs 180 degrees out of phase and with a zero path length difference are being combined. The two radiated signals effectively cancel each other out which is why the calculated value of the combined SPL response is effectively non-existent at less than -200 dB.

Any change in dimensions, no matter how small, will have a significant effect on the results.

Kind regards,

David
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Old 26th August 2010, 08:06 AM   #1402
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Default Bug Fixed

Quote:
Originally Posted by David_Web View Post
Getting some strange result in the loudspeaker wizard with this one using combined response.
Hi David_Web,

The bug you identified has now been fixed. The latest Hornresp release is Product Number 2800-100826. Thanks again for the feedback.

Kind regards,

David
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Old 26th August 2010, 01:41 PM   #1403
tb46 is offline tb46  United States
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Location: Texas
Hi David,

Thanks for the continuing effort, just down-loaded 2800-100826, and have not found any bug yet. :-)

Would it be possible to add the Compound Horn to the Loudspeaker Wizard with the "Response-Default-Output 2-Combined" feature as it is available for the bass reflex speaker?

Regards,
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Old 27th August 2010, 07:42 AM   #1404
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Hi Oliver,

Quote:
Originally Posted by tb46 View Post
Thanks for the continuing effort, just down-loaded 2800-100826, and have not found any bug yet. :-)
Excellent news, but please keep searching :-).

Quote:
Originally Posted by tb46 View Post
Would it be possible to add the Compound Horn to the Loudspeaker Wizard with the "Response-Default-Output 2-Combined" feature as it is available for the bass reflex speaker?
That's interesting, I thought the feature was already there. It works fine for me :-).

Note the "Compound Horn Loudspeaker Wizard" heading and the "Horn S5 - S6" and "Combined" options selected on the attached example screenprints. Can't you get the same thing, using the following data?

ID=28.00
Ang=0.5 x Pi
Eg=2.83
Rg=0.00
Cir=1.00
S1=80.00
S2=350.00
Con=60.00
F12=0.00
S2=350.00
S3=2400.00
Exp=75.00
F23=70.27
S3=0.00
S4=0.00
L34=0.00
F34=0.00
S5=100.00
S6=2000.00
Con=50.00
F56=0.00
Sd=350.00
Bl=18.00
Cms=4.00E-04
Rms=4.00
Mmd=20.00
Le=1.00
Re=6.00
CH=1
Vrc=4.00
Lrc=8.00
Ap1=0.00
Lpt=0.00
Vtc=900.00
Atc=350.00
Pmax=200
Xmax=5.0
Comment=Compound horn

Kind regards,

David
Attached Images
File Type: png Schematic.png (15.6 KB, 333 views)
File Type: png Response.png (21.6 KB, 330 views)
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Old 27th August 2010, 02:06 PM   #1405
tb46 is offline tb46  United States
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Default Compound Horn - Wizard

Hi David,

Thank you for the quick response. As you said it works, the difference is that I didn't break down the front horn into two sections (didn't use S2/S3/L23.) When I added values there the Wizard appeared, and worked great.

Original, no Wizard:

ID=28.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Cir=3.80
S1=400.00
S2=6000.00
Exp=22.00
F12=336.96
S2=0.00
S3=0.00
L23=0.00
AT=34.78
S3=0.00
S4=0.00
L34=0.00
F34=0.00
S5=300.00
S6=301.00
Con=40.00
F56=0.00
Sd=814.00
Bl=20.13
Cms=1.60E-04
Rms=1.98
Mmd=108.79
Le=2.02
Re=6.60
CH=1
Vrc=162.00
Lrc=40.00
Ap1=400.00
Lpt=1.80
Vtc=1600.00
Atc=900.00
Pmax=100
Xmax=5.0
Comment=Compound_Selenium_WPU1507_Le @ Fs_compound_short_example

New, Wizard works:

ID=28.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Cir=4.14
S1=400.00
S2=400.10
Con=1.80
F12=0.00
S2=400.10
S3=6000.00
Exp=20.20
F23=366.96
S3=0.00
S4=0.00
L34=0.00
F34=0.00
S5=300.00
S6=301.00
Con=40.00
F56=0.00
Sd=814.00
Bl=20.13
Cms=1.60E-04
Rms=1.98
Mmd=108.79
Le=2.02
Re=6.60
CH=1
Vrc=162.00
Lrc=40.00
Ap1=0.00
Lpt=0.00
Vtc=1600.00
Atc=900.00
Pmax=100
Xmax=5.0
Comment=Compound_Selenium_WPU1507_Le @ Fs_compound_short_example


Thanks again,
Regards,
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Last edited by tb46; 27th August 2010 at 02:13 PM.
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Old 27th August 2010, 04:20 PM   #1406
mige0 is offline mige0  Austria
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Location: Austria, at a beautiful place right in the heart of the Alps.
Thanks Bjorn & David for explanations - I hope I got it now

Michael
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Old 28th August 2010, 07:01 AM   #1407
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Quote:
Originally Posted by tb46 View Post
As you said it works, the difference is that I didn't break down the front horn into two sections (didn't use S2/S3/L23.)
Hi Oliver,

As indicated in the Hornresp Help file, the Loudspeaker Wizard works with single segment conical and parabolic horns, and all multiple segment horns. In your original design you had a single segment exponential horn. It is necessary to place these restrictions on the Loudspeaker Wizard so that the plane wavefront model is used in all cases - calculation times associated with the isophase model are too slow for it to be applied to the Wizard.

If you have a single segment exponential horn with parameter values S1, S2 and L12, then probably the easiest way to convert it into two segments for the purposes of using the Wizard, is as follows:

Segment 1:
Throat = S1
Mouth = S2
Length (Exp) = L12 - 0.01

Segment 2:
Throat = S2
Mouth = S2
Length (Exp) = 0.01

The very short cylinder at the horn mouth will make no perceptible difference to the overall results.

Kind regards,

David
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Last edited by David McBean; 28th August 2010 at 07:04 AM.
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Old 28th August 2010, 01:45 PM   #1408
tb46 is offline tb46  United States
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Default Compound Horn - Wizard

Hi David,

Thanks for the explanation. The wizard will work just fine as you described it.

Regards,
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Old 31st August 2010, 03:38 PM   #1409
Jmmlc is offline Jmmlc  France
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Hello Michael,

Quote:
Originally Posted by mige0 View Post
David, Jean-Michel - this spectrogram feature is smashing !!
Thanks for the kind words about the spectrogram feature in Hornresp.
What you surely noticed is it's speed and it's smoothness while keeping fine resolution). It takes a few seconds to run (after the IR response has been previously calculated). And remember Hornresp uses VBA as computing language, the speed of which one is quite slow.
(Eventually, if David is OK for that I can reveal a few tricks of my own about how to perform high speed quasi gaussian windowing and the fast sliding Fourier transform-not FFT.)

Quote:
Originally Posted by mige0 View Post
One thing I noticed is that the spectrogram seems to have different SPL scaling than the SPL plot.
Comparing the difference in SPL from 300Hz and 100Hz its about 30-40dB indicated by the spectrogram whereas its at a more realistic 15dB in the SPL plot ?
If I take your 2 reference frequencies 300Hz and 100Hz: the 300Hz shows on the spectrogram a red brick color (around 0dB ) and the 100Hz shows a yellow color (around -15dB). See attached graph. That's the difference of SPL between 30Hz and 100Hz we can see on the Power response curve.

But when analyzing a spectrogram we must also consider that the low frequency part of the IR spreads on a much more larger duration that the high frequency part. For a given frequency one point of the response curve has to be considered as the summation of the magnitude corresponding to the level of the spectrogram along the time width of the spectrogram. A smaller level on the spectrogram for a given low frequency component than for a high frequency component may results, due to its longer duration, in a larger level on the response curve (SPL curve).

Finally, the shape of the "convolving element" used to obtain the spectrogram while chosen in order to reduce at minimum wings effects (as we used to discuss about the choice of parameters for the CSD in ARTA) has a smoothing effect both in frequency and in time on the spectrogram, so, due to the finite(frequency / time) limits of the spectrogram window chosen we may have some smoothing effect on the border of the spectrogram (and specially around the 40Hz border).

Best regards from Paris, France

Jean-Michel Le Cléac'h
Attached Images
File Type: gif spectro_Mige0.gif (68.0 KB, 258 views)

Last edited by Jmmlc; 31st August 2010 at 03:41 PM.
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Old 31st August 2010, 10:27 PM   #1410
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Location: Johns Creek, GA.
I thought I read somewhere that there was a way to get a JMLC round horn. Am I right? How?
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