Hornresp

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tb46

Member
Joined 2006
Possible Problem w/ V.2870-110816

Hi David,

After installing the newest version (2870-110816) I encountered the following problem:

Some files saved with BR or ND come up as TH.

(OD files come up as OD. CH come up as CH. TH come up as TH.)

Warning: Once the new version is installed, and has been run, the data file cannot be opened with a previous version.

I had an older version (2830-110124) installed under a different name (Hornresp2), and it still functions just fine.

Regards,
 
Kolbrek

Kolbrek

Member
Joined 2007
kolbrek.hornspeakersystems.info/
dirkwright said:
OK, what is the advantage of having the driver see a resistive load? Does it increase efficiency or something? Do direct radiator type of loudspeakers see a resistive load in the free air? Why can't the resonant impedance peak be removed by a notch filter? I have not read the patent but I can do that today.
Click to expand...

Resistance dissipates energy, reactance stores it. By increasing the resistance compared to the reactance, you increases efficiency. Reactance anulling increases efficiency near the horn cutoff, where the horn load is dominated by the reactance of the air mass, that you just move back and forth.

Direct radiators mainly see a reactive acoustical load; the air mass that the diaphragm moves back and forth. There is a small resistive part there too (the energy dissipated in this acoustical resistance is what you hear as sound), but it is very small compared to the mass reactance. This is the reason for the low efficiency of direct radiators.

A notch filter can fix the electrical impedance peak as seen by the amplifier. It can't do anything with the efficiency of the acoustical coupling between the driver and the horn.

Bjørn
 
dirkwright

dirkwright

Member
Joined 2011
Kolbrek said:
Resistance dissipates energy, reactance stores it. By increasing the resistance compared to the reactance, you increases efficiency. Reactance anulling increases efficiency near the horn cutoff, where the horn load is dominated by the reactance of the air mass, that you just move back and forth.

Direct radiators mainly see a reactive acoustical load; the air mass that the diaphragm moves back and forth. There is a small resistive part there too (the energy dissipated in this acoustical resistance is what you hear as sound), but it is very small compared to the mass reactance. This is the reason for the low efficiency of direct radiators.

A notch filter can fix the electrical impedance peak as seen by the amplifier. It can't do anything with the efficiency of the acoustical coupling between the driver and the horn.

Bjørn
Click to expand...

OK, very interesting thanks! I think I have something pretty good with a 100Hz hyp-ex straight horn for my 12PE32 drivers. They are 74cm square by 105cm deep. Of course, I'll need a subwoofer or two....
 
T

tb46

Member
Joined 2006
Hi David,

Just a little more information to the problem I reported in Post #2141: I deleted the Hornresp folder with the newest update (2870-110816), and reinstalled a saved copy of Hornresp. This old version had most of the problem files. Then I updated to 2860-110805, and everything seems to work just like normal. So, as far as I can tell the problem occured between 2860-110805 and the latest greatest.

Regards,
 
D

David McBean

Member
Joined 2007
hornresp.net
tb46 said:
Hi David,

After installing the newest version (2870-110816) I encountered the following problem:

Some files saved with BR or ND come up as TH.

(OD files come up as OD. CH come up as CH. TH come up as TH.)

Warning: Once the new version is installed, and has been run, the data file cannot be opened with a previous version.

I had an older version (2830-110124) installed under a different name (Hornresp2), and it still functions just fine.

Regards,
Click to expand...

Hi Oliver,

Thanks for the feedback.

The format of the Hornresp.dat data file was changed with the release of Version 28.70. The existing file should have updated automatically without the user being aware of it. Files so converted are not backwards compatible - hence the warning message.

You indicate that some records saved with BR come up as Nd. Where does BR come from? There should be no BR driver arrangement option :).

The problem may have something to do with the fact that you are running multiple copies of Hornresp at different version numbers. If you attempt to share a common data file at any stage, then data corruption is likely to occur.

Would it be possible for you to send me a copy of the Hornresp.dat data file that does not convert correctly (before conversion is attempted) so that I can investigate further using your original uncorrupted file. My e-mail address is dmcbean@bigpond.com.

Has anyone else experienced a similar problem to Oliver?

Kind regards,

David
 
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dirkwright

dirkwright

Member
Joined 2011
David McBean said:
Hi dirkwright,

Yes. Most bass horns simulated in Hornresp are folded designs.

Kind regards,

David
Click to expand...

OK, but I guess what I was getting at is the program doesn't seem to take into account the affects of the folds on the performance of the horn. For example, I've read that folded horns typically do not go as high in frequency response as straight ones. There are losses in the folds, depending on how they are done. More specifically, the size and shape of the corners in the folding are a kind of acoustical filter. Certain frequencies are attenuated and others are allowed to pass. I have read that as the sound wavelengths approach the dimensions of the corners, they become more attenuated. I'm sure it would be very complicated to implement this kind of simulation, but thought I'd just share what I've read about folded horns.
 
dirkwright

dirkwright

Member
Joined 2011
dirkwright said:
OK, but I guess what I was getting at is the program doesn't seem to take into account the affects of the folds on the performance of the horn. For example, I've read that folded horns typically do not go as high in frequency response as straight ones. There are losses in the folds, depending on how they are done. More specifically, the size and shape of the corners in the folding are a kind of acoustical filter. Certain frequencies are attenuated and others are allowed to pass. I have read that as the sound wavelengths approach the dimensions of the corners, they become more attenuated. I'm sure it would be very complicated to implement this kind of simulation, but thought I'd just share what I've read about folded horns.
Click to expand...

I looked around and there is a lot of research in this area, but I'd have to pay to read the articles. Mostly, the research is about wave propagation in pipes.
 
dirkwright

dirkwright

Member
Joined 2011
John Sheerin said:
I have some information on my website about how sound waves propagate around horn bends. It might not be exactly what you're looking for, but it's a start.
Click to expand...

Thanks. I'm not really looking to design a folded horn but I find the subject interesting anyway. It would be awesome if David incorporated something like that into Hornresp, though as it stands now it is an incredible service to us to provide such a powerful software package for free. We didn't have this kind of stuff back when I last designed a horn in 1991. I'm really grateful for David's contribution.
 
dirkwright

dirkwright

Member
Joined 2011
John Sheerin said:
I have some information on my website about how sound waves propagate around horn bends. It might not be exactly what you're looking for, but it's a start.
Click to expand...

Very interesting article! thank you! Your animations are fascinating. The sound just seems to squish around the corners, sometimes getting confused reflections or just disappearing. It seems to me that folded corners are low pass acoustical filters that add a lot of distortion, but that's just a guess on my part.
http://www.jhsaudio.com/waves.html
 
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D

David McBean

Member
Joined 2007
hornresp.net
julienb34 said:
would it be possible to see an option to choose a frequency response curve between "Acoustic power" and "Acoustic pressure" like Akabak?
Click to expand...

Hi julienb34,

Select the Tools > Directivity > Response... menu command to show the pressure response.

Note that the tool only applies to finite single-segment non-negative flare horns.

You will find that the results are probably different to those generated by AkAbak, which uses a relatively simple directivity model compared to Hornresp.

Kind regards,

David
 
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