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Old 4th April 2011, 08:42 PM   #1811
rafaro is offline rafaro  Guatemala
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Default Unable to use air space in mouth side of driver in THs

Hornresponse gives unable to do response in THs. Trying to model THs with air space in both sides of driver to see if limiting higher frequencies especially in mouth side driver allowed more extended freq response and or flatter less peaky upper freq response. As I see it seems the upper freq from the mouth side driver returning from the apex 180 degree out of phase are interfering with the upper freq response. Is this the primary problem explaining the ragged response OR is it is it the harmonics of the fundamental being produced within this closed end horn causing the problem. By limiting the mouth side upper freq I was hoping to find out . Does anyone already know the answer?? David??
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Old 4th April 2011, 08:48 PM   #1812
rafaro is offline rafaro  Guatemala
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Default What is mechanism for the ragged and limited frequency extension in THs

Trying to model THs with air space in both sides of driver to see if limiting higher frequencies especially in mouth side driver allowed more extended freq response and or flatter less peaky upper freq response. As I see it seems the upper freq from the mouth side driver returning from the apex 180 degree out of phase are interfering with the upper freq response. Is this the primary mechanism explaining the ragged limited frequency extension OR is it is it the harmonics of the fundamental being produced within this closed ended horn causing the problem. By limiting the mouth side upper freq I was hoping to find out . Does anyone already know the answer?? David??
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Old 4th April 2011, 11:25 PM   #1813
soho54 is offline soho54  United States
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Quote:
Originally Posted by revintage View Post
I admit the Spreadsheet is wrongly written about Mmd in the export to Hornresp. Mmd should best be calculated in Hornresp. So I will remove the speaker data and only export the horn and volume data.
FWIW, if you check my worksheet out, the last version uploaded has an equation to calculate Mmd from Mms and the Sd.

It was either dead on, or within a hair of what Hornresp calculated for the dozen or so drivers I checked.
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Old 5th April 2011, 07:53 AM   #1814
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Quote:
Originally Posted by revintage View Post
In my spreadsheet Mms is used twice, when calculating VAS and when calculating Qes.
Hi Lars,

In Hornresp, Vas is calculated using Sd and Cms, and Qes is calculated using fs, Cms, Re and Bl:

Vas = Air_Density * Sound_Velocity ^ 2 * Sd ^ 2 * Cms

Qes = 1 / (2 * Pi * fs * Cms) * (Re / Bl ^ 2)

Mms can determined if necessary, as follows:

Mms = 1 / ((2 * Pi * fs) ^ 2 * Cms)

Kind regards,

David
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Old 5th April 2011, 08:00 AM   #1815
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Quote:
Originally Posted by revintage View Post
When using formula 49 and 50 we arrive at Leachīs Mmd actually being equivalent to Small/Thieleīs Mms.
Hi Lars,

Now that is a bit confusing :-).

Kind regards,

David
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Old 5th April 2011, 08:18 AM   #1816
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Quote:
Originally Posted by rafaro View Post
Trying to model THs with air space in both sides of driver to see if limiting higher frequencies especially in mouth side driver allowed more extended freq response and or flatter less peaky upper freq response.
Hi rafaro,

You will need to use AkAbak.

As far as I am aware, including a chamber on the mouth side of the driver is unlikely to make much of an improvement to the overall performance of a tapped horn system. I would be happy to be proven wrong, however :-).

Kind regards,

David
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Old 5th April 2011, 09:37 AM   #1817
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Quote:
Vas = Air_Density * Sound_Velocity ^ 2 * Sd ^ 2 * Cms

Qes = 1 / (2 * Pi * fs * Cms) * (Re / Bl ^ 2)

Mms can determined if necessary, as follows:

Mms = 1 / ((2 * Pi * fs) ^ 2 * Cms)
Hi David

Hard to remember it all as I did it in 2008. Will dig deeper in the spreadsheet and also check the Vas-version where Bl is calculated. Did it as Altec donīt show this in their data.

Those will give the same result as mine as I understand even if I didnīt use Cmsand insted used the S-T Fs formula. When doing Vas I made the faktor 14 from "Air_Density * Sound_Velocity ^ 2". Will change that as Sound Velocity can be coosen the spreadsheet.

Still mysterious about Mms=Mmd.

Hi soho54

As said above Marshall Leach uses Mms, not Mmd. Maybe he just made a typo. Will check your Mmd formula anyway. Saw you use the the same style of balancing out Fl and Fo. Do you use Mmd when calculating Hypex?

Last edited by revintage; 5th April 2011 at 09:45 AM.
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Old 5th April 2011, 02:39 PM   #1818
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Checked all formulas and they are the same. The difference is I used the first formula to solve Cms.

Cms=((1/(2*Pi*Fs))^2)/Mms

Vas=ρ*c^2*Sd^2*Cms

Qes=2*Pi*Fs*Mms*Re/(Bl)^2

Mms=((1/(2*Pi*Fs))^2)/Cms
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Old 5th April 2011, 05:10 PM   #1819
soho54 is offline soho54  United States
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Quote:
Originally Posted by revintage View Post
Hi soho54

As said above Marshall Leach uses Mms, not Mmd. Maybe he just made a typo. Will check your Mmd formula anyway. Saw you use the the same style of balancing out Fl and Fo. Do you use Mmd when calculating Hypex?
I only have Mmd in there for a Hornresp simulation export function I never finished. The rest of the page uses Mms.

I had a couple of people asking for a way to export the Excel file info into Hornresp Import format. I got about half way through with it, and they said "never mind," as they had gotten good at transferring the info over.

I though you might be able to use it to keep your Hornresp input section intact.
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Old 5th April 2011, 05:18 PM   #1820
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Hey Soho54,

Just came home from work and checked the AES-paper again.

It is clear Leach have used the wrong names.

Cmd is Cms

Mmd is Mms

Ie, our spreadsheets are right.

Hey David,

Just curious, how you use Mmd?

Last edited by revintage; 5th April 2011 at 05:20 PM.
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