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Old 12th April 2010, 07:19 AM   #1051
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Quote:
Originally Posted by djn View Post
Do you have any idea what flare or combination of flares would give me the lowest hz in the smallest size?
Hi djn,

In most cases traditional bass horns use either an exponential or a hyperbolic-exponential area expansion. This is because for a given horn size, the theoretical cutoff frequency is lower for these flare types, compared to other profiles - in other words, the low frequency throat acoustical impedance loading characteristics are superior.

Note that in horn design everything is a compromise though - for example, as the value of T in a hyperbolic-exponential horn is reduced, the horn volume becomes less, but the distortion at the throat is likely to increase.

This is why programs like Hornresp are needed - to help find the best balance :-).

Kind regards,

David
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Old 12th April 2010, 12:15 PM   #1052
Mark Kravchenko --- www.kravchenko-audio.com
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I'll add two cents.
For a given length and volume you always have to trade off efficiency as well. As in a smaller horn generally has a lower efficiency. There is jusy only so much efficiency available from the motor and the volume of air you are trying to excite.

Even that trick bandpass I designed is not much smaller than a comparable regular band pass.


So we get McBean's iron law stating that there is a finite maximum spl per given horn volume. And that the greater the horn volume the closer you get to the maximum attainable efficiency. The larger horn will also present lower levels of distortion near cutoff.

Mark
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Old 12th April 2010, 04:32 PM   #1053
djn is offline djn  United States
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Thank you David and Mark. One of the problems I am having is that every design I come up with looks like a hump when I go to SPL responce. I have not played with more than one segment though.
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Old 12th April 2010, 05:40 PM   #1054
djn is offline djn  United States
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OK, here is another question....if you don't mind. What is the difference by using an 8", 10" 12" or 15" driver. I have all sizes but want to do it right the first time. Cheers.
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Old 13th April 2010, 06:42 AM   #1055
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Quote:
Originally Posted by djn View Post
One of the problems I am having is that every design I come up with looks like a hump when I go to SPL responce.
Hi djn,

Try entering the parameters for your preferred driver into Hornresp, and then select menu Tools > System Design > With Driver.

This will give you a starting point for your design. You can work from there.

Kind regards,

David
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Old 13th April 2010, 07:02 AM   #1056
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Originally Posted by djn View Post
What is the difference by using an 8", 10" 12" or 15" driver.
Hi djn,

As a general rule - for ultimate bass performance in a conventional horn, bigger is usually better. This also applies to the driver.

I am pretty sure that someone will be able to find an exception to this rule, however :-).

Kind regards,

David
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Old 13th April 2010, 05:37 PM   #1057
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I found some odd behavior.
Using different mouth sizes on a Le Cléach horn I found that a very small change in size resulted in a dramatic change in response. Like a step happened.
Maybe some sort of rounding error?
The speed of the calculation seemed to change as well.

Also when bending the horn back 180* you seem to pick up a tremendous bass boost. Is this really true?
Attached Files
File Type: txt lec1.txt (365 Bytes, 20 views)
File Type: txt lec2.txt (365 Bytes, 12 views)
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Old 14th April 2010, 07:02 AM   #1058
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Hi David_Web,

Quote:
Originally Posted by David_Web View Post
Using different mouth sizes on a Le Cléach horn I found that a very small change in size resulted in a dramatic change in response.
The Lec1 horn is simulated using an isophase wavefront model and the Lec2 horn is simulated using a plane wavefront model. This is why the results are different. Hornresp automatically selects the model to use based on the input parameter values. It just so happens in this case that you have identified the cross-over point from one model to the other.

Quote:
Originally Posted by David_Web View Post
Also when bending the horn back 180* you seem to pick up a tremendous bass boost.
Do you have a design example to illustrate this?

Kind regards,

David
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Old 14th April 2010, 08:42 AM   #1059
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Which one would be more accurate? Lec1 or 2?

Also decreasing a Le Cléach horns mouth doesn't seem to have too bad influence in a mid horn. Would this be an ok compromise in regards to SQ?

Attached are 90* and 180* Le Cléach horn.
Same as above, only bigger.

*edit* Attached the wrong pic. Fixed now.
Attached Images
File Type: png Lec5.PNG (24.8 KB, 135 views)
Attached Files
File Type: txt lec3.txt (368 Bytes, 12 views)
File Type: txt lec4.txt (369 Bytes, 6 views)

Last edited by David_Web; 14th April 2010 at 08:49 AM.
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Old 14th April 2010, 12:34 PM   #1060
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by David McBean View Post
The Lec1 horn is simulated using an isophase wavefront model and the Lec2 horn is simulated using a plane wavefront model. This is why the results are different. Hornresp automatically selects the model to use based on the input parameter values.
Quote:
Originally Posted by David_Web View Post
Which one would be more accurate? Lec1 or 2?
do we need to know how to identify that software changeover?
How do we use Hornresp so that this anomaly is avoided?

I would hate to have chosen a big redesign for a calculation anomaly that affects the model and is not present in the real horn.
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