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Old 12th January 2006, 02:49 PM   #1
Volenti is offline Volenti  Australia
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Default Front loaded horn sanity check

Now I realize is about a bass horn but I'm posting here since more "horn guys" appear to frequent this area.

I'm building a dedicated HT room and intend to integrate a full bass horn, ~20-80hz bandwidth, the bulk of it will be located above the room in the vaulted roof space.

This is the design I've come up with in Hornresp;

This is the combined parameters for 2 15'' drivers;
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calculated response with ~400w input (about what I'll have available)
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horn geometry
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Any silly mistakes or errors you can see? I'd rather build this only once

I'll post some pics of the room and intended location/setup tomorrow.
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Old 12th January 2006, 10:27 PM   #2
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Looks good - How are you going to dohe twin 15's into the little throat? Can't imagine it making too much of a difference just curious - also is the back chamber sized right for the pair?
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Old 13th January 2006, 02:46 AM   #3
Volenti is offline Volenti  Australia
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The start of the horn will be set up similar to a 3 chamber bandpass enclosure (sealed outer chambers, vented center chamber), The rear chamber is split in 2 with each driver in 100L, I had to fiddle with both the rear chamber volume and the front chamber to get the response I wanted.

The whole bandpass section will be modular so I can take it off the horn and modify it as needed.
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Old 13th January 2006, 11:28 AM   #4
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I say go for it! I think it wil be devastating. Very low compromise!

The ability to change the backchamber/front chamber throat area is ideal - surely the horn if close to the contour and low resonance will perform as predicted.
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Old 13th January 2006, 02:40 PM   #5
Coolin is offline Coolin  Netherlands
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Using the same parameters but now without a front chamber the upper cutoff is virtually the same (although less steep) but with the benefit of a flater phase responce...

Are there any other benefits of a front chamber than being able to tune the upper cutoff a bit?

I cant help helping thinking of it as another energy storage mechanism that wont improve the sound quality....
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Old 14th January 2006, 09:45 AM   #6
Coolin is offline Coolin  Netherlands
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bump...

A drawback of posting here instead of the subwoofers section is that it moves out of sight very quick...

So what are you going to do Volenti ?
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Old 14th January 2006, 10:25 AM   #7
Volenti is offline Volenti  Australia
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Quote:
Originally posted by Coolin
Using the same parameters but now without a front chamber the upper cutoff is virtually the same (although less steep) but with the benefit of a flater phase responce...

Are there any other benefits of a front chamber than being able to tune the upper cutoff a bit?

I cant help helping thinking of it as another energy storage mechanism that wont improve the sound quality....
I didn't notice the phase response, thanks for the heads up, what I'd really like to see is some sort of group delay graph, especially that would show the delay from the length of the horn as well.

I'll do some more modeling.
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Old 14th January 2006, 10:32 AM   #8
Volenti is offline Volenti  Australia
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Quote:
Originally posted by Coolin
bump...

A drawback of posting here instead of the subwoofers section is that it moves out of sight very quick...

So what are you going to do Volenti ?
I'm a good month away from even starting on the horn it's self, I just need to get the overall design finalized so I can allow for it in the rest of the construction.

I will post construction pics when I have something usefull to show


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Old 14th January 2006, 10:43 AM   #9
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Try plugging the driver parameters and the dimensions you want into Martin King's Front Loaded Horn MathCad sheet (you can download a copy of MathCad 8 explorer from his site too), if you haven't already tried it. All the plots you could ever wish for, with predicted in-room responses coming in March too. www.quarter-wave.com

Could reap dividends.

Best
Scott
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Old 14th January 2006, 05:50 PM   #10
Coolin is offline Coolin  Netherlands
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Quote:
Originally posted by Volenti


I didn't notice the phase response, thanks for the heads up, what I'd really like to see is some sort of group delay graph, especially that would show the delay from the length of the horn as well.

I'll do some more modeling.

The length of the horn is ignored if i am not mistaken.

group delay = Phase responce but in a different "notation"

There also seems to be something wierd with the way hornresponce swings from -180 degrees to +180 degrees. It should start or end at 0 degrees
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