10" FLH Bass Reflex Design 20Hz extension. - diyAudio
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Old 17th August 2011, 09:33 PM   #1
Boscoe is offline Boscoe  United Kingdom
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Default 10" FLH Bass Reflex Design 20Hz extension.

It is late so I may have got this a bit wrong but I am confident in this design. It is a bass reflex with a front loaded horn basically, here goes. Using the Peerless XLS-269 10" driver. 225W for full power of 115dB.

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Enclosure; middle section is the reflex with port at the top and then the horn on far left and bottom. Cross hatched section is for driver placement, I will get some measurement for this later on.

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My largest concern of this design is the size of the ports and horn with cross sections of only 60cm square, I will look into that further tomorrow. Until then please suggest ideas and the like.

Thanks.
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Old 19th August 2011, 01:46 PM   #2
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I'm not the smartest when it comes to horns, but afaik horns are supposed to net you some actual gain. You're only getting about a 3db gain which is equal to a standard ported enclosure. You can elminate all that "horn" stuff on the end, and you'd have the same output.

The problem i'm seeing is you don't have a gradual expansion, just a slot port that wraps around itself. It'll give you low tuning for a ported enclosure, but you won't be getting any additional output.

Someone with more horn experience should chime in, But i beleive you're not getting any real gain with this enclosure, just a bit of extension.

Your impedance plot should have two peaks in it if its a properly built horn.

Edit: just noticed i was looking at group delay, not impedance, Check impedance for two peaks.

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Old 19th August 2011, 03:17 PM   #3
tb46 is offline tb46  United States
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Hi Boscoe,

Looks like you simulated a 6th order bandpass enclusure.

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Old 19th August 2011, 03:38 PM   #4
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This is a vented horn.
Vented bandpass horn? - Speakerplans.com Forums - Page 1
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Old 19th August 2011, 05:27 PM   #5
Boscoe is offline Boscoe  United Kingdom
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Quote:
Originally Posted by BP1Fanatic View Post
That's what I have made just with small ports which I didn't think would be ideal, I do achieve gain as I simmed the ported enclosure first to achieve the resonance first. I also don't beliveve a horn needs to taper? I have played around with a few which are quite happy with no taper although I do admit it's not really a horn then. I also get two peaks in the impedance, Have you plotted a regular vented enclosure in winisd to see how low the SPL gets at 20Hz?

Thanks keep the advice coming I am tinkering with the design, with the ports as they are what would the sound be like? I can't imagine it being very good forcing 115dB out of two small ports?
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Old 19th August 2011, 08:04 PM   #6
tb46 is offline tb46  United States
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Hi Boscoe,

What you presented in Post #1 is a BP6, the one BP1Fanatic linked to in Post #4 is a BP6 with one port in form of a short horn. The Hornresp Input in the linked thread is the more correct way of setting up a simulation, but yours should work too. Part of the difference you found between simulating in WinISD and Hornresp may be that your Ang entry is 1.0 x Pi whereas WinISD defaults to 2.0 x Pi (I'm assuming you used the BP6 box mode in Win ISD). Also, a horn without a taper is a pipe or tube, I think?

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Old 19th August 2011, 08:45 PM   #7
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Quote:
Originally Posted by Boscoe View Post
That's what I have made just with small ports which I didn't think would be ideal, I do achieve gain as I simmed the ported enclosure first to achieve the resonance first. I also don't beliveve a horn needs to taper? I have played around with a few which are quite happy with no taper although I do admit it's not really a horn then. I also get two peaks in the impedance, Have you plotted a regular vented enclosure in winisd to see how low the SPL gets at 20Hz?

Thanks keep the advice coming I am tinkering with the design, with the ports as they are what would the sound be like? I can't imagine it being very good forcing 115dB out of two small ports?
People do build stepped horns. Your pic could be considered a negative tapered stepped horn based on your HR inputs.

I take that back. I thought you went from 120cm2 to 60cm2 over a distance. You just started your PORT at 0.10cm.

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Old 19th August 2011, 08:57 PM   #8
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Here is a partial stepped tapped horn. Free Speaker Plans - Free Speaker Plans ? View topic - Beware the one eyed monster!
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Old 19th August 2011, 10:14 PM   #9
Boscoe is offline Boscoe  United Kingdom
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So is there anything wrong with my design? What will it likely to sound like? High distortion?
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Old 17th September 2011, 09:42 PM   #10
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To be a horn, there has to be an expansion (tapered or stepped) towards the mouth like horn instruments. Your design has straight ports which makes it a BP6. As long as your ports have enough area to keep the vent air speed below Mach 0.10, then you should be good on the distortion.
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