10" FLH Bass Reflex Design 20Hz extension.

[Boscoe]

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.

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.

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.

 

[Binary110]

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.

 

[tb46]

Hi Boscoe,

Looks like you simulated a 6th order bandpass enclusure.

Regards,

 

[BP1Fanatic]

This is a vented horn.
Vented bandpass horn? - Speakerplans.com Forums - Page 1

An externally hosted image should be here but it was not working when we last tested it.

 

[Boscoe]

This is a vented horn.
Vented bandpass horn? - Speakerplans.com Forums - Page 1

An externally hosted image should be here but it was not working when we last tested it.

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?

 

[tb46]

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?

Regards,

 

[BP1Fanatic]

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.

 

[BP1Fanatic]

Here is a partial stepped tapped horn. Free Speaker Plans - Free Speaker Plans ? View topic - Beware the one eyed monster!

 

[Boscoe]

So is there anything wrong with my design? What will it likely to sound like? High distortion?

 

[BP1Fanatic]

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.