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Horn Sub Input Please - Build In Progress!

73409 Views 260 Replies 20 Participants Last post by  iconrl
I am in the process of layout/design of my new theater room. I am going to be using PI 4 Speakers for LCR, and PI 1 Speakers for Surrounds. I designed a set of OD Horn Speakers to compliment the LCR and surround speakers as flanking subs to tame room modes. So the frequency range is 50-200hz

Since this is my 1st attempt at Hornresp and Sketchup, I am looking for input on my design and folding before proceeding further. So there will be 7 total of these flanking subs the front 3 will be under the PI 4's and the 4rears will be under the surrounds in a column configuration. The will be driven with 20 watts RMS.

I will be using a miniDSP 10x10hd, and the plan is to cross the flanking subs, with there respective mains, as well as matrix the LFE channel to theses subs as well for frequencies above 50hz, and then use the Low LFE subs for everything under 50-60hz.

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Advise taken, I am using 1/2 space sim in hornresp, so I assumed that would be close to in room...?

Yes and no.

Most reasonably sized rooms will have a bit of reflection reinforcement i the nether regions.

It really starts to get useful below thirty hertz. You get about 3 db here, and usually about 6 to 8 at 20 hertz.

Below this you are really working in the pressure field, as in the room is much to small to create a reflected true to length wave of the sounds. So you get even more reinforcement. At 16 hertz a great many studies have shown that there is about ten plus db of room gain.

Now for the good/bad news. Not very much program material has large peaks down that low. It's mostly higher harmonics or multiples of the low frequency fundamental notes.

Even nasty pipe organs are not that killer down low. A few are, and I have the recordings to show them off.

Some movies to have the odd bit of thunder.

SO what does this have to do with your box design?

You can reduce the size but not the path length and create a design that will produce what you want in room.

If you are really keen on getting this right there is a fairly simple method you can use if you have a measurement microphone and REW.
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Reasonably close to Ottawa is I.

Great! basement. I luvs designing for basements.

You will have room reinforcement up to your teeth.
Next little bit of advice.

Don't worry a whole bunch over the group delay effects. ( sorry chrapladm )

I have done quite a few horn loaded subs that should have had built in echo according to the naysayers. But the effects are very difficult to hear in the low end. Horns done well have vanishingly low distortion. In fact I have yet to have heard one that I found to be problematic in any way.

My background is in music by the way, I played in the brass section, and still can tune by ear an instrument I have not regularly picked up in 26 years. And I'm very picky in terms of quality of bass reproduction. I have heard most everything live and remember exactly what it sounds like. It's what drove me to start designing speakers in the first place!

Last bit of advice. Your ULF sub would be better as a FLH (front loaded horn) I can always tell the sound of a tapped horn. I never really enjoy them.


They tend to sound like vented boxes. A bit whooly on the low end. If you like that then it is you ticket to happy ville.

Last bit of advice. And this is a pat on the back at the same time.

Trust Hornresp if the following conditions have been met:

You have tested your drivers and are using the measured parameters as input to Hornresp.

You build exactly what you sim ( your folds look great )

Brace brace and brace some more. Horns are high pressure devices and the highest pressures are closest to the cones.

Then you will be grinning ear to ear.
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Thanks for the input. I can redesign them for sure. I have not heard a tapperd horn before, but I do prefer the sound of a sealed sub over a vented sub anyday.

I will resim the ULF subs.
If you can measure there is a fairly simple way to measure your rooms gain. ( transfer function )

You need a sealed sub and the ability to EQ it flat. You do this outside. As in measure and EQ it outside.

You don't have to be loud as all get out. What you need to be is louder than the rooms basic noise level. Fairly easy.

Play the same signal inside and measure the difference.

If you are using REW it will be fairly easy to see the difference using a multiple response curve graph.

Once you know what you have in terms of room gain you can design accordingly for your ULF horn. And then enjoy.

Tapped horn refers to the larger of your three horns.

The drivers tap the horn at a point other than the beginning only. This secondary tapped point creates a rise in the response usually at the third harmonic and higher.
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this design not applicable anymore
A beginning.

You could drop a little more if you want.

I have done a sub that is pretty much what works well. It is in this section of the forum under ultimate subwoofer.

You are using the eminence 10 for this?
No its a dayton classic 4 ohm. I will check out your build.
Revised ULF Sub, using 1 - 12" Driver.


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Not bad. How large is your box?

And did you consider a LAB 12?
Box is 570L. Lab 12 is double the cost, trying to take the cheap road, plus I will be building four of these boxes.
Cheap + intelligent choices = good engineering.

Have you modeled four in Hornresp?
Not yet but I think it should hit reference level no problem down to 15hz, my room volume is 2100 cu/ft.

Here is the updated flanking subs, box volume is 100L

Cheap drivers again!


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1st Draft of Seating Riser Sub, this will be the Selenium 12" LFE x 4.

I also did the approx. 4 driver response, which is 1w/1m.


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Back in front of a large screen.

So you should stick with your first design of the mid bass horns. A falling response will not help you in this range as there is very little room gain at the frequencies the midbass horn will be operating at.


Way to large of a rear chamber on the idea for the riser. You have basically designed a box with a very long vent.


Never load two horns into a single mouth the same size as it would be for one horn.

If you want a common mout you can do this. But it should be the summed area of two individual horns.
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Which selenium are you modeling?

Instead of nit picking I'll take a kick at the can for you.
Okay, will redo the midbass.

The box only seems large, because of the thickness of the riser, I maybe doing something wrong, but my model was for 140L per driver, so with 2 drivers I doubled to 280L. I could make it smaller, just cause more ripple in the response, so I increased to smooth out.

The mouth won't be a single, they will have the same size as modeled just exit at the same point, sorry for the confusion with the drawing.

The selenium is a 12PW5-SLF 12"

Just thought, in the case of the woofer chamber, I did not think that dimensions mattered just the volume of the chamber, as the driver does not no that only the volume of air behind it?

Also you said you where near Ottawa, I actually live in Stayner, which is just south of Wasaga Beach.
For a sub you want a woofer with a much lower Qts.

It is a basic thing in that a lower Qts driver means it is a stronger driver.

I'm looking through the eminence line up to see if there is anything similar in price that has some umph.

What is you maximum on price?
Here is my two cents:


I have used these and they blow away anything else in their price range.
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