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Horn Sub Input Please - Build In Progress!

73405 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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I'll make you a deal.

You tell me what you are using to do the folds for your horns, and I'll help you tweak them.
I hates Sketchup!

But a deal is a deal.

What are you trying to maximize in your setup?

Overall I like your folds, very well done.

So what are you hoping to achieve in this setup of boxes?

SPL will be insane to say the least.
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A quick bit of advice on the low frequency box.

This is to be a tapped horn I take it.

One thing you find in working in real rooms versus sim land is that a flat response in sim land will be greatly overblown in the real world. I have found that you can tailor the response of a sub to behave with a flat response in a real room.

The method used is to incorporate a bit of a falling response.
Music, home theater or both?

Home construction. You are using metric so I'm guessing you are not from the Us of A.

Homes constructed with timber framing behave a little differently to those done in blocks and bricks.

This will be one interesting room to be in that's for sure.
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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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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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?
Not bad. How large is your box?

And did you consider a LAB 12?
Cheap + intelligent choices = good engineering.

Have you modeled four in Hornresp?
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.
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.
Stayner is only five hours away.

I might be able to hear your system from my place!
Take the driver I suggested.

Slap it into your horn. You will be able to do two things. Shrink the rear chamber, and if you have ripple take a look at how much ripple. An undulation of 3 db up or down is not really noticeable.

Also if you buy eight or more of the Dayton Pro woofers you will get a discount.

The Selenium driver has very little excursion capability and therefore will have much higher distortion in a horn.
Graphs are one part of the design.

When you need a rear volume of 140 liters on a back loaded horn you have a driver that is not suited to horn loading.

Your choice. This is advice not a dictatorship.

I chimed in because I have been designing horns for the past twenty years, and I work as a consultant in driver and loudspeaker design.

There is an existing design up on this forum that meets almost all that you seek. And it is proven.

So this is not advice from someone who has simmed only.
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Short story is a long day and a short fuse.

I'll give you a good explanation in the morning.
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