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Old 20th November 2012, 09:14 AM   #11
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So what is the reason we can't front horn load an already port tuned driver/box/ported unit then? Seem like we would give the horn and extra 3db of gain delivered right in the through for it to further do its exponential voodoo too?
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Old 20th November 2012, 11:29 AM   #12
NEO Dan is online now NEO Dan  United States
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There is no reason you can't do this, but there are plenty of reasons for not doing it. #1 being that I don't think you can simulate it, so YMMV.

People do this all the time, it's called sticking the sub in a corner.

I guess we should ask what the driver and enclosure specs are...
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Old 20th November 2012, 12:32 PM   #13
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Well, one of the issues is that at the frequency where the port is working best, there is very little output from the main driver. At all other frequencies the port does less and less +/- that center frequency where the port is tuned.

I'm not sure this is a big problem, but it will cause a change in the way that the horn is loaded, since there is a compression ratio effect at the throat where the driver enters the horn flare.

You could set that for 1:1 or less, but the horn effect becomes reduced somewhat.

It's an interesting idea, but likely ur not the first person to think of it, so that *might* be why nobody has published this method, the reason being that it might not provide any benefit, and/or have deficits that can't be overcome.

I don't think you get any output gain from it, but that is just a speculation.

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Old 20th November 2012, 01:29 PM   #14
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Funny thread. Yes of course you can do it, and it has been done. You cannot sim it in hornresp, but maybe in akabak. The more common approach is to do a ported horn where the vent exits independent from the horn, thus the smaller horn handles the higher end while the port fills in the low. These also overlap with bandpass horns. Check out the forums at speakerplans.com
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Old 20th November 2012, 01:47 PM   #15
tb46 is offline tb46  United States
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Hi NEO Dan,

Post #12: "...I don't think you can simulate it..."

It should be possible to simulate a horn with sealed rear chamber in AkAbak, and then add a duct element in parallel to the driver.

Also, Fostex did something remotely similar?

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Last edited by tb46; 20th November 2012 at 01:52 PM.
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Old 20th November 2012, 02:16 PM   #16
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Quote:
Originally Posted by peteleoni View Post
Hi all. Please indulge me here. Is it possible to front horn load an already ported enclosure? In theory the port comes out in phase with the front in any properly designed box and greatly increases efficiency at fs. Why can not the whole kaboodle (driver front wave plus rear wave from port then be combined and fed into a folded horn? Would this not render an extremely efficient design?
A port is a Helmholz resonator, it requires a specific area and length for the size of the box to properly tune.
The horn starts with a small mouth, often not much larger than a decent size port.
A port iThe port tuning would be lowered by the horn, making it no longer contribute properly.
Ports can be put mid point (or so) in the horn, but placement is fairly critical for them to be effective.
For the most part, ports are just put on the front baffle of horn cabinets.

I made a ducted front loaded horn that works pretty well.
It uses a sealed compression chamber and ducts from the throat to the horn.

Lab 12 Domino DFLH

I spent more time getting it to work than any previous cabinet, and got a few less responses than your post already has .

Art Welter
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Old 20th November 2012, 02:26 PM   #17
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if you have an old ported speaker maybe you could try putting it in a cardboard box to play with it.. move it around and see what it does. i'd try it now but.. it's 7 am and my wife would strangle me for the noise.
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Old 20th November 2012, 07:17 PM   #18
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carboard box won't adequately simulate a bass horn...

tb46, that looks similar to what is a "Tapped Horn" except the port is at the exit... I think the OP wants to put the driver and the port both at the throat...

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Old 20th November 2012, 07:24 PM   #19
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FLH vented. Why of course. Altec A4 and A7 come to mind. Tannoy Westminster Royal. Or is a bass reflex front loaded horn not what you meant?
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Old 20th November 2012, 07:24 PM   #20
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That is right. What probably screws this up is the pressure at port.
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