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Back loaded corner horn [message #52959]

Sun, 14 December 2008 15:57

xsheaffer
Messages: 6
Registered: May 2009

Esquire

Hello Wayne/All,
I would like to adapt Pi corner horn design to back load a full range driver. However, I don't quite understand the criteria used to calculate the geometry/spacing of the speaker cab to the wall.

Wayne, could you please help me with the math behind this?

Thanks!

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Re: Back loaded corner horn [message #52960 is a reply to message #52959]

Mon, 15 December 2008 00:27

Matts
Messages: 359
Registered: May 2009

Grand Master

what driver are you using? does it have low enough frequencies to benefit from the corner horn concept?

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Re: Back loaded corner horn [message #52961 is a reply to message #52960]

Mon, 15 December 2008 11:28

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

Corner loading is pretty simple really. A corner confines the radiation pattern to eighth-space and in so doing provides 9dB DI. There are other issues to consider, such as crossover points and room modes, but those are specific to the design and the room. In the case of the π cornerhorn, the woofer and midrange are designed to overlap which reduces the floor bounce notch that would result from midhorn height. This makes the position of each important, as well as the crossover frequencies. But in the generic case of a horn placed in a trihedral corner, you can model this with Hornresp. Corner placement smooths the response and provides additonal on axis output. Again, this is highly modified by room modes, but those are room specific and so are probably a separate discussion. I suggest multiple subs for dealing with room modes, again, a different subject.

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Re: Back loaded corner horn [message #52963 is a reply to message #52961]

Mon, 15 December 2008 13:12

Matts
Messages: 359
Registered: May 2009

Grand Master

Wayne, maybe you should design a smaller cornerhorn using one of those little Fostex speakers or another full-range driver for those w/ WAF or xover-phobia....

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Re: Back loaded corner horn [message #52965 is a reply to message #52960]

Mon, 15 December 2008 14:04

xsheaffer
Messages: 6
Registered: May 2009

Esquire

The driver I am playing with is the Fostex FE103, which, obviously, is not a powerhouse. The idea here is to try to address the sloppy bass that is so common to BLH designs. I have heard Wayne's cornerhorns and he is certainly onto something. I want to extrapolate this concept to back loading because it seems like it may have the advantage of better time coherence with bass.

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Re: Back loaded corner horn [message #52967 is a reply to message #52961]

Mon, 15 December 2008 15:01

xsheaffer
Messages: 6
Registered: May 2009

Esquire

Wayne,
I remember in one of your tutorial papers (which I cannot seem to locate...GRRRRR), there was a factor used to calculate the spacing from the wall that I don't understand. IIRC it used a quantity "V" times sqrt 3, but I don't recall. Old age I guess...
The back loaded 1 driver approach is a little different than your Pi implementation, but I want to employ the same approach using a coupling chamber for the backwave of the one driver. The trouble is I don't have a very good understanding of the design parameters of the Pi corner horn! I am just getting started.
Wayne, could you steer me toward more info? Much appreciated any help you could provide!

Thanks!

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Re: Back loaded corner horn [message #52968 is a reply to message #52967]

Mon, 15 December 2008 16:36

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

You're talking about the old original PiAilgn.doc paper from the 1970's. It described some of my basic philosophies early on, and it also shows the formula that is used to calculate box sizes, both standard reflex boxes and cornerhorns. This document doesn't address some of the more recent features, like uniform directivity, CD compensation for compression drivers and a handful of other things that have become staples of π loudspeaker designs. But it does outline some of the core-value philosophies that I still hold today, and it also shows the basic layout of the cabinets.

More recent information can be found by doing a search of the π Speakers forum for documents about "cornerhorns".

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JBL 2115 / Fostex F200 [message #52969 is a reply to message #52963]

Mon, 15 December 2008 17:50

Wayne Parham
Messages: 18791
Registered: January 2001

Illuminati (33rd Degree)

The Fostex F200 looks very similar to the old JBL 2115, which was an excellent little 8" full range driver. I loved to make one π loudspeakers with them. Excellent sounding, but just a little limited in max SPL. They would do about 93dB/W/M, as I recall, and didn't like much more than about 50 watts. But for a small room, that's plenty.

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Re: JBL 2115 / Fostex F200 [message #52970 is a reply to message #52969]

Mon, 15 December 2008 20:41

Chris R.
Messages: 82
Registered: May 2009

Viscount

Here's a link to maybe what you are talking about. These are 6.5" drivers in a corner box with the port in the back. I hooked them up
as the mains once and they needed the bass boost switch to fill the room. I have the TQWP's made with 8" fostex drivers that I like well enough.

http://cerchaos.homeip.net:1280/woodworking6.html

Chris

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