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4 pi & 7 pi [message #39759]

Mon, 06 January 2003 12:10

spears_tears
Messages: 8
Registered: May 2009

Esquire

Hello.

I am looking for high efficiency speakers for a vintage tube amp and later on a SET amp.

Can anyone tell me what the difference is between the Theatre series, Bass Reflex speaker and the Corner Horn speaker. Both use the same horn and driver, so how do the differing designs change the sound.

Could someone direct me to any reviews of these speakers too.

Thank you, Spears.

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Re: 4 pi & 7 pi [message #39760 is a reply to message #39759]

Mon, 06 January 2003 12:37

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

The main difference in the cornerhorn is in the way the woofer drives the room. In the bass-reflex model, it is simply a direct radiator. But in the cornerhorn, it is positioned near the apex of the room corner, which places the woofer in eighth-space and forms a large conical horn expansion

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Re: 4 pi & 7 pi [message #39762 is a reply to message #39760]

Mon, 06 January 2003 12:50

wasteh202
Messages: 137
Registered: May 2009

Master

Wayne, while we are on the subject here with the Theater 4 & 7(corner-horn).

What is the reason for the cornerhorn having 3db more than the bass-reflex? Does it have to do with the corner-loading? Is the XO the same? I give up... what is it?

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One question Wayne [message #39763 is a reply to message #39760]

Mon, 06 January 2003 13:44

Edwin
Messages: 50
Registered: May 2009

Baron

Hi,
You said that if you take the cornerhorns away from the corner the effect will be a direct radiating speaker. Basing on this the Theater 7 will be a Theater 4? I don't have corners right now but will it be better to build a Theater 7 now and use it like a Theater 4 until such time that I can build a dedicated listening room with good corners? This question is only based on economics :-). Thanks

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Re: 4 pi & 7 pi [message #39770 is a reply to message #39762]

Mon, 06 January 2003 20:48

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

When compared to a bass-reflex speaker, the 3dB gain difference is due to an assumption that the bass-reflex speaker will radiate into quarter-space. Since the cornerhorn is used in eighth-space, there is 3dB gain in comparison. If we were comparing to free-space, we would have 9dB gain. See Chapter 3 of George Augsperger's "JBL Professional Sound System Design Manual" for more information.

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That's a tough one, Edwin [message #39771 is a reply to message #39763]

Mon, 06 January 2003 21:04

Wayne Parham
Messages: 18786
Registered: January 2001

Illuminati (33rd Degree)

I really like seven π cornerhorns. If a room will support them, that's what I'll use. I think even with marginal corners, I prefer them to four π's. But if you don't have corners, you really can't take advantage of π cornerhorns and would probably be better off with four π's instead. That's the advantage of four π's - They're more versatile, and they're simpler and less expensive too.

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Re: good stuff to learn--thanks [message #39772 is a reply to message #39770]

Mon, 06 January 2003 22:23

wasteh202
Messages: 137
Registered: May 2009

Master

Wayne, you are very paitent and always willling to help us listeners who do not have the knowledge and experience that you do. Thanks for taking the time to explain some things to me and help me to learn some new principals, and I never have to wait long to hear from you.

BTW-- I'm sure I'll have more questions for you in the future. I got the 2Pi towers complete except for the finish and trim. I'll post pics soon. I gotta say....THEY ROCK!!!!!

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Now it's even harder to decide :-) [message #39773 is a reply to message #39771]

Tue, 07 January 2003 00:11

Edwin
Messages: 50
Registered: May 2009

Baron

Thanks Wayne,
I think a few sleepless night will do it! I just hope the right thing to do hits me pretty soon. Edwin

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Re: 4 pi & 7 pi [message #39774 is a reply to message #39759]

Tue, 07 January 2003 03:33

JLapaire
Messages: 156
Registered: May 2009

Master

How about this? Build a 7 without the standoff section on the back and with the HF separate on top of the box. That way you can face the boxes into corners if you have them. The difference is in the lowest bass and is worth some effort if you (like me) want the deep stuff.
Actually, building the 7 without the standoff section might make corner placement easier if you have baseboard heat, since the standoff won't let the box go all the way into the corner.
I tried something like this, can email pics if you like.

John

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Yes, but... [message #39779 is a reply to message #39773]

Tue, 07 January 2003 13:22

mollecon
Messages: 203
Registered: May 2009

Master

After all, the reflex & the cornerhorn do share the same drivers. It could be argued that building a new box & changing to another X-over wasn't THAT big a deal... :-) But that's provided you DIY, of course.

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