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One more time [message #64675]

Sat, 13 November 2010 22:22

steve f
Messages: 238
Registered: May 2009

Master

Wayne,

Sorry, but I need to bother you one more time. Because of space restrictions, I was going to build a pair of 2 PI speakers set sideways. Trouble is, I love the CD of your horn loaded models. I don't want to give that up. The big question is "Has anyone tried to build a sideways mounted pair of 3 PI's?" Will that work? Low frequencies have sub reinforcement in my room.

Steve

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Re: One more time [message #64676 is a reply to message #64675]

Sat, 13 November 2010 22:36

Wayne Parham
Messages: 18787
Registered: January 2001

Illuminati (33rd Degree)

Not sure about that one. I think it would fit, so it might be worth a try. There have been several people do mods of one sort or another, even remember a few towers done based on three π and four π models. Not sure how much testing/optimization work was done on any of them.

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Re: One more time [message #64723 is a reply to message #64676]

Tue, 16 November 2010 02:51

steve f
Messages: 238
Registered: May 2009

Master

Wayne,

I'd like to give a 3PI tower version a try. Would you please send me 3 PI plans? Thank you.

Steve

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Re: One more time [message #64724 is a reply to message #64723]

Tue, 16 November 2010 03:31

Wayne Parham
Messages: 18787
Registered: January 2001

Illuminati (33rd Degree)

I've sent plans for the three three π loudspeaker. If you deviate from the dimensions shown, do check internal standing wave modes. One of the most common problems I see with tower configurations is internal standing waves lining up in an unfavorable way and causing response anomalies. When you make a tower, the positions of woofer and port become somewhat critical. This is true for any large speaker with a midwoofer used through the midrange, but even more so with towers. There's more potential for unwanted standing wave problems. See the posts at the link below.

Internal Standing Waves

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Re: One more time [message #64727 is a reply to message #64724]

Tue, 16 November 2010 11:52

steve f
Messages: 238
Registered: May 2009

Master

Thank you Wayne. I was planning on following your lead by trying a box shape similar to your 2 PI, measuring, and hopefully tweaking dimensions for the final project.

Steve

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Re: One more time [message #64728 is a reply to message #64727]

Tue, 16 November 2010 15:02

Wayne Parham
Messages: 18787
Registered: January 2001

Illuminati (33rd Degree)

I'm sure you can make it work, it's just not a slam dunk like it is with smaller boxes. Of course, smaller boxes trade-off extension or efficiency or both. So I'd rather deal with the added complexity of making sure the standing waves don't lump up around the port.

I think it makes sense to use the two π tower as a starting point, but you'll probably have the midwoofer and tweeter packed pretty tightly up top. It won't fit, to tell the truth, so you'll have to move 'em down a little. And cabinet volumes are different too, so you'll need to modify the dimensions for that as well. You can't just put the midwoofer and port the same distance from one another as they are in the two π tower and expect them to act the same because in this case, it isn't just the relationship between the two sound sources but also internal reflections, the distances to the top, bottom and sides. All this means it isn't apple-and-apples.

You'll just have to measure the speaker when you're done and hope for the best. Maybe build a sacrifical speaker first, and that way if it doesn't work out, you won't be out much. Use either scrap wood or perhaps MDF without a finish. If it measures well, you can add the veneer and finish after it has been proven in testing.

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Re: One more time [message #64737 is a reply to message #64728]

Wed, 17 November 2010 11:40

steve f
Messages: 238
Registered: May 2009

Master

Wayne,

My initial space requirements aren't that far from the 3 PI turned sideways. Most table/low cabinet furniture is 30-32 inches tall. I can make the box 31 inches, an inch taller. I would like to maintain a 15 inch width for the front baffle. That would leave 18 inches for depth. Not a huge change from your design, provided sideways works. Rolling Eyes

I agree with you. A sacrificial box is the way to go. I'll build one out of MDF that has removable panels, and a couple of different baffles. So the first trial will be a box of 31 X 15 X 18 placing the drivers height wise near your original design. I prefer to place the vent on the back. If it doesn't measure well, I'll add to my scrap wood pile & try again.

Steve

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