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Variation on a 2pi theme [message #38737] Sat, 19 October 2002 12:20 Go to next message
DRC is currently offline  DRC
Messages: 169
Registered: May 2009
Master
I'm nearly commited to making 40" tall Studio 2pi Towers using the 12" driver, and the 2002 compression driver mounted in a woodhorn 12" tractrix sitting on top.

Should I move the woofer closer to the top edge of the cabinet, since there will be no tweeter on board? What change(s) do I need to make to the port given the change in woofer and cabinet volume? If I go 3/4 instead of 5/8, do I need to further adjust the port size, or just reduce the thickness at the port to 5/8?


Keep your ears and your mind open.

Actually, it's a three π [message #38739 is a reply to message #38737] Sat, 19 October 2002 17:22 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)
What you are describing is essentially a three π speaker. For example, a Thermionic Series three π uses an Alpha 12 and a PSD2002 in a 6 cubic foot box, tuned to 25Hz. A Theater Series three π is similar, but uses a Delta 12LF and a PSD2002.

With each different model woofer, the box is tuned differently, appropriate for the motor's characteristics. If you use the Alpha 12, the box will need to be at least 5 cubic feet. So the cabinet size of the tower two would work pretty well, but the cabinet should be tuned a little lower. PiAlign recommends 5 cubic feet, which should be considered a minimum volume for that particular woofer. Other motors will have their own unique requirements for motor chamber, so it is best to match the woofer with an appropriate box. But it's pretty easy to do, and I think you'll be very pleased with your results.

The system you've described sounds nice, and if you need any of the parts, we have all of them in stock. We have everything available from the midwoofers and compression tweeters to the horn flares and crossovers. You might find it easiest to purchase a three π kit in the "π Speaker Kits" section rather than to order parts individually.

Re: Actually, it's a three π [message #38747 is a reply to message #38739] Sun, 20 October 2002 10:27 Go to previous messageGo to next message
DRC is currently offline  DRC
Messages: 169
Registered: May 2009
Master
Wow! You really believe in full responses, Wayne! cool. ;-)

Nearly as soon as I posted, I realized a 2pi didn't make a lot of sense for where I was going.

I'm in what gets referred to around here as the"tube-friendly" camp, although I think a lot of us are actually in the SET-friendly camp, which is even more demanding and less forgiving than some of the PP tube amps. So power handling is not a consideration, but keeping the amp happy is. The less compensating I have to do in the xover, the better I like it, so flatter uncompensated response looks like a good thing.

I'm going to use Martinelli horns w/PSD2002's. I'm thinking that I should be able to cross them over somewhat lower than the smaller flare on the face of the spkr cab allows. Does this make sense?


Keep your ears and your mind open.

Now it's a four π [message #38748 is a reply to message #38747] Sun, 20 October 2002 13:12 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)
You're going to build a super pair of speakers, I can tell. Don't crossover the PSD2002 very low though - They'll begin to distort and sound unnatural. If you want a low crossover point, I suggest running a different compression driver.

I'm sure you'll be very pleased with the midrange response of the Delta 15, so don't hesitate to crossover high.

Dave, You always have to have the biggest Pi's on the block! [message #38751 is a reply to message #38747] Sun, 20 October 2002 13:31 Go to previous messageGo to next message
Garland is currently offline  Garland
Messages: 269
Registered: May 2009
Grand Master
Check out the Pi 10's. REAL Loudspeakers! Have fun on the 2nd is it? Wish I could make it.

G.

Re: Dave, You always have to have the biggest Pi's on the block! [message #38753 is a reply to message #38751] Sun, 20 October 2002 18:22 Go to previous messageGo to next message
DRC is currently offline  DRC
Messages: 169
Registered: May 2009
Master
Yer killin' me! I'm really just chasing the smoothest upper midrange, but the size is rather scary. May have to "back off to the Theatre 4's." ;
-)
Thanks for not saying, "What in heaven's name do you need more speakers for?!?"

Actually the meeting's the 3rd. I goofed on the first announcement. I try to keep 'em on a Sunday.

10's! Yeah, now yer talkin'!


Keep your ears and your mind open.

Re: Now it's a four Pi [message #38754 is a reply to message #38748] Sun, 20 October 2002 18:31 Go to previous messageGo to next message
DRC is currently offline  DRC
Messages: 169
Registered: May 2009
Master
Wayne, please send me the plans for the Theater 4's. I've heard Garland's, and they sound great.

And no matter what he says, the 10's are out of the question. (At least as long as I live on the 3rd floor!) ;-)

Thanks for all the info. Can't wait to build these babies!
Keep your ears and your mind open.

You've got mail! [message #38755 is a reply to message #38754] Sun, 20 October 2002 21:34 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)

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