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3 Pi sub questions [message #91304] Sat, 04 January 2020 23:52 Go to next message
OneBean is currently offline  OneBean
Messages: 37
Registered: May 2009
Baron
I have been wanting to build new subs for my home theater. My current subs are in large ported cabinets, and the drivers are not very robust. The 3 Pi sub looks like a nice size, and appears to play deep and loud, with a robust driver. I have a Sony home theater receiver that has a single RCA sub out, and offers built in room correction, by using a microphone to listen to the rooms and make adjustments. Currently, the single RCA sub out goes to a Crown PA amp capable of delivering around 600 watts per channel into 4 ohms with a high dampening factor (over 1000 at 100 Hz if I remember correctly). Is 600 watts enough for 2- 8 ohm Lab12's in parallel?

If I added 2- 3 Pi subs flanking the right and left main speakers, and then added 2 more 3 Pi subs in the corners of the room, how would I attach these 4 subs to my equipment?

Do the subs have built in cross overs, so they don't need individual active crossovers?

Is there a risk of phase cancelation with all those subs placed around the room? Most subs from manufacturers have a phase switch or knob to get the phase right.

What is included in the kit?

I'm guessing 4- 3 Pi subs in my room (approximately 30' wide x 18' deep) would recreate explosions very nice if implemented correctly. Is anyone here running 4 of these in a home theater?

Onebean
Re: 3 Pi sub questions [message #91306 is a reply to message #91304] Mon, 06 January 2020 08:59 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

The three Pi sub kit is really just a woofer and port material. We also include the connector panel, a "π" logo and a printed copy of the plans. There is no passive crossover included.

The crossover, as you've rightly indicated, is specific to the application. Flanking subs use a different crossover than distributed multisubs. And those are different than a traditional single sub application, which I do not recommend, by the way.

There are many suitable crossovers and amps you can use. The simplest would be to mount a plate amp to the back of the box. But most plate amps have limited crossover options. You can also use a separate amp with MiniDSP, which would allow you a great deal of flexibility for crossover filters. Flanking subs use a 100Hz second-order Butterworth filter, which is a one-click setting in MiniDSP. Distributed multisubs can usually be run from the LFE channel.

More about multisubs and flanking subs at the link below:
Re: 3 Pi sub questions [message #91309 is a reply to message #91304] Mon, 06 January 2020 21:45 Go to previous messageGo to next message
OneBean is currently offline  OneBean
Messages: 37
Registered: May 2009
Baron
Wayne, thank you for the reply, I'm reading through all the FAQ's. Please send the plans for the 3 Pi subs, and 2 Pi bass reflex speakers.
Re: 3 Pi sub questions [message #91314 is a reply to message #91309] Tue, 07 January 2020 09:08 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

You've got mail!
Re: 3 Pi sub questions [message #91319 is a reply to message #91314] Tue, 07 January 2020 11:03 Go to previous messageGo to next message
OneBean is currently offline  OneBean
Messages: 37
Registered: May 2009
Baron
Thank you!
Re: 3 Pi sub questions [message #91321 is a reply to message #91304] Wed, 08 January 2020 08:04 Go to previous messageGo to next message
OneBean is currently offline  OneBean
Messages: 37
Registered: May 2009
Baron
Wayne, on the 3 Pi sub enclosure, is there any internal bracing needed?
Re: 3 Pi sub questions [message #91322 is a reply to message #91321] Wed, 08 January 2020 08:55 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17639
Registered: January 2001
Illuminati (33rd Degree)

No bracing needed. Panel resonances are way outside the passband. No need for insulation as damping material either, for a similar reason. The internal standing waves are also far above the passband.
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