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subwoofer for my 4Pi [message #47922] Sun, 09 October 2005 16:41 Go to next message
jshoc is currently offline  jshoc
Messages: 23
Registered: May 2009
Chancellor
I have been enjoying my 4Pi's over the past year, and think that it might be time to complement them with a subwoofer.

My 4Pi's are ruffly 6.5 cu.ft., with PSD2002 and Delta Pro 15s tuned I think to 42Hz.

I don't have time to build a subwoofer so I was thinking about a commercial unit.

Would I adjust the port length of my 4Pi - and tune it to a higher frequency - perhaps 150Hz (is this possible). Or do I modify the crossover so the cutoff for the Delta Pro is higher?

Hakn

Re: subwoofer for my 4Pi [message #47924 is a reply to message #47922] Sun, 09 October 2005 21:53 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

Don't modify the four π speaker, but you may want to high-pass the signal going to it. For subs, I'd suggest a JBL 2245 in a 10.0ft3 box tuned to 30Hz or a LAB12 in a 3.5ft3 box tuned to 22Hz. I can send plans if you like. I realize you said you didn't have time to build, but you could probably find a good cabinetmaker in your area to build speakers for you.


Re: subwoofer for my 4Pi [message #47933 is a reply to message #47924] Mon, 10 October 2005 13:19 Go to previous messageGo to next message
jshoc is currently offline  jshoc
Messages: 23
Registered: May 2009
Chancellor
Wayne,

Thanks for the quick response!
Please send a copy of the Lab12 based plans.

Hakn Sr.

You've got mail! [message #47936 is a reply to message #47933] Mon, 10 October 2005 18:55 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)


Re: You've got mail! [message #48016 is a reply to message #47936] Sun, 16 October 2005 08:43 Go to previous messageGo to next message
jshoc is currently offline  jshoc
Messages: 23
Registered: May 2009
Chancellor
Thanks for the plans Wayne!

Next challenge is trying to get the right audio synergies..
The 15in Delta Pros in my 4 Pi Towers (JLapaire - tune to 42Hz) in comparison to the LAB 12 have a difference in sensitivity by more that 10dBs.
In a 3.5ft3 enclosure (ported) I would have to apply lots of power at the LAB 12 - something like a QSC RMX1450(900 Watts Bridged Mono into 8ohms) or RMX2450 (1200 Watts Bridged Mono into 8ohms)- Lab 12 is a 6 ohm speaker. Will this work?
So I don't overlap the low end - I would high-pass the signal going to the Lab 12 at 125Hz (? - thinking out loud).
Alternatively - I could use a plate amp.
Using the line level inputs and outputs, which will remove the bass from your Delta Pro 15in drivers. Adjust the level controls to match.
I would prefer using the Pro-amp approach with high-pass, as I want to leave the 4 Pi's alone - they sound great!
Haknhendrix Sr.


Re: You've got mail! [message #48017 is a reply to message #48016] Sun, 16 October 2005 09:08 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

You can use a plate amp with variable crossover and set it where it works best in your room. You'll probably crossover somewhere between 60Hz and 100Hz. Or if your preamp already has subwoofer outputs, you can use a prosound amp like QSC or Crown. The driver impedance won't be a problem for amps such as these.


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