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Re: 4PI Cabinet plans / question [message #75036 is a reply to message #75035] Sat, 22 December 2012 09:46 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

thatsnasty wrote on Sat, 22 December 2012 02:39
I have my 4Pi's built and they sound fantastic!
The center is sealed as I was talking about above, but I had a question.

I'm currently crossing over the center at 80hz and the L/R at 50hz. I originally had the center at 50hz as well, but during more bass heavy content, I saw it was seeing some pretty decent excursion.

I was wondering if you had an idea how much power the 2226H can take with a 50hz cross in a sealed box?
My receiver (pioneer vsx-1018) will put out around 100-150w at max so just making sure I don't blow the thing up, lol.

That's one of the main reasons I prefer vented boxes. They reduce excursion while at the same time adding extension. And in the modal region, the changing phase of a Helmholtz resonator is unimportant, so it's definitely better to run vented mains.

Still, the center channel looks nicer sealed, and I think your solution is a good one. They just can't take quite as much power, but they can be high passed a little higher for protction, as you've done. When high-passing the mains, do it as low as you can to increase overlap/blending so the room modes are mitigated as much as possible with multiple sound sources. The high-pass numbers you've chosen are just about perfect.

Here are some response and excursion charts, for comparison:

index.php?t=getfile&id=946&private=0
Response of four π loudspeaker

index.php?t=getfile&id=950&private=0
Woofer excursion on standard four π loudspeaker

index.php?t=getfile&id=948&private=0
Response of four π with port removed to make a sealed system

index.php?t=getfile&id=951&private=0
Woofer excursion on sealed four π
Re: 4PI Cabinet plans / question [message #75037 is a reply to message #73067] Sun, 23 December 2012 01:05 Go to previous messageGo to next message
thatsnasty is currently offline  thatsnasty
Messages: 12
Registered: June 2012
Location: Niagara Falls
Chancellor
Thanks Wayne, that pretty much clears everything up!
No point in crossing it lower then 80hz, that's what subwoofer(s) are for (when they are finished Very Happy ).

Cheers and hope you have a great holiday.
Re: 4Pi loudspeaker performance data [message #75360 is a reply to message #75037] Sun, 27 January 2013 00:06 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

More information:

http://www.pispeakers.com/Measurements/fourPi_phase.gif
four π loudspeaker amplitude and phase response


Re: 4Pi loudspeaker performance data [message #75362 is a reply to message #73067] Sun, 27 January 2013 12:29 Go to previous messageGo to next message
dheflin44 is currently offline  dheflin44
Messages: 47
Registered: November 2012
Location: Carrollton, TX
Baron
Hi Wayne,

Do you recommend a high-pass starting just below the port tuning frequency to limit excursion?

Thanks,
Darrell
Re: 4Pi loudspeaker performance data [message #75363 is a reply to message #75362] Sun, 27 January 2013 12:59 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

If you are going to run high power levels, then sure, a high-pass filter at the Helmholtz frequency makes sense.
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