Software to model downfiring woofer???

Paul W · 12th March 2006, 02:03 PM

What software can be used to model the response of a downfiring woofer? I'm particularly interested in how the "slot" at the floor modifies higher frequency output. The slot may act as a low-pass filter but I'd like to better understand how it operates.

ThomasW · 13th March 2006, 07:27 PM

I bet you could model a bandpass design with the opening sized appropriately

Rademakers · 13th March 2006, 10:08 PM

That's how I did it. It's a reflex so I modeled it as a 6th order BP with the first chamber/port equal to the reflex. The airvolume below the woofer being the 2nd chamber and the opening being the port. In my case I made sure that the tuning for the second chamber was well above the crossoverpoint as didn't wanted a 6th order BP.

The lack of distortion compared to normal reflex mounting is eminent. It can be crossed much higher without the ussual coloration of the sound that it used to have at different crossoverfrequencies in several enclosures. People standing next to it actually don't believe it's on, untill it's off.

A simulation will show a (24 dB) rolloff without return to axis, in practice it will be more of a (large) dip in the response.

Wkr Johan

Paul W · 18th March 2006, 04:55 AM

Okay...thanks. I'll try that this weekend.

12th March 2006, 02:03 PM	#1
Paul W diyAudio Member Join Date: Oct 2003 Location: North Georgia	Software to model downfiring woofer??? What software can be used to model the response of a downfiring woofer? I'm particularly interested in how the "slot" at the floor modifies higher frequency output. The slot may act as a low-pass filter but I'd like to better understand how it operates.

13th March 2006, 07:27 PM	#2
ThomasW diyAudio Member Join Date: Oct 2001 Location: 5280'	I bet you could model a bandpass design with the opening sized appropriately __________________ Cult of the Infinitely Baffled (Resource for IB sub builders)

13th March 2006, 10:08 PM	#3
Rademakers diyAudio Member Join Date: Jan 2005 Location: Rotterdam, NL	That's how I did it. It's a reflex so I modeled it as a 6th order BP with the first chamber/port equal to the reflex. The airvolume below the woofer being the 2nd chamber and the opening being the port. In my case I made sure that the tuning for the second chamber was well above the crossoverpoint as didn't wanted a 6th order BP. The lack of distortion compared to normal reflex mounting is eminent. It can be crossed much higher without the ussual coloration of the sound that it used to have at different crossoverfrequencies in several enclosures. People standing next to it actually don't believe it's on, untill it's off. A simulation will show a (24 dB) rolloff without return to axis, in practice it will be more of a (large) dip in the response. Wkr Johan __________________ Impossibilities we do immediatly, miracles take slightly longer.

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18th March 2006, 04:55 AM	#4
Paul W diyAudio Member Join Date: Oct 2003 Location: North Georgia	Okay...thanks. I'll try that this weekend.

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