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Old 6th December 2009, 04:08 AM   #1
Pallas is offline Pallas  Pakistan
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Default Software to model a 4th order bandpass with a PR instead of port(s)

Over the winter I'm thinking about experimenting with some spare drivers (Peerless 830500, aka XLS12) and PR's I have and experimenting with a 4th order BP using a PR instead of ports.

Does any current software allow one to model a 4th order BP with PR? If it runs natively in OSX then that would be incredible, though I know of no modeling software at all that runs natively on Macs. I do have Parallels with WinXP Pro so I can run my Mac in cripple mode and use non-OSX software if I must.

Alternately, mathematically how could one "convert" a PR of known Fs, Q, Vas, and Mms to a "port dimension" that one could plug into Unibox, etc?
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Old 6th December 2009, 12:48 PM   #2
Ron E is offline Ron E  United States
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Quote:
Originally Posted by Pallas View Post
Over the winter I'm thinking about experimenting with some spare drivers (Peerless 830500, aka XLS12) and PR's I have and experimenting with a 4th order BP using a PR instead of ports.

Does any current software allow one to model a 4th order BP with PR? If it runs natively in OSX then that would be incredible, though I know of no modeling software at all that runs natively on Macs. I do have Parallels with WinXP Pro so I can run my Mac in cripple mode and use non-OSX software if I must.

Alternately, mathematically how could one "convert" a PR of known Fs, Q, Vas, and Mms to a "port dimension" that one could plug into Unibox, etc?
Go the other way, take a port of known dimension (in this case use a port with the same area as the passive). TAke the length that unibox spits out and calculate the mass of air in a port this length plus 0.73 times the diameter. This is the mass your passive should have.

Unibox does PR's, just not in the bandpass section. Since it plots the PR component response, you can model using unibox. Model a sealed box the same size (Vb) as the sealed chamber you will use with your bandpass box. Make a new driver - enter the resonant frequency and Qtc, (Qec and Qmc will increase by the same ratio) from the sealed box results and use a modified Vas that is Vac = Vb*Vas/(Vb+Vas)

Now model this new driver in a PR box the same size as the vented portion of your bandpass and look at the graphs for just the port/PR response.

If I didn't explain it well enough, I can model it for you and post a graph (my spreadsheet does PR's) if you come to a decision on a woofer and PR /box size combination.
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Old 6th December 2009, 06:42 PM   #3
Pallas is offline Pallas  Pakistan
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Thanks, Ron. I'm going to try that out both ways and get back to you.
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Old 7th December 2009, 09:59 AM   #4
Henkjan is offline Henkjan  Netherlands
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I expect that LspCAD will be able to simulate this in more detail, also taking the parameters of the PR into consideration.

http://www.ijdata.com/
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Old 7th December 2009, 10:40 AM   #5
Ron E is offline Ron E  United States
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Nothing against LspCAD, I'm sure it is a good program. Unibox takes the PR into account, and this method works. A 4th order bandpass is just a vented box with no contribution from the woofer, which is why you look at the port or PR only response. The sealed chamber modifies the parameters of the driver with increased stiffness.
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Last edited by Ron E; 7th December 2009 at 10:45 AM.
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Old 7th December 2009, 09:00 PM   #6
Pallas is offline Pallas  Pakistan
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Originally Posted by Henkjan View Post
I expect that LspCAD will be able to simulate this in more detail, also taking the parameters of the PR into consideration.

http://www.ijdata.com/
Even if lspCAD could do it plug and chug, I'm not spending that much money on Notamac software for a whim. Now, if it were OSX-native, maybe...
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