4th order bandpass-passive radiators

slipfirep40 · 12th November 2012, 06:38 PM

Looking to build a pair of mid-bass modules utilizing a fourth order Bandpass enclosure, with passive radiators rather than ports.

I want to use PR rather than ports for the purpose of acoustical filtering of harmonic distorsion produced by the active drivers, as well as avoidance of port noise or frequency irregularities which have been attributed to ported fourth orders.

I am also open to the idea of an aperiodic vent if beneficial.

The drivers I would like to use are the Vifa NE-225w-08 along with two Dayton SD215 Passive radiators.

Here is a diagram of what I am shooting for:

I want to use these as mid bass modules, ala the Geddes approach to subwoofer integration, along with one large low frequency sub. As such, I would like to make these as small as reasonable, without sacrificing sound quality.

I would like for it to be flat between 50-90 hz or thereabouts.

Tried to model it myself in winISD, But Ive never used the program before, and I don't think I did it right. Looked like crap.

Any help would be appreciated.

tb46 · 12th November 2012, 07:59 PM

Hi slipfirep40,

I don't mess around a lot win WinISD, but I'll attach a quick entry using the LAB15 and an 18"Dia. duct. Under vent you find the duct length, and from that you can calculate the air mass, which is the moving mass of the respective (in this case 18"Dia.) passive radiator. You have to enter your components of choice into WinISD.....

For another approach you could model this in Hornresp, export the data to AkAbak, replace the "duct" with a passive radiator. This would also allow you to enter acoustic damping material and filters.

Regards,

slipfirep40 · 13th November 2012, 01:15 AM

Thanks for the info.

16 bit Akabak told my 64 bit windows to pound sand.

Has anyone actually built a 4th order with/ passive radiator? I have found about a dozen threads where people discuss the possiblity, but not one of them ended with a build. So I guess I am treading on uncommon ground here?

slipfirep40 · 13th November 2012, 11:51 AM

I know this is kind of putting the cart before the horse, but this is the form factor that I am shooting for:

If these vifa drivers just won't work well in a Bandpass enclosure, what other 8" drivers will?

12th November 2012, 06:38 PM	#1
slipfirep40 diyAudio Member Join Date: Jan 2012	4th order bandpass-passive radiators Looking to build a pair of mid-bass modules utilizing a fourth order Bandpass enclosure, with passive radiators rather than ports. I want to use PR rather than ports for the purpose of acoustical filtering of harmonic distorsion produced by the active drivers, as well as avoidance of port noise or frequency irregularities which have been attributed to ported fourth orders. I am also open to the idea of an aperiodic vent if beneficial. The drivers I would like to use are the Vifa NE-225w-08 along with two Dayton SD215 Passive radiators. Here is a diagram of what I am shooting for: I want to use these as mid bass modules, ala the Geddes approach to subwoofer integration, along with one large low frequency sub. As such, I would like to make these as small as reasonable, without sacrificing sound quality. I would like for it to be flat between 50-90 hz or thereabouts. Tried to model it myself in winISD, But Ive never used the program before, and I don't think I did it right. Looked like crap. Any help would be appreciated.

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13th November 2012, 01:15 AM	#3
slipfirep40 diyAudio Member Join Date: Jan 2012	Thanks for the info. 16 bit Akabak told my 64 bit windows to pound sand. Has anyone actually built a 4th order with/ passive radiator? I have found about a dozen threads where people discuss the possiblity, but not one of them ended with a build. So I guess I am treading on uncommon ground here?

13th November 2012, 11:51 AM	#4
slipfirep40 diyAudio Member Join Date: Jan 2012	I know this is kind of putting the cart before the horse, but this is the form factor that I am shooting for: If these vifa drivers just won't work well in a Bandpass enclosure, what other 8" drivers will?