Purifi-based monitor - options

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IslandPink
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#31 Re: Purifi-based monitor - options

Post by IslandPink »

It's a slightly bigger volume and a shorter port - but I like the effect of the wadding around the port interior. I will do a simulation first.
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IslandPink
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#32 Re: Purifi-based monitor - options

Post by IslandPink »

Unfortunately he explains nothing about his choice of volume and port size/length.
I did a basic Hornresp set-up for it with unlined port, then changed the port diameter ( on the basis he'd put felt in there ) until I got the closest match to the measured impedance curve ( with lined port ). This came out about 20cm^2 area, which suggest the port acts as if it's about 5cm dia ( though more damped ).
If I sim that for SPL it looks like this -
PurTroels_SPL.JPG
PurTroels_SPL.JPG (49.45 KiB) Viewed 283 times
The group delay doesn't look too pretty.
So I'm not sure this convinces me to build it.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )
chris661
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#33 Re: Purifi-based monitor - options

Post by chris661 »

A peak before rolloff will tend to ring.

Make the port longer to drop the tuning. The result should be a smoother frequency response, and I'd also expect the group delay to improve and/or push issues down in frequency.

Another option would be to go sealed, and EQ the speaker + room result.

Chris
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#34 Re: Purifi-based monitor - options

Post by Ant »

Try an aperiodic slot rather than a port? God knows how you would model it though
Ten square inches per cubic foot of cab volume was about the best info i could come up with for sizing
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chris661
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#35 Re: Purifi-based monitor - options

Post by chris661 »

IIRC, Hornresp can model it if you morph it into an offset-driver alignment.

Chris
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