I have a Pair of Scanspeak 15M/4624G 5.25 inch midrange drivers. What would be the ideal size for the containment of those drivers? I was thinking of using some 5" PVC pipe that would be glued to the back of the baffle. how long should that 5" PVC pipe be ? Thanks🙂
Is it running anywhere near it's pistonic range?? If not does it really matter too much?
With a Vas of only 3.7litres i think anywhere between Vas and Vas/2 would work.
otherwise just plug the numbers into any box program and see what size a Qtc=0.55 or Qtc 0.7071 equals.
150mm pipe length equals 1.9litres ~, of course you need to deduct driver displacement, so howzabout 200mm or 8inches internal .
Why not run the tube all the way through the box? Front to back TL style
With a Vas of only 3.7litres i think anywhere between Vas and Vas/2 would work.
otherwise just plug the numbers into any box program and see what size a Qtc=0.55 or Qtc 0.7071 equals.
150mm pipe length equals 1.9litres ~, of course you need to deduct driver displacement, so howzabout 200mm or 8inches internal .
Why not run the tube all the way through the box? Front to back TL style
that would involve modelling to give a good answer, but if it isn't in its pistonic mode I don't think much change.
Qtc's above 0.7071 can start to have a hump in the response at box resonance and can have better power handling in a sealed enclosure at the expense of SPL. none of that really matters if the XO is high enough to avoid that resonance, say 300Hz or so
In a traditional mid-range application, with n x-over above ~300hz as Moondog55 has pointed out (often as high as 700hz or more), the "box" can be very tiny and the alignment has basically no effect... Consider for a moment, the number of "sealed back" mid-range drivers that work quite well.
However... I believe there are real world advantages to building the mid-cab larger than necessary. A larger space, allows for more dampening material, which allows more of the back-wave from the driver to be converted to thermal energy rather than being reflected back through the driver. The idea being, that the sound coming off the front of the driver is not colored by the sound coming off the back of the driver.
I have thought to myself, that when using a "pipe" as a chamber for a mid-range, one might find that lining the inside and outside of said pipe with asphalt type acoustic deadening sheets, and then stuffing the interior of the pipe with traditional acoustic deadening material like polyfill or something like it, and running the pipe all the way to the rear of the cab to maximize volume, would probably not be a bad approach to creating a sort of "IB" effect for the driver.
However... I believe there are real world advantages to building the mid-cab larger than necessary. A larger space, allows for more dampening material, which allows more of the back-wave from the driver to be converted to thermal energy rather than being reflected back through the driver. The idea being, that the sound coming off the front of the driver is not colored by the sound coming off the back of the driver.
I have thought to myself, that when using a "pipe" as a chamber for a mid-range, one might find that lining the inside and outside of said pipe with asphalt type acoustic deadening sheets, and then stuffing the interior of the pipe with traditional acoustic deadening material like polyfill or something like it, and running the pipe all the way to the rear of the cab to maximize volume, would probably not be a bad approach to creating a sort of "IB" effect for the driver.
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