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How much bigger does the Vb seem to the new coupled driver?
Not at all, twice, or not quite twice?
Being sealed, what density of fibreglass to use? What effect could fully stuffed have.
There will be two sealed subs, and two TL's in the front wall corners.
I would use a mask when cutting and fitting fibreglass. Hair-spray on skin and a soapy shower afterwards, to boot.
Noting that I will be using several (4?) 1/3rd octave Eqrs to get from 150 Hz down as flat - across the 2-person listening area - as possible.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Follow Ups:
It's not clear to me what you're asking since you list both closed box and TL.
If clamshell means two drivers face to face the resonant frequency and the Qts of the double drivers stay the same. But the Vas is halved and the efficiency of the doubles drops 3 dB. So the box behind the clamshell drivers is half the size for the same roll off.
Apart from the fact that a TL is most unlikely to use clam-shelled drivers. Nor would it help. ....
I was asking about sealed boxes using two OOPhase drivers.
Thanks for answering that question.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
So even with an Rb enclosure VAS halves with two face-to-face (OOP) drivers!
So I have the option of adding a passive radiator to each sub, if I find that the Eq required down at ELF is running us out of power.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Is what you mean. Yes as the other reply said only half the box volume is required for the two for the same performance as one in a box twice as big. Don't forget to wire the drivers out of phase too. We used that design in car audio when the customer wanted a small box.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
I will be powering each driver individually with one channel each from a stereo power amp, and yes, out of phase. This I believe reduces the demands on each amp's power supply, possibly raising headroom.
There may eventually be 5 subs. The two sealed ones mentioned, a reflex box I've had for a long time, and two TLs in the 'front' wall's corners with KEF B139s. I've yet to build the TLs!
The idea being to get as smooth a bass response as possible, before applying Eq to both channels. I'll be using 1/3rd octave Eq after the low-pass filters. I hope to be able to do 16Hz pedal reed notes.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
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