design basics

[dancing-dave]

I want to do some speakers with a 10" woofer for bass and a 10" coaxial for the ~100Hz and higher range. My question is should both drivers share the same rear chamber for bass reflex, or should they be sealed from each other and have their own respective vents?

[Mr. Widget]

The latter will be much easier to design and be more predicable.

What drivers are you using?

Widget

[GordonW]

I agree with Widget. Unless the drivers have THE EXACT SAME T/S parameters (ie, same resonance, compliance, cone mass, motor strength, etc), they should DEFINITELY be in seperate enclosures.

Even with identical parameter drivers, it's probably still a good idea to use seperate cabinets. You might want to try staggered tuning (one driver ported to a different frequency than the other), among other tuning options... this can work well in making the bass rolloff smoother and more gradual, which usually sounds better than a more "brick wall" steep rolloff...

Regards,
Gordon.

[whgeiger]

Originally posted by dancing-dave
I want to do some speakers with a 10" woofer for bass and a 10" coaxial for the ~100Hz and higher range. My question is should both drivers share the same rear chamber for bass reflex, or should they be sealed from each other and have their own respective vents?

DD,

a) For below 100 Hz., recommend use of a driver with a larger [Vd](=[Sd]*[Xmax]) than the 10" woofer provides. Only this unit should be placed in reflex enclosure.

b) For frequencies above 100 Hz., place the co-ax driver in a separate sealed enclosure. It should be lined with 1" or thicker felt or equivalent acoustic resistance to suppress reflected energy. If the driver has a low [Qts] and high [Fs], then be prepared to equalize bottom end droop in the c/o.

c) Use an active c/o to feed the two enclosures (separate power amps.). A passive c/o should provide sufficient filtering for the co-ax driver.


Regards,

WHG