I've previously used a sealed 50L enclosure for my Seas A26 woofers with great success. But they are obviously quite large.
So I was wondering how small I could possibly go if I implemented some sort of aperiodic loading?
Or will aperiodic loading simply reduce the Q, but not provide lower extension like an actual larger enclosure would?
So I was wondering how small I could possibly go if I implemented some sort of aperiodic loading?
Or will aperiodic loading simply reduce the Q, but not provide lower extension like an actual larger enclosure would?
I've been studying sealed vs low tuned vents, which some have dubbed quasi sealed or extended bass shelf....somehow in my brain this is related to the aperiodic vent...the restricted port has a low tuning to I think....the thing with a small port is turbulence but with the restricting damping it is lessened....if modelled in HornResp you'd just need to assume the port velocity with damping material in place, to make sure it doesn't become vocal. A port/slot tuned very low....like 15hz?....and then stuffed (further lowering tuning)...a long with full stuffing inside the cabinet...good to go I think? I don't know for sure, I just made it up....the measurements look good to me, with like a 1-2db increase at 30hz?
Aperiodic loading reduces the Q, but the bass rolls of at 18dB/octave compared to the 12dB/octave of a sealed enclosure.
A couple of comments based on a past design application
The Seas A26RE4 is quite versitile. You can put it in a 1 cu. ft. sealed & heavy stuffed enclosure and realize a half space F3 of around 44Hz. This assumes a series Resistance Gain of around .7 ohms which is typical of a 14-15 ga. series air core, low pass inductor one would use assuming a 6 or 12 db/ oct. passive crossover. Total free air QTS works out around .42. With series inductor and Zobel, FS drops to 23.5 Hz, again, Free air. Enclosure QTC is .92 - .95 depending on the actual series inductor used.
In box resonance (FC) is around 55 Hz. Amax (ripple) is centered around 83 - 85 Hz with a .9 db value. Half space F6 is around 38 Hz. In most rooms with the enclosure 24" off the floor and 30" out from a rear wall, the in room F3 is close to the predicted half space F6, just under 38 Hz. All are are very usable hi-fi values. Have done this for center channel applications. Simple.
The Seas A26RE4 is quite versitile. You can put it in a 1 cu. ft. sealed & heavy stuffed enclosure and realize a half space F3 of around 44Hz. This assumes a series Resistance Gain of around .7 ohms which is typical of a 14-15 ga. series air core, low pass inductor one would use assuming a 6 or 12 db/ oct. passive crossover. Total free air QTS works out around .42. With series inductor and Zobel, FS drops to 23.5 Hz, again, Free air. Enclosure QTC is .92 - .95 depending on the actual series inductor used.
In box resonance (FC) is around 55 Hz. Amax (ripple) is centered around 83 - 85 Hz with a .9 db value. Half space F6 is around 38 Hz. In most rooms with the enclosure 24" off the floor and 30" out from a rear wall, the in room F3 is close to the predicted half space F6, just under 38 Hz. All are are very usable hi-fi values. Have done this for center channel applications. Simple.
Depends. I have seen real measured results with a slower roll-off.
Aperiodic is still not one of those boxes that does not yield to analytic design.
The smallest aperiodic box is usually the biggest box you can live with. You will get less bass in a smaller box.
dave
Sorry I'm a bit confused. How does a series resistor (either through an inductor or actual resistor) and/or zobel lower the bass extension?
Thanks!
By raising the QE. There are programs available to determine how much the woofer's total Q changes. You can find one of these calculators here: Calculate new Qts with Series Resistor Experiment with different values and different woofers. J