I am designing a subwoofer for PA use for a friend. A prime factor is cost, so arrays of 18"ers just wont do. The sub doesn't really have to reach too low, about 40hz will do. Also, it has to be effiecient, since he want to run it off his 100w amp that he already has. So i started thinking, what type of enclosue has good effeciency? I came up with this idea:
the bandpass enclosue has to ported sections: one port fires into a transmission line (tuned for 40hz) and the end of that line joins with the other port at the throat of a horn.
ALso, the bandpass enclosure will have two subs in an isobarik arrangement, so that both channels of a stereo amp can be used (with a mono signal), and so the bandpass enclosure can be smaller. this should work because all of the output of a 6th order bandpass is via the ports, and the T-line inverts the phase of one port, which then reinforces the output from the first port. The horn then directs the sound, so none is wasted behind it where there are no listeners. Of course this would be a ridicuoulsly large system, i think the horn mouth has to be 9m^2 or close to it, and the T-line has to be long too (i think 10-30m) ... i have all the calculations done, just not handy. My main concern is if the t-line will act as a port, making neither of them work as predicted. I think this may be compensated for by making the t-line crossection much larger than the port's. is this type of system feasible or not? according to some very rough calulations, from various sources, this may have up to a 110db 1w/1m sensitivity when using 93db drivers...that could make your ears bleed running off a 100w amp...
P.S. it doesn't have to sound "great" either, as long as its really loud and really cheap, it will maily be used for small outdoor concert/parties
I am probably going to use 2 12" woofers, any suggestions?
DO you think that this would actually hit 110db sensitivity, or is that misleading?
[Edited by Yoda on 10-22-2001 at 06:46 PM]
the bandpass enclosue has to ported sections: one port fires into a transmission line (tuned for 40hz) and the end of that line joins with the other port at the throat of a horn.
ALso, the bandpass enclosure will have two subs in an isobarik arrangement, so that both channels of a stereo amp can be used (with a mono signal), and so the bandpass enclosure can be smaller. this should work because all of the output of a 6th order bandpass is via the ports, and the T-line inverts the phase of one port, which then reinforces the output from the first port. The horn then directs the sound, so none is wasted behind it where there are no listeners. Of course this would be a ridicuoulsly large system, i think the horn mouth has to be 9m^2 or close to it, and the T-line has to be long too (i think 10-30m) ... i have all the calculations done, just not handy. My main concern is if the t-line will act as a port, making neither of them work as predicted. I think this may be compensated for by making the t-line crossection much larger than the port's. is this type of system feasible or not? according to some very rough calulations, from various sources, this may have up to a 110db 1w/1m sensitivity when using 93db drivers...that could make your ears bleed running off a 100w amp...
P.S. it doesn't have to sound "great" either, as long as its really loud and really cheap, it will maily be used for small outdoor concert/parties
I am probably going to use 2 12" woofers, any suggestions?
DO you think that this would actually hit 110db sensitivity, or is that misleading?
[Edited by Yoda on 10-22-2001 at 06:46 PM]