Well, I ran the program with a 2.2 cubic foot box with 4 3 inch diameter holes, one inch long.
Umm, that was three inches, not three centimeters, right?
Reason I am asking is that the four 3 inch diameter holes tune the box quite high-to 103 Hz. this gives a really, really big "boom" in the midbass region.
I spliced the bass response graph with the response graph for midrange given on the Eminence site. The chart is just the response of the 15 inch Eminence-I am not even considering the response of the piezo horn here. As you can see, the response is hardly smooth. The midrange is visibly suppressed compared to the midbass. Each one of the horizontal graph lines represents 1 dB.
A speaker tuned this way will have a huge kick for bass guitar, which is prevalent in popular music. But deeper bass is nonexistent and midrange is muffled.
Umm, that was three inches, not three centimeters, right?
Reason I am asking is that the four 3 inch diameter holes tune the box quite high-to 103 Hz. this gives a really, really big "boom" in the midbass region.
I spliced the bass response graph with the response graph for midrange given on the Eminence site. The chart is just the response of the 15 inch Eminence-I am not even considering the response of the piezo horn here. As you can see, the response is hardly smooth. The midrange is visibly suppressed compared to the midbass. Each one of the horizontal graph lines represents 1 dB.
A speaker tuned this way will have a huge kick for bass guitar, which is prevalent in popular music. But deeper bass is nonexistent and midrange is muffled.
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Bull:
One more thing. Normally I prefer ported designs for PA work, since ported saves excursion. In this case, however, I just might make an exception.
You boxes are basically too small for the Eminence Beta-15 to work well in the ported mode. You will not be able to go very deep, regardless of what you do.
My suggestion is a simple one-stuff all four holes. It need not be wood-for a temporary experiment, any cloth, tightly stuffed, will do. This will turn the ported box into a closed box.
The graph of your box, ported and sealed, is below. You will lose that one-note "bass kick" with the ports tuned to 103 Hz, but in return you will get deeper bass, and the midrange should emerge. You will need to turn up the volume to get the same "bass kick", but it really was an artificially created situation.
Even without any aid from the port, your Eminence Beta-15 is able to put out about 115 dB at 65 Hz, which is about all your amp can drive it to anyway.
Try stuffing the ports tightly closed. Let me know how it sounds. 🙂
The red line is the response for your box with the ports open.
The blue line is the response of your box with the ports stuffed closed.
One more thing. Normally I prefer ported designs for PA work, since ported saves excursion. In this case, however, I just might make an exception.
You boxes are basically too small for the Eminence Beta-15 to work well in the ported mode. You will not be able to go very deep, regardless of what you do.
My suggestion is a simple one-stuff all four holes. It need not be wood-for a temporary experiment, any cloth, tightly stuffed, will do. This will turn the ported box into a closed box.
The graph of your box, ported and sealed, is below. You will lose that one-note "bass kick" with the ports tuned to 103 Hz, but in return you will get deeper bass, and the midrange should emerge. You will need to turn up the volume to get the same "bass kick", but it really was an artificially created situation.
Even without any aid from the port, your Eminence Beta-15 is able to put out about 115 dB at 65 Hz, which is about all your amp can drive it to anyway.
Try stuffing the ports tightly closed. Let me know how it sounds. 🙂
The red line is the response for your box with the ports open.
The blue line is the response of your box with the ports stuffed closed.
Attachments
kelticwizard said:My suggestion is a simple one-stuff all four holes. It need not be wood-for a temporary experiment, any cloth, tightly stuffed, will do. This will turn the ported box into a closed box.
You might also try part way between. Take some fiberglass insulation -- say 3" or 4" thick and compress it between a layer of mesh (plastic rain gutter mesh works great) on the inside of the port and the outside of the ports. This will give you an aperiodic enclosure which may reduce that peak even more (aperiodic design is not well defined so you may well have to play a bit).
dave
i was jsut looking around on partsexpress and i found this
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-069
where it says its useable down to 1,800 hz and matches with the 15x5 1/2 horn.
now what DOESNT make sense
is that this says it only goes down to 1.5khz
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-082
and yet is supposed to be like ksn1188A(which is speced to go down to 800hz) who to believe?
and how big of a horn woudl you need to get that low anyway? would a 12x4 one do? where would that put me(hz wize)? am i correct in my thinking, that partsexpress more likely mislabelled the specifications?
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-069
where it says its useable down to 1,800 hz and matches with the 15x5 1/2 horn.
now what DOESNT make sense
is that this says it only goes down to 1.5khz
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=270-082
and yet is supposed to be like ksn1188A(which is speced to go down to 800hz) who to believe?
and how big of a horn woudl you need to get that low anyway? would a 12x4 one do? where would that put me(hz wize)? am i correct in my thinking, that partsexpress more likely mislabelled the specifications?
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