I scored a pair of old JBL srx double 15 enclosures. The boxes where useless for my purposes (tuned much too high), so I decided to make something useful from them.
The first problem was that winisd could not simulate a tapered vent. Classe and PetterPersson at HifiForum pointed me in the right direction. If you put the port at the bottom of the box it can be modelled in Hornresp. Imperial at Hififorum encouraged me to place it at the bottom for some extra low extension.
Glueing 3 sheets of 12 mm pine plywood with visco elastic glue in a press I made for the purpose.
Measured outdoors in 1 pi:
Trying to fix the drop at 300:
It was not successfull. I cross them over at 170 Hz.
I was pleasantly surprised by the energy these can deliver. They can be used in small clubs. My nepheiew Anton uses them in his home stereo and ocassional dj gigs. These are fun playing Scrillex very loud!
In hindsight it was more trouble than it was worth rebuilding the old cabs. I should have taken them to the dump and built new ones.
I have no idea what this kind of design is called. MLTL perhaps? Compared to the winisd simulation of the equal box size, this box has more output in the 50 to 100 range. I belive that it works like a bass reflex at low frequencies, and then there is a quarter wave at 75 Hz giving it a nice kick in that region. At 150 the half wave is controlled by the speaker placement. The standing wave at 300 is impossible to control with damping material. Maybe a helmholz chamber could do that?
An externally hosted image should be here but it was not working when we last tested it.
The first problem was that winisd could not simulate a tapered vent. Classe and PetterPersson at HifiForum pointed me in the right direction. If you put the port at the bottom of the box it can be modelled in Hornresp. Imperial at Hififorum encouraged me to place it at the bottom for some extra low extension.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Glueing 3 sheets of 12 mm pine plywood with visco elastic glue in a press I made for the purpose.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Measured outdoors in 1 pi:
An externally hosted image should be here but it was not working when we last tested it.
Trying to fix the drop at 300:
An externally hosted image should be here but it was not working when we last tested it.
It was not successfull. I cross them over at 170 Hz.
I was pleasantly surprised by the energy these can deliver. They can be used in small clubs. My nepheiew Anton uses them in his home stereo and ocassional dj gigs. These are fun playing Scrillex very loud!
In hindsight it was more trouble than it was worth rebuilding the old cabs. I should have taken them to the dump and built new ones.
I have no idea what this kind of design is called. MLTL perhaps? Compared to the winisd simulation of the equal box size, this box has more output in the 50 to 100 range. I belive that it works like a bass reflex at low frequencies, and then there is a quarter wave at 75 Hz giving it a nice kick in that region. At 150 the half wave is controlled by the speaker placement. The standing wave at 300 is impossible to control with damping material. Maybe a helmholz chamber could do that?
I think it maybe is even more valuable to present projects that didn’t turn out exactly as one had hoped for at the start. There are a lot to be learned from these kinds of experiences too. Another god thing with this is when you say that you are happy with a construction or a project I know you are truly honest in that because you have by this post showed that you aren’t afraid of showing stuff that you are not so satisfied with. Thanks a lot! 
/Forsman
/Forsman
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