I have my Alpair 7p sealed in a pine box with MDF for the front baffle, I have to buy a big sheet of MDF to replace the pine in the cabinet.
This sheet would be enough to try out some 1200x1200mm open baffles.
Before, a 500x700mm MDF open baffle sounded way too lean with the 7p.
The larger baffles would push the roll off point down an octave to 200Hz, which is gonna help a lot with that.
Will it be enough? not sure... I was totally satifisfied with bass quantity from the sealed 7p and the quality was excellent.
What are the implications of using a huge baffle like this, most importantly on the mids and highs? is it a waste of time? (assume more would do it otherwise)
This sheet would be enough to try out some 1200x1200mm open baffles.
Before, a 500x700mm MDF open baffle sounded way too lean with the 7p.
The larger baffles would push the roll off point down an octave to 200Hz, which is gonna help a lot with that.
Will it be enough? not sure... I was totally satifisfied with bass quantity from the sealed 7p and the quality was excellent.
What are the implications of using a huge baffle like this, most importantly on the mids and highs? is it a waste of time? (assume more would do it otherwise)
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Yes it is going to push the lower responses down further & further...that wave traveling that far trying to swing around to the other side. Remember, that big wavefront is also going to try swinging around at the bottom..but since its on the floor, its going to travel further still , trying to seek out that opposite...meanwhile, another wavefront is traveling forward towards your ears too, having given up seeking an opposing wavefront.
Mids & highs?...it's not really going to do anything to affect those...matter of fact, you should put the single driver at some random percentages left right, up & down...say 0.618 & 0.707 ?...now where did I get those numbers, I wonder? ...some cotton batting wrapping the rear basket...too big to have it three-plus feet away from the wall for a backwave to give it some "Direct reflector" effects.
--------------------------------------------------------------------Rick....
Mids & highs?...it's not really going to do anything to affect those...matter of fact, you should put the single driver at some random percentages left right, up & down...say 0.618 & 0.707 ?...now where did I get those numbers, I wonder? ...some cotton batting wrapping the rear basket...too big to have it three-plus feet away from the wall for a backwave to give it some "Direct reflector" effects.
--------------------------------------------------------------------Rick....
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I may use some light passive eq before the amp to boost bass as typical listening will low be enough to accommodate, do you mean parametric EQ to fix the more complex issues with response?
Don't see how that's possible, as there's very little bass to speak of looking at the sim.
jeff
so you can see a big OB could may have acceptable bass to my standardsDon't see how that's possible, as there's very little bass to speak of looking at the sim.
jeff
No ..... Just some boost at the low end to compensate
for the baffle rolloff .
So i made quick and dirty baffle from some pine planks for just one of the drivers, a couple of 400x1200mm planks side by side for 800x1200mm baffle.
It has *some* bass, not non-existent bass like the other smaller baffle but not enough either, however much more importantly it sounded absolutely awful on this baffle... so that settles that.
It has *some* bass, not non-existent bass like the other smaller baffle but not enough either, however much more importantly it sounded absolutely awful on this baffle... so that settles that.
There is a good reason almost none is building single driver OB speakers. Most are using some kind of woofer support like the slot-loaded-open-baffle.
If I plug the math into calculations I got from Linkwitz Rileys dipole max-spl spreadsheet we have 20cm3 displacement for the alpair 7p. Even with a 800 mm wide baffle with a fequal of 120 hz (dipole spl = monopole spl) the max spl at 100 hz is 91 dB @ driver xmax.
Thats not a lot, and that is with excessive 800 mm wide baffles.
The driver would perform a lot better if you highcrossed it at 200 hz or higher given a ~ 300 mm wide baffle and used woofers to cover below. Probably closer to 250-300 hz if you want to use a smaller baffle.
If I plug the math into calculations I got from Linkwitz Rileys dipole max-spl spreadsheet we have 20cm3 displacement for the alpair 7p. Even with a 800 mm wide baffle with a fequal of 120 hz (dipole spl = monopole spl) the max spl at 100 hz is 91 dB @ driver xmax.
Thats not a lot, and that is with excessive 800 mm wide baffles.
The driver would perform a lot better if you highcrossed it at 200 hz or higher given a ~ 300 mm wide baffle and used woofers to cover below. Probably closer to 250-300 hz if you want to use a smaller baffle.
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If you put the A7p in an infinite baffle it will have a system Q = Qts = 0.5. This is a bit lower than most prefer. A little EQ will help but it is a 4” driver with limited excursion so quantity will be limited.
There are few drivers that will produce decent bass in a (large) OB without EQ. In my experience the VIsaton B200, an Omnes 8” and a Korean-made 6.5” that was specifically made for OB. At one diyFEST we constructed a 16’ wide OB and the bass was staggering… probably a bit over the top.
dave
There are few drivers that will produce decent bass in a (large) OB without EQ. In my experience the VIsaton B200, an Omnes 8” and a Korean-made 6.5” that was specifically made for OB. At one diyFEST we constructed a 16’ wide OB and the bass was staggering… probably a bit over the top.
dave
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