how does the wave forms for diffraction on a baffle?
do they start from the driver following the surface,
or does it starts to reflect right at the end of the drivers onward ??
I wouldn't see any problem using difference surface material to try eliminate the phenomen ....
wich freq range is affected by diffraction ?
would materials like felt or foams affect this freq ?
the use of any loose hair of fibers on the surface should absorb alot of energy passing through it ...could work good
Please John elaborate on diffraction
Then is there any use at all for the rear waveguide or cylinder from my first sketch ?
assuming i'd use concave wings ...
still waiting for facts on moving dipole center off back
do they start from the driver following the surface,
or does it starts to reflect right at the end of the drivers onward ??
I wouldn't see any problem using difference surface material to try eliminate the phenomen ....
wich freq range is affected by diffraction ?
would materials like felt or foams affect this freq ?
the use of any loose hair of fibers on the surface should absorb alot of energy passing through it ...could work good
Please John elaborate on diffraction
Then is there any use at all for the rear waveguide or cylinder from my first sketch ?
assuming i'd use concave wings ...
still waiting for facts on moving dipole center off back
Dipole tweaks
Gentlemen;
I find the suggestions on this site very helpful. I made an OB for my Wharfedale Super 12 CS-ALs , augmented with the Super 3 tweeters & 12CS woofers. The baffle size started at 16"x 33".
The first modification was to add a 2x4 to one side to offset the speakers as implied by the Edge program. I believe the sound was improved but the change was not dramatic.
I read a suggestion that baffles that leaned back lost staging. I changed from an 11 degree slope to vertical with a noticeable improvement in the sound stage.
Another suggestion was the 2" radius edge treatment. I happened to have some carpeting rolls that was 4 1/4" O.D.
I cut them 33" long & took a 1 1/2" section out of them to enable them to fit on the sides of the baffles. They look like columns on a building wall but the definition of the instruments & singers was improved very dramatically. Even as ugly as I think they are, I'll be dressing them up & keeping them. My wife (who generally doesn't have any opinions about my sound system) has told me how much improved the separation of the left & right sounds are.
Without any bass boost, the OBs have clear, but insufficient bass. The BSR sub woofer I've pressed into service "smears" the definition of stand up bass notes.
I'm adding second 12 CS woofers (wired in parallel) to each baffle at floor level & 90 degrees to the existing woofers. The existing woofers will XO at about 300 Hz & the added woofers will XO at about 150 Hz. I'll then be able to be rid of the sub woofers.
Thanks for the discussions. Keep them coming.
dobias
Gentlemen;
I find the suggestions on this site very helpful. I made an OB for my Wharfedale Super 12 CS-ALs , augmented with the Super 3 tweeters & 12CS woofers. The baffle size started at 16"x 33".
The first modification was to add a 2x4 to one side to offset the speakers as implied by the Edge program. I believe the sound was improved but the change was not dramatic.
I read a suggestion that baffles that leaned back lost staging. I changed from an 11 degree slope to vertical with a noticeable improvement in the sound stage.
Another suggestion was the 2" radius edge treatment. I happened to have some carpeting rolls that was 4 1/4" O.D.
I cut them 33" long & took a 1 1/2" section out of them to enable them to fit on the sides of the baffles. They look like columns on a building wall but the definition of the instruments & singers was improved very dramatically. Even as ugly as I think they are, I'll be dressing them up & keeping them. My wife (who generally doesn't have any opinions about my sound system) has told me how much improved the separation of the left & right sounds are.
Without any bass boost, the OBs have clear, but insufficient bass. The BSR sub woofer I've pressed into service "smears" the definition of stand up bass notes.
I'm adding second 12 CS woofers (wired in parallel) to each baffle at floor level & 90 degrees to the existing woofers. The existing woofers will XO at about 300 Hz & the added woofers will XO at about 150 Hz. I'll then be able to be rid of the sub woofers.
Thanks for the discussions. Keep them coming.
dobias
rear shape of front radius
If I could manage a shaped plywood baffle, that looks like a "C" (or a half circle) from the top, would the rear waves react badly?
I wonder if the 4 inch diameter tubes are necessary to the rear waves reaching the front. Visually, I would prefer a "warped" baffle than the unappealing, but effective, "4 inch columns" I now have.
dobias
If I could manage a shaped plywood baffle, that looks like a "C" (or a half circle) from the top, would the rear waves react badly?
I wonder if the 4 inch diameter tubes are necessary to the rear waves reaching the front. Visually, I would prefer a "warped" baffle than the unappealing, but effective, "4 inch columns" I now have.
dobias
Member
Joined 2003
Here is a "C" shaped baffle. An 8" radius provides excellent diffraction control. Be careful to damp any cavity resonances, otherwise no problem.
An externally hosted image should be here but it was not working when we last tested it.
Diffraction
JinMTVT,
In other words, I'd be losing the benefits of the 4 inch "columns" over the rear waves as well as the front waves?
Thanks for the response , Jin.
I guess I'm stuck with the columns if I like the results. Sorta like the fur idea... it may work but getting used to the looks is another problem.
dobias
JinMTVT,
In other words, I'd be losing the benefits of the 4 inch "columns" over the rear waves as well as the front waves?
Thanks for the response , Jin.
I guess I'm stuck with the columns if I like the results. Sorta like the fur idea... it may work but getting used to the looks is another problem.
dobias
Re: Diffraction
i was more reffering to the polar response of the loudspeaker ... not sure if it is what you understood
diffraction was kindly and greatly explained on the first page of this thread by : john k...
dobias said:JinMTVT,
In other words, I'd be losing the benefits of the 4 inch "columns" over the rear waves as well as the front waves?
Thanks for the response , Jin.
I guess I'm stuck with the columns if I like the results. Sorta like the fur idea... it may work but getting used to the looks is another problem.
dobias
i was more reffering to the polar response of the loudspeaker ... not sure if it is what you understood
diffraction was kindly and greatly explained on the first page of this thread by : john k...
Member
Joined 2003
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