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Help with OB baffle sizing

S

Sax & Guitar

Active Member
I am 16 pages into the OB Epiphany thread, and the designs keep getting more and more complicated.
I want a reasonably-sized flat panel OB baffle in which to fit my chosen 8" coaxial, high QTS driver. Range of the coaxial is 35hz to 20khz, resistance is 7.6 ohms, and sensitivity is 87 db@1watt@1meter. The speakers will be driven by a 13wpc SS amplifier. I am arbitrarily leaning toward 20" x 38" baffles with 15 degree leaning to put the speaker aimed at the listener, but I have no math or other input to justify my chosen size other than aesthetics and WAF.
For those who have built flat panel OB, am I on the right track? I don't want additional woofers and crossovers, just the single coaxial on each baffle. How far down the baffle should each speaker go? What determines the sizing of the baffle, as I have seen huge baffles and relatively tiny ones.
Thanks in advance for your input.
Sax & Guitar
 
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What is the woofers qts?
I have used 20" wide baffles in the past with 8" drivers.
You can start wide and cut down a little at a time, or use cardboard as a test.
Generally speaking wider will give more bass and narrow will give better imaging.
 
Sax & Guitar said:
I am 16 pages into the OB Epiphany thread, and the designs keep getting more and more complicated.
Click to expand...
If you want to see what a complicated design looks like, check out Siegfried Linkwitz's designs:
https://www.linkwitzlab.com/
Basically, the bigger the baffle, the more bass you will get. How big is big enough? I take the Quad ESLs as my guide and I've found a similar to size to them gives me enough bass.
There's a diffraction effect at the edge of the baffle and having the driver placed so the distances to the top edge, right hand edge and left hand edge are different prevents the diffraction effects from clumping together at the same frequencies.
There's a lot of information on the Linkwitz site.
You might find this useful too:
https://www.hi-fiworld.co.uk/index....akers-part-20-open-baffle-room-responses.html
 
@rothwellaudio:
Thanks for the tip on non-centered placement from top and both sides! Still need a sense of how far down the panel I should place the single coaxial driver...

@opnly bafld:
The FS is 51hz. How does this resonant frequency interact with the stated range of the speaker (35hz to 20khz)?

Thanks to you both for your input!
Sax & Guitar
 
Sax & Guitar said:
Thanks for the tip on non-centered placement from top and both sides! Still need a sense of how far down the panel I should place the single coaxial driver...
Click to expand...
Read the Hi-Fi World article in the link above. It gives a good overview without getting too heavy with maths and detail like the Linkwitz site does.
 
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