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Bohlender Graebener RD50 Planar Transducer
Can these be run open back? or do they need rear air loading??
I've owned neo 8pdr's for years open back. love em....
They can be used open back, but the phase cancellation means they do not provide nearly as much low end as they would with an enclosure that controls the back wave.
Date published: 2012-10-15
What woofers would be a good choice to pair with these?
I like the idea of these. I am currently building a line array and since these have a wide freq response I was thinking of doing a Martin Logan Electrostatic-esque type build with these. 8" or 10" in a 1cft box and then these above them. I don't listen at very loud volumes, I just don't want the sub to do all the low end work. I'd want some low-mid punch. If Bohlender Graebener made woofers I'd get a pair of those but since they don't, who would compliment these guys for some low punch around 90-300hz?Thanks in advance!
We have many options that will work well in this passband. The Dayton Reference series mid-basses would work well and are our best sellers.
Date published: 2013-12-21
Can you give an example recommended enclosure?
What would a good closed enclosure look like? Can I incorporate a woofer in the same enclosure? Would a trapezoid shape with a woofer at the base be a workable design?
In answer to putting the woofer in the same enclosure, "Yes" that is fine, but separate enclosures are far, far more versitile and allow you to optimize both imaging and bass response within the room at the same time.If you decide to put the woofer in the same enclosure, remember to isolate the back wave in a sub-enclosure so it doesn't push around the BG driver's membrane. And remember to "flush-mount" the driver; BD drivers are designed to be mounted from the backside of the front enclosure baffle, failing to do this will cause diffraction issues.In answer to the shape question, "Yes", you could use a Trapezoid, but I suggest a standard Rectangle, rather than a Trapezoid. Trapezoids are much more difficult to make than are Rectangles and Trapezoid enclosures are less important than lots of other things, such as a good roundover on the front baffle edges. Using a Trapezoid or other non-parallel wall "shapes" provide less benefit than does addressing a number of other issues, such as 100% fill of stuffing or implementing Baffle Step Compensation (BSC) as part of optimized Crossover Design.[by the way, (BSC) will be affected by cabinet width and distance from the back wall. Shape is even less important than the quantity and location of damper/stuffing used. Many studies on the effects of cabinet design and shape are available for the hobbiest. Check out the "Loudspeaker Design Cookbook" for more information.]BG has previously offered cabinet designs in support of the DIY market (but I don't this this information is readily available from them any more), and BG recommended basic retangle enclosures. As I recall, BG suggested a minimum depth of 3.5 inches because 3.5 inches is standard wall cavity depth, but I urge you to use a depth closer to 6" and to use 100% fill of damping to control standing waves and to prevent the back wave from bouncing right back through the membrane of the BG driver.Another thing to remember is that since the shape of the BG planar magnetic driver is long and narrow, most enclosures are going to be very tall in comparison to the width; enclosures of such proportions require heavy stuffing at the top and bottom to control the standing waves in that direction.Best wishes for success.
Date published: 2013-01-07