Flush Mounting Drivers

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Tarkers
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#1 Flush Mounting Drivers

Post by Tarkers »

I class myself as a novice DIYer when it comes to speaker building. One issue I've been grappling with is the issue of diffraction (a) from cabinet edges and (b) lack of driver rebating.

With respect to the former, the jury still seems to be out regarding whether cabinet 'round overs' are worth bothering with unless they are substantial (e.g. a 40mm radius or larger). Offset tweeter positioning with unequal distances from each side and the top seem desirable.

As far as (b) is concerned, rebating the baffle for the drivers has to be done by a third party unless you have a router - which I don't. I suppose one possibility would be to laminate an additional piece of MDF or whatever to effectively do the flush mounting. But the other approach is simply to front mount and have the drivers stand proud of the baffle.

If this last approach is taken, what level of sound degradation are we seriously talking about? I'm looking at a two way with the bass/mid running full range and tweeter with simple cap and resistor. I have both 10 inch (SEAS, ex Dynaco) and 8 inch drivers to play with.
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Ali Tait
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#2 Re: Flush Mounting Drivers

Post by Ali Tait »

Another approach could be to mount the drivers behind the baffle. Seen it in some vintage designs.

Welcome to the forum btw.
Tarkers
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#3 Re: Flush Mounting Drivers

Post by Tarkers »

Cheers Ali. Yes, my old Wharfedale Lintons had rear mounted drivers.
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Scottmoose
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#4 Re: Flush Mounting Drivers

Post by Scottmoose »

Indeed, welcome to the forum.

In order,

1/ Yes, to a point the jury is still out, although this is rather context dependent. For example, you can often get a small, but significant improvement (measured and audible) by moving from a 3/4in to a 1in roundover, most obviously with tweeters that have a wide radiating axis. Worth it? YMMV.

2/ Unless the drivers are designed for surface mounting, you really want to avoid that for best results. Laminating thin pieces of MDF, cork, or some form of fabric to the front will bring improvements acoustically, although since I'm lousy at construction, I'll leave details to those actually qualified to say something. One point though: if something like BB ply is used for the front baffle, it's technically possible to flush-mount the drivers without a router. You 'just' need a sharp knife, chisel, and some patience to remove individual plys. Derek Walton built a pair of Ariels like that as I recall: temporarily fix the driver to the front, carefully score around it, (equally carefully!) remove ply layer with chisel & repeat.
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Tarkers
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#5 Re: Flush Mounting Drivers

Post by Tarkers »

Cheers Scott. If I go the BB ply route, I can get the panels cut and routed fairly locally, but at a price. If I go the MDF way, then B&Q is much cheaper, but then finishing is more of a pain. The tweeter in question is a SEAS TFFC on what will be a 240mm (no round over) or 250mm wide baffle (using the 8 inch drivers).
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