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Wednesday, June 13, 2012

The Grill Effect: Woofer Covers

This is not about grill cloths.
I'm assuming that those vary widely, and essentially soften the high end (treble),
with the lighter the fabric, the sparser the weave, the better.

I'm talking now about bass woofer screens, made of metal.
These appear to physically block half the radiating area or more.
I'm guessing that these metal grills cause significant effects:

(1) They must cause half-power size reflections back into the speaker cone, and 'shadow' cancellation at odd frequencies, especially for woofers that are going up to 120 - 1200 Hz.

(2) They must cause sound wave diffractions around the grill pattern, and perhaps add harmonic or intermodulation distortion to the original sound-waves.

(3) They must also possibly contribute "whistles", i.e., wind noises, especially with loud subwoofers and large excursion speakers.

This so far is just in my head.

But I was thinking that you could have almost as good protection (which is the main purpose for me, as opposed to looks, which are always dubious) with thin metal screening,
i.e., protection from pencil-poking, cap cave-ins, and furniture corners, falling drunks etc.,
But with a coarse, but thin metal screen there should be a lot less effect on sound(?).

I'm interested to hear others' experiences in this area,
and product evaluations, because I see little out there in the minimalist direction.

I wish they'd just make cheap covers for say 10" / 12" woofers that were black, see-through, and of a light enough gauge to be of no concern.

Taking covers on and off is a needless creation of non-productive labor,
and all the screens I've seen so far block way too much,
and I am thinking a thin metal screen would be as protective in 90% of accidents.
Also, prices (with shipping) are all over the map, but generally way too expensive (as much as drivers!).
What are manufacturers thinking?
Why would I pay as much for a grill as for an expensive, carefully engineered speaker driver, made of exotic components?


Worst-Looking and probably worst performance:
Click the image to open in full size.
12" Waffle speaker grill ($5.95 + $7.00 shipping)

+points: cheap, protects from most accidents.

- points: Doesn't protect from pencil-pokes, wires, chopsticks, or drink spills.

Moderately Better:

Click the image to open in full size.
12" Subwoofer grills ($25.20/pair, $20 shipping = $24 ea)

+points: Slightly better looking, better protection
- points: I can by a good woofer for the same price.

Best Found So Far:

Click the image to open in full size.
Two-Piece 12" Grill: ($18 + $20 Shipping = $38 ea! minor break on shipping quantities)

+ points: Best looking, best protection from pokes and spills.

- points: Still blocks air movement very significantly. Price is ridiculous.

A Fourth kind of option is this sort of thing:
Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

But these are also expensive, ranging from $15 + shipping to $50 (who are they kidding),
and they are almost all outright garish and ugly looking.
Who can stand to look at these? Only Pioneer seems to have any fashion-sense, and it ain't great.
On top of this, they only protect the speaker from the crudest of accidents (large falling objects).

I'm thinking a much better solution is some kind of spaced screening, bake-painted black and trimmed square (maybe bent).
The idea is metal screening to stop puncture or ripping,
and small enough holes to stop pencils and pens, yet not block air-flow.
Also, you should be able to source this stuff by the yard, (i.e., for 12" - 15" speakers per yard)
at a decent price.

And why doesn't any speaker-cover manufacturer take this seriously and offer a decent product?

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