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Eliminate Electrovoice Metal Speaker Grill Rattle
By Sid of Stone Marmot
Jan. 31, 2009
The old 1980's Electrovoice (EV) speaker cabinets with angle aluminum on all the edges were great cabinets. Examples are the B115-M, B215-M, S12-2, S15-3, S18-3, LF215, FM12-2, and FM12-3. They were very solidly constructed, had great speakers in them, and sounded very good, particularly with bass guitar and electric guitar. But, over time, the metal grills protecting the speakers on all these cabinets would start to rattle, particularly when playing lower frequencies through the cabinets.
Examining my EV B115-M cabinet showed that the grill is supported at the top and bottom by being clamped between the aluminum edge protector and the wood of the cabinet. The underside, that is, the side that is against the metal grill, of the aluminum edge protector has a strip of foam that separates it from the grill. Figure 1 shows a picture of the top edge of the cabinet with the aluminum edge protector removed and laying on top of the cabinet. The sides aren't supported but are instead stiffened by bending the metal grill at a 90 degree angle in towards the cabinet.
Figure 1 - EV speaker cabinet edge with edge protector removed
This should be sufficient to provide a strong, secure, and rattle free attachment for the metal grill, and it does when the cabinets are brand new. But, over time, the foam between the aluminum edge protector and the grill disintegrates and the grill becomes loose. You also now have a metal to metal contact between the grill and the edge protector. This is what causes the rattle.
This can be easily fixed by replacing the now disintegrated foam with foam weatherstripping that is readily available in almost any place that sells home improvement supplies. I myself used 3/16 inch thick “Camper Seal Foam Tape,” simply because I had a lot of it already left over from previous projects. This stuff comes 1.5 inches wide which I had to cut in half (3/4 inches wide) to fit under the aluminum corner protector without sticking out beyond the edge. This foam weatherstripping has an adhesive on one side, as do most of these tapes, which makes application easier.
Many of these cabinets also have a rectangular cutout in them for a high frequency attenuation control. Figure 2 shows a picture of the one on my B115-M. You also need to remove the screws that secure the frame around this cutout and put some more foam under this frame and reinstall the frame. You can barely see some of this gray foam between the top edge of this frame and the grill in Figure 2.
Figure 2 - Cutout for high frequency control
These fixes solved the rattle in my grill. They should also solve the rattle in yours, unless your grill is severely bent. If it is bent, you need to straighten it out first, making sure the grill isn't touching any speakers.
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