Step-by-Step: How to Front-Mount Drivers on a Damaged Baffle Board (w/pics)

[BassDogDoc]

Part 1

Since I've only found limited information and never in a concise format (with photos), I decided to photo document my front-mount technique for loading drivers on a damaged baffle board and post it here.

For me, this is usually needed when I buy a used cabinet or combo amp and discover previous damage done to the baffle board, but I've also done it if there is a lot of buzz or rattle from the driver vibrating against the baffle board, often because air is leaking around the driver's mounting surface.

In this particular example, I'm repairing my vintage Acoustic Amplification Corporation 106 bass cabinet (2 x 15").

For space reasons I'm putting only image thumbnails in the body of the text... just click on them to see the full size version.


Parts list (I got mine from Home Depot):

1/2 inch Rigid 1-hole Strap (4 pack) @ $0.64 each pack x 2 packs


1/4 in.-20 tpi x 5/16 in Tee Nut (4 pack) @ $1.18 each pack x 2 packs


1/4 in.-20 x 1-1/4 in. Round Head Machine Screw (4 pack) @ $1.18 each pack x 2 packs


1/4 in. x 5/8 in. Flat Washers @ $0.12 each x 8 individual washers


1 in x 1/4 in x 120 in. Self-Adhesive Sponge Rubber Weather Strip @ $4.95 for a 10 ft spool


Tools:
Phillips screwdriver
Workman's pliers
Pencil
1/4 in drill bit + Electric drill
Scissors

Procedure:
a) Lay the cabinet down on its back and remove the current retaining bolts or screws that hold the drivers in place, but don't pull the drivers out.

b) Take the 4 rigid straps (make sure you get the rigid kind as they are thicker and stiffer) and use the workman's pliers to partially straighten out the curve in the part of the strap tip that extends beyond the ridge down the center of the strap. Don't try to bend the portion that has the ridge as this is too difficult and also what gives it strength.


c) Lay the 4 rigid straps on the driver rim, evenly spaced around the perimeter, making sure they don't extend onto the edge of the paper cone. Use a pencil to trace the hole of each one onto the baffle board... be sure holes don't occur on top of any bracing that may be on the back side of the baffle board.


d) Remove the rigid straps and pull the drivers, being careful to unhook the wires from the drivers (take note of which wire attaches to each terminal).

[Continued next post]

 

[BassDogDoc]

Part 2

e) If bolts were used, take a screwdriver and push it into the hole to pop the old tee nuts out the back side of the baffle board. You see here how these had torn through the wood in my cab.


f) Use the drill and 1/4 inch bit to drill out the new holes you've marked for your new tee nuts. The shaft of the tee nut is a bit bigger than 1/4 inch so you'll have to run the drill bit up and down and around the edges to make it a bit bigger.


g) Push the new tee nut up into the hole from the backside of the baffle board, getting the teeth to anchor into the wood. From the front side, thread a machine screw and washer into the tee nut and use a screwdriver to hand tighten it down. This fully seats the tee nut into the wood. Be sure not to use a drill with screwdriver bit for this part as it tends to be too powerful and can strip the nut out of the wood. When done, remove the machine screw and washer, leaving the tee nut implanted in the wood. Do this for all the new holes.


i) Use scissors to cut the weatherstripping foam lengthwise for about 25 inches and then re-roll it. Start applying one of the self-adhesive strips of foam around the opening for the driver, making sure to keep it flush to the edge. If you remove the paper backing as you go you can easily "bend" it to follow the curve of the edge. When at the end of that strip, cut it from the roll and continue with the other strip. When completing the circle, just cut the excess off leaving enough to bring the two ends together.


j) Place the driver back into the opening, making sure it is centered and the body of the frame doesn't rest against the edges of the baffle board. Remember to hook up the wires.

k) Place the rigid straps back over the edges of the driver, aligning the holes of the straps with your new anchor holes. Put the machine screw and washer through the strap hole and gently thread onto the tee nut and hand tighten with the screwdriver. Continue doing this in an "alternating opposite side" pattern around the driver (rather than just going around the circle), until all straps are on.


i) Put the grill cover back on and there you have it! A solidly mounted driver that doesn't rattle or buzz with an airtight seal around the edge. Most grill covers hide the hardware well enough (these show up due to the camera flash), but if you'd rather, you could spray paint them black before mounting to hide them even more.


I hope this helps out those of you that find you are in need of a similar repair.

I'm also sure that some of you have all kinds of modifications from this technique that you've developed specific to your situation and experience, so feel free to make additional tips and recommendations below.

-Clint, aka BassDogDoc

 

[basscooker]

I'd like to add one detail. If attempting a fix like this on a baffle board made of MDF or similar material (or if the original ply is particularly torn up); some silicone, wood glue or PL on the original tee nut or driver mounting holes would help prevent any material from rattling loose. It could find its way between the basket and cone, creating a new rattle. Also be sure to take a quick second to run a shop vac or sweeper hose around the inside of the cab before you put it all back together, being careful not to damage or grab any batting or insulation in the process.

 

[BassDogDoc]

Great suggestion, basscooker!
I also do a final vacuum sweep, but haven't experienced the "debris rattle" you speak of... I'll consider that step on my next project!