Question: front mounting older 15" Altec drivers (i.e. 515, 604, 605)

[joyspring]

Are any of you user board members successfully front-mounting older Altec 15" drivers (604/605/515)? They're obviously designed to be rear-mounted as the inside face of the mounting rim has those lovely cast-in stiffeners :-/ I'd like to avoid baffle diffraction from rear-mounting for my new 605 enclosures.

I've been thinking about using an extra thick gasket and cutting radial slots in both the baffle and gasket to achieve a rigid mounting but fear that this may result in air leakage.

Any solutions or ideas?

Many thanks,
Bob

[Jim Easley]

Using the method you described could work but, cutting the 16 slots in your cabs would be a bit of work. It doesn't look like the slots would have to be very deep depending on your gasket thickness. As the slots would be at a 45 degree angle to the face of the cabinets little material would be removed from the face. If any leaks did occur they could easily be eliminated with plastic modeling clay or even plumber's putty. Neither of these dry out and should give you an airtight seal.

Jim

[Charles Chance]

When contemplating building a pair of Model 19's using 416A's, I was faced with the same problem. I thought about doubling-up the front baffle, cutting the internal layer at about 15" so the woofer would pass completely through, and the external layer at 13 5/8" or whatever it took to mount the 416A. This would place the woofer at the same position that it needed to be for the Model 19. However, my domestic supervisor has decided that the fall leaves, the need for a new kitchen floor and other items are higher on my priority list, so my idea may have to wait.

[Frankie C]

I have been successful at front-mounting woofers in the following manner. I drill a pilot hole on center to the speaker diameter. I use a home-made plexiglass template as a compass to route a counter-bore to the depth of the flange and the stiffening ribs about 1/32" more than the outside diameter of the speaker. One or more passes are made at different diameters as needed to c-bore the full width of the mounting flange. I make another cut half way through the baffle at the diameter of the through hole and do the same from the other side of the baffle to cut the through hole. Mounting holes are drilled for 1/4-20 "T" nuts. I place a very generous bead of GE Silicone caulk around the c-bore, enough to completely fill the area between the flange and baffle, place the 1/4-20 bolts in place and scrap off any excess that oozes out along the edges. I let this dry for 24-48 hours, tighten the bolts, and the jobs done. Been using this method for about 20 years without any problems.

[joyspring]

Hi everyone,

Many thanks for the ideas, suggestions and tips!

I'm thinking of using a combination of the solutions presented here; routing and counterboring the baffle, cutting the radial slots but using a round-section insulation at the circumference of the mounting rim between the edge and mounting screw holes.

For the hardware itself, this is how I'm proposing to mount the 605 to the baffle (from outside to inside):

1/4" cap head hex screw
washer
605A
baffle
1/4" T-nut

Any alternate mounting hardware suggestions?

Many thanks again!
BobR

[hal333]

I am not familiar with that speaker but I did front-mount some EV 15 inch woofers.

I used some very nice bolts that had an allen wrench hex socket built in. I'm not sure what you call them but they look nice.

From the outside in I used the hex socket bolt, a small washer, EV 15 inch speaker, baffle, washer, hex nut.

Here's the good part - I assembled the bolts, washers, and nuts without the speaker in place and then secured the washer and nut located on the inside of the cabinet with a glob of hot-melt glue (be carefull to stay clear of the inside of the nut and the threads.)

Then I put the speaker in place and fastened it with the hex bolts to the nuts on the other side of the baffle with ease. Just make sure everything lines up perfectly with the holes on the speaker before you hot-melt the nuts to the back of the baffle.

Worked for me.