Crossover mounting on rear wall
In the last week or two it was discovered (or was it lack of forethought) that the XR6s couldn't be tipped on their side to inspect the input jacks without possible damage to the crossovers, which were stuffed inside wrapped in packing material. The
crossovers HAD to be installed permanently before any further tests or restoration could proceed.
Marking and drilling center hole
The mounting process began by determining where to best drill mounting holes in the Crossover Boards. The top-center holes were already there (probably production stations.) A strip of 1/4" thick by 3/8" wide plywood was used to space the boards from the top wall as seen in the photo below. The boards are then centered left-to-right and a pencil was used to mark the edges/corners.
>> Many photos below were taken upside down looking through the crossover port from above with the speaker on its back. <<
Strip of 1/4" thick by 3/8" wide plywood used to space the boards from the top edge (view inverted.)
After the top-center hole is spot drilled, the board is removed and hole is drilled to a depth of 1/2" or until the countersink cutter just makes contact. Turns out that we had a
battery powered articulating screwdriver that was
perfect for drilling inside the XR6 cabinets through the narrow crossover port. Some photos as follows:
Tiny battery powered screwdriver with hex-drive wood screw pilot bit (view inverted.) PERFECT for the job!!
Fortunately
Craftsman has a wood screw Pilot Bit Set (4-piece) available with 1/2" long leading drill points for only $7.99. Since the cabinet walls are 3/4" thick HD particle board, the #8 bit was again PERFECT for drilling to depth. Here you see the pilot bit with hex-shank is inserted into the mini screwdriver. The holes are then opened up by 0.006" with another drill bit.
A second drill is same diameter (0.120") as the sheet metal screw minor diameter. The correct drill-size is important in order to thread the holes properly!!
Marking and drilling side holes
Once the top-center screw is installed and holding the board in place along the spacer strip, the side screws can be marked and drilled. Best is to drill the crossover boards (glass epoxy) to the same diameter as the Pilot bit, then open them up for #8 clearance holes later on. This improves hole alignment.
View of lower right mounting hole being spotted with bit (view inverted.) Crossover board is removed to drill 1/2" deep. See top screw in place to align.
Another view of the handle and 0.120" drill bit which is the same as the minor diameter of the #8 sheet metal screws. This shot is flipped 180° which would be the
view when normally looking through the crossover port. The cabinet is laying on its back.
>> It is recommend to have a vacuum handy to suck out chips and drillings at each step of the process. <<
Photo of lower left pilot hole being opened up by 0.006 in.
Here are
three crossover board mounting holes drilled and threaded into the back wall of the cabinet.
Three mounting holds drilled with threads cut (screws driven to depth w/o boards.)
Once the pilot holes are drilled, the
screws are driven into the holes to cut the threads with a
STUBBY #2 Phillips screwdriver. There isn't much trouble threading in the screws with the correct diameter holes. If the pilot hole is too small the Phillips bit will 'jump' the screw-head slots and ruin them!!
>> Mounting screws are #8 x 1-1/2 inch Sheet Metal, Phillips head, 3 each. <<
Crossover Board mounting
High quality 1" thick
foam pads were used
INSIDE the three mounting screws. Foam cannot be drilled as it will be torn and destroyed. Since the crossovers boards were dissimilar with large BASS inductors located in slightly different positions, the lower-right mounting holes weren't in the same spot for S/N 1634 and 1635 (see screw locations near LARGE inductors.) Therefore foam pads of different width (~1/2") were used. Below is a foam pad (bottom-side up) with double sided tape being applied.
High quality 1" thick, medium stiffness foam with double-sided mounting tape applied. These pads are fixed in place between the screws.
Additional strips of foam could be attached OUTSIDE the mounting screws, extending to the board edge for better support and damping. That would be a good future upgrade!!
Mounting complete
S/N 1634 Crossover Board mounted with edge connector oriented down.
S/N 1635 Crossover Board mounted with edge connector oriented down.
Difficult exposure settings and post processing on these photos.
Close 'em up and Play
It was getting to be 5:00 pm and time to close 'em up and play some music. The crossover cover/fuse wires were attached and the systems tipped back into the standing position. As you can see, the
fuse terminals are easily accessible through the front port.
View of crossover board through top port. A very neat job!! The boards are held firmly with three #8 screws and access to the fuse terminals is excellent.
The XR6s are sounding GOOD
We enjoyed listening to the local Country FM station through dinner into the evening, and later played a DVD video from 9:30 to 11:45 pm. The XR6s have a different sound than the Thiels, definitely softer and warm and not as aggressive. The bass extends low to 20 Hz, but it can't compare to the tight and coherent bass extension of the Thiels.
These XR6 speakers are keepers for all day listening!!
The older S/N 1635
still cannot pass power handling tests below 85 Hz. There could be an air leak, and perhaps a wire buzzing on the bass driver or the voice coil is rubbing. Below 20 watts they are fine, but there speakers must MEET ALL SPECS as McIntosh guarantees when
NEW.
-Greg