The XR6s are finally back together again and operational!!
It was a very busy weekend and the
reassembly took two days. Saturday was preparation day, soldering the wires to the fuse holders and terminating them. Next was installation of the Upper Mid domes.
Later in the afternoon the woofers were installed. On Sunday the crossovers were installed and the cover plates re-attached. The speakers were tested using a B&K audio signal generator at various frequencies and power levels.
Here are some pics:
Upper mid domes on the bench, one measured 9.9 ohms and the other 10.4 ohms. Screen on left is black, the right one is a slight shade of gray.
Tinsel wires can be seen under the perforated covers/screens in both the above and below photos.
Close-up of the installed Upper Mid dome with tinsel wires under the cover/screen.
Driver plate touch-up
The Sharpie pen can be used to touch-up everything from the edges and tips of Mc heat sinks to dome driver base-plates.
The edges of the aluminum base plates got scraped during rebuild. A Sharpie pen makes them `black´ again. You can see where new adhesive was applied.
New wires to Fuse Holders
Wires should have been soldered to the fuse holders first, then twisted and trimmed to the same length before attaching the QD terminals so they would be all the same length. There's only ~1/2" error in length, which is not a show stopper.
Wires were terminated and cut to 15", then soldered to the fuse holders.
Driver installation
The Upper Mids were installed first using Deoxit on each terminal. Then the woofers were installed. The large bass driver gaskets are still intact after more then 30 years!! Laying the cabinets down on the carpet and swinging the doors open onto the sectional sofa works well.
View of the XR6 cabinet. Note inside the crossover opening, a cabinet top screw apparently has a misaligned pilot hole.
Grill rattles
There was a concern about grill rattle. Someone, perhaps the original owner used black tie-wraps to the attach the grill to the horizontal grill frame dowels. That should work ok, yes?
Indicator lamps and EQ
The ORANGE warning lamps come on as expected around 100 watts CW. Both LEFT and RIGHT lamps light-up at the same power level thanks to the NEW precision resistors installed on the crossover boards. The recapped MQ104 works fine and the five bass boost positions work ok.
Crossovers
The crossovers were wrapped in packing material and set inside the upper cabinet compartment, propped up against the back wall behind the inside brace. Due to the height of the inductors the bubble wrap is lifted off the power resistors and will not melt. The crossover boards will be CAREFULLY attached to the inside back wall. I believe it was a wise more to fore-go the crossover enclosures. That whole assembly and its damping issues were eliminated. The enclosures are being stored in a safe place, should anyone want to reinstall them.
How do they sound?
Initial tests with an audio Sig-gen were good and all drivers were radiating. There was a problem with the RIGHT S/N 1635 woofer. It has a `buzz´ at all frequencies below ~85 Hz at power levels above 20 watts continuous sine wave. It sounds like a wire is against the cone, but I fear it's the voice coil. This driver may need to go back to the NewFoam. They have a warranty (one year was it?) so there's no big risk, however at higher power levels (20 to 100 watts) the driver goes into a 'whop-whop-whop-whop' mode below 30 Hz, like a helicopter blade!! What do you suppose that means? :scratch2:
Generally I like the way they sound, with more lower mid presence that the Thiels. Both LEFT and RIGHT XR6s sound well matched, as they are only 3 to 4 feet apart right now. We played a Blue-ray DVD "Black Hawk Down" last night and they sound fine. They're warm and much less harsh that the Thiels, but lack the transient attack.
More photos
New shiny black #6, #8 and #10 x 1" stainless steel screws were purchased to replaced the original sheet metal screws, some of which were `lunched up´ from previous servicing. The factory screws were apparently from multiple sources and inconsistent in shaft and head diameter. The new screws are more uniform. Additional photos of the reassembled XR6s will be posted soon.
They sure are beautiful looking.. and have a nice warm and full sound!!
-Greg