Charles’ Quad 63 Repair - see below for Quad based sub-woofer

Rob,

 I've been Very remiss in not getting back to you regarding the success of my –63 rebuilding project. Both speakers are working wonderfully and I went so far as to construct a “Quad subwoofer” (if that is an appropriate title) using blown panels and appropriate hardware purchased from QS&D here in the US. A picture of the almost-final set-up is attached. The subwoofer incorporates a plate amplifier in the base, which adds the two stereo channels together and rolls off the highs starting around 100hz. Useable response goes down to the 30’s.

 Anyway, upon reflection the major comments I have regarding the rebuild process which may not have been covered thoroughly in your instructions have to do with dis(re)assembly and testing.

 Regarding disassembly – I suggest emphasizing that both halves of the individual panels be marked (say with an ascending number from top to bottom (1;2;etc) so they don’t get mixed up AND get oriented correctly when re-assembling. I did not number mine and realized later that the “front’s and backs” of my panels inevitably got mixed up.

 I did find that the polyethylene (s/b polyurethane – Rob) glue is far superior to the “crazy glue” in its ability to secure the Mylar to a panel. 

 Regarding testing – I was VERY concerned that the finished panels could exhibit differing “sensitivities” and so I built a testing jig so I could excite each panel at 1000hz and measure it’s response a certain distance away. Turned out I needn’t have mattered – every rebuilt panel measured within a dB or so.  I was also concerned about current “leakage” which could draw down the polarizing HVDC. As I don’t have a way to measure 5+ KV, I realized that Quad supplied a way to determine leakage by observe the flickering of the little neon bulb mounted on the HV power supply PC board. This bulb can be observed by removing the little round rubber “plug” above the “on-off” switch. This bulb is effectively in series with the HVDC supply and the panels and any blinking/illumination indicates a discharge. With freshly rebuilt speakers, my bulbs were blinking twice a second or so. After a few months of operation, the blinking has slowed to perhaps once every two seconds -which is apparently fine per the gentlemen at QS&D. I didn’t check this before the rebuild but would surmise that a speaker with hissing or arcing panels would exhibit a rapidly pulsing or constantly glowing neon. 

 In any case, the rebuild(s) appear to be a complete success. Thank you for supplying the kit, which enabled me to rejoin the most musical connection afforded by the –63. I will offer to help anyone in the US who may be “struggling” with it. They can call me at (607) 432-0528.

Finally, can the polyethylene glue be obtained locally?

 Charles King    

quadwooffront

 

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