Post by Owen Y on Jan 2, 2017 10:24:50 GMT 12
This well-worn Quad 33 preamp (manuf late 60s - early 70s) has been restored to working condition, as previously described on AudioEnz. However, the volume control was v hit & miss down at low levels, dropping out on 1-ch or the other. I discovered that the shaft bushing was v worn & had enough play side-to-side to lose 1-ch if you wobbled it! Note the exceedingly tidy Quad wiring & use of early ribbon cable.  So, with a little help from Clarry, a new (old stock) Japanese Noble, 50kΩ Dual Gang pot with 2-pole mains switching, was found.  (Quad British pot top, with newer Noble pot below.) Cheers, Owen
|
Post by Owen Y on Jan 29, 2017 14:57:05 GMT 12
I've put up mainly some pics of the Quad 33 restoration saga to date (Part 1), here, if interested. As you can see, Quad's standard of construction, back in '67, was to be marvelled at - and any restoration or mods need to (try to) meet this high standard. 
|
Post by Owen Y on Jan 29, 2017 15:06:20 GMT 12
The first problem.... The new Volume Pot is Japanese, so its 'bushing' (the threaded bit that inserts through the chassis front panel) is 10mm, slightly bigger diameter than the 60s British 3/8 inch (9.525mm)  Finally, I get to put the Dremel tool, that I was given to me for Xmas 12 mths ago, to some good use - with a grinding stone to enlarge the chassis hole..... 
|
Post by Owen Y on Jan 29, 2017 15:10:42 GMT 12
Secondly, the shaft is cut down to length to match the old one. This Dremel thing is useful, this time with mini-cutting wheel..... 
|
Pundit
Post by papahemi on Jan 29, 2017 15:31:25 GMT 12
you gotta love your Dremel, so handy
We are what we pretend to be, so we must be careful about what we pretend to be.
|
Post by Owen Y on Jan 29, 2017 15:31:52 GMT 12
Third, the 'flat' on the new shaft is not in the right place - such that the volume knob rotation position indications were all wrong. Again, the Dremel with grinding stone, carefully with some trial & error.... 
|
Post by Owen Y on Jan 29, 2017 15:40:52 GMT 12
Finally....the new pot with re-soldered wire connections - it's quite a bit smaller (as you can see above), so i couldn't quite replicate Quad's fanatical tidiness with the rear (mains on/off switching) wiring  The wires are a bit short, stretched. 
|
Post by Owen Y on Jan 29, 2017 15:49:28 GMT 12
Anyway, it's a beautiful pot (Noble has always been a good choice for vol pots, better IMO than ALPS), it feels smooth & has good rotational feel (not too low friction/loose) & the channel dropouts have gone, right down to zero vol. The taper (log curve) is a bit slower down low - so there's a bit more fine gradation in loudness down there & a bit more treble/detail has appeared 
|
Pundit
Post by neilsan on Jan 29, 2017 20:23:08 GMT 12
Hmmm.Think the boy gave me one way back.Must find it.(Dremel) Looks like it could be handy!
|
The wires are a bit short, stretched.
