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Vinyl Grinder
07-02-2008, 01:11
Ok i'm on a mission to build the best simple stereo One in/out Passive pre (I have great self control as in one source only)

I've studied potentiometers & such over the years trying most.There's actually not that many superb ones that fit my ideals.So i'll stick with what i know..

This is the plan. a pair of single channel SFERNICE 'PII VYN' Cermet linear pots with Vishay bulk foils resistor wired between wiper & ground for each pot (Law Faking).As any pot is not totally accurate channel seperation wise i find it best to use two single pots rather than on dual pot...These pot then will give a far better spec than your standard Log pot (in which Law Faking mimics), cleaner more accurate but nice & smooth. A lot complain about scratchy you get when using Cermets but these SFERNICE pots are the best of a ll Cermets.

I can safely say this pot in a box would be a very superior sounding arrangment.To over come the turning two knobs at once! i have two knobs specially machined, both with groove around, near the base as to accommodate (but not too tight) 'O' ring around both, one of the knobs a lot made longer than the other as not to get fingers caught on the 'O' ring when using volume, so you get both your pots turning together, whilst turning just the one, if you get my meaning..

Shortest possible path from pot to socket (bare silver wire) IAR 'Wonder solder' as always..i'm even considering wiring the interconnect directly to the pots reducing a set of RCA chassis sockets & plugs.Enclosured play a part (Thinking about this one) but money is on Hardwood/Acrylic for choice...

So good luck to me..

Filterlab
07-02-2008, 12:05
A lot complain about scratchy you get when using Cermets but these SFERNICE pots are the best of a ll Cermets.

Funny what folk moan about, scratchy they may be (or not) but once set at a level there's no audible interjection by the control. Same as folk who won't buy a component without a remote. :confused:

How's this going mate? I can always sell you a lovely passive. ;)

spendorman
07-02-2008, 12:40
Tried the "O" ring thing years ago, my pots (not up to the quality of yours) were a bit stiff, resulting in the "O" ring giving a little, so, channel balance could affected. I was never sure that the pots were completely in step. Gave up on the idea, but I suppose it may work. Perhaps anti backlash gears would be a possible solution.

spendorman
07-02-2008, 12:58
Just thought of a simple solution, may not be liked, but simple and probably effective. Mechanically join the pot shafts end to end. The control wheel can be mounted on either shaft. The cosmetics of the system can be made to suit. Once set up, the pots should stay in step.

Vinyl Grinder
07-02-2008, 14:32
Just thought of a simple solution, may not be liked, but simple and probably effective. Mechanically join the pot shafts end to end. The control wheel can be mounted on either shaft. The cosmetics of the system can be made to suit. Once set up, the pots should stay in step.

Hi Paul

Yeh was thinking about something like that & running a dummy shaft between & through the facia.

spendorman
07-02-2008, 16:32
Not quite sure how the dummy shaft works, but if the two pot shafts were joined your "O" ring drive could be used to drive them and if any slippage occurs it dosn't matter. This may be what you were thinking. Not so easy without pics! and my drawing ifs terrible.