Hi all.

Looking at my F76s again as my grayhills from digikey will be shipping this week, so I should be able to finish my units off and am looking at changing my input/output pots. The ones I've got are citeks that I ordered from Farnell in an attempt to mimic the original BOM, but they ended up being a bit tight fitting and I want to use something smaller.

Anyway, I've been looking around and found some potentially great pots from alpha (small and 5% tolerance!), but I'm a bit concerned about their power rating.

Can anyone tell me what minimum power rating I can get away with for the input/output pots?

I've looked at the audio schematic and it seems like they're just being used as voltage dividers after the THAT1246 and input amp respectively, but that's pretty much where my ability to work out what's going on ends!

I've looked at the THAT1246 data sheet, and it says "The 1240-series devices are typically capable of supplying 25 mA into a short circuit", but obviously that's the short circuit case they're talking about and I don't know what that says about normal operation. Assuming straightforward usage, the THAT1246 is probably configured for -6 dB operation. The data sheet also says: "For example, with ±18 V supply rails, the 1240-series parts have a maximum output signal swing of +23 dBu". Now I don't really know my decibel related units at all, so I just had to google for a calculator like this one:

http://www.sengpielaudio.com/calculator-db-volt.htm and type in some numbers which gave me 30.947147054 volts peak to peak. Now I know that P = IV, so that suggests that power = 31 * 0.025 for the short circuit case, which is 0.775 watts but that seems pretty huge. Can anyone help me with the methodology? I'd rather know how to work this stuff out so that I can feel confident about the result rather than just choosing a suitably big potentiometer with regards to power rating and trusting to luck...

I've also had a think about the output of the IJ input amp stage, but I'm at a loss with this one unfortunately. Help on what power rating the pot should have would be appreciated...

It seems like the smaller ones have lower power ratings, so I just want to make sure they can handle it. Obviously bigger power rated pots are available, but they tend to be larger in size too...

FYI, the ones I'm looking at are these:

http://uk.mouser.com/ProductDetail/Alpha-Taiwan/RV120F-10-15F-A10K/?qs=%2fha2pyFadugrQN9O93rLvSvPxd4VhM3GzU2Z7E8cvnKWhZmlVeObpw%3d%3dbut notice that their power rating is only 40 mW (but their tolerance is 5%!).

Thanks for any and all help,

Kaz