Here comes the Valvecaster!!

[Jimmy-H]

So I got this wired up correctly - 94ohms measured resistance, onto +ve leg of 100uF (63V) cap to ground.  V+ from junction of cap and resistor to circuit.  And here's what I don't understand: I get a measured 4.21V after the resistor.  That just don't seem right to me!  What am I missing here?

What your missing there?
It's not that hard.
I had the same problem with my subcaster (see the original thread: http://www.diystompboxes.com/smfforum/index.php?topic=63479.480 )
It's because of the low resistance of the heater.
So you get a voltage drop.
It's better to use a well regulated 12 volt power supply, this will solve all your humming problems

Cheers

[ACS]

Thanks Jimmy, but I think you're a bit confused on 'regulated' vs 'filtered'.  My wall wart is very well regulated - in that it puts out a consistent 12V no matter what load is being drawn.  Where it falls down is that is poorly filtered, and this is what is letting the noise through.  I SHOULD be able to get rid of this with the right filtering, which so far is evading me.

[Michael Allen]

http://geofex.com/Article_Folders/Power-supplies/powersup.htm