i am building MXR dynacomp ftom tonepad. the schem idicates a 50k pot, but here in brazil they dont sell 50k pots the closer is 47k or 54K , .. so if i put a 3k resistor in the 47k it wil work close to the 50k right? but where i put it? befor the leg 1 or between leg 1 and 2? (leg of the pot) thanks =)
47K should work without any problems in place of a 50K pot.
The actual resistance of a pot is always +/- a few K, worst I ever had was a 100 K pot measuring only 89K! Maybe I should spent a little bit more then 50 cent per pot :wink:
I think this is going to depend on your application. You won't get quite the range you would with a 50K pot if you use a 47K pot witha 3k resistor in series. Where you put your 3k resistor depends on where you want to lose your range right? you can go from 0 - 47k with a total resistance or you can go from 3 - 50k. To keep some range you could always use the 54K pot and put a 675K resistor in parallel. I don't know... just some ideas.
*edit* Thats true... in practice a 50K pot might actually be 47K, so it probably wont matter
Pots are usually within 10% of their stated value anyways, so it would not be unreasonable to buy a "47k" pot that turns out to be 42k or 50k and not unreasonable to buy a 50k pot thatturns out to be 45k.
Don't worry about it.
I don't buy 'em for that anymore [say FF Gain control]
I use a 2k with about 4k7 on it and get a sum of about 1k4-1k5
EZ to tag resistor on the pot, if you want it fine tuned for Osci-probls..
especially going from a higher value......or as an 'opposite alternate' method...tag some extra R's there and if it's not enough value , pull or cut them out till the gain is 'there'.
I personally like have ing a 'little extra 'turn' on that pot.