substituting values

[sfr]

So I built three pedals (Orange Squeezer, Dist+ and Brown Sound in a Box, three from my "mean to do someday" list) today, (but I haven't finished wiring them up yet)  On one I didn't have the appropriate resistor, so I ran two together to make the appropriate value, but in a couple spots I didn't have the right cap or resistor values in my parts bins, so I went with "close enough".  I marked down which things I replaced, so if it's really off, I can go back and fix them when I get the right parts; and I've done this before usually with no problem - but I was wondering, are there general rules of them for how close is "close enough" when forced to make part substitutions?  I assume this would change with circumstances like if it's for biasing or not, and what have you, but I was just curious what people had to say.

[ahermida]

I normally build the pedal the 1st time with whatever values the schematic has or close enough.  Once I know the pedal works, then I start replacing resistors with pots (to tweak) and installing socket strips in the caps so it makes it easy to change without soldering.  I think many people here do the same.  If  you do something wrong, the smell of burnt components or the sound (or lack of it) will let you know.

Alf

[Paul Perry (Frostwave)]

What you can "get way with" unfortunately varies entirely with the circuit, and where you are in the circuit. But, generlly speaing, doubling or halving a resistor won't burn out any fx boxes (unless it is supplying bias to a BBD maybe!). And caps, the same.
But there is no point troubleshooting a "non-worker" unless you built it EXACTLY as they said..

[ExpAnonColin]

For the most part, if you substitute a 100k resistor when it asks for 95k of resistance, you'll be OK.  More likely to effect the sound than make it blow up.  However, if it asks for 2 watt and you put in half watt, that's a recipe for destruction.  My general rules are...  if I don't have the exact right components, I need to stock up.

-Colin