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Old 17th March 2008, 09:14 PM   #1
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Default Replacing old pots

I have a friend with an amp from the 60's. When the volume pot is turned, the volume of the amp seems to jump from very quite to very loud at about the 3 to 4 positions and then get a little loud as it is maxed out. I think that it should behave less jumpy. Here is the schematic. http://www.gibson.com/Files/schematics/G20A,%20G30A.pdf

Can I replace the pots with 1/2 watt ones or do they have to be 1watt?
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Old 18th March 2008, 08:50 AM   #2
Mooly is offline Mooly  United Kingdom
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Hi, You can replace with whatever will phsically fit. Wattage does not come into it here. Use a pot with an audio or logarithmic taper for volume, if replacing bass/treble pots these must be linear.
Regards Karl
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Old 18th March 2008, 10:36 AM   #3
djk is offline djk
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The bass/treble pots are also log taper.
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Old 18th March 2008, 12:28 PM   #4
Mooly is offline Mooly  United Kingdom
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Oop's , Absolutely right djk, it's just a passive Baxandall network.
Regards Karl
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Old 18th March 2008, 11:27 PM   #5
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Thanks guys. Would a different resistance on the volume pot make it less jumpy?
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Old 19th March 2008, 08:39 AM   #6
Mooly is offline Mooly  United Kingdom
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Hi, You need a 47 or 50 k pot, value is important in this case as it works with the other components around it to determine the characteristics/response curve of the tone controls. It is a common value. the jumpiness is caused by either wear or dirt on the carbon track.
Karl
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