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Old 23rd December 2011, 11:01 AM   #1
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Default gallien krueger 800rb - confusion over replacement pots

My 800rb has a lot of "crunchyness" when I turn various controls and so I thought I might need to replace a few of the pots. After opening up the amp, I can see that 5 of the pots in it have been replaced previously - with aftermarket ones.

I downloaded the schematics from this site as well as a service memo listing the pots used in this amp.

Now for my problem. The schematics show all pots to be 25K's but the service memo lists both 25K and 50K pots for almost everything. The pots that have been replaced are all 50K but the originals that were not replaced are 25K.

It seems odd to me that you can just swap out a 25K pot with a 50K pot in a circuit in the first place.

Does anyone know what pots should actually be used?
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Old 23rd December 2011, 11:13 AM   #2
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I would go with whatever it says in the service memo. It's not a good idea to replace tone pots with different values, but most volume stages have reasonable tolerance for different values, (in SS amps at least).
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Old 23rd December 2011, 11:45 AM   #3
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As far as pots go, there's not a lot of difference between 25K and 50K, and you can probably use either value with no difference you can see or hear.
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Old 24th December 2011, 03:21 AM   #4
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Thanks for the info.

Anyone know any sites to purchase pots online?
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Old 28th December 2011, 01:18 PM   #5
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I don't think that 25K and 50K pots are interchangable.

I came across an internal design sheet from GK that noted how the 800RB needed to be changed to handle 50K pots rather than the original 25K pots. There were many changes other than just the pots themselves.
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Old 28th December 2011, 03:04 PM   #6
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Quote:
Originally Posted by 4ofN View Post
I don't think that 25K and 50K pots are interchangable.

I came across an internal design sheet from GK that noted how the 800RB needed to be changed to handle 50K pots rather than the original 25K pots. There were many changes other than just the pots themselves.
The differences will only be slight, different range of the tone controls - something you wouldn't notice.
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