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Hoffman Amps Forum image Author Topic: 25K - RA POT?  (Read 4142 times)

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Offline blueznet

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25K - RA POT?
« on: August 15, 2011, 09:41:57 am »
Trying to replace a worn out intensity pot on a 67 Fender Vibro-Champ.

Anyone know of a Vendor that would carry this pot? I looked at Doug's pots and he does not have them.

I have searched for the 25K Reverse Audio and can't seem to find one either.

Thanks,
Darrell
*/ "Building a tube amp is very simple, but it takes a genius to understand the simplicity." /*

Offline John

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Re: 25K - RA POT?
« Reply #1 on: August 15, 2011, 10:43:23 am »
http://www.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=184223688

If Mouser doesn't have 'em, dunno who would. Good luck!
Tapping into the inner tube.

Offline jeff

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Re: 25K - RA POT?
« Reply #2 on: August 15, 2011, 12:19:11 pm »
There's a way using a bigger pot with a resistor to "trick" a linear pot into thinking it's a reverse audio pot. It won't be exactally the same thing at full rotation but it may a way to get a better responding control if you can't find a RA pot.

Good luck.

http://www.geofex.com/article_folders/potsecrets/potscret.htm

Offline blueznet

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Re: 25K - RA POT?
« Reply #3 on: August 16, 2011, 07:10:42 pm »
Can't believe why no one has the 25k RA pot. Would a 50k RA work for the intensity on this Blackface Vibro-Champ?
*/ "Building a tube amp is very simple, but it takes a genius to understand the simplicity." /*

Offline OldHouseScott

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Re: 25K - RA POT?
« Reply #4 on: August 17, 2011, 12:24:59 am »
Yes, it should work fine. You might want to change the cathode resistor it's connected to down to 47k to keep the total resistance at about 100k when cranked all the way up, but it's not necessary.
OldHouseScott
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stratele52

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Re: 25K - RA POT?
« Reply #5 on: August 17, 2011, 03:46:45 am »
blueznet , you can't fix the pot ?

Offline blueznet

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Re: 25K - RA POT?
« Reply #6 on: August 20, 2011, 06:45:25 am »
Yes, it should work fine. You might want to change the cathode resistor it's connected to down to 47k to keep the total resistance at about 100k when cranked all the way up, but it's not necessary.

You mean the 68k down to 47k?
*/ "Building a tube amp is very simple, but it takes a genius to understand the simplicity." /*

Offline OldHouseScott

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Re: 25K - RA POT?
« Reply #7 on: August 22, 2011, 08:02:50 am »
Yes, that's the one, although it's not strictly necessary to change it.
OldHouseScott
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