Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: navdave on May 10, 2012, 02:42:30 pm
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Did CBS use all audio taper pots in the tone stack or were the midrange
and treble controls linear taper?
http://www.el34world.com/charts/Schematics/files/fender/CBS_100w_TWIN_REV_SUPER.pdf (http://www.el34world.com/charts/Schematics/files/fender/CBS_100w_TWIN_REV_SUPER.pdf)
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They are all marked with the value and "A" in the AB763 Twin Reverb schematic. However, it's common knowledge the mid control is linear.
Judging from the standard control types in the Duncan Tone Stack Calculator, the Treble and Bass control are log taper (audio), and the Mid control is linear.
If you have a silverface in front of you, measure and know for yourself. If you don't, go with what's typical for Fender tone stacks.
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Thank you sir it makes sence to use a linear pot for the mid control considering
its only 10k and a audio taper for the highs so it won't be so bright especially if you're using single coil pickups.
I played one of these silver face twin reverb and fell in love with it. I just want to make sure I get everything right on the clone I'm building which is a single channel non-tremolo non-reverb.
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I'm starting to doubt myself now...
Despite what I see on the Tone Stack Calculator, more evidence is turning up for a 10k log taper mid pot. Other Fender schematics with a layout indicate the mid pot is a 10k audio pot, while the reverb control is a 100k linear pot. Same for Hoffman's info on the AB763 board.
So it looks like I had it backwards, unless someone with an original Fender can confirm a linear mid pot.