Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on August 03, 2020, 11:27:06 am

Title: Fender specific treble pots
Post by: Leevi on August 03, 2020, 11:27:06 am

Custom Vibrolux reverb uses special treble pots.


https://el34world.com/charts/Schematics/files/Fender/Fender_custom_vibrolux_manual.pdf (https://el34world.com/charts/Schematics/files/Fender/Fender_custom_vibrolux_manual.pdf)


Since it is difficult to find them is there any way to replace them any other value or just use standard 250KA pots?


/Leevi

Title: Re: Fender specific treble pots
Post by: 66Strat on August 03, 2020, 11:52:54 am

Weber has a 350K pot tapped at 70K, as used in the Blonde Showman and Bassman amps.

https://www.tedweber.com/wp354at (https://www.tedweber.com/wp354at)

Title: Re: Fender specific treble pots
Post by: brewdude on August 03, 2020, 01:30:26 pm

This was originally posted on the amp garage.

Title: Re: Fender specific treble pots
Post by: Leevi on August 04, 2020, 01:42:24 am

The Custon Vibrolux Reverb uses 250K/50K taper. Maybe this 350K/70K workaround is close enough?
/Leevi

Title: Re: Fender specific treble pots
Post by: Latole on August 04, 2020, 03:42:31 am

I'll use/ mod this circuit  : Custom 68 Vibrolux use B 250K pot ,( see first picture )no taper like the Custom Vibrolux reverb ( second picture) .

Title: Re: Fender specific treble pots
Post by: Leevi on August 04, 2020, 08:45:15 am

Yes,  this is one option
/Leevi

Title: Re: Fender specific treble pots
Post by: HotBluePlates on August 06, 2020, 01:47:20 pm

Quote from: Leevi on August 03, 2020, 11:27:06 am

Custom Vibrolux reverb uses special treble pots. ... is there any way to replace them any other value or just use standard 250KA pots?

Quote from: 66Strat on August 03, 2020, 11:52:54 am

Weber has a 350K pot tapped at 70K ...
https://www.tedweber.com/wp354at (https://www.tedweber.com/wp354at)

Quote from: Leevi on August 04, 2020, 01:42:24 am

The Custon Vibrolux Reverb uses 250K/50K taper. Maybe this 350K/70K workaround is close enough?

The note says "250k 20% tap" right?  So that's how we're getting "250kΩ tapped at 250k*0.2 = 50kΩ."

350kΩ * 0.2 = 70kΩ.  So unless you can buy the exact pot from Fender, just go for the commonly available 350kΩ tapped pot.