Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Boone on December 02, 2013, 06:51:14 pm

Title: No load tone pot for amp vs switch?
Post by: Boone on December 02, 2013, 06:51:14 pm

Hello everybody, I have amp 1 vol 1 tone. I would like to switch the tone stack for in/out option. I am thinking of creating this in one of two ways: a no load tone pot or a mini toggle. As far as no load pot goes,can I make the pot no load the opposite side that has been done in the past? In other words, either remove copper or dab of nail polish at (zero end of pot travel) in other words, no load when turned to zero instead of when pot to 12? Will a no load pot fully remove the cap on right lug and jumper to vol pot on center lug? Also, if this is not possible is it possible to wire a DPDT switch for on/off DPST to lift two wires in off position? Thanks

Title: Re: No load tone pot for amp vs switch?
Post by: HotBluePlates on December 02, 2013, 08:41:19 pm

What specific amp model?

If the tone control is like a 5F2-A Princeton or 5E3 Deluxe, a no-load pot won't work. The tone control in these amps have a cap at either end of the resistance track, so you can't break the circuit the way it's done with a guitar tone control.

Instead, your better option is a DPST mini-toggle switch, which breaks the connection from the 500pF cap to the volume control wiper, and from the tone control wiper to the volume pot (if the circuit is like the 5E3). In other words, you'll need 2 places disconnected to get the tone control out of the circuit for-sure.

Of course, if you have a different amp or different tone control circuit, the suggestion might be different.

Title: Re: No load tone pot for amp vs switch?
Post by: Boone on December 03, 2013, 07:45:19 am

I have 5F2-A type. I cannot find ANY mini toggles that are DPST. Got any advice on wiring a DPDT for on/off DPST?

Title: Re: No load tone pot for amp vs switch?
Post by: sluckey on December 03, 2013, 07:59:13 am

Only use 4 lugs from the DPDT.

Title: Re: No load tone pot for amp vs switch?
Post by: Willabe on December 03, 2013, 08:21:44 am

Mouser and Digikey have them.

             Brad    :icon_biggrin:

Title: Re: No load tone pot for amp vs switch?
Post by: kagliostro on December 03, 2013, 10:14:59 am

What about to use a PP pot for the tone control ?

http://www.ebay.it/itm/BOURNS-PUSH-PULL-POT-250K-or-500K-A-or-B-NEW-/380782616305?pt=UK_Guitar_Accessories&var=&hash=item58a8699ef1 (http://www.ebay.it/itm/BOURNS-PUSH-PULL-POT-250K-or-500K-A-or-B-NEW-/380782616305?pt=UK_Guitar_Accessories&var=&hash=item58a8699ef1)

K