What pot to use for master volume mod on Valve Junior amp

[Some Bozo]

I samick you not. 5 watts is too h4rdcor3 for my purposes
I did an experimental mod using a crusty old pot from my dodgy old Vester strat copy which reads as 470 K and it seems to do the business, but just to make sure I'm getting the best I want to get a shiny new pot, so should I just buy a 500k guitar pot or should I be getting some other type ?

[Marshall]

[Some Bozo]

The rating would be much too high...

[ash]

Google is bound to find you some "How-to" info on that exact mod. Could be anywhere between 10k and 1M depending on where in the chain you put it.

[Azza]

I found a pdf that has loads of mods for the vj; depending on your experiment it may have the info you need. It certainly has lots of ideas.

http://www.s2amps.com/docs/vj_kit_inst.pdf

It's about 307kB

[Some Bozo]

Google is bound to find you some "How-to" info on that exact mod. Could be anywhere between 10k and 1M depending on where in the chain you put it.

It's done by replacing the R5 resistor with a pot, the R5 is apparently

"Resistor R5 on the schematic dumps some signal to ground before feeding the power tube in addition to
setting the input impedance of the EL84 grid (much like R1 does for the first triode). You can increase
power tube overdrive by increasing this resistor up to 1M or decrease it by reducing the value down to
something like 56K. Any value between 33K and 1M is okay here.
65. Replace R5 with a higher value resistor (>220K) for more power tube overdrive or a lower value
(<220K) for less power tube overdrive"

So 500 K seems to be in the ballpark. Will an ordinary guitar pot do ? I'm guessing that even just after pre-amp it's got a lot more juice going through it than a guitar puts out...

[ash]

Use a pot that is similar to the other pots in it. Probably any 16mm panel mount type with the appropriate terminals for wiring it in and the appropriate shaft to fit the knob on to it. Power handling won't be an issue. The resistor in there is probably only rated 1/2 watt. If its a master vol, its just handling signal levels. If it was handling power levels it would be an attenuator, not a master vol.

[ant]

Get whatever pot you like.. 500k will have more bass. According to you guys 220k resistor is stock so get a 220k /250k pot if you want to stay stock.

As it has only 2 preamp gain stages you wont get much distortion happening with a MV but if you use a pedal it will be sweet.

[Some Bozo]

Use a pot that is similar to the other pots in it. Probably any 16mm panel mount type with the appropriate terminals for wiring it in and the appropriate shaft to fit the knob on to it. Power handling won't be an issue. The resistor in there is probably only rated 1/2 watt. If its a master vol, its just handling signal levels. If it was handling power levels it would be an attenuator, not a master vol.

Cheers