When to Isolate Input & Output Jacks

[jonyoungyi]

Hi, I just finished a 5F1 and feel like the volume isn't as loud as it should be. (I can max out the volume pot and still "comfortably" play without blowing out my ears).

I figured some of the signal might be shunted to ground, so I think my potentiometer is bad or one of the lugs is touching ground where it shouldn't or my output jack isn't supposed to be chassis grounded. (from what I read, a amp with NFB should have an isolated output?)

Anyway, the more I read about isolating jacks, I hear mixed responses, and more personal preference answers, as opposed to "rules of thumb".

Was wondering if someone where can shed some light on the topic of WHEN TO ISOLATE INPUT AND OUTPUT JACKS.

Thanks!

[sluckey]

Input and output jacks on a 5F1 do not need to be isolated. One of the input jacks will be high and the other will be low. It's possible to miswire the input jacks and get low volume.

Who's layout did you use?

[jonyoungyi]

Hey sluckey,

I used the 5F1 layout/kit from Hoffman :D

I did wire the input jack to a DPDT switch that switches between two different resistors, so I could have a stray wire or something there.

I'm finishing up a Hoffman Blues Junior layout and am curious about Isolated INPUT/OUTPUT jacks for that build.

From what I read, it seems the INPUT jack is NOT isolated and grounded to chassis, while the output jacks should be isolated, as the OT secondary ground should be separate from the rest of the circuit. Does that sound right? *scratches head*

[sluckey]

Hoffman's BJ conversion does not use isolated jacks for input or output. If you still want to isolate the output jack you will need to use an isolated jack and run a wire from the sleeve lug on the jack to the main ground lug.

[jonyoungyi]

Awesome, thanks so much for the confirmation!