Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Oddvar on May 09, 2018, 01:55:34 am

Title: Groundin jacks
Post by: Oddvar on May 09, 2018, 01:55:34 am

Hi.  I am a bit confused about whether the input jacks should be isolated from the chassis or not?  And the speaker jacks, should they be isolated?

Title: Re: Groundin jacks
Post by: tubenit on May 09, 2018, 06:54:06 am

What amp are you referring to?  Please be more specific.

So far,  I've never isolated an input jack or speaker jack on any amp I've built.  I've isolated jacks in other functions such as relay switching for example.

You may wish to look up Hoffman's grounding scheme in his great Library of Information.

with respect, Tubenit

Title: Re: Groundin jacks
Post by: Ed_Chambley on May 09, 2018, 12:18:39 pm

I have never isolated an input jack on purpose.  I have used Cliff Jacks for a Marshall look.  Since the guitar cable shield is needing a ground, even isolated jacks are grounded.  Most of the time my preamp ground buss is connected to the input jack's ground.


You certainly can isolate them if you want.  I built an amp in an antique wooden silverware box in a star pattern and took all the grounds to earth ground.  Quiet as can be, but will alarm you if one of oyu earth grounds on an outlet is come loose.


Attached is some good info.  It comes from the Vlave Wizard site.