Welcome To the Hoffman Amplifiers Forum

September 08, 2025, 09:55:28 am
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Groundin jacks  (Read 2159 times)

0 Members and 1 Guest are viewing this topic.

Offline Oddvar

  • Level 2
  • **
  • Posts: 305
  • I love Tube amps
Hoffman Amps Forum image
Groundin jacks
« 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?

Offline tubenit

  • Global Moderator
  • Level 5
  • ******
  • Posts: 10274
  • Life is a daring adventure or nothing at all!
Hoffman Amps Forum image
Re: Groundin jacks
« Reply #1 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

Offline Ed_Chambley

  • Level 4
  • *****
  • Posts: 3785
  • Nothing is too old.
Hoffman Amps Forum image
Re: Groundin jacks
« Reply #2 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.

 


Choose a link from the
Hoffman Amplifiers parts catalog
Mobile Device
Catalog Link
Yard Sale
Discontinued
Misc. Hardware
What's New Board Building
 Parts
Amp trim
Handles
Lamps
Diodes
Hoffman Turret
 Boards
Channel
Switching
Resistors Fender Eyelet
 Boards
Screws/Nuts
Washers
Jacks/Plugs
Connectors
Misc Eyelet
Boards
Tools
Capacitors Custom Boards
Tubes
Valves
Pots
Knobs
Fuses/Cords Chassis
Tube
Sockets
Switches Wire
Cable


Handy Links
Tube Amp Library
Tube Amp
Schematics library
Design a custom Eyelet or
Turret Board
DIY Layout Creator
File analyzer program
DIY Layout Creator
File library
Transformer Wiring
Diagrams
Hoffmanamps
Facebook page
Hoffman Amplifiers
Discount Program