Re: [Harp-L] Ground Switch on amp?

[MARK BURNESS <markwjburness@xxxxxxxxxxxxxx>]

Hi Brian,
 
The ground switch reverses the polarity of the wall AC fed to your amp, to prevent a build up of electrical potential (volts) on the amp's chassis, that may cause hum, or electrical shock in use (if there is voltage on the chassis & you touch something that is connected to ground, like a PA mic, then you become the intermittent ground wire...with accompanying sparks & shocks, usually to the face if you are a singer!). The smaller amps can have the 2 prong cords flipped over in the wall socket to achieve the same result.
 
It is much safer to have the 2 prong AC cords swapped out for grounded, 3 prong cords and dispense with the ground switch/cap to the chassis from wall AC. I very strongly recommend you do this.
 
Regards, Mark.


________________________________
From: Brian McInnis <bluesharpteacher@xxxxxxxxxxxxx>
To: "harp-l@xxxxxxxxxx" <harp-l@xxxxxxxxxx> 
Sent: Saturday, 13 April 2013, 12:32
Subject: [Harp-L] Ground Switch on amp?


Hey List
I collect Vintage Kay tube amps for show and for performance with diatonic and chromatic, have them in all sizes and speaker configurations.
Some of the larger and higher wattage ones have a ground switch.  What is this for? Is it because there is a 2 prong plug and grounding plugs were not used or widely used in the late 50's and early 60's? any thoughts?

Thanks
Brian in Brooklyn