Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Medman on October 06, 2013, 02:17:47 am

Title: 5f1
Post by: Medman on October 06, 2013, 02:17:47 am

I am about to assembly my amp and she where you can ground one side of the heater circuit  from transformer and just run 1wire to tubes and I Have seen the heater wires run to pilot light and 100ohm resisters go to ground and run twister pair to tubes. Is one better than other to keep out hum. Thanks JP

Title: Re: 5f1
Post by: TIMBO on October 06, 2013, 02:35:07 am

If your heaters do not have a centre tap then use two 100ohm resistors to ground and defiantly twist the heater wires together, I use two different coloured wires that way its easier to get the phasing right if there is more that two preamp tubes.  :icon_biggrin:

Just looked at the schem and the phasing is not a problem when there is only one preamp tube. this will give you an idea on the heater wiring   http://www.ceriatone.com/images/layoutPic/fenderLayout/Champ-Ultra-Layout.jpg (http://www.ceriatone.com/images/layoutPic/fenderLayout/Champ-Ultra-Layout.jpg)  :icon_biggrin:

Title: Re: 5f1
Post by: sluckey on October 06, 2013, 08:29:40 am

Quote

I Have seen the heater wires run to pilot light and 100ohm resisters go to ground and run twister pair to tubes.

much better

Title: Re: 5f1
Post by: tubeswell on October 06, 2013, 10:32:02 am

'nother vote for twisted pairs. Twisting AC pairs together helps cancel out EMF surrounding the wires, which eliminates a potential source of unwanted coupling and hum.