pas filament supply

yero · 18th April 2011, 09:23 PM

I am building the pas-3 high level preamp. I outboarded the power supply using two power supplys. The B+ as well as an indepentant 12v filament supply that is not a voltage doubler. my question is do the returns of the two supplies need to be grounded together. I an experiencing 120hz hum.

nigelwright7557 · 18th April 2011, 09:40 PM

Yes they need to have the commons joined together.

Sometimes the heater voltage is floated of 40 volts to decrease hum.

yero · 18th April 2011, 10:05 PM

floating the heaters at 40v. how is that done

18th April 2011, 09:23 PM	#1
yero diyAudio Member Join Date: Mar 2010 Location: Medina, N.Y. near Rochester N.Y.	pas filament supply I am building the pas-3 high level preamp. I outboarded the power supply using two power supplys. The B+ as well as an indepentant 12v filament supply that is not a voltage doubler. my question is do the returns of the two supplies need to be grounded together. I an experiencing 120hz hum.

18th April 2011, 09:40 PM	#2
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Yes they need to have the commons joined together. Sometimes the heater voltage is floated of 40 volts to decrease hum. __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Need help choosing a filament supply	phrarod	Tubes / Valves	0	30th November 2009 04:00 AM
Yet another DHT filament supply	astouffer	Tubes / Valves	25	5th July 2009 11:08 PM
Parallel vs. series filament supply - or another filament idea	engels	Tubes / Valves	11	13th May 2007 01:06 PM
Rectifier that doesn't need own filament supply?	CarlyBoy	Tubes / Valves	15	10th October 2006 01:29 PM
DC Filament power supply	oldstyle	Tubes / Valves	26	2nd November 2002 01:26 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

18th April 2011, 10:05 PM	#3
yero diyAudio Member Join Date: Mar 2010 Location: Medina, N.Y. near Rochester N.Y.	floating the heaters at 40v. how is that done

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)