5AR4 heaters

audio_moksha · 22nd February 2008, 02:06 AM

I have a hammond power transformer with a 5V 4A secondry that I want to use with the 5AR4. Only problem is that the 5AR4 is rated for 5V 1.9A. Can I use the 4A tap anyway or what can I do to drop the current to 1.9A? Thanks in advance.

SpreadSpectrum · 22nd February 2008, 02:09 AM

This only means that the secondary is capable of 4A. Ohm's law dictates that your filament will draw only 1.9A since the resistance is constant (once the filament warms up). It will be fine.

dsavitsk · 22nd February 2008, 03:40 AM

But, it is likely that you will get a little more than 5V from the winding if you only draw 1.9A, particularly so with a Hammond which seem to run a little high anyway, so you may want to measure to be sure you are within the tube's specifications.

audio_moksha · 22nd February 2008, 05:43 AM

Sounds good! Thanks fellas.

22nd February 2008, 02:06 AM	#1
audio_moksha diyAudio Member Join Date: Oct 2006 Location: Los Angeles	5AR4 heaters I have a hammond power transformer with a 5V 4A secondry that I want to use with the 5AR4. Only problem is that the 5AR4 is rated for 5V 1.9A. Can I use the 4A tap anyway or what can I do to drop the current to 1.9A? Thanks in advance.

22nd February 2008, 03:40 AM	#3
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	But, it is likely that you will get a little more than 5V from the winding if you only draw 1.9A, particularly so with a Hammond which seem to run a little high anyway, so you may want to measure to be sure you are within the tube's specifications. __________________ http://www.ecpaudio.com

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22nd February 2008, 02:09 AM	#2
SpreadSpectrum diyAudio Member Join Date: Nov 2007	This only means that the secondary is capable of 4A. Ohm's law dictates that your filament will draw only 1.9A since the resistance is constant (once the filament warms up). It will be fine.

22nd February 2008, 05:43 AM	#4
audio_moksha diyAudio Member Join Date: Oct 2006 Location: Los Angeles	Sounds good! Thanks fellas.

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