Phase change when adding gain stage?

bereanbill · 15th May 2009, 10:40 AM

I want to add a gain stage to an amplifier by using 1/2 of a dual triode originally used as a second input. This will put the signal 180 degrees out of phase will it not ? Will I need to reverse the plate leads on the OT?

ray_moth · 15th May 2009, 08:20 PM

Assuming that the stage you want to add will be a grounded cathode stage then, yes, it will invert the phase. However, you only need to reverse the connections to the OPT if the added stage will be within a global NFB loop, to prevent the FB from becoming positive..

15th May 2009, 10:40 AM	#1
bereanbill diyAudio Member Join Date: Jan 2009	Phase change when adding gain stage? I want to add a gain stage to an amplifier by using 1/2 of a dual triode originally used as a second input. This will put the signal 180 degrees out of phase will it not ? Will I need to reverse the plate leads on the OT?

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15th May 2009, 08:20 PM	#2
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	Assuming that the stage you want to add will be a grounded cathode stage then, yes, it will invert the phase. However, you only need to reverse the connections to the OPT if the added stage will be within a global NFB loop, to prevent the FB from becoming positive..