Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: luthierwnc on March 27, 2021, 09:34:28 am

Title: question about heater reference on separate cathode grounds
Post by: luthierwnc on March 27, 2021, 09:34:28 am

Hi Guys,  I haven't found this one before and thought I'd check.  I'm in the thinking stage of an EL34 cathode-biased amplifier and am planning to use separate cathode resistors and bypass caps.  To help with possible hum, I've almost always tied the heater center-tap (or artificial center-tap) to the power tube cathodes.  In this case, I'm not sure if just using one of them a) works, b) makes it worse or c) is ineffective.
Any thoughts will be appreciated, thanks, Skip

Title: Re: question about heater reference on separate cathode grounds
Post by: sluckey on March 27, 2021, 10:55:37 am

Either cathode works equally well and just as effect as if the cathodes were tied together.

Title: Re: question about heater reference on separate cathode grounds
Post by: luthierwnc on March 27, 2021, 12:28:36 pm

Thanks Steve.  That drops the parts count a little.  I'll still need to make a 100 ohm fake center-tap to tie in.  Cheers, sh