Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bieworm on January 14, 2021, 09:37:21 am

Title: Artificial heater center tap question
Post by: Bieworm on January 14, 2021, 09:37:21 am

Is there a difference between the use of 2x 100 ohm or 2x 220 ohm?

Title: Re: Artificial heater center tap question
Post by: kagliostro on January 14, 2021, 11:04:06 am

Different current flow, so different current consumption

a bit of info

http://www.valvewizard.co.uk/heater.html (http://www.valvewizard.co.uk/heater.html)

Franco

Title: Re: Artificial heater center tap question
Post by: PRR on January 14, 2021, 02:22:42 pm

No.

(Franco is not wrong; but in any tube amp the 0.017A difference is insignificant.)

Title: Re: Artificial heater center tap question
Post by: kagliostro on January 14, 2021, 04:09:27 pm

I was meaning that the current consumption (the fact that the difference is minimal between the two values is irrelevant) is the (only) difference (I can see) in the two different options and the question was about difference in use of 100 or 220 ohm resistors


Franco

Title: Re: Artificial heater center tap question
Post by: pdf64 on January 14, 2021, 04:36:19 pm

As the value of such balancing resistors is increased, the poorer the effectiveness of the decoupling (ie to 0V circuit common) they provide. So if taken too far, problems could result, eg noise and unexpected coupling between various parts of the amp’s circuit.
So I suggest not to take their value too much higher than you’ve done, eg don’t go higher than 2 x 470ohms.

Title: Re: Artificial heater center tap question
Post by: Latole on January 15, 2021, 03:42:44 am

current consumption;

With 100 ohms ; one side is 6,3 / 2 = 3,15V

3,15/100 ohms = 0.0315 Amps

with 200 ohms : 3.15/ 200 = 0.0158 Amps