Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on April 24, 2017, 06:06:59 am

Title: Is this an improvement to virtual earth on heaters PS ?
Post by: kagliostro on April 24, 2017, 06:06:59 am

I've seen this schematic and I would like to know if it worth to apply it on guitar amp circuits

a 20K pot will not require to be a high W rated unit because of the small current crossing it (also if paralleled with 2 x 10K resistors)

(http://i.imgur.com/U3CGpIC.jpg)

Thanks

Franco

Title: Re: Is this an improvement to virtual earth on heaters PS ?
Post by: PRR on April 24, 2017, 11:00:15 am

That is said to be for "direct heated" tube. None of our usual g-amp tubes are direct heated.

Even used as claimed, it makes no sense. The cathode current must flow in several K Ohms of variable resistance, much more resistance than we usually put in a cathode return.

I think someone didn't think about it.

> 20K pot will not require to be a high W rated

6.3V in 500 Ohms is less than 0.1 Watts.

Title: Re: Is this an improvement to virtual earth on heaters PS ?
Post by: kagliostro on April 24, 2017, 11:21:47 am

Thanks for the answer PRR

Franco