Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on April 28, 2015, 07:17:48 am

Title: Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?
Post by: kagliostro on April 28, 2015, 07:17:48 am

Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?


(with the obvious purpose to reach early crunch effect)


Thanks


K

Title: Re: Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?
Post by: jjasilli on April 28, 2015, 08:12:03 am

Yes, adding a screen resistor is a standard Champ upgrade.  See, e.g., my VibroChamp Schematic attached.  You can increase the value of the resistor for effect.


I'm suspicious of pots.  Another alternative is a SW to select between R values in pentode mode; maybe also add triode mode.   

Title: Re: Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?
Post by: kagliostro on April 28, 2015, 08:49:48 am

Thanks JJasilli

which was your personal reason on adding this mod ?

Was the fact that is "good practice" to add a G2 resistor for G2 protection purpose

or you were looking for earlier compression effect ?

Thanks

Franco


p.s.: A rotary swith with multiple resistors ......... interesting idea

Title: Re: Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?
Post by: jjasilli on April 28, 2015, 09:37:54 am

I did it for "good practice", not for tone. 


BTW I tried the KOC mod of 2.2K screen resistors in an EL-84 amp, but didn't like it.  Tried some in-between values but didn't notice much difference. 

Title: Re: Has anyone tried a resistor or pot between the PS and G2 in a 5F1 amp ?
Post by: kagliostro on April 28, 2015, 09:43:30 am

Thanks


Franco