Can’t Use Filament Anti-Hum Resistors?

[UltraHookedOnPhonix]

Can I use two 100 Ohm resistors to ground on the filaments of the 6.3V supply if the transformer wiring is center tapped?

I’m using the Overtone layout at:
http://ceriatone.com/images/layoutPic/O ... pril08.jpg

Nik at Ceriatone told me I’d burn the two resistors if I did this but then how would I go about using “anti-hum” resistors?

Much appreciated!

[dave g]

The "anti-hum" resistors you're talking about are normally used to create a "virtual" center tap when the transformer doesn't have one...since your transformer has a center tap, the resistors aren't going to do anything for you.

[UltraHookedOnPhonix]

Well, that about clears it up!

Seems as if the simpler something gets, the more confusing it is! (strictly speaking for myself!)

Thanks.

[heisthl]

If you MUST have them (for historical accuracy etc). Just don't connect the center tap.

[odourboy]

According to KOC, a pair of well matched resistors (or a hum balance pot) will generally do a better job at hum elimination than using the center tap since the center tap isn't usually perfectly 'centered'.

[butwhatif]

the tube filaments enter into the equation an unbalancing of the windings by their loading, hence the call for a hum balancing pot---

[UltraHookedOnPhonix]

Thanks guys!

Then, for historical accuracy, I would simply disconnect the "0" leading to ground between the two 3.15V windings when using the matched 100 Ohm resistors correct?

Metal Film 1W cool?

[heisthl]

yup

[ic-racer]

Not to add anything new but, to confirm what the others are posting. I have mine hooked up like below (the only reason I used 220R was that I did not have any 120R laying around the day I wired that part.) I think the calculated power dissipation is 0.3 watts.

Looks like I see a red (2%) band on the ones in the #124 photos but was not sure if those are MF or CF by appearance, but the original #124 post implied resistors like these would be CF. "5. Other than the Dale plate load resistors for V1 and V2 and the precision metal films for their respective cathodes, all other resistors used seem to be carbon film.--Gil"

odurboy mentioned the 'hum balance' and I want to add that I have been working with a six tube 6L6 amp recently and I find myself tweaking the hum balance frequently. A hum balance control is a great thing and it really lets you remove all hum (though 50w and 100w amps may not benefit as much.)

[butwhatif]

some amps benefit greatly from a balance control

[FUCHSAUDIO]

some amps benefit greatly from a balance control

A hum balance (and perhaps a filament lift circuit (about 2.0 volts above ground works nicely) can get an amp almost as quiet as DC filaments.