220 ohm Resistor Wattage?

[greg788]

What's the dissipation spec (wattage) of the eight 220 ohm carbon film resistors?

[Paul Birkeland]

The ones going from the power transformer to the chassis should be at least 1/4W parts.  The rest of them could carry a much lower power rating but often times resistors like this end up being more delicate than we would like for point to point wiring.

[greg788]

Should RP-G2 be a wirewound instead of carbon film since it appears to be the grid stopper? Or being a single stage with zero feedback, is oscillation at radio frequencies N/A here?

[Paul Birkeland]

A non-inductive part is a good idea for a grid stopper, so a wirewound is really the worst choice for that.  We used to provide carbon composition resistors for this particular spot because they are completely non-inductive, but they are also fragile and like to snap if they get moved around too much.  The carbon film resistors we supply are a happy compromise. 

[greg788]

Aside from the line level 220 ohm resistors, which other ones do you feel are worth upgrading? For example, I have my eye on the RL, which is the 10K wire wound. And if I upgrade those, should I stay with wire wound like a Mills? Replacing the stock 220 ohm carbon films with 1/2 watt Takman carbon films seemed to provide a minor improvement in smoothness

[Paul Birkeland]

The 10K plate load resistor will be removed with the first upgrade.  The little 150uF cap could be replaced with something else, and that cap is very much in the signal path.  220uF/16V is a reasonable alternative value that's probably more commonly found.

[greg788]

I may not do the upgrade so is 10k wirewound worth upgrading? And should I stay with wirewound or would an audio spec (non-magnetic) 5w metal oxide be a better bet?

[Paul Birkeland]

I think a metal oxide would be a downgrade from the wirewound we provide.  A Mills resistor would work just fine.

A constant current source is the best choice for replacing this part.

[Mucker]

The little 150uF cap could be replaced with something else, and that cap is very much in the signal path.  220uF/16V is a reasonable alternative value that's probably more commonly found.

I just replaced the stock caps with what you suggested above and could swear it did in fact make a noticeable difference. The caps were swapped with Elna RFS SILMIC II. Very smooth and sweet cap. Thanks for the suggestion PB!

https://www.digikey.com/en/products/detail/elna-america/RFS-16V221MH5-5/2171165

[greg788]

I just replaced the stock caps with what you suggested above and could swear it did in fact make a noticeable difference. The caps were swapped with Elna RFS SILMIC II. Very smooth and sweet cap. Thanks for the suggestion PB!

https://www.digikey.com/en/products/detail/elna-america/RFS-16V221MH5-5/2171165

They make a significant difference. Between Silmic II, Nichicon Muse (KZ?) and Nichicon Fine Gold, I feel that the Fine Gold sounds by far the best in that position. The resistor next to it also makes a significant difference, ditto all resistors in the signal path. I went with my usual Takman REX for all of those, except a Shinkoh for Rp-G2. Mills 5W for the 10K Rl is also worthwhile

[Mucker]

Great feedback, thank you! I must however admit I am electrically illiterate 

[Paul Birkeland]

The cathode bias resistor for the 6V6 is largely out of the signal path.  The Nichicon KA is also worth trying out.

[Mucker]

Thank you for the info. I am going to sit on the Silmic II for a while as the sole change. I wasn't expecting as big of change that I am hearing. Pretty amazing.