1 watt plate resistors.

[joesatch]

i was told from various sources that 1 watt plate resistors are fine. Well these 1 watt metal film i have are tiny!  are you folks sure 1 watt metal film is enough? these things are the size of a grain of rice

[pullshocks]

I just installed some of those, so I sure hope so….,

[shooter]

bust out a breadboard, a 'lil math, test for smoke 

[joesatch]

i have doubts

[Willabe]

Some years back, over at Kevin O'Connor's tube amp forum, guys were having trouble with the small body resistors in the B+ power supply. They couldn't take it and were dying.

They went back to the larger body R's and then no more problems. 

I don't trust them, the small sized body R's.

[tubeswell]

Also check the voltage rating of resistors that you are wanting to use where there are big voltage swings

[AlNewman]

For plate resistors, I think they're fine.  As power or dropping resistors, I'm not so sure.  I use them quite a bit and haven't had a failure yet.

[joesatch]

gonna use them in V1 and V2 plates. hopefully no issues. if i have trouble sleeping i'll pull em

[tubeswell]

check the voltage rating

[joesatch]

check the voltage rating

350V  probably not enough fml

[tubeswell]

check the voltage rating

350V  probably not enough fml

350v is okay for a preamp plate or cathode load resistor given the likely range of voltage swing. Wouldn’t use them as single bleeder resistors in the power supply tho.

[pullshocks]

Well, they look smaller than what I'm used to, but not *THAT*   bad


Time will tell on the longevity.....

[HotBluePlates]

i was told from various sources that 1 watt plate resistors are fine. Well these 1 watt metal film i have are tiny!  are you folks sure 1 watt metal film is enough? ...

The resistor's power-rating is about temperature-rise.

"When this resistor dissipates 1 watt, the body-temperature will not rise more than ____ degrees."  And we de-rate the resistor to dissipate less than its rating to keep it cool.


The implication is something about this resistor's construction enables it to throw off heat-to-the-air faster/better than older designs, such that it does not need a big surface-area to lose heat to the air via convection (or as-much surface-area as older designs).

If you want to use a 5w resistor because you like the size & look, you can use a 5w resistor.  Or get used to some newer ones being a lot smaller than what you used in the past (and assume you're gonna need a meter to verify their value, because reading the color codes is impossible).

[Guy77]

Just as a reference. I have been inside several two rock 100 watt amps and they use the tiny 3mm x 8mm KOA CF resistors on the plates of several preamp tubes. 

They hold up fine and they are only 1/2 watt. 
Here is the data sheet on them
https://www.mouser.ca/ProductDetail/660-CF1-2C683J

I was surprised when I saw them too!

Cheers
Guy