1/4 watt resistor crisis

[joesatch]

ran out of 1 watts dont have any 1/2 watt. working on a tonestack circuit so the voltages should be pretty low. can i use 1/4 watt resistors?  specifically 1/4 watt into preamp grid?

[bmccowan]

First - my Mainer answer; don't matter to me.
Next - I suspect if you do the math - it's fine. Bunches of reissue PCB based amps use them.
Next - I wouldn't, given that I could get the resistors the project deserves in a few days for cheap money. You work on a lot of amps - why not just order up a whole kit of all values. Its so nice to have what you need on hand.

[kagliostro]

The bigger the resistor the low the intrinsec noise

I use metal film 2W resistors and bigger where required

I can see them better, they have a better look on the Board and I can handle in an easier way than the invisible 1/2 - 1/4 ones

Franco

[dwinstonwood]

I just bought a bunch of 600mW (0.6 Watt), 1% Vishay's in all of the typical guitar amp values. I had always searched for and bought 1/2 Watt's in the past.
The Vishay MBx/SMA - Professional series has a huge range of values.
I even bought some 90.9K's, a weird value that can balance LTP outputs much closer than the usual 82K (if that's what you want).
They averaged about 26 cents a piece @ 10 or more, so a paid a bit more for them.

Just go to your favorite online electronics supplier and apply these filters:

Metal Film-Through Hole
Vishay
600 mW
1% Tolerance
MBx/SMA Series

[pdf64]

With resistors, watch out for their voltage rating. Many types have a 250V limit, standard sub 1W is 350V.

[dwinstonwood]

Thanks pdf64.

The Vishay 600mV series I referenced above do have a 350V rating:

https://www.mouser.com/ProductDetail/Vishay-Beyschlag/MBB02070C9092FC100?qs=LkqrmUh5PII7wRxfAHYqwA%3D%3D

[dbishopbliss]

I even bought some 90.9K's, a weird value that can balance LTP outputs much closer than the usual 82K (if that's what you want).

What change (improvement???) do you notice by having the outputs more balanced?

[dwinstonwood]

What change (improvement???) do you notice by having the outputs more balanced?

I would say none! 

I was playing with this calculator, and 90.0K gets darn close, so, why not? I bought some.
https://www.ampbooks.com/mobile/amplifier-calculators/long-tailed-pair/calculator/
But, I don't think my ears would notice a difference. 

[joesatch]

i found a hack. so i am good!

[PRR]

WHAT "tonestack"?

But for argument/example, the usual Fender stack played LOUD may have 100Vrms across the first 100k resistor.

100V^2= 10,000

10,000/100,000 is 1/10 Watt