45-based SET -> Pass Labs F4

[jdubs]

Guys, what is the recommended resistor value for wiring across the output terminals of an SET amp based on the 45 tube for an SET->F4 setup?

I've seen references to 20r and 22r.

Thanks,
Jim

 

[ZUM911]

I thought Nelson recommended 8 ohm or so. that's what I used on the output of my Yamamoto 45 to the F4. Sounded fine

 

[jdubs]

Thanks ZUM911. Do you know what power handling is appropriate for the resistor assuming my 45 amp kicks out about 2 watts / channel? Does it matter?

 

[DougL]

For a 2 watt, 8 ohm load I would want an 8 watt resistor to limit power compression.

Also, think about trying higher than 8 ohms for the load.
You will probably get less distortion with a 32 ohm or higher load.
This would also allow a smaller resistor, say 2 watts, to be sufficient.
I think you should experiment a bit.

HTH

Doug

 

[ZUM911]

I have 12 watt mills across the terminals. mostly because that's what i had on hand. also the output trannies of the Yamamoto are set to the 8 ohm tap, so that made sense to me

 

[jdubs]

Thanks once again, guys. How important is resistor quality, here? I assume that tight tolerance levels between the resistors is important. Not that many "audiophile" 5w and above resistors out there. I think the Mills MRA-5 and MRA-12 series look pretty good.

-Jim