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MGH 2nd October 2012 09:07 PM

What resistors to use on KT88s tubes?
My KT88 power amp requires 2 and 5 watt resistors on the grid, screen (?), and cathodes. I was thinking Kiwami's here, just because someone told me he had good experience with these in this application because of their slightly warm balance. I was told the Mills noninductive resistors are also good, but how do these compare to the Kiwami? Any other recommendations? Thanks.

AJT 3rd October 2012 12:36 AM

i use carbon comps on the screens and grid....

mr2racer 3rd October 2012 12:51 AM

Carbon composition stray with age and absorb moisture. If you like that sound then use them for control grids only. For the cathodes use metal film. Personally I prefer metal film throughout.

MGH 3rd October 2012 01:01 AM

Are Mills carbon or metal film?

speakerfritz 3rd October 2012 02:05 AM

don't carbon resistors increase in resistance as they over heat....basically slowing down an over current condition due to a blowing tube? That being the case....carbon for power and control circuts and metal film for signal paths. Could be over simplifying.

AJT 3rd October 2012 02:45 AM

i have carbon comps that strayed in value in storage....but hey i use them anyway, in not so critical places such as control grids and screens.....

but i agree metal films are best to use anywhere...

Davec113 3rd October 2012 04:35 AM

I replaced Kiwame cathode resistors in my Simple SE SET amp with Mills a few months ago. It uses a 12BH4 driver > EL34 triode strapped, no feedback.

Personally, I would not use Kiwame again, IMO they are a bad recommendation for hi fi. They are a tone control that warms (distorts) and softens the sound, with an accompanying loss of resolution. The Mills were a noticeable improvement, they sound much cleaner and I hear more detail in the music. Kiwame are also relabeled from another brand that costs under $.50, I forget which one.

My advise is to mix types of resistors, because they each have an effect on the sound and if you use different types it will spread out the effects. I would only use carbon comp as gridstopper. If price isn't a factor I'd look into Vishay bulk film types, they are too rich for me at nearly $10 each but people who try them seem to like them.

kevinkr 3rd October 2012 05:57 AM

:up: I'll just echo and say my experience with the Kiwame was exactly the same.

I would not use carbon comp resistors in any circuit where a high current fault can occur, I've seen more than one of them go up in flames when a tube runs away. Very smelly and can damage other nearby components. This is true also for many carbon film types as well.

disco 3rd October 2012 06:21 AM

Then there's solid carbon (ancient and extinct) and (modern) thick film. I use those last for high power solutions like in a regulator. Any thoughts besides the price? (Dave, in europe they have the same price as those 10W Mills WW ;)).

MGH 3rd October 2012 11:17 AM

Davec113, Vishay makes bulk metal film resistors that can handle 5 watts?

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