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Looking at my amp it looks like the previous owner had installed an Audio Note brand tantalum resistor of 3k3 value in the control grid stopper position of this SE KT88 amp. Is this the appropriate value (and more importantly) type of resistor for this position? I'm wondering if the AN tantalum resistors work properly at HF/VHF or if I should swap it for a carbon film variety such as Kiwame or AmTrans or the like? Or, if a "ferrite bead with lead" would be a more efficient way to go. And no, unfortunately I don't own a scope. Thanks!
Follow Ups:
First off, I'm just a DIY'er with a bit of experience, not an EE or pro tech so I can only talk about what I know from my own experience. I'll say so if different.
My experience originally comes from following the posts of Voltsecond.(some search results linked below).
If you're into experimenting (and this IS a DIY focused forum) you could try different values if interested. As much as some people would say they make no audible difference, I have found that a lower value can sound a little better than a higher value. (Same with grid to ground reference resistors too.) It's intentionally vague. I don't have an absolute ratio but I can say that in changing a 1K to a 150 Ohm grid stopper I have heard a difference.
A 3K3 value seems very high to me but maybe that is what is needed or maybe they just want to eliminate any possibility at all without regard to any unknowns and without need to measure.
If the stopper is being used to prevent oscillation at RF frequencies, the value that accomplishes that is the value that I believe is the one to use. If there's no problem without, then I don't use any.
If you look at Voltsecond's posts , he makes it clear that mounting orientation and lead dress take precedence over resistor composition. I have found that his advice works for me.
The more I think about it, the more I think that its probably Audio Note wanting to pack their offerings into as many positions as possible. That is- that Audio Note wants to show that they use their Audio Note passive components in their amplifiers and other offerings... even if it means having to triple the value of a resistor in order for it to function properly in that position.
Yeah- maybe it takes three times the value (3.3k) of tantalum to achieve the same resistance at high frequencies of a carbon comp 1k...
Well, I guess the next question is can I put these in series? PCX has NOS Riken CC in the 3.3k value... thinking to triple-parallel these for my gridstop for a combined value of 1.1k...
Grid stoppers require carbon film.
Any resistor with a spiral resistive track will be less effective for this purpose than carbon comp. How are the tantalums made?
Everyone has a favourite.
I like Takman carbon films in most places. Kiwame have their place for higher power in some places like PSU droppers and long tails in diff pairs. I prefer Allen Bradley for grid stoppers.
Haven't tried the AN tantalum as a bit expensive for me.
Value is not so critical. Usually they install 1k in that position. Although carbon comp resistors are recommended as a grid stoppers Audio Note is using tantalum in all upper level products so you're likely fine. Avoid Kiwane in any position
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