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Wojtek wrote:

has supposedly very nice Obbligato line of film HV caps .

Thanks, the high nominals the have only 630V and they are larger than I would like to have. Does anyone know how those Obbligato sound in PS?

hagtech wrote:

So what is with the ferrite beads?  Do you find they are necessary?  Seems to me the resistors right on the socket would be good enough.  Especially with the grounding of the center pins.  I run beads all the time in my digital signals, but avoid as much as possible for analog.

As you can see I did not leave ferrite beads out and I did use 47R grid stopper at all channels. I even put 2 ferrite beads on MF channel (you can see it on picture). I have to admit that I did use Milq without ferrite beads and without the grid stopper (still keeping 50R between the screen and grid that serve the same anti-oscillation purpose). I did not detect any oscillation-related problems… but only with good tubes. I did not play with “too life” tube in the situation when I did not use stoppers. Also, I did not detect or research that the ferrite beads affect sound in negative way. I do not think they should…

The good 6E5P/6E6P are oscillation-free would it be with ferrite beads or not. They might have some minor oscillation for a few minutes after the start while they are cold and then when they reach their cruise temperature the oscillation should be gone. What is interesting that the 6E5P/6E6P’s oscillation is much softer and less annoying (even dangers) then the oscillation of other UHF 100-300MHz tubes. The WE417A, the WE437A, the 6842 when they got aroused were very atrocious. The 6E5P/6E6P oscillations very mildly and gently – it is like a difference between the Plinian and Hawaiian types of volcano eruption. The 6E5P/6E6P when it age might develop some minor HF noise – it is an easy sign to spot and identify a worn up tube. BTW, I did not detect any oscillation pattern differences between 6E6P-DR – the military and tighter tolerance and the regular 6E5P.

So, the story is that I keep the ferrite beads in there. I do not know if it is necessary. My behavior with the ferrite beads is more like the behavior of that nun who said “Good protect anyone who protect themselves”, while she put a condom on her candle….

Can I stay without the ferrite beads and grid stopper? Probably I can. The grid “bias” resistor is very high that forms with Miller capacitance of the tube a near 100kHz filter. The bias voltage the come directly to the grid is from gas tube. The gas tube voltage is not regular voltage but very “slow” voltage and it might do the additional comforting of the grid. So I might go away without ferrite beads and the grid stopper... but the question is why would I need it?  There are some “protective” benefits from them but are they the course of any problems?  Did you detect that a ferrite beads affect sound in any negative way? If so, then might it be the size and the type of the ferrite beads?

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