Help with tube specs

Hi Harry,

I wouldn't worry about the 500+ volts. The tube just sees the difference between the plate and cathode voltages. I suppose it is possible that there might be a small fraction of a second somewhere during the turn-on process where that difference is significantly greater than the much lower value it subsequently stabilizes at, but I'd be very surprised if that could cause any problems. And I see that the tube is rated to withstand up to 450 volts, provided that the 450V does not persist for a long enough period of time, in combination with high current levels, for the resulting power dissipation to be a problem.

The 450V rating, btw, is the same as the rating of the original Western Electric tube. I can't see any reason why exceeding that number by 10% or 20% or so for a small fraction of a second, if it were to happen at all, might cause a problem.

As far as the second part of your question is concerned, given the precautions you would be taking, and the substantial margin between the 28W absolute maximum rating and the 20.5W someone measured with the same model amplifier but probably with a different type of 300B, and also the margin between the 65 ma he measured and the tube's 80 ma maximum current rating, intuitively it strikes me as a reasonable gamble. But hopefully someone with knowledge and experience that is more directly relevant than mine will chime in.

Best regards,
-- Al

Hi Onemug,
I hope these mesh plate 300b work out well for you.If that`s the case I`d be interested to read your impressions.I`ve not heard this particular tube but it has a very good reputation for excellent sound quality.This is a true mesh plate design as opposed to a'perforated' plate copy.
Regards,

Al, thanks so much. I take responsibility for whatever happens but armed with your knowledge it feels pretty safe.

Charles, will do.

Hi Onemug,
I always agree with Al's and Charles's opinions wholeheartedly.
I am also a devote of the 300b as is Charles, and with his take on his Tak's, I believe!!
I currently use a pair of RP's with a secondary pair in the waiting as I got a nice deal on a quad set.
Starting fresh, I would go with your choice of EML true Mesh Plate. Very interesting.
I also have a pair of 45 amps which need more immediate attention on power tube replacement. EML is where I will go.

Isochronism,

I love the 45 also. I had Fi 2a3 monos that could use the 45 with a rectifier sub but never felt I got the full experience of a true 45 amp. Right now I'm using another 2a3 amp that also can use the 45 tube but use this amp in an active x/o system for the tweeter and with it seeing only 2.8k and above, I don't hear much difference between the 2a3 and 45 so I just use the 2a3 in it.

I have a pair of almost NOS Tung-Sol 45's and a pair of Sophia Meshplate 45's that are gathering dust. If you ever think about letting go of your extra set of RP's, let me know and maybe I could use these 45's as a partial trade for them. I would dust them off first. :-)

btw, I did order a pair of the EML 2a3 meshes along with the 300b's meshes. I figure whatever the mesh does, might as well have the blend at the x/o be as good as possible.

I have tried using 2 300b amps in this bi-amp system (nice on paper having the same type amps) but the 2a3 (and 45) just do the highs better for me.