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Anybody familiar with Nature Sound Permalloy (47% nickel) transformers sold by April sound? They were made by Nakamura Corp in Japan. Best operating conditions and circuit recommendations ?I emailed Steve but he is too busy to advise beginners:)
Thanks, W
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nt
Observe, before you think. Think before you open your yap. Act on the basis of experience.
You can ask Steve Berger . He still answers his email listed on AprilSound website and list online catalog with those Opts included. Not sure when/if it was updated.
Rgrds,W
Thank You Jim !
What I have is NS-30. The print on the trans says 3k/80mA max 8W.
I think they should be lovely in 2a3/Vt52 amp driving horns from 80 hz and up.
W
Glad to help. If their OPTs are anywhere near as nice as their permalloy chokes, they should sound wonderful! I would recommend keeping current draw below 75 mA (though that's probably not a concern with either the 2A3 or VT52).FWIW: I just finished up a VT52 amp - used a 5k OPT - a great tube!
Edits: 06/03/14
Yes
It's a wonderful tube and my personal favorite. Unfortunately, I have only one pair of Sylvania Vt52 and a pair of Sylvania 6a3 which I will use for everyday duty (and vt52 for special days ) I guess VT52 is a single plate version of dual 6A3.
If it's not a secret what operating point did you use in your circuit for VT52?
The VT52 is also known as the 2C45 and/or the '45 Special.'
See the link below for more info.I'm running mine with 7.0 vac on the filaments; 340 vdc plate-to-ground with an R(k) of 1k35 ohms (two 2k7 12 Watt Mills resistors in parallel). I'm going on memory here, but I believe the bias is approx 55 vdc.
As you might expect, the Western Electrics are the best sounding VT52s, although the other triple-V filament VT52s are almost as good.
Edits: 06/03/14 06/03/14 06/03/14 06/03/14 06/03/14 06/03/14 06/03/14
From the information in the link, I speculate that the higher (7v) filament rating was used specifically for transmitters because they are intermittent - the loss of lifetime is not a problem if you run it less than 60 seconds at a time. They may well have been identical to the more conservatively rated 6.3v filaments. The specifications are not really independent of the intended application.
FWIW, 7 volts is a standard voltage for three lead-acid cells under continuous charge, as they would be in an automobile, airplane, etc. The same cells used as storage batteries would give a standard 6.3 volts until they become discharged.
Filaments and heaters were often designed to accommodate a range of heater voltage for these reasons - dry cell and hearing aid tubes were especially subject to filament voltage abuse, and presumably tube manufacturers had the technology to deal with it.
The Nature Sound SE OPTs were permalloy transformers designed for 8 Watts and max unbalanced DC of approx 75 mA.The more common NS-30 had a single 3k primary, while the NS-70 had multiple primary taps to allow for 2.5k, 3.5k, 5k and 7k loads. I believe they were essentially identical except for the more flexible options on the NS-70's primary.
I have used their permalloy chokes, but have never used their OPTs. Hope this helps.
Edits: 06/03/14 06/03/14
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