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In Reply to: RE: 7058 or 12AX7 posted by DAK on August 23, 2015 at 12:11:15
Yes, 13V +/- 1.5V. But I don't think they are actually 7058's.
Info appreciated anyway. Thanks.
Follow Ups:
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Understood. But can you tell by using the meter as I described?
My guess is u r right. If it was a center tap for each 12.6V fil, then overall, fils in series would be 24V; not likely. It could be a center tap for two 6.3V fils in series; which would make it a mobile ready (ruggedized and higher than usual filament V capable), capable of using 13.5 to 14V DC filament 12AX7.
Get a 12AX7 setup ready for 6.3V AC filaments, using pin 9 as CT; but be prepared to somehow raise the filament voltage. Testing it like a 12AX7 in circuit, how bright is the filament with 6.3V ? If very dull orange, I would not be afraid to step up the fil voltage to say 7-7.5V. If it is bright orange at 6.3V, we have our answer that you are in possession of a ruggedized 12AX7 mislabelled, or simply capable to run as a filament series connected, higher than usual filament voltage 7058 with mobile ready ability.
My old sportscar was very capable of a 1.0 G force with its flat riding(no tilting while turning; only limited drift) hard suspension. The thought of using 7058s to drive 1625s(12.6 to 14V capable 807 type), using the car battery to light the filaments did cross my mind. However, when you have a buzz bomb, you usually want to hear the engine buzzing; which it did very well...
I don't know what I would have used to vary the voltage but I appreciate the suggestions. Fortunately, Jim chimed in and confirmed my multimeter test as being viable. I have 12AX7's.
Thanks
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