Military spec on tubes... important?

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skrasms

Well-known member
Joined
Jun 16, 2004
Messages
72
Location
Gary/Purdue-Lafayette
I'm looking at old tube compressor schematics and noticing a lot of the tubes have suffixes like WGT, GTY, WGTA, and things along those lines. My hunch, based on a girth of complete inexperience, is that these are military spec tubes that just spec out better than their counterparts without the corresponding suffixes. Is that right? Would I be able to use a standard 5Y3 in a circuit that calls for a 5Y3WGTA, or is there more involved?
 
> Would I be able to use a standard 5Y3 in a circuit that calls for a 5Y3WGTA

Almost always: yes.

First look on Frank's site for the original datasheets: there may be some difference in maximum ratings. But if you are copying old pro audio, they usually ran well within the ratings of the base part.

The mil-spec versions also passed extra testing for life and vibration. Sometimes they were special, but most often they were plucked from standard production on a good day, tested, and sold at a higher price. Back In The Day, we paid more for a Known-Good tube: using the lowest-price versions in a many-many-tube studio might cause too much downtime. But especially in the 1950s and 1960s, replacement tubes were mostly very-very good, even if they did not have the mil-spec number (and price).
 
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