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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: So what kind of Mullard is this? posted by Mike Cole on December 29, 2006 at 12:03:48:
This certainly goes against the widely accepted view that genuine Philips tubes will have the etched codes in the glass, but I have several tubes that I am convinced are Philips (as opposed to the often similar Japanese) tubes that have symbols in the glass base.Many of the early generation Philips tubes had the codes printed in black on the base of the tube as opposed to the etched codes on the lower section of the glass. When researching the Philips codes, you will notice many reversed, one letter characters or symbols to designate the factory. I have seen tubes that are identical in construction to known Philips tubes that will not have the glass etching, but will have one of the strange character codes in the base of the glass that conforms to the tube construction of the factory indicated by that character.
I've never read where this was done, but I tend to believe that it happened. I expect we will someday be able to confirm this. As an example, I have an Ultron boxed tube that has the reversed F in the base of the glass and is a very unusualy constructed tube. The reversed F was a Philips code for Marconi valves and I think the tube is indeed a Marconi, though there is no etching in the glass.
I'm certainly no authority on valves, but I have a ton of EL84 type tubes from dozens of factories and am always trying to learn a bit more about them. The EL84 type being a relatively modern valve design, the early versions were produced with rapidly changing construction techniques and multiple revisions as the type aged.
If you consider the rash of rebranding that occured, even between British, German and US tubes, it shouldn't be considered tabu to question the validity of the "if it ain't etched, it ain't real" accepted wisdom, though I would agree that it is the safest bet and true more often than not.
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Follow Ups
- Re: So what kind of Mullard is this? - Catch22 22:22:35 12/31/06 (0)
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