• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Does anyone recognise this 12AU7?


2005-10-20 12:57 pm
I purchased these 6 tubes in an ebay auction:

Does anyone recognise the 'donut' shaped logo on the third tube from the left?

I think the others are (from left): Brimar, Marconi, ?, Amperex, Telefunken, Mullard.


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Looks to me like the trade mark of Bentley Acoustics. They were a company that supplied valves by mail order but the country of origin was variable. I have for example a Bentley Acoustics 5Z3 that was made by Westinghouse in Canada. I think they re-badged a lot of ex-military valves and also many from other countries like Italy, Germany and Russia. Pinnacle and Z & I Aero were similar companies.