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Phil Allison[_2_] Phil Allison[_2_] is offline
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Default Electro Harmonix Valves ??


**Hi to the amp techs,

there is something odd about the HEATERS in current production EH branded
valves.

If you check a 12AX7EH, 12AT7EH or 12AU7EH, you get 32 ohms between pins 4
and 5.

Check any other brand and the reading is 10 to 14 ohms.

The EH ones still draw 160mA at 12.6 volts like the others.

Similar but smaller differences exist with EL34EHs and 6V6EHs too.

That Bugera I posted about a few days back would NOT have developed the
nasty AC fuse blowing fault it did if EH brand 12AX7s were fitted - as the
start up heater current would be 3 times less.



.... Phil