6N6P vs 6N6P-I

Test cards

Description

Some people think 6N6P-I is a better version of 6N6P. This is not quite so. The I stands for impulse, and the I-Version is for switching purposes, or any other which requires higher anode current in impulse form. If there is one thing, electron tubes do NOT like, it is impulse current, That is because this damages the cathode surface. To make this work still, the I-Version has higher heater current. However, the life time of this tube is specified with only 500 hours! The standard version has 2500 hours, so 5x more, and that is a brutal difference. I do not really know, if the 500 hours means only the impulse capability is guaranteed, and after that it can still be used with reduced capability for audio. But when it is like that, you may as well use the 6N6P right away. Or, it is not like that, and the tube is run on higher cathode temperature, so a little bit like a kamikaze tube, and then indeed after 500 hours, it begins to loose quality.

In the factory, the I-Version is tested with positive grid voltage, for highest peak capability. Since it is used for switching anyway, it is not tested for microphonics.

The standard version is tested at negative grid voltage only,and tested for microphonics, and is the signal version.

At this moment we have a test card only for the standard version.

6N6P is a very good alternative for 6H30. Differences are small, and 6N6P seems somewhat better for audio, because it has higher gain, and can do higher signal voltage.