• 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.

1626's watt?

I am confused about 1626....
In the datasheet, like this
1626 datasheet

It's plate Input max wat is 6.25W and plate disspation is 5W.
If I set the max plate watt is 5.5W, the output power of 1626 is less than 0.7W ( even less than 0.6W)

If I set in 6.25W, I didn't get more than 0.7W.


I want to make a SE Amp for 1626. The crude estimation, 1626 should be reach in 1W ( 20% of max plate disspation watt).

Have any work point is better than I set in plate 200V, bias -24V.


Paid Member
2003-06-12 7:04 pm
Maine USA
> 20% of max plate disspation watt

That is VERY crude, and often not true.

> any work point is better than I set in plate 200V, bias -24V.

The 1626 is almost dead below 100V. So at 200V supply, you can only swing barely 100V, half your input power is wasted.

In theory, use a much higher supply voltage. But: the 1626 is not rated for a high supply voltage, you will have to reduce bias current so the plate won't melt, and that quickly leads to a load impedance that is awful high for best sound.

The 1626 was designed to be a very clean radio oscillator. In most applications, it would be adjusted for cleanest output, and then its weak power boosted-up in power amplifier stages. Yes, you can also use it to drive a load directly, but it was not designed to make big power and you are stuck with that fact.

As Skyrader says: half-watt or whole-watt is not much of a difference. I've had lots of fun with an efficient speaker and a 0.3 watt amp. When I need more, I need MORE, like 10 or 100 watts.