SE Amp with Thoriated Tungsten output tube

euro21 said:

https://i0.wp.com/www.bartola.co.uk/valves/wp-content/uploads/2014/05/814-SE-class-A1.png

The anode current must be higher, if you want any appreciable power.

At 540V, 100mA (big OPT!) the predicted power about 3+ W, at not so low load.

814 SE Amplifier: measurements – Bartola(R) Valves

As you can see in Ale measuring, the 814 triode A1 region is limited, if you use it at low (below 500V) anode voltage.The anode current must be higher, if you want any appreciable power.At 540V, 100mA (big OPT!) the predicted power about 3+ W, at not so low load.

Click to expand...

You get up to 5W in A1 with 5K and 500V supply.

They amp Ale built used 600V plate voltage and was driven in positive grid field and, from memory, it developed 10-11W with very low distortion (less than 1%). The A1 power was 3W but that is because of the high quiescent current for optimal A2 drive. But if you bias at lower current you get more power in A1. I designed the transformers that replaced the Lundahls...

The only real disadvantage if the drive is limited to A1 is that one has to consume 32.5 VA to light up the filament for just 4-5W (clean, at least) output power. As always, there is no free lunch...

You get up to 5W in A1 with 5K and 500V supply.They amp Ale built used 600V plate voltage and was driven in positive grid field and, from memory, it developed 10-11W with very low distortion (less than 1%). The A1 power was 3W but that is because of the high quiescent current for optimal A2 drive. But if you bias at lower current you get more power in A1. I designed the transformers that replaced the Lundahls...The only real disadvantage if the drive is limited to A1 is that one has to consume 32.5 VA to light up the filament for just 4-5W (clean, at least) output power. As always, there is no free lunch...