• 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.

C3m 300b SET question

Hello,

3,7 w with 2,6 % Thd is low.

For SE class A, More you are power with acceptable THD, better the sound it is with low power.

The standard design is 7 w with 5 % of THD.

Best design is > 10 w with only 3 % of THD.


One part depend of the driver and second part of the 300 B.

When the driver design use a heavy load for example C3 g 24 k to 30 k, the dynamic line load go down. The result is more swing with less THD.

But when you turn on the amplifier you must have a sequence of PSU'S.

Exemple.

Heat for all tube immediat

Negative voltage of 300 b progressive 15 s

Hight voltage driver progressive 30 s

Hight voltage 300 b progressive 45 s


With this sequence tubes have a long life.

A rule for good stuff is to run the tube to 80 % of plate dissipation.

The standard load of 300 B is between 2,3 k to 3,5 k for good sonic experience.

Eric
 
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If you need only 3 w,

2 E55L in // without driver 1,5 k plate load and 150 V plate voltage and you have 3 W with 3 % THD. It is a sigle stage amplifier, very simple with very nice sound.
 
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