There is not much one can do wrong in such a CF design.
- provide enough clean gain. The 6C33C will have a gain of about 1/2 in CF, so for 1W in 8ohms (2,83VRMS), the driver will have to provide at least 2x2.83VRMS, say 6VRMS.
- provide enough current in the output stage. Pure class A, so the 200mA (based on the choke figure) of standing current can only swing between 0 and 400mA. Output power with 200mA is about 8ohm * 0.2 * 0.2 = 320mW. So, more 6C33Cs and a bigger choke!
- provide enough clean gain. The 6C33C will have a gain of about 1/2 in CF, so for 1W in 8ohms (2,83VRMS), the driver will have to provide at least 2x2.83VRMS, say 6VRMS.
- provide enough current in the output stage. Pure class A, so the 200mA (based on the choke figure) of standing current can only swing between 0 and 400mA. Output power with 200mA is about 8ohm * 0.2 * 0.2 = 320mW. So, more 6C33Cs and a bigger choke!
the 6080. can also be used.....otoh, the 6DK6 is still a dollar a pop at Stan's ...Summer Dollar Days - Vacuum Tube Sale - $1.00 Vacuum Tubes
There is not much one can do wrong in such a CF design.
- provide enough clean gain. The 6C33C will have a gain of about 1/2 in CF, so for 1W in 8ohms (2,83VRMS), the driver will have to provide at least 2x2.83VRMS, say 6VRMS.
- provide enough current in the output stage. Pure class A, so the 200mA (based on the choke figure) of standing current can only swing between 0 and 400mA. Output power with 200mA is about 8ohm * 0.2 * 0.2 = 320mW. So, more 6C33Cs and a bigger choke!
So it is only usable for headphones and high Ohmic speakers.
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