A friend built a 10-tube version, and was very happy with the result. Ca 100 watts into 8 ohms, if I recall correctly. He made no significant changes to the design, except maybe more PSU capacitance (?).
Later, he built a slight variation (different input and driver tubes and a subtle variation in topology) with 12 tubes per channel. This doesn't produce any more power into 8 ohms, but it does somewhat better with a thougher load, such as 4 ohms. (You would need higher B+ / B- voltages to get more power into 8 ohms, because the output voltage hits the 0 volt line, and grid current sets in - unless you redesigned the amp to run in pentode mode, but this is somewhat complicated.) He liked this amp even better.
The project is presented at the supplied link. It's in Swedish, but there are pictures that might be of interest, esp. on page 10.
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=17321
Cheers,
Later, he built a slight variation (different input and driver tubes and a subtle variation in topology) with 12 tubes per channel. This doesn't produce any more power into 8 ohms, but it does somewhat better with a thougher load, such as 4 ohms. (You would need higher B+ / B- voltages to get more power into 8 ohms, because the output voltage hits the 0 volt line, and grid current sets in - unless you redesigned the amp to run in pentode mode, but this is somewhat complicated.) He liked this amp even better.
The project is presented at the supplied link. It's in Swedish, but there are pictures that might be of interest, esp. on page 10.
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=17321
Cheers,
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