The owner and I discussed the whole situation, we decided that rather than spending a lot of money on OP transistors that didn't exactly match the original good set anyway, it would be best to replace all for new.
All the attributes of the proposed replacements that Oilmaster mentioned above made sense to me as well as a much bigger SOA. So you won't always be using the amplifier with your heart in your mouth, with an ever dwindling supply of expensive original OP transistors in the background.
As regards 'square pin round hole' - AK member Kale solved this using gold plated round pins soldered to the TO-3P transistor leads. However I have seen a Youtube video on AK where this was not thought necessary and the square pins were rounded with a combination of pressure, and some careful filing, I am still thinking about this aspect.
The thread that AUD101 referenced is the kind of thread that convinced me that the TO-3P's could be the perfect replacements.
However this thread gives the exact type numbers:-
http://www.audiokarma.org/forums/index.php?threads/au-919.291461/page-4 - see post #76
One piece of good news is that no cutting of the transistor tabs will be needed due to the design of the heatsink in the BA-F1.
All the attributes of the proposed replacements that Oilmaster mentioned above made sense to me as well as a much bigger SOA. So you won't always be using the amplifier with your heart in your mouth, with an ever dwindling supply of expensive original OP transistors in the background.
As regards 'square pin round hole' - AK member Kale solved this using gold plated round pins soldered to the TO-3P transistor leads. However I have seen a Youtube video on AK where this was not thought necessary and the square pins were rounded with a combination of pressure, and some careful filing, I am still thinking about this aspect.
The thread that AUD101 referenced is the kind of thread that convinced me that the TO-3P's could be the perfect replacements.
However this thread gives the exact type numbers:-
http://www.audiokarma.org/forums/index.php?threads/au-919.291461/page-4 - see post #76
One piece of good news is that no cutting of the transistor tabs will be needed due to the design of the heatsink in the BA-F1.
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