TU8600S: Are 2A3 tubes viable?

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Hi all and Victor,

My 8600SVK is on the way - very much looking forward to getting it up and running. :cool:

I will mainly be using it as headamp for my 1266 Abyss off the speaker terminals.

For this application, 2A3 would suit better than 300b tubes - 4W per channel would be safer in this case, plus it seems that 2A3 tubes are arguably cheaper for better quality, and the audio stream may be improved. It would also be excellent to retain the 300b functionality should I require more juice to power speakers.

Obviously, some mods are required - will need a different R-Core trans.

The TU-8233 already has this feature and even includes auto sensing, which I presume would be tricky to implement in the 8600. However, perhaps the 8233 R-Core transformer can be used in the 8600, probably with a manual switch between 2.5V and 5V.

Also, I guess the plate voltage on the 8600 is 330V? This is too hot for the 2A3 which should be 290V - perhaps this can be also regulated through switching in order to get the best of both worlds?

Would this be viable and how could I get my hands on a Kitamura Kiden Pheonix EK TU8233 power trans goodness?

The other alternative is a 2.5V filament transformer, but there is little space to place one in the chassis of the 8600.

The other mods I am looking to implement:
- a bypass switch for the inputs so it behaves as a power amp (I have a headamp GSX2 to use a pre).
- maybe a stepped attenuator down the track?
- switchable output between the 8ohm speaker terminals and an additional 4 pin headphone XLR jack.

Cheers!
 
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