Finally A80 got a tube out-put stage in play back, I keep the first stage for EQ and second stage for calibrate of the original, just make a very simple tube circuit each channel with only one single tube, one transformer for out-put, one 2.4v rechargeable battery for bias and one resistor in gird to ground, that is all. simple is the best, I choose WE437A my favor tube for here because of similar gain to the original out-put stage, also a volume control for dubbing tape use and a mercury selector switch for back to the original stage for easy ABX test, there are three coupling tantalum cap ( from picture small color in blue) in the first two stages replaced by big Solen in black color,because of the size has to be link from out side. two power supply in separate case, choke in-put with 6CA4 Mullard and DC regulated voltage for filament. I connect to the Studer B62 for test drive because both B62 and A80 are the same amp in use.
result ? I will never back to the original stage again but the total parts costed almost same as you can get a working A80 from Ebay!
tony ma
result ? I will never back to the original stage again but the total parts costed almost same as you can get a working A80 from Ebay!
tony ma