Hi Tom,
thats it. I have a Fine Arts A9009 new bought in the nineties with much more power, no noise and nearly no distortion - and - in comparisim to the old ones Sansui 3000, TR 707E, Harman Kardon 930, Kenwood KA 6000 no Sound. It`s just dead sounding. o.k., the old ones had to be rebuild but then they are really good.
My TR707E sound on small Heco interiors 230s better as my FineArts A9009 with my T+A TMR160MK2. A friend of mine has tree Accuphases.,just forget it. And he has many many nice old ones. I think we compare AU777 against AU777a next time (both best rebuild). He also has AU555 and AU999. I don`t think one of thees is better.
I mesured my AU-777a, and just biased it perfectly. 30w per Channel. Thats it.
It was tricky to bias the protection circuit right, because of the changing of the Emitter-Resisors from the Power Transistors, this takes much time but i think i have done it. The first time the protection cuts off wasn`t fine.
Hi David,
thank you too.
I have measured all components i take off from the 777a, with an LCR-bridge, Electrolytics from 20Hz to 200KHz. And if there were capacitors which have much more capacity in an old amplifier, and it works perfect i try to get near the same capacity when i put the new ones. So there were 3,3uF-Elnas which have 7,5uF, and so on. If there wasn`t enough space i took the other side of the pcb.
There are just two elektrolytics which were dead (2uF instead of 1000uF). The rest was just working fine. But with the Silmics, Muses, Wimas, and other Nichicons and so on it was better...
And Yes the power resistors from down side are really hot on the pcb, perfect tip from you and the bourns pots are really good too.
Here is a nude from my TR707E
It was my second restauration project after my Modell 3000. And with my experience from the last years i will make my (next) TR707A just a little better. My TR707A is now stock from 1965 and better sounding as the most new high end.
Greets Rainer