The AU-9500 was the top of the line model when Sansui’s founder and perfectionist, Mr. Kosaku Kikuchi, retired in 1974 and the AU-9500 satisfied his highest expectation.
These amplifiers are now over 40 years old and need attention to remain dependable. Even a modern electrolytic capacitor has about a 20 year life. So if you are listening to 40 year old amplifier with the original electrolytic capacitors you are not hearing how the amp performed when new.
This AU-9500 was completely disassembled for access and cleaning. Look at the before and after photo of the tone VR. It is important to clean all these parts.
1/ Replaced all the electrolytic capacitors with modern equivalents. The only exception being
the electrolytic caps in the signal path. These have been replaced with film types.
2/ Replaced power supply filter capacitors.
3/ Replaced signal path ceramic capacitors with C0G types. These are low noise and very
stable.
4/ Replaced the failure prone 2SA726 transistors with KSA992, a modern low noise transistor.
5/ Replaced output speaker relay.
6/ Replaced variable potentiometers for bias and DC-offset adjustment.
7/ Replaced speaker A spring terminals with 3 way binding posts so it is possible to use bare
wire, small spade connectors or banana plugs.
8/ Added a new grounded power cord.
9/ Replace pre-out, main-in connectors with
Eichmann phono plugs.
10/ The transistors were mismatched when I received this amp so I replaced all with new
OnSemi devices.
11/ The power light was replaced with an LED.
These new parts don’t change the original “Sansui Sound”. That sound is in the circuit design but the modern components improve reliability and because of the lower noise of these parts may improve the perceived sound quality.
I don’t have a turntable or tape deck anymore but I tested the inputs using a 1kHz sine wave and they work as intended. I didn\'t test the DIN socket.
In my opinion you would have to spend many thousands of dollars to best the sound quality of an AU-9500 with a modern amplifier and then you wouldn’t get the tone controls or the input level controls. All very useful. Speaking of sound, I have also owned a Sansui AU-70, AU-111, AU-9900, AU-11000A, 881, and a 9090. The tone of the AU-9500 falls between the lush warmth of the 9090 and the neutral sounding AU-11000A. Both great at revealing detail but the AU-11000 is to sterile for my ears. The AU-9500 has just slight edge of warmth. Of course this is listening with my ears and in my system. If I had all these amps and was forced to choose one to keep, my choice would be the AU-9500. Great amp.
