Sansui AU-9500

The AU-9500 was the top of the line model when Sansui’s founder and perfectionist, Mr. Kosaku Kikuchi, retired in 1974 and it has been written that 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. 

When I first received this amplifier one of the driver boards had a hole through the board from a burned resistor. I was able to bridge the trace and get the amplifier functioning but it always bugged me. So when I had a chance I had new driver boards made. They are copies of the originals but 2 layer instead of 1 and marked for modern components. These new 2 layer boards better separate the traces and with new metal film resistors also helps to lower noise.

I will include the original boards with the sale.

Additional work completed:

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 5B4 rectifiers with modern 6A bridge rectifiers.

4/  Replaced signal path ceramic capacitors with C0G types. These are low noise and very

     stable.

5/  Replaced the failure prone 2SA726 transistors with KSA992 and 2SC1313 with KSC1845, 

     both modern low noise transistors.

6/  Replaced output speaker relay with new Omron relay

7/  Replaced variable potentiometers for bias and DC-offset adjustment.

8/  Replaced speaker A spring terminals with 3 way binding posts so it is possible to use

     bare wire, small spade connectors or banana plugs.

9/  Replace driver boards with new 2 layer driver boards.

10/ Cover repainted

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 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.