SC330
Not an Sansui, in its original trim nice but nothing special. The owner of this set gave me the freedom to do whatever could be done to achieve ultimate performance.
The original power transformer produced a mechanical hum so fitting a toroidal transformer would be the logical choice. I had one on the shelf, originally intended for an AU317, that fitted beautifully and since the supply voltage of an AU317 and this power amp is practically the same, it matched electrically as well.
Looking around for a set of power supply capacitors I came across perhaps the wildest idea I have ever realised in any amplifier. I double checked with the owner if he would approve of it, and he did, so I cut two big holes in the original back panel of the amplifier to ‘outboard fit’ these two 33000 uF 63 Volts capacitors.
The brackets fitted only just; the lower lug had to be folded inwards and I cut two M4 size screws to exactly fit underneath the capacitors.
The bottom panel had to be strengthened to hold the toroidal transformer in place.
New 4 mm speaker connectors and new gold plated input RCA’s are fitted.
New 3-pin type Sanken power transistors and Hitachi driver transistors are fitted.
Blue LED illumination for the VU-meters.
SY330
The original rather flimsy power transformer with only one secondary coil is replaced with one that has both a higher secondary voltage as well as a symmetrical coil.
A very straight-forward design of only two dual op-amps, a phono preamp and a line/tone amp, I chose to fit the Analog Devices OP275 for its smooth and sweet yet clear tonal character. Sitting on DIP sockets they can easily be replaced for someting else if the owner wants to experiment.
This op-amp accepts a power supply voltage of + / – 22 Volts absolute maximum value, so I set the supply voltage at nearly + / – 20 Volts to achieve maximum performance and headroom. Carbon composite resistors are known for their excellent sound quality in an audio circuit, but measuring and matching the values is mandatory.
The resulting sound quality of this set is one of unbelievable accuracy, control and detail. The extreme impulse power of the new power supply enables the amplifier to deliver equally extreme instant impulse power.
