Design philosophy – Sutherland PhonoBlock User Manual

Page 4

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Much of the PhonoBlock’s effortless musicality can be attributed to power supply capability. The power

supply is not ‘sized’ for the gain stage’s load. On the contrary, gain stage power requirements place

an insignificant load on the power supply’s capacity. The power available to the amplifier section is a

bedrock solid foundation. Precisely defined by fixed current regulators, shunt voltage regulators right

at the load and over 100,000 microfarads (per mono chassis) for energy storage. It takes nearly 20

seconds for this huge reservoir to fill up when AC power is applied.

For a design guided by simplicity, the PhonoBlock’s power supply may, at first, appear plenty compli-

cated. Admittedly, it is both simple AND complex. It is a long chain of individually simple elements.

Each element has a function of either filtering or regulation (also doing a filtering function). Each ele-

ment inserts a level of isolation. The accumulated isolation is unprecedented.

The chain looks like this:

AC power entry connector

AC fuses

First torroidal transformer

Dual pi ferrite bead / film capacitor filter

Second torroidal transformer

From here, there are two parallel power paths. One for the first

gain stage and another one for the final gain stage. EACH of

the two separate paths has these elements.

Slow recovery, discrete diode, full-wave bridge rectifier

Initial filter capacitors

Constant current regulator

First RC pi filter

Second RC pi filter

Shielded ribbon cable between shielded compartments

Cross over from the right compartment to the left compartment