Design philosophy – Sutherland PhonoBlock User Manual
Page 4
DESIGN PHILOSOPHY
POWER SUPPLIES
POWER SUPPLY:
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