New From Sutherland Engineering - the Duo mono block phono stage!
The short story is:
The DUO is
derived from the cost no object Phono Blocks and the cost-optimized
The long story is:
No expense was spared in the design and
construction of the Phono Blocks. The
Phono Blocks are at the pinnacle of phono preamp performance. It just doesn't get any better.
The 20/20 was designed to get the most performance
possible at its predetermined price point.
To get there, extra was spent to
get premium parts and circuitry into the signal path. Consequently, some expenses were squeezed
out of less important areas. Those
trade-offs have worked very well. The
20/20 has delivered an extremely high level of performance at a reasonable
price. It is an incredible performance
What if all the price constraints in the 20/20
were lifted ? The price goes up, the
performance goes up. It starts looking a
lot like the Phono Blocks.
The actual signal path of the 20/20 is quite
good. It uses a circuit very similar to
the Phono Blocks. In critical positions,
it also uses the same premium quality (and high cost) components. Very little was held back in that area.
The opportunity for upgrade is focused on a more
refined power supply, improved circuit board properties and dual chassis
Power supply discussion:
The 20/20 uses external, bench-top power
supplies. They are cost effective,
reliable and offer good performance.
Each supplies output is extensively filtered and regulated into one +/-
15 volt source for both of the gain stages.
The Phono Blocks have built in AC power
supplies. There is an IEC power inlet
on each chassis to accommodate the user's personal power cord choice. Two completely separate power sections (each
providing isolated +/- 15 volts) are provided for each channel. One for each of the two gain stages. Each is independently filtered and regulated
to provide the ultimate foundation for the gain stages.
Each DUO has a built in AC power supply. There is an IEC power inlet on each chassis
to accommodate the user's personal power cord choice. The shielded power supply module has one
output. That output is split into two
branches. One for each of the two gain
stages. Each of those branches is
independently filtered and regulated to provide a substantial foundation for
the gain stages.
Circuit board properties:
Circuit board dielectric properties can introduce
detail damaging artifacts into the signal,
The DUO mitigates circuit board dielectric
properties using the same approach that has worked so well in the Phono
Blocks. Circuit board thickness is
doubled from the standard 1/16” thickness to 1/8” thickness. Not only is dielectric absorption addressed,
but further advantages are realized with an extremity rigid platform for
component mounting. It is the
cost-no-object, preferred way to go.discussion:
Anytime two conductors are at a different voltage potential,
there is an electric field generated between them. The dielectric (the insulation between
conductors) within that field become involved in charge storage. If not carefully considered, that extra
charge storage can time smear details of a musical signal. Circuit board material is a dielectric. With normal double-sided construction, there
are copper conductors on each side of the board. Unintentionally, a new capacitor is
introduced into the circuit, formed by top surface copper, bottom surface
copper and the circuit board dielectric sandwiched between the two. It is NOT the quality of capacitor we want to
have in a high-end signal path. Some
manufactures make the situation even worse by going to multi-layer boards in
the analog audio sections. Instead of
two layers of copper, there are four or more layers of copper. Even worse than that, the dielectric between
layers is much thinner and the undesired capacitive effect is inversely
proportional to thickness. At best, some
manufactures make small, incremental improvements by using exotic board
The Duos addresses the issue of circuit board dielectric by
doubling the thickness of an FR4 fiberglass circuit board. Just that one choice reduces electric field
strength by one-half. Additionally,
the area of copper interacting with board dielectric is also reduced in
critical regions. Signal lines are kept
narrow. Power lines are extremely
wide. Such choices get us refined
performance. Good solid advantages based
up the application of good solid physics.
Dual chassis construction
A sense of space and dimensionality is conveyed by the
difference in the left and right channel information. To preserve those auditory clues, each
channel must be isolated from the other and not spill over.
Both the DUO and the Phono Blocks use a stack of
two mono phono preamps for stereo.
Absolutely nothing is shared between the left and right channels. Each channel is a completely free standing
mono phono preamp. That is the
ultimate in channel separation. The
ultimate in spatial listening involvement!
FR-4 fiberglass circuit boards, Double-sided with plated thru
holes. 1/8” thick for extra rigidity
and minimal dielectric influence.
Dale/Vishay 1% metal film resistors
Wima Polypropylene capacitors for power supply by passing and
Custom wound, 1% polystyrene film capacitors for equalization
14 gage cold rolled steel base
baked epoxy powder coat finish
1/2 “ thick anodized aluminum panel
anodized in front panel artwork
gold plated, Teflon insulated RCA connectors
gold plated configuration headers and shunts
Release the top cover by removing the four knurled
screws. Audio boards are located on the
right side of the enclosure. On the left
side of each circuit board you will find headers for receiving the plug-in
configuration shunts. Legends printed on
the circuit board clearly indicate position and function.
47.5 k Ohm
1 k Ohms
17” x 2 ½” x 12 each DUO
23 x 18 x 9 each DUO, packed in shipping box
DUO, packed in shipping box