Since its introduction
last year, Sophia Electric S.E.T. 300B single ended amplifier has
been well received for its sonic beauty as well as artistic chassis
design. Continue its tradition, the new mark II model is being made
in the U.S.A. All mark I models can be converted into the new version
with no fear of being out of date. Every Sophia Electric S.E.T.300b
amp is design and built with upgrade potentials.
Construction Quality:
9 watts per channel and a Single ended no Negative feedback design.
Chassis is made of premium Japanese mirror stainless steel. Fitted
with highest quality 24K gold plate nameplate, knobs and tube socket
rings. The gold plate items were further coated with a layer of
protective coating for durability. A visual design firm was commissioned
to come up with this Patent protected four column feet chassis,
using Titanium and Nickel coatings.
Point to point wiring with high quality wires. All capacitors and
resistors are name brand audiophile grade made in Germany, Japan
and the United States. Carefully selected parts for each function
for the best sound. No guarantee it will last forever (nothing will),
but 20 years later it will still be good looking and maintain its
great sound.
The Circuit design:
There are many different ways to design a 300b amp, the following
are some of the most popular ways:
SRPP design is to use the upper half (one triode) to provide the
lower half of a 6SL7 tube for more favorable linear performance
operating. The sound is extended in frequency. This SRPP arrangement
is superior than using a plate resistor to do the same function.
However, the 1-2 ma current the 6SL7 operates at is far from needed
for a 300B. The lower current driver arrangement results very dry
sounding.
The choice of using One 6SN7 (two triodes inside) to serve as input
and drive tube to drive 300b would have more romantic sounding than
SRPP (slightly more current than SRPP). Many internet DIY discussions
seem favor this arrangement over the SRPP 6SL7. The popularity of
these arrangements in many ways is due to the cost considerations
and simplicity. Namely less tubes are needed (one 6SN7 or one 6SL7
per channel).
In the current market, there are a lot of commercial 300b amplifiers
either use SRPP 6SL7(12at7) or 6SN7 mu follower drive 300b. They
all sound fine for its price range, however, neither designs have
enough current drive capability to drive 300b tube to the maximum
potential. Here is some tech discussions of driver selections regarding
current issues.
Sophia Electric engineers like the SRPP for input stage for more
frequency extension, and add one El-34 in triode connection per
channel for current needed to drive 300B. El-34 is famous for its
sweet, extended sound. Triode connection has very linear performance.
We use a lot of current in the drive stage further enhanced the
sonic performance.
The final design of this amplifier sounded shockingly dynamic,
super sweet and liquid. There are more bass kicks than a typical
Push and pull amplifier, there are more drive capability than most
people ever thought possible for a 9watts x 2 amp.
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