mono PSE 2A3 amplifier.
kit has everything you want. The output tubes are driven
through an interstage transformer, just like in the
flagship of the Sun Audio line (SV-300BSM). Using an
interstage does have several advantages. The driver
tube can make a much larger voltage swing, has lower
distortion, higher gain and the grid of the output tube
is connected through a much lower (dc)-resistance to
ground. However the"concept" depends heavily
on the quality of the interstage transformer. A good
interstage is much more difficult to design as an output
transformer. The supplied interstage is specially designed
and made by Tamura.
use of parallel 2A3 not only increases output power
(or when you look at it in a different way, reduce distortion
for a given output level) but also increases the damping
factor. The damping factor tell you something about
the control an amplifier has on the connected loudspeaker.
The higher the damping factor, the better the control.
Normally "feedback" is used to increase the
damping factor, but sound wise this is not the way we
want to do it.
The interstage makes also for a much easier wiring schematic.
Parts count is even lower then in a CR design (anode
resistor + coupling capacitor). This amplifier does
not use a PCB, but is still easily assembled.
A simple schematic is used. Input tube is a parallel
connected 6SN7 tube. The output of this stage is DC
connected to the grid of the triode strapped 6V6GT tube.
The 6V6GT is connected to the primary side of the interstage
transformer. The output tube girds are connected to
the secondary side of this interstage.
The 2A3 tubes are "self-biased" with an individual
SV-2A3TSX uses the same new chassis as the SV-2A3/300BE
Sun Audio has developed a new chassis for their SV kits.
The new chassis looks almost exactly the same as the
old version (so happy that they did not change that),
but the humm balance potentiometers have been relocated.
These are now located directly in front of the output
tubes and can be set without the need to put the amplifier
(brands of) output tubes are made a little different.
When changing output tubes it is sometimesnecessary
to adjust the "humm balancing potentiometer"
to achieve the lowest output humm.
Re-designing the chassis also offered the possibility
to use new high quality input sockets and new loudspeaker
To increase reliability and sound, expensive Yamamoto
tubes sockets are supplied for the output tubes.
• Mono amplifier
• 1x 6SN7 input tube
• 1x 6V6GT driver tube
• 1x 5U4G rectifier
• 2x 2A3 output tube: 6W output power
• Input impedance : 100KOhm
• Output terminal : 8 Ohm
• Frequency response : 20Hz ~ 25KHz / -3dB
• Output noise : 2,5mV or less
• Dimensions : W360xH190xd270
• Weight : 16Kg.
tubes, output tubes and rectifier are included.
230Vac Power transformer
(2 pcs mono bloc)