that further improve the U280-
SC’s already excellent
imaging.
Damping is critical to overall performance including
smoother transient response and overall staging. Further
improvements in quickness, dynamics and the overall life-
like listening experience result.
Our new Power Supply is virtually indestructible due to
specially designed regulation technology that protects the
amp from major tube failures.
Zero Feedback
The U280-SC does not use negative feedback as do
most tube amplifiers. Negative feedback results in a loss
of detail and sound richness. Margules has developed the
BEFS (Back Electromotive Force Sensor), which changes
the
amplifier's
output
impedance
per
the
load
requirement. BEFS permits the amplifier to drive difficult
speaker loads with exceptional efficiency, dynamics and
extended controlled bass.
The U280-SC's innovative design is complemented with a
fine new finish, new silver coated epoxy pc boards,
military grade potentiometers, precision metal-film
resistors and audio grade interstage capacitors.
SETUP
IMPORTANT: The amplifier should be unplugged from
the wall outlet.
First, choose the proper output impedance accordingly to
your speaker; both channels should be the same (1).
2 ohms from 1 to 2 ohms load
4 ohms from 4 to 8 ohms load
8 ohms from 8 up ohms load
In Mono mode always use both channels of the amplifiers
in ultralinear or triode mode (2) in the same output
impedance range.
The recommended settings are the following:
2 Ohms should not be used
4 Ohms from 2 to 4 ohms load
8 Ohms from 4 to up ohms load
If used as Stereo or Mono mode (3) the Triode/Ultralinear
mode should be the same in both channels.
Next, connect the speakers to the output binding posts,
red to red and black to black (4); the input signal of the
amplifier to the output signal of the preamplifier (5), see
also figure 1 for more details.
If you are not using a preamplifier set the level controls to
minimum, otherwise full clockwise (6).
Check the power switch in the back of the amplifier to be
off (7). Then connect it to the AC outlet of the wall, check
that all connections are OK and flip the switch to on.
Wait until the meter reads 43 ma! (8)
The panel meter is the actual current passing through the
right front output tube. When overpasses the 100ma, you
