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4
DESIGN FEATURES
• Pure Class A Output Topology for the utmost in musicality and definitive
power output. Soundstream's unique design allows the Class A amplifiers to
deliver incomparable sonics or, when operated at lower impedances, to
provide phenomenal amounts of power.
• Uncompromising Design and Construction including mil-spec glass
epoxy circuit boards and high current custom gold-plated solid brass
connections that will accept up to 4 gauge power/ground wire.
• Quad Factor™ Circuitry - Soundstream’s newest power supply design
allows the Class A amplifiers to make four times the power when going from
a 4 ohm stereo load to a 2 ohm stereo load, and again when going from a 2
ohm stereo to a 1/2 ohm stereo load!
• Coherent Stereo
TM
/Mixed Mono selection for either “pure” stereo operation
or mixed mono for simultaneous stereo and mono.
• Chassisink
TM
Darlington Power Array - Soundstream’s “overbuilding” of
the output section incorporates multiple output transistors instead of a few
for faster, stronger power delivery. The transistors are sandwiched between
the circuit board and the heatsink in a design called Chassisink
TM
to ensure
cool, efficient amplifier operation.
• PowerGrid Power Supply Design - All power supply components are
located near one another, connected by thick, wide PCB traces, which
ensures rapid, high current delivery. The entire power supply is isolated on
one side of the circuit board while the audio stage is located opposite it,
guaranteeing minimal noise.
• Ultra-Low ESR Capacitance Bank - Multiple small input power capacitors
are used to provide a lower ESR (Equivalent Series Resistance), which
means more power in and out faster.
• Smart Thermal Rollback - Most amplifiers shut off when they get too hot.
In the unlikely event the REFERENCE Class A amplifier reaches 85° C, it will
gradually roll back its average power (without affecting the dynamics). Once
the amplifier has cooled off, it returns to full power output. If overheating
should continue, a second thermal sensing protection circuit will shut off the
amplifier if the heatsink reaches 95° C.
• Fault Monitor LED on the top panel notifies you of blown power supply
fuses.
• 1/4 ohm Drive Ability - The REFERENCE Class A amplifiers are designed
to drive virtually any load—all the way down to 1/4 ohm stereo (1/2 ohm
mono).
• Dual Discrete Class A Drive Stages - Over six times the drive current of
17
LSE.Q THEORY AND USE (continued)
This is due to the loss of any
appreciable resistive air mass. At
frequencies below resonance, the
woofer starts to behave as if it were
mounted in “free-air”. If we wish to
improve the performance of a
vented system, we should remove
these unwanted signals from our
system. These can be removed by
adding a subsonic filter. Figure 5 shows the effectiveness of LSE.Q on
woofer excursion. Woofer travel is 7.5 mm at 10 Hz, with LSE.Q
properly adjusted, this excursion can be
reduced to less than 1 mm. This is of great
benefit to lowering woofer distortion and
increasing output.
Adjustment
An easy method of optimizing your existing
subwoofer enclosure with LSE.Q's “Hz” control
is as follows.
1 Adjust frequency and boost control to full
CCW position. (See figure 6)
2 While listening to music with strong bass content at a moderate level,
slowly adjust frequency control clockwise. Listen for a reduction of
bass response. Now, rotate
frequency control slightly
backwards. This serves the purpose
of removing the “subsonic” bass
energy.
Soundstream’s LSE.Q contains the
same type of circuit with the added
benefit of infinite adjustability. Our
“Q” and “Hz” control can provide
virtually any combination of boost
10 Frequency (Hz) 50 100 200
Xd
(mM)
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
FIG. 5 Limited Excursion
NOTE: The LSE.Q circuit on the Class A 10.0 can be defeated for flat
operation down to 20 Hz by placing the LSE.Q switch in the "OUT"
position. You may wish to use this option to achieve a higher S/N Ratio
when using ultra-high efficiency speakers, such as compression
FIG. 6 LSE.Q Setting
dB
Frequency (Hz)
-20
-30
10
-25
-15
-10
5
0
-5
10
50 100 200
FIG. 7 Various Settings