Cary Audio Design SLI-80 - Manual (Page 5)

INTRODUCTION
Congratulations!
You have purchased one of the most exotic integrated stereo audio amplifiers available. Within its power
range, the SLI 80 displays the operating characteristics of a true "high-end" amplifier. Careful design,
parts selection and proper circuit topologies contribute to incredible reliability and enjoyment.
For the technically minded, a review of the circuit in your new SLI 80 is in order. Your new SLI 80
integrated stereo amplifier operates in a class A/B-1 mode utilizing a negative fixed bias supply. The KT-
88/6550 output tubes are configured in push-pull. The triode mode provides 40 watts/channel of output
audio power and switching to the ultra-linear mode yields 80 watts/channel of output power. In the
opinion of the designer the triode mode sounds the best.
The output transformers in your SLI 80 are the most important component in the amplifier and have
been specifically designed by Cary Audio Design for use in the SLI 80. Negative feedback is derived from
a separate winding on the output transformer. This feedback winding and circuitry is used to reduce the
noise floor and improve the speaker damping characteristics. Only 4 dB of feedback is utilized. The phase
inverter is a self-balancing split load configuration utilizing the 6SN7 octal base dual triode. The
preamplifier circuit is a resistive coupled Class A triode voltage amplification stage. The power supply in
the SLI 80 features a 200% duty cycle EI laminate power transformer.
The high voltage section features full wave vacuum tube (CV-729/5U4) rectification (not cheap voltage
doublers used in many amplifiers) to a PI-L capacitive network. The input signal from the volume control
is direct coupled (DC) to the first grid of the 6922. There are no coupling capacitors in line with the input
signal on the SLI 80. The sub-woofer output is derived from a voltage divider network on the input stage
of the SLI 80.
A great deal of attention during design of your new SLI 80 was concentrated on the "overload recovery"
ability of the amplifier. The ability of an amplifier to instantly recover from clipping is much more
important than is commonly believed. In the power war of amplifier manufactures the mentality is
focused on high and then even higher power output to solve the clipping problem. When in reality the
most critical aspect is how fast a recovery an amplifier can achieve after overload. Most of the music
being listened to in an average listening room is only requiring about 3 watts of power. It is on the
transients of loud low frequency program material that tremendous signal voltages will appear at the
input of the amplifier. It is in this situation that the overload recovery ability of an amplifier is of critical
concern. The SLI 80 will overload symmetrically at any frequency in the audio band-pass. The SLI 80 will
also yield faithful reproduction of extremely low frequencies at full output levels. Power transformer,
power supply regulation and output transformer design and careful shaping of the overall frequency
response curve all play a very important part in the ability of the SLI 80 to recover quickly when
overloaded. The high voltage rail will fluctuate no more than a volt between soft and loud passages.
Another technical feature of your new SLI 80, aside from how compact and gorgeous it looks, is the
delightful, sensual beauty of the music it recreates. The first thing that will strike you about the SLI 80
integrated amplifier is the incredible transparency and resolution of detail in the music. The SLI 80's
sensual nature is best revealed in the sense of life it displays in female vocalists.
The SLI 80 integrated presents music with such presence and directness, you'll be drawn into the music
hour after musically satisfying hour. This is the result of circuit techniques, which eliminate any
discernible crossover notch at low levels, and also contributes to the freedom from listening fatigue. The
SLI 80 will draw you in even further as you realize how lucid and utterly uncolored neutrality reveals
delicate nuances in the sound stage.
Enjoy the music and of course please read this complete manual for a complete understanding of trouble
free operation.
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