Introduction - Cary Audio Design SLI 80 Owner's Manual

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.
(not cheap voltage
The high voltage section features full wave vacuum tube (CV-729/5U4) rectification
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.
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