Pioneer sa 7800 brochure

Page 2

Weve Incorporated "Cool Class-A Concept
in Our "Non-Switching Amp
for Amazing Improvements in Faithful Musicality.

lMAGNI-WIDE POWER AMP - Lower distortion over superwide frequency/
power range in Pioneer-exclusive Non-Switching output.

INEW SUPER-LINEAR RETs & PIONEER VARl-BIAS-Original and exclusive
technical triumphs for higher fidelity.

IDC CONFIGURATION AMPS -Power and flat amps are DC to eliminate
phase and transient distortion.

lHlGH S/N RATIO-Advanced circuitry and high-quality parts ensure
87dB Phone and 110dB AUX signal-to-noise.

INEW PEAK METER -Easy-to-read fluorescent meter displays instant
peaks over wide 60dB range for each channel.

IPOWER OUTPUT -Continuous 65 Watts per channel, 10Hz to 20kHz at
8 ohms, 0.009% THD or less.

NON-SWITCHING" POWER AMP

Pioneers MAGNl-WIDE Policy Defined
The remarkable "non-switching amplifier
configuration in the power amp of the SA-7800.
as explained below. has made it possible to live
up to each of the 12 key points covered In our

Magni-Wide amp policy. They add up to the

elimination of all that stands in the way of truly

excellent fidelity in actual musical reproduction.

These aim at the:

( 1) Expansion of dynamic range.

( 2) increase of power output.

( 3) Removal of switching distortion.

( 4) Lewering of noise and harmonic distortion,

( 5) Ending of lntermcduiation distortion,

( 6) Widening of power bandwidth.

( 7) Expansion of frequency range,

( s) improvement of phase.

( 9) Flattening of frequency response.

(10) Reduction of dynamic envelope distortion.

(11) Reduction of transient lntermodulation
distortion. and,

(12) Improvement of overall dynamic
characteristics.

With the new PVB (Pioneer Vari-Bias) Circuit
and very advanced Super-Linear RETs at work in
the "non-switching" power amp of the ss-reoo.
each of these factors has been optimized.

Pioneer's Non-Switching" Output

Class-A amplifiers tend to waste up to 75% of
their power supply as heat-making them terribly
inefficient when asked to handle anything but
relatively small voltages. For this reason.
Class-A amps are normally employed only In the
preamplifier circuits In audio. or in hybrid
Class-A8" power amps as explained below.

In the Sit-7600. Pioneer has perfected a way to
take advantage of the distortion-free Class-A
configuration for the power amp output.

A little background: The reason @33st amps
are typically inefficient (i.e. why they run "hot")
is that their push-pull complementary output
transistors are always ON. always consuming
energy whether or not a signal Is present for
them to amplify. A bias current is constantly
applied for this purpose, Class-B amps. on the
other hand. are arranged so that their transistors
switch on and off as waveforms appear and
disappear in the input signal. This lets them run

cooler. with efficiency as high as approx. 70%
under ideal conditions. But. the onloff switching
of Class-B presents a major obstacle to true
high fidelity performance In the form of switching
distortion (also called "notching distortion").
Our new "non-switching power amp ends this
problem. Dramatically lmpoved high-frequency
response and higher efficiency are realized
in a novel and effective way.

For Better than Class-AB"

Seeking a temporary solution to the Clasa~AI
Class-B paradox. audio engineers not long ago
hit on the so-called "Cless~A8" configuration.
When the listener required an output of more
than three watts or so. he selected the
Class-B function by means of a switch (more
sophisticated versions provided automatic AB
aeiection). This didnt raise the efficiency of
Class-A. nor did It and the hazards to tonal
quality caused by switching distortion In Class-B.
It merely offered an "either/or" choice. Our new
"nonvswitching" amp. however, is a far better
solution. And here is how It works: