Yamaha RX-V740RDS - Manual (Page 4)

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High Current Amplification Achieves Low Impedance/
High Current Power from Input to Output.
The Importance of High Current
Although power rating is often the first
thing customers look at in a receiver, high
power output does not necessarily mean
good sound. High current level is a much
more important factor. Yamaha receivers
has always had fairly high current levels,
but with the RX-V740RDS, we have further
improved this performance.
What It Does
In brief, Yamaha High Current
Amplification achieves low impedance,
high current power from input (power
supply circuit) to output (speaker
terminals). This drives the speakers much
more smoothly and dynamically, for better
sound from all sources, including 2-
channel audio.
Specific Improvements
The first problem to be overcome was the
difference in voltage that ordinary
receivers suffer between the power
supply and amplifier circuits, caused by
current fluctuations. This was solved by
using custom-made, high-grade block
electrolytic capacitors and a copper grip
for one-point grounding. Another current
drop is generally seen between the
amplifier circuit and the speaker
terminals, caused by the cables, speaker
output relays, copper circuit boards, and
so on. To increase current here, we used
an extra-large, low-impedance
transformer and gold-plated speaker
relay contacts.
6-Channel High Power,
Discrete Amplifier Configuration
The RX-V740RDS will deliver as much as
140W of power (DIN) to each of six
channels (two main, two rear, one centre
and one rear centre). This is more than
enough to fill even the largest rooms with
vibrant music and Richter-scale sound
effects. 6-4 mixdown is also provided, for
enjoying 6-channel input sources from
four or five speakers you already have on
hand with or without subwoofer.
High Dynamic Power Capability
The RX-V740RDS is capable of delivering
large amounts of reserve power for
accurate reproduction of the high energy
peaks that are especially prevalent in
digital audio sources. This emphasizes the
music’s dynamic qualities and provides a
sharper sound image.
Linear Damping (Main L/R Channels)
Level variations due to high amp
impedance tend to reduce an amplifier’s
damping factor, and frequency variations
cause it to fluctuate. This circuit cancels
the effect of these variations, maintaining a
high, stable damping factor, for superior
articulation of all sounds and better
frequency response.
Anti-Resonance ToP-ART Base
Supporting the heavy heat sinks and
circuit board is Yamaha’s ToP-ART base,
which has exceptional anti-resonance and
damping characteristics. Beneath this
base is the bottom of power amplifier, part
of the heavy chassis which is also
The voltage (A) of Block Electrolytic Capacitors and voltage (B) of
Power Transistor Collector should be ideally at the same level. However,
when the current become large, there will be a big difference in the
level of each voltages.
Voltage level difference between A (power supply circuit) and B
(amplifier circuit). Voltage level difference between C (amplifier circuit output) and D
(speaker terminals).
High Current Amplification Conventional Amplifier High Current Amplification Conventional Amplifier
There is also a level difference between Output of the Power Amplifier
(C) and Speaker Terminals (D), which is caused by the copper of the PCB,
Speaker output relays, cables and so on, resulting in reduced sound
quality.
GND
Power
Supply
Circuit
Amplifier
Circuit
A B
GND
Power
Supply
Circuit
Amplifier
Circuit
C D
High Current Amplification Principle