| Triple parallel push-pull configuration delivers 170 watts/channel of
quality power into 8 ohms
| Current feedback principle assures great sound and rock-stable operation
| Logic-controlled relays allow very short signal paths
| Dedicated toroidal transformers and power amplifier and power supply
| Balanced inputs
| Supplied remote commander
| Two sets of large speaker terminals
| Based on extensive experience in building superb separate-type amplifiers,
Accuphase proudly presents the E-406V, an integrated amplifier destined
to become a new reference. Using only the finest of parts, the E-406V delivers
sound quality on a truly high level. Dedicated transformers for the preamplifier
and power amplifier sections and carefully designed circuit layout ensure
total separation of these two blocks. A switch even allows using the preamplifier
and power amplifier as independent components.
Accuphase's highly acclaimed current feedback topology virtually eliminates phase shifts in the upper
frequency range and assures uniform frequency response which does not change with gain. Phase
compensation can be kept at a minimum, and high amounts of negative feedback with their associated
disadvantages are no longer required, resulting in excellent transient response, with superb sonic
transparency and detail.
The power amplifier output stage employs a triple parallel push-pull configuration, using power
transistors designed for high-current audio applications. This improves drive capability especially
with critical low-impedance loads. The preamplifier section is designed around a current feedback
line amplifier and is driven by a dedicated toroidal power transformer which eliminates any possibility
of interference from the power amplifier.
A total of eight input positions including two balanced inputs provide welcome flexibility, including
two option slots on the rear of the amplifier for optional input boards. Besides a line-level input
board, Accuphase offers an analog disc input board for MM or MC cartridges, allowing reproduction of
analog records with outstanding sonic quality.
The tape enthusiast will welcome provisions for two tape recorders, with
easy dubbing in both directions. Summing active filter type tone controls
and loudness compensation are further advantages. High-performance logic
relays are used for signal switching, and a supplied remote commander lets
the user operate the unit from any point in the room. The E-406V is an
integrated amplifier with a full complement of features and simply great
Robust power amplifier section delivers 170 watt per channel into 8 ohms
or 220 watts per channel into 4 ohms
The power transistors in the output stage are high-current devices designed
specifically for audio applications. They possess optimum frequency response
as well as excellent forward-current transfer ratio linearity and switching
performance characteristics. By using these transistors in a triple parallel
push-pull configuration, the amplifier is able to handle load fluctuations
with ease. Operation remains stable at all times, even when driving reactive
low-impedance loads. The rated output of 170 watts per channel into 8 ohms
or 220 watts per channel into 4 ohms provides more than ample performance
Current feedback circuit topology in power amplifier and line amplifier
sections prevents phase shifts
When the gain of an amplifying circuit increases, frequency response, i.e.
the bandwidth that can be handled by the amplifier, becomes more narrow.
To counter this effect, a commonly employed echnique called negative feedback
(NFB) routes part of the output signal back to the input. Conventional
amplifiers employ voltage NFB, whereby the output voltage is used for the
feedback loop. In the E-406V however, the signal current rather than the
voltage is used for feedback. At the sensing point of the feedback loop,
the impedance is kept low and current detection is performed. An impedance-converting
amplifier then converts the current into a voltage to be used as the feedback
signal. Since the impedance at the current feedback point is very low,
there is almost no phase shift. Phase compensation can be kept to a minimum,
resulting in excellent transient response and superb sonic transparency.
Discrete-type line amplifier for superior sonic purity
A differential pure complementary push-pull circuit is used, with an emitter
follower output stage. Current feedback topology further enhances circuit
operation and reduces the need for phase compensation, resulting in effortless,
utterly natural and transparent sound.
Highly reliable logic-controlled relays
Program source switching is performed by logic-controlled relays which
are arranged so as to permit the shortest possible signal paths. The hermetically
sealed relays are high-quality types developed specifically for demanding
communication applications. The contacts are twin crossbar types plated
with gold for minimum contact resistance and outstanding long-term reliability.
Tone controls use summing active filters for pure sound
The tone control circuitry in the E-406V was specially designed with summing
active filters such as found in high-quality graphic equalizers. Figure
5 illustrates the operation principle of this circuit. The flat signal
is passed straight through, and only when an adjustment is required, the
characteristics are created at F1 and F2 and added to the signal, thereby
producing the desired change. This design provides efficient control without
degrading signal purity.
Separate power transformers for power amplifier and preamplifier sections
Dedicated high-efficiency toroidal transformers are used for the power
amplifier and preamplifier sections, to eliminate the possibility of mutual
interference. Toroidal transformers which use heavy-gauge copper wiring
on a ring-shaped core have various advantages, such as very low impedance,
small size, and high conversion efficiency. These characteristics make
this transformer type ideally suited for audio applications. The E-406V
uses transformers with near-circular core caliber. This allows near-circular
coil windings with high packing density, resulting in low leakage flux
and minimum vibrations. In addition, the smaller ferrite core diameter
and copper windings with high specific gravity mean low ferrite losses
and low inrush current.
Two sets of heavy-duty speaker terminals
The oversize speaker terminals are made of extruded high-purity brass material
which accept also heavy-gauge speaker cable. Two sets of outputs with a
speaker selector are provided, and bi-wiring (supplying the same signal
via dual leads to speakers with separate high-frequency and low-frequency
inputs) is also possible.
|Large, direct-reading peak power meters
The large analog power meters have a peak hold function which lets you
easily monitor the output level of the rapidly fluctuating music signal.
Thanks to logarithmic compression, the meters cover a wide dynamic range.
Versatile input configuration including balanced connectors
The input selector of the E-406V controls a total of eight positions, including
two positions for optional input boards installed in rear-panel slots.
Two of the standard inputs are designed for balanced connections which
are impervious to externally induced noise, ensuring signal transmission
with optimum sonic purity.
SEPARATE switch allows independent use of preamplifier and power amplifier
Separate preamplifier outputs and power amplifier inputs controlled by
a selector switch allow use of the preamplifier section and the power amplifier
section as separate components.
The rear panel of the E-406V provides two slots in which optional input
boards can be installed in a matter of minutes. Two types of boards as
shown below are available. * Both boards use the AAB (Accuphase Analog
Bus) interface. * Any board can be installed in any empty slot.
Line Input Board LINE-10
This option board provides an additional set of conventional line inputs which can be used to connect
a CD player, tuner, or other component with analog output.
||Analog Disc Input Board AD-10
This board contains a high-performance, high-gain phono equalizer. The board can be used with any type of phono cartridge.
Internal DIP switches control MM/MC operation, MC input impedance, and
subsonic filter on/off.
Input impedance:47 kilohms