Class-A
INTEGRATED STEREO AMPLIFIER

E-700

Accuphase Laboratory, Inc.

1E-700 is a succession model of E-650, the 6th generation
Accuphase Class-A integrated stereo amplifier.
The preamplifier section provides a Balanced AAVA
volume control with a fully refined ANCC circuit, and thedistortion and noise performance are pursued to the limit.
The power amplifier section adopts the MOS-FET in afour-fold parallel push-pull arrangement, expanding theclass-A operating range to 35W into an 8Ω load.
E-700 combines the ambiance and musical expression
only a superlative class-A amplifier can offer.

1

Dimensions and Weight• Same unit dimensions but lighter weight
than E-650– Width 465mm– Height 191mm– Depth 428mm– Weight 24.9kg

Accuphase Laboratory, Inc.

2

The dimensions are the same, but the weight is slightly
lighter than E-650 (E-650: 25.3kg).

2Internal View
Left channel
power amp module

High-efficiency large toroidal transformer

56000μF capacitor x 2

Right channel
power amp module
Volume sensor
mechanism
Balanced
AAVA module

Accuphase Laboratory, Inc.

3E-700 inherits Accuphase's traditional amplifierconstruction of a mono-block structure.
Large power transformer and capacitors are positioned
between L and R channel separated the power amplifier
blocks.
Accuphase newly developed high-capacity 56000uF filter
capacitor after repeated sound quality studies and also
installed a custom-made volume sensor mechanism,
which has distinguished operation feeling and ultimate
reliability.
The balanced AAVA circuit block is located near the front
panel.

3

Output power• Rated output power is increased by 16% from E-700
8Ω4Ω*

2Ω*

E-650
E-700
E-650
E-70030W35W
60W
70W
120W

E-650
E-700

140W
Rated output power*Limited to music signals

Accuphase Laboratory, Inc.

4E-700’s rated continuous output power is 35W/8Ω inclass-A.
This output value is a 16% increase compared to E-650,
meaning the Class-A operating range has been
expanded to 35W.
The clipping output power is more than 70W/8Ω. E-700
perfectly drives any loudspeaker, even in low impedance
conditions.

4

Ultra low noise• Actual output noise voltage 11% lower than the E-650– Guaranteed SN-ratio: 103dB
E-650

33.1 μV

E-700

29.6 μV
11% down
Actual output noise voltage (@9 o’clock volume position)

Accuphase Laboratory, Inc.

5

E-700 shows remarkable progress in noise performance
than E-650.
The actual output noise voltage at the normal volumeposition when listening to the music is 11% lower thanthe previous model.
The guaranteed SN ratio is 103dB, which is 1dB better
than E-650.
Improving noise performance is important to convey theemotion of the music. Accuphase will make all efforts toreduce noise as much as possible with each new product.

5

Technology for ultra low noise• Balanced AAVA Architecture• ANCC installed for noise and distortion cancellation
Input buffer amp

V to I converter

I to V converter

Left channel
ANCCRight channel

AAVA Module

Accuphase Laboratory, Inc.

6For E-700, Accuphase thoroughly reviewed the Balanced
AAVA implementations.
Balanced AAVA places a buffer amplifier that produces astrong current at the front of the VI converter to reducenoise.
In addition, a buffer amplifier is placed in the front stageof the VI converter to drive the entire AAVA powerfully.

6Super high damping factor• 25% higher than the former model E-650 and has the samevalue as Class-A stereo power amp A-80
25%UP
E-650

800

E-7001000
Guaranteed damping factor

Accuphase Laboratory, Inc.

7E-700 achieves a guaranteed damping factor of 1000.
It is 25% higher than the former model E-650 and has
the same value as the Class-A stereo power amplifier A80.
*Damping-Factor, DF: An index of speaker driving ability.
A higher Damping-Factor amplifier has higher speakerdriving ability.
DF = 8 ohm / Output-impedance

7

Technology for high damping factor• Very low output impedance power amplifier engine– MOSFET 4 parallel push-pull output stage– Same circuit configuration as Class-A stereo power amp A-80

Output stage

Output stage

E-650 Power Amplifier Module

Power MOSFET

E-700 Power Amplifier Module

Accuphase Laboratory, Inc.

8E-700 power amplifier engine is significantly enhanced
and more powerful than the former model.
The output impedance is lower by four-fold parallel pushpull output stage arrangements of MOSFETs.
*E-650 has three-fold parallel push-pull output stage
arrangements of MOS-FET.

8Technology for high damping factor• Balanced Remote-sensing– Feedback from speaker terminal proximity– Signal-line and GND-line sensing
Signal sensing

Speaker terminal+ Signal- GND
GND sensing

Power Amplifier

Accuphase Laboratory, Inc.

9Remote sensing is the technique to lower the amplifier's
output impedance by the negative feedback with signal
sensing from nearby the speaker terminals.
Balanced remote sensing is the technique to lower theoutput impedance by signal sensing and the GNDsenses.
Balanced remote sensing improves the Damping Factorand Total Harmonic Distortion and Intermodulation
Distortion.

9

Technology for high damping factor• Speaker protection equipped with the MOS-FET switch circuit• Short signal path configuration
MOS-FET switch

Large speaker terminal

Edgewise coil

Output module

MOS-FET
On-resistance: 0.96mΩ

Accuphase Laboratory, Inc.

10

Mechanical relays are the typical components forspeaker protection, but the contact resistance of
mechanical relays is higher than people think.
Also, mechanical relays have physical contact, making
them unreliable for long-term use.
Therefore, Accuphase has chosen the MOS-FET switch
instead of conventional mechanical relays for speakerprotection.
Thanks to this MOS-FET switch, the damping factor,reliability, and sound quality are all improved.
E-700 adopted a new MOS-FET with a low on-resistanceof 0.96mΩ (E-650 used 1.6mΩ on-resistance MOS-FET).
Making signal paths thick and short also helps attain low
impedance as well.
10

Pursuing further product safety and reliability• Power amplifier– Newly-developed protection circuit using Photo-couplers– Temperature sensors are installed on the heatsink
Photo-couplerTemperature sensor

Power amplifier module

Accuphase Laboratory, Inc.

11The newly designed output protection circuit can detect
any short-circuiting of the speaker terminals with due
consideration for product safety.
Temperature sensors that detect the heatsink
temperature are installed on the heatsink. Thanks to this,the unit accurately ascertains the high-temperature alarmin the power amplifier section.
Thanks to the photo-coupler, the detected short-circuiting
information is completely isolated from the music signal
to minimize the negative effects on the sound quality.
*When these protection circuits are activated, the unit
completely interrupts speaker output and makes thepower meters flash to indicate the abnormal condition.

11

Furthermore…
• Ready for the option board DAC-60 and AD-60– Sampling frequency on the front display– Input impedance, MC/MM, Subsonic filter selectable

Multi-function display

Option Boards

Input selector for the option boards

Accuphase Laboratory, Inc.

12E-700 accepts the digital input board DAC-60 and analog
input board AD-60.
You can see the figure of the sampling frequency input ofDAC-60 on display and can choose any preferred input
sources with the selector on the front panel.
The gain values of AD-60 can be set to 66dB for MC and40dB for MM, and the MC Input impedance can beselected from 4 values, “200 ohms” is newly added.

12

Appendix “ANCC”• ANCC: Accuphase Noise and distortion Canceling Circuit– To detect and cancel the noise and distortion at the input stage ofthe amplifier
Detects noise anddistortion components

Current
inputRVoltage
outputInjects the cancelingcurrent

Current to voltage
converter circuit

Detection amp

ANCC

Accuphase Laboratory, Inc.

13

ANCC: "Accuphase Noise and Distortion Canceling
Circuit" is installed in AAVA's current-to-voltage converter.
Canceling noise and distortion are realized by detecting
the components of noise and distortion at the input stageof an I-V converter circuit and by injecting the cancelingcurrent, which contains the reversed polarity of thosecomponents.
ANCC is a highly effective technology at any volumeposition.

13