Accuphase E-212 Brochure

m Parallel push-pull output stage delivers quality power: 90 watts per

channel into 8 ohms m Current feedback circuit topology provides
outstanding high-range phase characteristics m Logic-controlled relays
for optimum signal routing m Tone control circuitry m Option boards
allow digital signal input or high-quality analog disc reproduction

Enjoy high-grade CD reproduction enabled by option board with high-

Input

Output

precision MDS type D/A converter digital input. Power amplifier uses current
feedback principle for outstanding high-range phase characteristics and
impeccable sound quality. Wide-band power transistors in parallel push­pull configuration deliver 115 watts per channel into 4 ohms or 90 watts per
channel into 8 ohms.

The Accuphase E-200 series of integrated
amplifiers is one of our core product ranges,
renowned for technological excellence and
impeccable quality. The model lineup so far
consisted of the E-210, E-210A, and E-211.
With the E-212, we are now introducing a
further refined version of the E-211, featuring
latest circuit design topology and top-notch
materials. Sound quality has reached an even
higher level than before, presenting a superbly
matched blend of performance, features, and
musicality.
The power amplifier section of the E-212
boasts excellent phase characteristics and
smooth reproduction thanks to the highly re­nowned current feedback principle. In the out­put stage, a parallel push-pull arrangement of
high-current power transistors designed for
demanding audio applications is used, allow­ing the amplifier to drive even very low imped­ance loads with ease. The preamplifier sec­tion has its own power supply to eliminate in­teraction with the power amp circuitry. Tone
controls, loudness compensator and other
features let the user tailor the sound if desired.
Up to two tape recorders can be connected
for recording and playback, and terminals for
two sets of speakers are provided, making the
E-212 a flexible and attractive performer. In
addition, various options make the E-212 even
more versatile. A digital input board with MDS
(Multiple Delta Sigma) D/A converter allows
direct input of the digital signal for example
from a CD player for ultra-pure music repro­duction. An option board for reproduction of
analog records is also available.

Parallel push-pull power unit delivers
115 watts/ch into 4 ohms or 90 watts/ch
into 8 ohms

The power transistors used in the output stage
are multi-emitter devices designed for audio
applications, with optimum frequency re­sponse, forward-current transfer ratio linear-

High-current power transistors

ity, and switching performance characteristics.
By connecting these devices in a parallel push­pull configuration (Fig. 1), the E-212 achieves
low internal impedance. The transistors are
mounted to large heat sinks for efficient dissi­pation of thermal energy. This lavish design
results in high-quality power output capabili­ties rated for 115 watts into 4 ohms, 105 watts
into 6 ohms, or 90 watts into 8 ohms per chan­nel.

Current feedback circuit topology in power
amplifier section assures outstanding
phase performance in high frequency range

In the E-212, signal current rather than volt­age is used for feedback. Figure 2 shows the

Current adder

Input

Buffer

Fig. 2 Current feedback amplifier principle diagram

I-V

converter

Trans-impedance

amplifier

Current NFB

network

Amplifier

Output

operating principle of this circuit. 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 (current adder in
Figure 2) 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. Fig-

ure 3 shows
frequency
response for
different gain
settings of
the current
feedback
amplifier. The
graphs dem-

Fig. 3 Frequency response with current feedback

(Response remains uniform even when gain changes)

onstrate that
response remains uniform over a wide range.

Highly reliable logic-controlled relays

To realize the shortest possible signal paths,
all switching is performed by logic-controlled
relays arranged in an optimized layout. 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 long­term reliability.

Gold-plated input/output

jacks connected directly to relays

Tone controls use summing active filters
for highest sound quality

The tone control circuitry in the E-212 was
specially designed with summing active filters.
Figure 4 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.

Tone control characteristics

Bias stabilizing

circuit

Fig. 1 Power amplifier circuit diagram (one channel)

Fig. 4 Tone control circuit diagram

(summing active filter type)