m Separate MM/MC amplifier circuitry ensures ultra low noise m Highly precise
equalization with only ±0.3 dB RIAA deviation m Versatile impedance switching withthree settings for MM and six settings for MC m Gain switching enables high gain ofup to 70 dB m Three analog player inputs with separate settings memory m Balanced
and unbalanced analog outputs m Polarity selector for balanced outputs

The Ultimate Phono Equalizer Amp — Separate circuitry for MM and MCensures ultra low noise performance and outstanding RIAA precision. Versatileload impedance selector with three settings for MM and six settings for MCbrings out the best in every cartridge. Subsonic filter, and high gain capabilityof up to 70 dB with gain switching. Three analog player inputs with separate
settings memory for each input.
The analog phono record is experiencing a quiet boom
among discerning music lovers. It goes without saying thata phono equalizer of high quality is essential to extractthe enormous richness of sonic information engravedon vinyl records. Furthermore, the selection of tonearm,cartridge and other parts of the playback system requiresa thorough understanding of audio fundamentals. This isa field where some investment of time and effort can yield
immensely satisfying results.
Accuphase has gained considerable expertise in designingand building phono equalizers, either integrated inpreamplifiers or available as option (AD-2810 and AD-20).
In response to the wishes of audiophiles worldwide, wehave now developed the C-27 as a high-end standalone
phono equalizer amplifier, capable of exploring thepossibilities of the analog disc to the fullest.
Because the output signal level of a record player isextremely low, high-gain amplification is required before
supplying the signal to subsequent stages. Distortionand noise should be kept to an absolute minimum, andexcellent linearity from low to high frequencies is also amust. In the C-27, these goals are achieved by employing
completely separate amplifier sections for MM and MC,each with optimized circuit topology and strictly selectedparts for no-compromise performance. S/N ratio, THD,
high-frequency characteristics, linearity and all otherparameters approach the ideal in performance. What’smore, the C-27 is perfectly equipped to accommodate awide range of cartridge output voltage ratings and load
impedance requirements. To ensure optimum matching,
three different settings for MM and six different settings
for MC can be selected.
Designed to raise the bar for phono equalizer amplifiers,
the C-27 will bring out the characteristics and musicalqualities of any phono cartridge to optimum effect,
providing pure music enjoyment from those legendary
analog discs.

C-27 Functions and Features■ Separate MM/MC amplifier configuration ensures ultra low noise■ Highly precise equalization: RIAA deviation only ±0.3 dB■ Monaural construction with separate toroidal power transformers
MM/MC indicationand separate equalizer boards for left and right channel■ Versatile impedance switching options
MM 1kΩ, 47kΩ, 100kΩMC3Ω, 10Ω, 30Ω, 100Ω, 300Ω, 1kΩ

Load impedance indicators

Load impedance
selector

Power transformer■ Subsonic filter(10 Hz, -12 dB/octave)■ Gain switching enables highSubsonic filter andFilter Gain selector
gain of up to 70 dB
gain indicators
buttonbutton■ Equalizer PCBs made from Teflon* (glass fluorocarbon resin)with low dielectric constant and low loss
Filtering capacitors* Teflon is a registered trademark of DuPont USA.

■ Gold-plating of all major parts in signal path
■ Three inputs for analog players or tonearms, each with a separate
memory for MM/MC, load impedance, gain, subsonic filter andother settings(LEDs show selection status)

Input selector

MM Amplifier Section+IMPEDANCESELECTORLEFT
CHANNEL–■ Two separateboard assemblies forleft and right channel,
using Teflon substrate andcarrying dedicated MM andMC amplifiers, phono equalizer
amplifiers, and logic relays for signal
switching to ensure shortest possible
paths between inputs and outputs.

MMAMP

1kΩ
RIAA EQUALIZERNETWORK

47kΩ
100kΩ

1DC SERVOGND

UNBALANCED

GAIN

LEFT
CHANNELINPUTS

2MC Amplifier Section

GND
IMPEDANCESELECTOR

3+3Ω

GND

–10Ω

–

FEEDBACKNETWORKBALANCEDSUBSONICFILTER–1

RIAA EQUALIZERNETWORK100Ω

LEFT
CHANNELOUTPUTS–1+MC
AMP

30Ω300Ω
DC SERVOFEEDBACKNETWORK1kΩGAIN

INPUT
SELECTORRIGHT
CHANNELLOAD
IMPEDANCE

MM/MCselector

BALANCECONNECTION

GAIN

MM-MC

FILTER

Same as LEFT CHANNEL

C-27 Circuit Diagram

Completely separate MM and MC sections
One of the biggest challenges for a phono equalizer amp is the problem of noise. How to achieve high S/N ratio is a crucial point. In order to precisely
match the circuit configuration to the different requirements of MM and MC cartridges, the C-27 features separate sections employing purpose-selectedcomponents and optimized operating points. This uncompromising approach results in outstanding S/N ratio, minimum distortion, and excellent frequency
response characteristics. Amplifier performance finally approaches ideal levels.

MC amplifier section

MM amplifier section

The MC section must provide low internal
impedance over a wide range to properly
handle the output voltage of MC cartridges,
which is a level of magnitude lower thanthat of MM cartridges. Residual noise of
the amplifier therefore needs to be kept
to an absolute minimum. This is achievedby using an “8-parallel ultra low noisetransistor differential push-pull circuit” toguarantee high S/N ratio.

The MM section must provide a high impedance input while
also reducing residual noise. To achieve this, FET devices
were selected for the initial stage. The circuit configuration
is defined as “3-parallel low noise FET buffer amplifier” +“6-parallel ultra low noise transistor differential push-pullcircuit”.

+B+B

Q17Q1Q3Q5Q 11Q7Q 13

Q21Q 15

Q39Q23Q9Q19

Q1Input

OutputQ2Q4Q6Q8Q 10

Q12Q 14

Q37Q33Q 16

Q35Q3Input

OutputQ2Q4Q40Q24Q36Q20Q18Q34Q22Q38-BUltra low noise transistor differential
push-pull circuit in 6-parallel configuration

Low noise FET buffer amplifier in 3-parallel configuration-B

Equalizer Components

DC Servo Amplifier

Equalizer Components
Ultra low noise transistor differential
push-pull circuit in 8-parallel configuration

MM Amplifier Section
Circuit Diagram

DC Servo Amplifier
Gain Control

Gain Control

MC Amplifier Section
Circuit Diagram

Performance Graphs

Other Functions and Features■ Balanced and unbalanced analog outputs■ Side panels with elegant persimmons wood finish[dB]
10[dB]
1088664422Input jacks and ground connector

00-2-2-4-4-6-6-8-8-10
10-10
10High-reliability parts selected for sound quality

1001k
Frequency [Hz]

10k

100k

1001k
Frequency [Hz]10k

RIAA deviation (MM amplifier)

RIAA deviation (MC amplifier)Input voltage vs. THD characteristics (MM)Input voltage vs. THD characteristics (MC)100k

Balanced output connectors

Polarity selector for balanced outputs● In the factory default condition, theswitch is set to the left position (pin+) as shown in the photo.
● Only change the switch position if theconnected preamplifier or integrated
amplifier requires the (pin+) setting.

C-27 Guaranteed Specifications■ Front panel[Guaranteed specifications are measured according to EIA standard RS-490.]● RIAA DeviationMM

10 - 100,000 Hz
20 - 20,000 Hz
10 - 100,000 Hz

MC● Total Harmonic Distortion● Gain±0.5 dB±0.3 dB±0.3 dB

0.005%*INPUT → BALANCED/UNBALANCED OUTPUT
GAIN button OFF (Normal) MM: 30 dB
MC: 60 dB
GAIN button HIGH
MM: 40 dB
MC: 70 dB● Input Sensitivity (at rated output: 1 kHz, 2 V)MM
30 dB:
63.2 mV
40 dB:
20.0 mV
MC60 dB:
2.0 mV
70 dB:
0.63 mV● Maximum Input Voltage (1 kHz, THD 0.005%)
MM
30 dB:
300 mV
40 dB:
95 mV
MC60 dB:
9 mV
70 dB:
2.9 mV■ Rear panel● Maximum Output Level (THD 0.002% 20 - 20,000 Hz)
BALANCED/UNBALANCED OUTPUT: 8.0 V● Input Impedance
MM settings: 1 kilohm, 47 kilohms, 100 kilohms
MC settings: 3 ohms, 10 ohms, 30 ohms, 100 ohms,
300 ohms, 1 kilohm● Rated Output and Output Impedance
BALANCED OUTPUT
2V
UNBALANCED OUTPUT 2 V● S/N Ratio
Input terminal

MM, 30 dB
MM, 40 dB
MC, 60 dB
MC, 70 dB
Subsonic filter indicator
Gain indicator
Load impedance indicator
For MM: 1kΩ, 47kΩ, 100kΩ
For MC: 3Ω, 10Ω, 30Ω, 100Ω, 300Ω, 1kΩ
MM-MC indicator
Input selector 1, 2, 3Power switch
Load impedance selector
Subsonic filter button
Gain selector

MM-MC selector
Player input jacks 1, 2, 3Player ground connectors
Unbalanced output jacks
Balanced output connectors
Balanced connection polarity selector
AC power connectorn Supplied accessories:m AC power cordm Audio cables with plugs (1 m)m Cleaning cloth

50 ohms
50 ohms

Input shorted (A weighting)
S/N ratio at rated output
110 dB102 dB
98 dB
90 dB● Minimum Load Impedance BALANCED/UNBALANCED OUTPUT: 10 kilohms● Crosstalk–90 dB or less (10 kHz)● Residual Noise (A-weighted) GAIN button OFF (Normal)
GAIN button HIGH

MM : 6 μV or less
MC : 25 μV or less
MM : 16 μV or less
MC : 63 μV or less● Subsonic Filter–12 dB/octave, 10 Hz● Power Requirements

AC120 V/230 V (Voltage as indicated on rear panel)
50/60 Hz● Power Consumption

35 W● Maximum Dimensions

WidthHeightDepth● Mass

14.5 kg (32.0 lbs) net
20.0 kg (44.1 lbs) in shipping carton

465 mm (18-5/16")
121 mm (4-3/4")
405 mm (15-15/16")

Remarks
This product is available in versions for 120/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

mSpecifications and design subject to change without notice for improvements.

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