Accuphase C-27 Brochure

Page 1

m Separate MM/MC ampliﬁ er circuitry ensures ultra low noise m Highly precise

equalization with only ±0.3 dB RIAA deviation three settings for MM and six settings for MC up to 70 dB and unbalanced analog outputs

m Three analog player inputs with separate settings memory m Balanced

m Versatile impedance switching with

m Gain switching enables high gain of

m Polarity selector for balanced outputs

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The Ultimate Phono Equalizer Amp — Separate circuitry for MM and MC

ensures ultra low noise performance and outstanding RIAA precision. Versatile

load impedance selector with three settings for MM and six settings for MC

brings out the best in every cartridge. Subsonic ﬁ lter, and high gain capability

of 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 that a phono equalizer of high quality is essential to extract the enormous richness of sonic information engraved on vinyl records. Furthermore, the selection of tonearm, cartridge and other parts of the playback system requires a thorough understanding of audio fundamentals. This is a ﬁ eld where some investment of time and effort can yield immensely satisfying results. Accuphase has gained considerable expertise in designing and building phono equalizers, either integrated in preampliﬁ ers or available as option (AD-2810 and AD-20). In response to the wishes of audiophiles worldwide, we have now developed the C-27 as a high-end standalone phono equalizer amplifier, capable of exploring the possibilities of the analog disc to the fullest. Because the output signal level of a record player is extremely low, high-gain ampliﬁ cation is required before supplying the signal to subsequent stages. Distortion and noise should be kept to an absolute minimum, and excellent linearity from low to high frequencies is also a must. In the C-27, these goals are achieved by employing completely separate ampliﬁ er sections for MM and MC, each with optimized circuit topology and strictly selected parts for no-compromise performance. S/N ratio, THD, high-frequency characteristics, linearity and all other parameters approach the ideal in performance. What’s more, the C-27 is perfectly equipped to accommodate a wide 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 ampliﬁ ers, the C-27 will bring out the characteristics and musical qualities of any phono cartridge to optimum effect, providing pure music enjoyment from those legendary analog discs.

C-27 Functions and Features

■

Separate MM/MC ampliﬁ er conﬁ guration ensures ultra low noise

■ Highly precise equalization: RIAA deviation only ±0.3 dB

■ Monaural construction with separate toroidal power transformers

and separate equalizer boards for left and right channel

■ Versatile impedance switching options

1k, 47k, 100k

3, 10, 30, 100, 300, 1k

Load impedance indicators Load impedance

■ Subsonic ﬁ lter

(10 Hz, -12 dB/octave)

■ Gain switching enables high

gain of up to 70 dB

Subsonic ﬁ lter and

gain indicators

■ Equalizer PCBs made from Teﬂ on* (glass ﬂ uorocarbon resin)

with low dielectric constant and low loss

* Teﬂ on 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 ﬁ lter and other settings

(LEDs show selection status)

Input selector

Filter

button

selector

Gain selector

button

MM/MC indication

Filtering capacitors

MM/MC selector

Power transformer

LEFT

CHANNEL

LEFT CHANNEL INPUTS

RIGHT

CHANNEL

GND

MM Ampliﬁ er Section

IMPEDANCE

SELECTOR

1kΩ

47kΩ

INPUT

SELECTOR

MM-MC

100kΩ

IMPEDANCE

SELECTOR

3Ω

10Ω

30Ω

100Ω

300Ω

1kΩ

IMPEDANCE

LOAD

–

RIAA EQUALIZER

NETWORK

DC SERVO

GAIN

MC Ampliﬁ er Section

AMP

–

RIAA EQUALIZER

NETWORK

DC SERVO

GAIN

Same as LEFT CHANNEL

■ Two separate board assemblies for left and right channel, using Teﬂ on substrate and carrying dedicated MM and MC ampliﬁ ers, phono equalizer ampliﬁ ers, and logic relays for signal switching to ensure shortest possible paths between inputs and outputs.

–

SUBSONIC

FILTE

FILTER

–1

FEEDBACK NETWORK

–1

FEEDBACK NETWORK

BALANCE

CONNECTION

UNBALANCE

BALANCED

LEFT CHANNEL OUTPUTS

C-27 Circuit Diagram

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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 conﬁ guration to the different requirements of MM and MC cartridges, the C-27 features separate sections employing purpose-selected components and optimized operating points. This uncompromising approach results in outstanding S/N ratio, minimum distortion, and excellent frequency response characteristics. Ampliﬁ er performance ﬁ nally approaches ideal levels.

MM ampliﬁ er section

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 conﬁ guration is deﬁ ned as “3-parallel low noise FET buffer ampliﬁ er” +

“6-parallel ultra low noise transistor differential push-pull circuit”.

MC ampliﬁ er 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 than that of MM cartridges. Residual noise of the ampliﬁ er therefore needs to be kept to an absolute minimum. This is achieved by using an

transistor differential push-pull circuit

guarantee high S/N ratio.

“

8-parallel ultra low noise

”

Input Input

Ultra low noise transistor differential push-pull circuit in 6-parallel conﬁ guration

Low noise FET buffer ampliﬁ er in 3-parallel conﬁ guration

Output Output

Equalizer Components

DC Servo Ampliﬁ er

Gain Control

MM Ampliﬁ er Section

Circuit Diagram

Ultra low noise transistor differential push-pull circuit in 8-parallel conﬁ guration

MC Ampliﬁ er Section

Circuit Diagram

Equalizer Components

DC Servo Ampliﬁ er

Gain Control

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Other Functions and Features

■ Balanced and unbalanced analog outputs

■ Side panels with elegant persimmons wood ﬁ nish

Input jacks and ground connector

High-reliability parts selected for sound quality

Balanced output connectors

Polarity selector for balanced outputs

● In the factory default condition, the switch is set to the left position (pin

+) as shown in the photo.

Only change the switch position if the

● connected preampliﬁ er or integrated

ampliﬁ er requires the (pin +) setting.

Performance Graphs

[dB]

-2

-4

-6

-8

-10

10 100 1k 10k 100k

Input voltage vs. THD characteristics (MM) Input voltage vs. THD characteristics (MC)

Frequency [Hz] Frequency [Hz]

RIAA deviation (MM ampliﬁ er) RIAA deviation (MC ampliﬁ er)

[dB]

-2

-4

-6

-8

-10

10 100 1k 10k 100k

■ Front panel

[Guaranteed speciﬁ cations are measured according to EIA standard RS-490.]

● RIAA Deviation MM 10 - 100,000 Hz ±0.5 dB 20 - 20,000 Hz ±0.3 dB

C-27 Guaranteed Speciﬁ cations

MC 10 - 100,000 Hz ±0.3 dB

● Total Harmonic Distortion 0.005%

● Gain *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

MC 60 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

■ Rear panel

MC 60 dB: 9 mV 70 dB: 2.9 mV

● 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 2 V 50 ohms UNBALANCED OUTPUT 2 V 50 ohms

● S/N Ratio

S/N ratio at rated output MM, 30 dB 110 dB MM, 40 dB 102 dB



Subsonic ﬁ lter indicator Gain indicator Load impedance indicator For MM: 1k, 47k, 100k For MC: 3, 10, 30, 100, 300, 1k MM-MC indicator Input selector 1, 2, 3

MM-MC selector Player input jacks 1, 2, 3 Player ground connectors Unbalanced output jacks Balanced output connectors Balanced connection polarity selector AC power connector



Power switch Load impedance selector Subsonic ﬁ lter button Gain selector

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.

n Supplied accessories:

AC power cord

Audio cables with plugs (1 m)

Cleaning cloth

MC, 60 dB 98 dB MC, 70 dB 90 dB

●

Minimum Load Impedance

BALANCED/UNBALANCED OUTPUT: 10 kilohms

● Crosstalk –90 dB or less (10 kHz)

●

Residual Noise (A-weighted)

MC : 25 V or less

GAIN button HIGH MM : 16 V or less MC : 63 V or less

GAIN button OFF (Normal) MM : 6 V 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 Width 465 mm (18-5/16")

Height 121 mm (4-3/4") Depth 405 mm (15-15/16")

● Mass 14.5 kg (32.0 lbs) net

20.0 kg (44.1 lbs) in shipping carton

Input terminal

Input shorted (A weighting)

Speciﬁ cations and design subject to change without notice for improvements.

http://www.accuphase.com

K0850Y PRINTED IN JAPAN 851-0183-00 (AD1)