● AAVA volume control for high performance and outstanding sound● Separate power transformers for left and right channels ● Selectable preamp
gain ● Fully modular construction with separate left/right units for each amplifier
stage ● Logic-controlled relays for shortest signal paths ● Independent phaseselection for each input position ● Optional phono equalizer unit allows
playback of analog records ● Side panels with elegant natural wood finish

Further advanced AAVA volume control elevates performance to a new realm— A preamplifier for the next generation, featuring AAVA technology
developed for the C-2820. Modular design of AAVA and other amplifier
sections realized in a dual-mono construction with separate power supplies.
Preamplifier overall gain selection setting and phase selection settings for each
input position stored in memory. Numeric indication of volume level. Optional
phono equalizer unit allows playback of analog records with ultimate fidelity.
■ Short and straight signal
paths, along with logiccontrolled relays for signal switching assurehigh sound quality andlong-term reliability.
■ Versatile arrangement ofline and balanced input
and output connectors.

Line input and output connectors

Balanced input and output connectors■ EXT PRE function allows use of external preamplifier.
■ Selectable preamplifier gain with three settings (12 dB,18 dB, 24 dB).
■ Output phase selectable individually for each input,
with visual indication. When INV LED is lit, output
phase is inverted. When LED is out, phase is normal.

Gain selector
LED indicators for
EXT PREfunction andphase selector
button■ Dedicated headphone amplifier ensures great sound andfeatures two selectable gain settings (standard, +10 dB)
for optimum matching to headphone efficiency.
■ Fully balanced input circuit shuts out external noise.
■ Side panels with beautiful natural wood finish.
■ Tone controls using summing active filters for optimum
sound quality.

Principle of tone control circuitry(summing active filter)

184162140

Boost

16612−2−8−10−12−14640−2−1610100

1k10kFrequency in Hz

100k

1M

40−4−6−8−12−4182Cut

Response in dB−6High
frequency
range

range

Response in dB

8SUBSONIC FILTER：ONLow

12 frequency

LOUDNESS COMPENSATOR：ON

10−4−18OUTPUT

INPUT■ More versatile features:● Provisions for recording and playback with a recorder● Loudness compensator enhances low end presence● Attenuator (-20 dB)● Subsonic filter for removing ultra-low-frequency noise● Numeric indication of preamplifier overall gain and volume level

Response in dB

The Precision Stereo Control Center C-2420 reflects
the refined sonic sensibility of Accuphase while incorporating advanced technology features developed for
the C-3800 and C-2820. A full model change has further elevated performance and sound quality to newheights.
Ever since being first introduced in the C-2800 preamplifier in 2002, AAVA technology has been continuallyrefined and improved, while of course retaining the underlying principle. The AAVA volume control operates
fully in the analog domain, but it eliminates all potentiometers from the signal path. The advantages of thisapproach are many: outstanding S/N ratio, extremely
low distortion, no change in frequency response andsound quality at any listening level, no left/right level
differences or crosstalk, and no other performance related degradations. The conventional concept ofvolume control in analog preamplifiers is now well andtruly a thing of the past. Like the C-2820, the new
C-2420 features a high-rigidy, high-precision volumesensor extruded from a solid aluminum block andlinked directly to the massive volume knob. Both operation feel and accuracy of operation are significantly
improved by this design.
The C-2420 features separate power supplies for left
and right channel, each with a dedicated power transformer, filtering capacitors and peripheral circuitry. Modular units for the line input, balanced input, AAVA, andother circuit stages are arranged separately for left andright channels, to eliminate any risk of unwanted electrical or mechanical interaction between the two stereochannels. A wide variety of versatile functions make theC-2420 a true control center. There are tone controls
designed for optimum sonic performance, a loudness
compensator, subsonic filter, recorder related functions,overall preamp gain selection, EXT PRE provision foruse of another preamplifier, individual phase selection
for each input position, and more.
The separately available Phono Equalizer Unit AD-2820
supports both MC and MM cartridges and allows thereproduction of analog records with utmost fidelity.
Advanced technology enables performance andsound quality on a level that approaches the realm of
top-of-the-line products. The C-2420 ushers in a newera of preamplifier excellence.

101001kFrequency in Hz

10k100k

Frequency Response / Subsonic Filter Characteristics Loudness Compensator Characteristics−1610BASS
adjustment range

TREBLE
adjustment range

10010k1kFrequency in Hz

Tone Control Characteristics

C-2420 Block Diagram−100k

- Extruded from solid aluminum block - High-rigidity volume sensor construction
Turning the volume knob on the front panel causes the knob position
to be detected. A corresponding signal is sent to a CPU which in turncontrols the action of the AAVA circuitry accordingly. This volume sensor mechanism was developed by Accuphasein-house. The massive knob provides a solidand smooth operation feel and further enhances position detection accuracy.

parts in the* Interior
image are simulated.

■ Supplied remotecommander RC-220
Allows volume
adjustment, input
source switching, andother operations.

AAVA (Accuphase Analog Vari-gain Amplifier) Volume Control■ Total of 18 V-I converter amplifiers, with dual buffer
amplifiers in input stage for powerful drive capability■ AAVA ensures high S/N ratio, low distortion, as well as uniform frequency response and sound quality at any volume

The AAVA input stage uses separate buffers for the inverted andnon-inverted side of the balanced input, and features 18 V-I amplifiers,
with the amplifiers for the upper two bits being paralleled for further
improved S/N ratio.

Because AAVA does not introduce a change in impedance, there isno deterioration of S/N ratio at any volume setting, and frequency response remains totally uniform. Therefore the tonal quality is practically not altered.

■ No more left/right tracking differences or crosstalk■ Volume control resolution

Because the channels can be kept separate, there is virtually noleft/right tracking error also at very low volume levels, and crosstalk
does not present a problem.

■ Amplifier display shows accurate gain
When the volume knob is turned, the selected volume level is clearly
indicated by the numeric display on the front panel.

AAVA adjusts the listening volume by means of 16 weighted V-I converter amplifiers which are controlled by current switches. The number ofpossible volume steps set by the combination of these converter amplifiers is 2 to the power of 16 = 65,536.

■ Attenuator and left/right balance control also implemented by AAVA
Keeping the circuit configuration simple helps to maintain high performance and sonic purity.

16 current switches(65,536 possible combinations)

AAVA configuration in C-2420

12122＋
BUFFER

I-V Converter
Reconversion ofcurrent into voltage

123＋INPUT−Currentvalues areaddedBUFFER(Music signal)

I-V■ High performance and sound quality to last
AAVA unifies the amplifier and volume control functions, resulting in acircuit that is electrically very simple. Long-term reliability is excellent,with performance and sound quality that will remain unchanged also
after prolonged use.

■ AAVA means analog processing
The AAVA circuit converts the music signal from a voltage into a current,
alters gain by means of current switches, and then reconverts the current
into a voltage. The entire process is carried out in the analog domain.

■ Same operation feel as a conventional high-quality
volume control
Operating the volume knob feels exactly the same as with a conventional control, and operation via the remote commander is also possible.

AAVA operation principle

The music signal is converted into 16 types of weighted current
by V-I (voltage - current) converting amplifiers [ 1/2, 1/22, ... 1/215,1/216 ]. The 16 currents are turned on or off by 16 current switches,
and the combination of switch settings determines the overall
volume. The switching operation is controlled by a CPU to match
the position of the volume control knob. The combined current
forms a variable gain circuit that adjusts the volume of the musicsignal. The respective currents are combined and converted backinto a voltage by an I-V (current - voltage) converter.

OUTPUTGAIN

LEVEL DISPLAY

1215
1216

V- I Converter
Conversion into current with 16
weighting stages (1/2 - 1/216)

CPU

VolumeBalance
Attenuator

CPU detects position of volume knob and operates
current on/off switches according to knob position

Volume knob is turnedand position is detected

AAVA uses a unit amplifier configuration comprising the input buffer, 16 V-I amplifiers and current switches, current summing circuit, I-V converter amplifier, etc. Left and right channel circuitry is kept separate on each board.

Dedicated Phono Equalizer UnitAD-2820

Analog records can be reproduced by installing the dedicated phono equalizer unit AD-2820 in a special slot on the rear panel.
The AD-2820 features separate input circuitry for MC and MM cartridges to ensure optimum matching for each cartridge type.
The balanced output stage configuration minimizes noise and ensures highly pure playback. The printed circuit boards are
made from glass cloth fluorocarbon resin and housed in a sturdy aluminum case for complete protection against any externalinterference. Shortest possible connection between inputs and amplifier circuitry assures outstanding S/N ratio.
■ MC

Gain:
Input impedance:

60/70 dB, switchable
10/30/100/300 ohms, switchable

■ MM

Gain:
Input impedance:

30/40 dB, switchable
47 kilohms* For information regarding use in other preamplifier models(C-2810, C-2410 etc.), or regarding compatibility withprevious phono equalizer units (AD-2810 etc.), pleasecontact the Quality Assurance Department of Accuphase.

+BQ 13
Q 15–Q2

Q 11

EQUALIZERELEMENTINVERTER+Phono equalizer amp uses
a dual mono configuration

Q 17

Q5Q 16Q 12Q 19Q 14
Q3INPUT■ Function setting controls onC-2420 front panel

Q4
MMQ7

AD GAIN

Q 20
Q 18

Q8

Q9Q 10EQUALIZERELEMENT

MCMC/MM300Ω

MC/MM100ΩOUTPUT+MC 60 dB
MC 70 dB

MMMC

MC LOAD10Ω–

MM 40 dB

Q130Ω

MM 30 dB

Q6

DC SERVO AMP.

AD GAIN selector–BCircuit diagram of phono equalizer unit AD-2820 (one channel)

MC LOAD selector buttons and LED indicators■ Front panel

AD-2820 installed

C-2420 Guaranteed Specifications
specifications are measured according to EIA standard RS-490. AD stands for "Analog Disc".
* Guaranteed
are shown for phono equalizer unit AD-2820 installed.
* Specifications
Gain
selector
set to 18 dB position.
*● Frequency Response BALANCED/LINE INPUT:

3 - 200,000 Hz
20 - 20,000 Hz
AD INPUT (MM/40 dB, MC): 20 - 20,000 Hz
AD INPUT (MC/30 dB):
20 - 20,000 Hz● Total Harmonic Distortion (for all inputs)

0.005%● Input Sensitivity,
Input Impedance

Input Sensitivity

Input■ Rear panel
AD-2820
installation slot

@1@2@38.0 mV
2.5 mV
0.25 mV
0.08 mV
252 mV

2.0 mV
0.63 mV
0.063 mV
0.02 mV
63 mV● Rated Output Voltage, BALANCED/LINE OUTPUT:
2V
Output Impedance REC (with AD input):
252 mV● Signal-to-Noise Ratio,
Input-converted noise@4

q Input selector
w Recorder buttons ON / PLAY
e LED function indicatorsr Stereo/mono selector buttont Volume control knoby Power switchu Output selector
i Bass/treble controlso Phase selector button!0 Tone control on/off button!1 Display on/off button!2 Subsonic filter!3 Headphone level selector!4 MC load impedance selector button!5 Balance control!6 Gain selector 12 dB / 18 dB / 24 dB!7 AD gain selector!8 Loudness compensator button!9 Attenuator button

@6@7

@8★

@0 Headphone jack
@1 Line input connectors TUNER / CD / LINE 1, 2 ,3
@2 Recorder playback/recording connectors@3 Line output connectors (2 sets)@4 EXT PRE input connectors@5 Balanced input connectors (2 sets)@6 Balanced output connectors (2 sets)
With line input signal: w negative (-), e positive (+)
With balanced input signal: same phase as source equipment(Can be switched with phase selector button o )@7 EXT PRE input connectors (balanced)@8 AC power supply connector (for supplied powercord)★

10/30/100/300 ohms, switchable
10/30/100/300 ohms, switchable

40/20 kilohms

50 ohms
200 ohms

Input shorted (A weighting)
S/N ratio at rated output
94 dB
AD-MM/30 dB INPUT
84 dB
AD-MM/40 dB INPUT
80 dBAD-MC/60 dB INPUT
72 dB
AD-MC/70 dB INPUT
109 dBBALANCED/LINE
Input● Maximum Output Level BALANCED/LINE OUTPUT:(0.005% THD, 20 - 20,000 Hz) RECORDER REC (with AD input):@5Inputimpedance
47 kilohms
47 kilohms

For rated output For 0.5 V output impedance

AD-MM/30 dB INPUT
AD-MM/40 dB INPUTAD-MC/60 dB INPUTAD-MC/70 dB INPUTBALANCED/LINE
Pressing this button
opens the sub panel.

+0, -3.0 dB+0, -0.2 dB±0.2 dB±0.3 dB

6.0 V● Maximum AD Input Level MM [30/40 dB] INPUT:(1 kHz, 0.005% THD)MC [60/70 dB] INPUT:

310/96.5 mV
9.5/3.2 mV● Minimum LoadImpedance

600 ohms
10 kilohms● GainGain selector:
18 dB（85 dB
85 dB
85 dB
85 dB
107 dB

7.0 V
6.0 V

● Maximum LINE Input Level BALANCED/LINE INPUT:BALANCED/LINE OUTPUT:
RECORDER REC:EIA S/NBALANCED/LINE INPUT → BALANCED/LINE OUTPUT:
18 dB
LINE INPUT→ BALANCED/LINE OUTPUT:
18 dB
AD [MM: 30/40 dB] INPUT → BALANCED/LINE OUTPUT: 48/58 dB
AD [MM: 30/40 dB] INPUT → REC OUTPUT:
30/40 dB
AD [MC: 60/70 dB] INPUT → BALANCED/LINE OUTPUT: 78/88 dB
AD [MC: 60/70 dB] INPUT → REC OUTPUT:
60/70 dB
* Gain selector can be set to 12/18/24 dB● Tone Controls）

Turnover frequency and adjustment range

BASS: 300 Hz ±10 dB (50 Hz)
TREBLE: 3 kHz ±10 dB (20 kHz)● Loudness Compensation +6 dB (100 Hz)● Subsonic Filter

10 Hz: -18 dB/octave● Attenuator-20 dB● Headphone Jack Suitable impedance: 8 ohms or higher
Output Level: 2 V (40 ohms)● Power Requirements AC 120 V/220 V/230 V 50/60 Hz (Voltage as indicated on rear panel)■ Supplied accessories● Power cord
● Audio cables with plugs (1 m)● Remote commander RC-220● Cleaning cloth● Power Consumption 34 watts● Maximum Dimensions Width 465 mm (18-5/16")
Height 150 mm (5-7/8")
Depth 409 mm (16-1/8")(Depth 414 mm with AD-2820 installed)● Mass19.2 kg (42.3 lbs), 20.1 kg (44.3 lbs) with AD-2820 installed

25.0 kg (55.1 lbs) in shipping carton
Remarks★ This product is available in versions for 120/220/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
★ 230 V version has an Eco Mode that switches power off after 120 minutes of inactivity.
★ The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

●Specifications and design subject to change without notice for improvements.

http://www.accuphase.com

K1205YPRINTED IN JAPAN

850-2177-00（B1）