PRECISION STEREO PREAMPLIFIER● "AAVA Volume Control" for high performance and outstanding sound● Separate high-efficiency toroidal power transformers for left and right channels● Selectable preamp gain ● Fully modular construction with separate left/rightunits for each amplifier stage ● Logic-controlled relays for shortest signal paths●Independent phase selection for each input position ● Printed circuit boards
made from glass cloth fluorocarbon resin ● Elegant cabinet with natural wood finish

Further refined AAVA volume control reaches new heights
A preamplifierfor the next generation, featuring AAVA technology developed for the C-3800.
Total of 16 unit amplifiers for left and right channels, using printed circuit boards
made from glass cloth fluorocarbon resin. Dual-mono construction with separate
high-efficiency toroidal transformers providing plenty of reserves. Optional
phono equalizer unit allows playback of analog records with ultimate fidelity.
■ Ideal full mono construction with amply dimensioned power
supplies for left and right, employing high-efficiency toroidaltransformers and high-quality filtering capacitors(10,000 µF x 4).
■ Short and straight signal paths, along with logic-controlled
relays for signal switching assure high sound quality andlong-term reliability.
■ Printed circuit boards in signal transmission circuitry madefrom glass fluorocarbon resin with low dielectric constant andlow loss.
■ Versatile arrangement of balanced and line input and output
connectors (10 inputs, 5outputs).

High-efficiency toroidal transformers■ EXT PRE function allows
use of external preamplifier.
■ Output phase selectable
individually for each input,
with visual indication. When
INV LED is lit, output phaseis inverted. When LED isout, phase is normal.

Line input and output connectors

Balanced input and output connectors■ Selectable preamplifier gain with three settings(12 dB, 18 dB, 24 dB) allows optimum matching tosystem requirements, including speaker efficiency.
■ Dedicated headphone amplifier ensures greatsound and features three selectable gain settings(LOW, MID, HIGH) for optimum matching toheadphone efficiency.

"EXT PRE" selector

Gain selector

Phase selector
button

LED indicators■ Massive cabinet with natural wood finish enhances
the solid visual appeal of the unit.

■ More versatile features:● Provisions for recording andplayback with a recorder● Three-stage loudness
compensator enhances low
end presence● Attenuator (-20 dB)● Subsonic filter● Alphanumeric indication of input
position and volume level
Loudness compensator characteristics

41028420

LOUDNESS COMPENSATOR：ON/OFF

COMP 2COMP 1

OFF−2−4
101001kFrequency in Hz

10k

100k

0
Response in dB

6COMP 3

Headphonelevel selector

612

Response in dB

The top-of-the-line preamplifier C-3800 fromAccuphase has received lavish praise from audio
experts and music lovers the world over for its
outstanding performance and sound quality. TheC-2820 incorporates AAVA technology developed for the C-3800 and features strictly selectedmaterials and parts. Its entire circuitry has beenfurther refined and improved, making it a fullmodel change from its predecessor C-2810.
AAVA is fundamentally different from the digital
signal processing approach involving A/D andD/A conversion. The volume control operates
purely in the analog domain. Using AAVA tochange the volume means that the high S/N ratio
and low distortion of the amplifier remain totally
unaffected. Frequency response and sound quality do not suffer at any listening level. There are
no left/right tracking differences or crosstalk, andno other performance related degradations. The
conventional concept of volume control in analog
preamplifiers is well and truly a thing of the past.
Another benefit of AAVA is the fact that it consists entirely of highly reliable semiconductor
parts, so that performance and sound quality willremain undiminished for many years to come.
The C-2820 features separate power supplies forleft and right channel, each with a dedicatedhigh-efficiency toroidal power transformer andfiltering capacitors. A total of 16 units for the line
input, balanced input, AAVA, and other circuit
stages are arranged separately for left and rightchannels on a mother board. This full mono construction eliminates any risk of unwanted electrical or mechanical interaction between the twostereo channels.
The printed circuit boards are an importantelement of a preamplifier both regarding electrical performance as well as sound quality. In theC-2820, these are made from glass cloth fluorocarbon resin with low dielectric constant andminimum loss. Loudness compensation, subsonic filter, and other important preamplifierfeatures are covered, and all parts and materials
used in this top-notch analog preamplifier havebeen carefully selected on the basis of sonicperformance. The result is a product that ushers
in a new era of preamplifier excellence.

−2−4SUBSONIC FILTER：ON−6−8−10−12−14−16−18

1

10100

1k
10kFrequency in Hz

100k

1M

Frequency response/subsonic filter characteristics

Balanced AAVA (Accuphase Analog Vari-gain Amplifier) Volume Control
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 music signal. The respective
currents are combined and converted back into a voltage by an I-V (current - voltage) converter.

AAVA is a radically different volume control principle thatresistors from the signal path, providing top-notch performanceby changes in impedance, high signal-to-noise ratio and low■ 18 V-I converter amplifiers, plus 4 buffer amplifiers

in input stage for powerful drive capability

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

■ Volume control resolution

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.

■ AAVA ensures high S/N ratio, low distortion, and uniform

frequency response and sound quality at any volume

Because AAVA does not introduce a change in impedance, there is nodeterioration of S/N ratio at any practical volume setting, and frequency
response remains totally uniform. The sound is always perfectlytransparent and the tonal quality is practically not altered.
The amplification circuitry of the C-2820 consists of various
assemblies for input buffer, AAVA circuitry, balanced
output, headphone amplifier etc. (total 16 unit amplifiers).

■ No more left/right tracking differences or crosstalk

Because the channels can be kept separate, there is virtually no left/right tracking
error also at very low volume levels, and crosstalk does not present a problem.

̶Extruded from solid aluminum block̶
High-rigidity volume sensor construction
Turning the volume knob on the front panel causes the actual
volume level position to be detected. The corresponding signal issent to a CPU which in turn controls the action of the AAVA
circuitry. The massive knob provides a smooth operation feel andfurther enhances position detection accuracy.

* Interior parts in the image are simulated.

■ The unit amplifiers that handle thesignal transmission are mounted on amotherboard, and left and right sections are kept completely separate. An 8 mm thick frame madeof hard aluminum provides
firm support and prevents
mutual interference byelectrical shielding andsuppressing physicalvibrations.

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

operates in the analog domain and eliminates all variable
and sound quality. Because the music signal is not affecteddistortion are maintained at any volume control setting.

Operation principle of AAVA in C-2820■ AAVA means analog processing

1−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.

2

mented by AAVA

■ High performance and sound quality to last

■ 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.

BUFFER

23＋INPUT(Music signal)

Currentvalues
are added

BUFFEROUTPUT
FEEDBACKBUFFER

215
1−

AAVA unifies the amplifier and volume control functions, resulting in acircuit that is electrically very simple. Long-term reliability is excellent, withperformance and sound quality that will remain unchanged also after
prolonged use.

I-V Converter
Reconversion ofcurrent into voltage

1−Keeping the circuit configuration simple helps to maintain highperformance and sonic purity.

221−

The selected volume level is clearly shown by the numeric display in thecenter of the front panel.

1−BUFFER■ Amplifier display shows accurate gain

■ Attenuator and left/right balance control also imple-

16 current switches(65,536 possible combinations)

216

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

CPU detects position of volume knob and operates
current on/off switches according to knob positionVolume knob is turnedand position is detectedDedicated Phono Equalizer Unit AD-2820
Analog records can be reproduced by installing the dedicated phono equalizer unit AD-2820 in a rear-panel slot.
The AD-2820 features separate input circuitry for MC and MM cartridges to ensure optimum matching. Along withthe balanced output stage configuration this minimizes noise and ensures highly pure playback.
■MCGain:60/70 dB, switchable
Input impedance: 10/30/100/300 ohms, switchable■MMGain:
30/40 dB, switchable
Input impedance: 47 kilohms+BQ 13Q 15–

EQUALIZERELEMENT

INVERTER+Q2

Q 11

Q 16

Q 12Q 17

Q5Q 19Q 14■ Function setting controls on
C-2820 front panel

Q3

INPUT–B

Q1

MC/MM
MM

MC/MM
MM

Q6–

MM30dB

Q4

MM40dB
MC60dBOUTPUT+AD GAIN

Q 20

MC70dB

Q7

Q8

Q9

Q 10

MCQ 18EQUALIZERELEMENTMCAD-2820 installed30Ω

300Ω

10Ω

AD GAIN selector

100Ω

MC LOADDC SERVO AMP(C-2810, C-2410 etc.), or regarding compatibility withprevious phono equalizer units (AD-2810 etc.), pleasecontact the Quality Assurance Department of Accuphase.

Circuit diagram of phono equalizer unit AD-2820 (one channel)

MC LOAD selector buttons■Front panelq* For information regarding use in other preamplifier models–BC-2820 Guaranteed Specifications
w e rt yu i o!0* Guaranteed specifications are measured according to EIA standard RS-490.
* Gain selector set to 18 dB position●Frequency Response

BALANCED/LINE INPUT:

3 - 200,000 Hz +0, -3.0 dB
20 - 20,000 Hz +0, -0.2 dB
AD INPUT (MM/40 dB, MC): 20 - 20,000 Hz ±0.2 dB
AD INPUT (MM/30 dB):
20 - 20,000 Hz ±0.3 dB●Total Harmonic Distortion (for all inputs)●Input Sensitivity,Input Impedance!1!2 !3 !4 !5 !6!7

■Rear panel
AD-2820
installation slot

@0@1@4
q Input selector

LINE 3, LINE 2, LINE 1, BAL, CD-BAL, CD,TUNER, AD-1 (OP), AD-2 (OP)w Output selector

EXT PRE, ALL, BAL, LINE, OFFe Input display
r Gain selector 12 dB, 18 dB, 24 dB
t Balance control
y Loudness compensator selector OFF, 1, 2, 3u Headphone level selector
LOW, MID, HIGH

!8 !9Pressing this button
opens the sub paneli Volume level indicatoro AD gain selector!0 Volume control knob
!1 Power switch!2 Phase selector button!3 Stereo/mono selector button!4 Display on/off button!5 Subsonic filter!6 Recorder output on/off and play buttons!7 MC impedance selector buttons!8 Headphone jack

@5@6

@7★

!9 Attenuator button@0 Line input connectors

TUNER, CD, LINE 1, 2 ,3

@1 Recorder playback/recording connectors@2 Line output connectors (2 sets)@3 EXT PRE input connectors@4 Balanced input connectors (2 sets)
CD-BAL, BAL@5 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 !2 )@6 EXT PRE input connectors (balanced)@7 AC power supply connector (for supplied power cord) ★

Input Sensitivity
Input
impedance
For rated output For 0.5 V output
AD-MM/30 dB INPUT
2.0 mV
8.0 mV47 kilohms
AD-MM/40 dB INPUT
0.63 mV
2.5 mV47 kilohms
AD-MC/60 dB INPUT 0.25 mV
0.063 mV 10/30/100/300 ohms, switchable
AD-MC/70 dB INPUT 0.08 mV
0.02 mV 10/30/100/300 ohms, switchable
BALANCED/LINE
63 mV 40/20 kilohms, switchable
252 mVInput●Rated Output Voltage, BALANCED/LINE OUTPUT
Output Impedance RECORDER REC (with AD input)●Signal-to-Noise Ratio@2 @30.005%

2V
252 mV

50 ohms
200 ohms

Input shorted (A weighting)
S/N ratio at rated output
94 dB
AD-MM/30 dB INPUT
85 dB
AD-MM/40 dB INPUT
80 dB
AD-MC/60 dB INPUT
73 dB
AD-MC/70 dB INPUT
111dBBALANCED/LINE
Input●Maximum Output Level (0.005% THD, 20 - 20,000 Hz)
BALANCED/LINE OUTPUT:
RECORDER REC (with AD input):

7.0 V
6.0 V

●Maximum Input Level BALANCED/LINE INPUT:

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 Load
Impedance

600 ohms
10 kilohms

BALANCED/LINE OUTPUT:
RECORDER REC:EIA S/N
86 dB
86 dB
86 dB
87 dB
110 dB●Gain (gain selector: 18 dB) BALANCED/LINE INPUT → BALANCED/LINE OUTPUT:→ REC OUTPUT:
Gain selector allows LINE INPUT
12/18/24 dB setting AD［MM:30/40dB］INPUT → BALANCED/LINE OUTPUT:
AD［MM:30/40dB］INPUT → REC OUTPUT:AD［MC:60/70dB］INPUT → BALANCED/LINE OUTPUT:AD［MC:60/70dB］INPUT → REC OUTPUT:

18 dB
0 dB
48/58 dB
30/40 dB
78/88 dB
60/70 dB

●Loudness Compensation 1: +2 dB (100 Hz), 2: +4 dB (100 Hz), 3: +6.5 dB (100 Hz)●Headphone Jack Output Level: 2 V (40 ohms)
Suitable impedance: 8 ohms or above
Gain (LOW, MID, HIGH): ±10 dB from standard MID level●Subsonic Filter

10 Hz: -18 dB/octave●Attenuator−20 dB●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 477 mm (18-3/4") Height 156 mm (6-1/8") Depth 412 mm (16-1/4")(Depth 414 mm with AD-2820 installed)●Mass23.7 kg (52.3 lbs) net (24.6 kg (54.2 lbs) with AD-2820 installed)
31.0 kg (68.3 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.
★ 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

K1105Y PRINTED IN JAPAN

851-0210-00（B1）