Owner's ManualContents• Introduction ……………………………………………………………………… 2• Features ………………………………………………………………………… 2• Important Safety Instructions ………………………………………………… 4• Handling Precautions …………………………………………………………… 6•Accessories ……………………………………………………………………… 7• Front Panel Functions ………………………………………………………… 8• Rear Panel Functions………………………………………………………… 11• Cautions regarding Handling……………………………………………… 13• Maintenance ………………………………………………………………… 13•Troubleshooting ……………………………………………………………… 14•Service Contact Preparations ……………………………………………… 14• CE and FCC Certiﬁcates …………………………………………………… 15•Speciﬁcations ………………………………………………………………… 16

Introduction
Thank you for purchasing HD53N.
Please read through and refer to this Owner’s manual to use your HD53N
safely and adequately. It is recommended that you keep the unit’s packaging
available for future transportation needs.

Features• HD53N is a very high grade headphone ampliﬁer as well as a complete HiFi-

solution for music lovers with headphone priority. Due to the integrated power
amplifier HD53N can be the center of a very high grade music-listeningequipment.
• HD53N incorporates a truly balanced circuitry and consequently offers

balanced headphone operation as well as a balanced speaker output.
Of course a standard unbalanced headphone terminal is also available.
Balanced operation makes the signal very clean due to independence of theground level. The slew-rate is twice of the unbalanced output. Regardless ofthe headphone type used the improvement is easy to hear.
•The whole amplifier circuitry is using the unique LEF technology, which

offers very low distortion without the need of global feedback loops degrading
sound. LEF allows a single-ended-ampliﬁer design, which just works in pureclass A operation, with much higher efﬁciency than a traditional design. All
outputs are directly driven by LEF ampliﬁer stages.

2• HD53N’s design also allows the easy variation of the ampliﬁer gain. Consequently

used an intelligent gain management (IGM) replaces a traditional volume control
with a lot of advantages:- It uses the full signal level of the source and thus avoids dynamic losses andimproves S/N-ratio.
- The ampliﬁer noise level is signiﬁcantly reduced and reaches the usual noiselevel just on maximum volume.
- The ampliﬁer’s sound quality improves when using lower gains. Generally the
maximum gain is rarely needed, while traditional ampliﬁer designs always use themaximum gain.
•A headphone ampliﬁer has a very wide range of usage requirements. From low

impedance (16 Ohm) headphones with high sensitivity up to high impedance types(300 Ohm) which require much higher voltage levels. At last the speaker operation
is a different requirement. HD53N offers two different basic gain settings whichallow the matching of a speciﬁc headphone. It also automatically changes the gain
for leveling XLR and RCA inputs. This makes HD53N a very versatile headphone
ampliﬁer.
• HD53N’s headphone output (LOW) is guiding the headphone’s movement by

having a very low output impedance. Most (high grade) headphone will benefit
from a strong amplifier control, but some headphones lack of low frequency
substance when driven with a very low impedance source. For this purpose
HD53N offers a second unbalanced output (HI) with 120 Ohm impedance.
• For a truly balanced ampliﬁer of course there is one balanced XLR input which isrecommended to use. This matches perfectly to sources like DA53N D/A converteror other balanced sources. For those who don’t have a balanced source HD53N
also has a standard RCA input. For preserving most of the balanced advantages
this RCA input is handled differentially by HD53N without ﬁxed ground connecting.
This is a quasi-balanced operation which shows much better measurement
speciﬁcation than the traditional RCA connection. Both inputs can be connected at
the same time and the input selector is located at the front panel.

3

Important Safety Instructios

Caution: To reduce the risk of electric shock,
do not remove the cover or rear panel. It does
not contain any user-serviceable parts. Refer
servicing to qualiﬁed service personnel.
The lighting flash with arrowhead symbol,
within an equilateral triangle, is intended toalert the use to potential shock hazards within
the product’s enclosure.
The exclamation point within an equilateraltriangle, is intended to notify the user tothe presence of important operating andmaintenance (servicing) instructions in theaccompanying documentation.

WARINIG: TO PREVENT FIRE OR SHOCK HAZARD, DO
NOT EXPOSE THE APPLIANCE TO RAIN OR MOISUTRE.
1) Read these instructions.
2) Keep these instructions.
3) Heed all warnings.
4) Follow all instructions.
5) Do not use the unit near water.
6) Clean only with a dry cloth.
7) Do not block any ventilation openings. Install in accordance with the
manufacturer’s instructions.
8) Do not install the unit near any heat sources such as radiators, heatregisters, stoves, or other apparatus (including ampliﬁers) that produce heat.
9) (For USA, Canada: ) Do not defeat the safety purpose of the polarized or
grounding-type plug. A polarized plug has two blades, with one blade wider
than another. A grounding type plug has two blades and a third grounding
prong. The wide blade or the third prong is provided for your safety. If theprovided plug does not ﬁt your outlet, consult an electrician for replacementof the obsolete outlet. (For European Countries: ) Do not defeat the safety4purpose of the grounding-type plug. This plug has two poles and a third grounding
hole. The third hole is provided for your safety. If the provided plug does not ﬁt youroutlet, consult an electrician for replacement of the obsolete outlet.
10) Protect the unit’s power cord from being walked on or pinched, especiallyaround the plugs, convenience receptacles, and where it exists the unit’s casing.
11) Only use attachments/accessories speciﬁed by the manufacturer.
12) Only use the unit with a cart, stand, tripod, bracket, or tablespeciﬁed by the manufacturer or sold with the unit. If using a cart,
exercise caution when moving the cart unit combination to avoid
injury from it tipping over.
13) Unplug the unit during lighting storms or when leaving it unused for extended
periods of time.
14) Refer all servicing to qualiﬁed service personnel. Servicing is required when
the unit itself, its power-supply cord, or plug has been damaged in any way, whenliquids have been spilled onto the unit, when foreign objects have fallen into theunit, when the unit has been exposed to rain or moisture, when the unit does notoperate normally, or when the unit has been dropped.

Caution• Do not expose the unit to drips or splashes.
• Do not place any objects ﬁlled with liquids, such as vases, on the unit.
• Do not install the unit in a conﬁned space, such as within a bookcase or similar

piece of furniture.
• Plug the AC power cord into an easily accessible AC wall outlet, so it can bequickly unplugged in case of emergency.
• Do not remove the protective housing with a screwdriver.
• Use of controls or adjustments or performance of procedures other than thosespeciﬁed herein may result in hazardous radiation exposure.
• If the unit seems to be malfunctioning, contact a qualified service station.

Discontinue use of any malfunctioning unit.

For CANADA:AC POWER CORD CONNECTION
CAUTION:TO PREVENT ELECTRIC SHOCK, MATCH THE BLADE WIDTH OF THE PLUG
TO THE SLOT WIDTH. THE PLUG MUST BE FULLY INSERTED TO THE SLOT.
5

Handling Precautions
1. Connecting Other Devices
Unplug HD53N’s AC power cord from the outlet before connecting or disconnecting otherdevices. Exercise caution when handling the AC power cord. When disconnecting the AC cordfrom a socket, make sure you pull the plug, and not the cord itself.
2. Turning Power ON/OFFYour system components should be turned ON/OFF in the following order to avoid generating
noise from your headphones and speakers, and damaging the headphones and speakers
themselves or other devices:
Turning power ON: Turn HD53N’s volume to the minimum and power ON at last, after turning
ON the DA converter or CD-player connected to HD53N.
Turning power OFF: Turn HD53N’s volume to the minimum and power OFF ﬁrst, before turning
OFF connected units.
3. Handle with Care
Avoid exerting excessive force on the cabinet, the volume and selector knobs and pushswitches of HD53N.
4. Avoid Electrostatic Discharge
Like all complex electronic devices, HD53N is sensitive to electrostatic discharge. A discharge
may cause malfunction or damage.
5. Installation
Use of an audio rack is recommended to maximize the sound quality and performance of
HD53N. Installation and use of HD53N in the locations described below may cause deterioration
in sound quality or malfunctions.
• Locations exposed to direct sunlight, such as windowsills, and other exceptionally warm
locations, such as near heating appliances (surrounding temperature higher than 35 ℃ ), or
exceptionally cold locations (surrounding temperature lower than 5 ℃ ), may prevent HD53N
from functioning adequately.
• Damp locations exceeding 90% humidity may cause HD53N’s metal parts to rust, causing theunit to malfunction.
• Dusty locations may cause HD53N to malfunction. The accumulation of dust outside and insidethe unit may lower the performance of music signal amplification. It may also cause contact
failure of the switches and/or noise.
• Otherwise, avoid installing HD53N close to other transformers and electrical motors, so as
to prevent the pickup of induction hum. Also, avoid mounting HD53N on surface that may beaffected by vibration.
6. Avoid Lightning Strikes Damages
Disconnect the AC power cord from the AC outlet when there is a thunderstorm in your vicinity.
7. Condensation
When HD53N has been brought into a warm room when the exterior temperature is cold, orwhen the room temperature rises sharply from using a heater, condensation may occur fromboth inside and outside the unit, hampering its performance. If this happens, leave HD53N
unused in the room for 1 to 2 hours (depending on the amount of condensation), so as to bringthe unit’s temperature closer to the room temperature. The condensation should go away
gradually.

68. Listening Etiquette• Excessive sound pressure from headphones and earphones can cause hearing
impairments. Take care not to increase the volume too much.
•When adjusting the sound volume level, make sure you do not disturb other people andyour neighborhood.

Accessories
The packaging of HD53N should contain the following:
1. HD53N unit
2. AC Power Cord
3. Owner’s manual

NOTE: Keep the packaging available for future transportation needs.
The AC power cord is for use with HD53N exclusively, and should not be
used for other devices.

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Front Panel Functions
❸

❶

❷

❹

❺

❻

❶ POWER button
Push the POWER button to turn HD53N ON respectively OFF.
When HD53N is turned ON the display will blink “INPUT” and “XLR” or“RCA” indicators during the unit is in starting-up. Approximately 20 seconds
later once the display changes to indicate the selected INPUT and light up again setting (“LOW GAIN” or “HIGH GAIN”) and output (“HEADPHONE” or“SPEAKER”) indicators, HD53N is ready for use.
Starting input and output are the last selected input and output when HD53N
was turned off. Press ❺ INPUT selector button and ❸ HP/SP selector button
to change to different input and output.
Note: When you need to turn the power OFF and back ON again, wait forleast 20 seconds after turning the unit OFF to prevent malfunction.

Before turning HD53N ON or OFF, turn the volume knob to theminimum to avoid a switching noise or sudden and big sound fromthe headphones or speakers, which may result in damaging theheadphones or speakers, or injuring your ears. Headphones or
earphones should be taken off before HD53N is turned ON and OFF.

❷ HEADPHONE Output
Headphone output is a combination type of two standard 6.3mm headphone
and a balanced XLR jacks.
A)Headphones with 6.3mm plug
For Standard headphones with a 6.3mm plug there are two outputs withdifferent output impedances.
8

HI designed for 120ohm

LOW for first choice• LOW (right side / output impedance approx. 10 Ohm): First choice for best headphone

control.
• HI (left side / output impedance approx. 120 Ohm): Sound tuning option for headphones

designed for 120 Ohm output.
Notes:*Sound level from LOW and HI is different even at the same volume position. Generally
LOW output sounds louder.
*Offering the 120 Ohm option has historical reasons: Using a series resistor was aneasy way to adjust volume of high and low impedance headphones. This practice wasleading to some headphones being tuned to sound better with 120 Ohm. Comparing
and listening both outputs may be the best way to ﬁnd the output which can produce
your preferred sound quality.
*For using a headphone with 3.5mm mini plug, purchase a 6.3mm conversion plug froma dealer.
B)Headphones with balanced XLR plugs
Connect a headphone XLR plug for the left channel to the jack marked with L at the left
side, and connect another XLR plug for the right channel to the jack marked with R at
the right side. Pinning: 2=Hot(+), 3=Cold(-).
Balanced output impedance is nearly 0 Ohm.
Never use any kind of adaptors from XLR to an unbalanced headphone plug! It
may destroy HD53N and/or the headphones!
Balanced XLR Pinning.

4

Balanced Left Channel

Balanced Right Channel

9Before connecting or disconnecting the headphone plugs,
turn the volume knob to the minimum and take off theheadphones or earphones from your ears to avoid a sudden
excessive sound pressure or noise, which may cause hearing
impairment.

❸ OUTPUT(HP/SP) selector button
Press the HP/SP button to select an output from headphone and speaker. The
selected output indicator “HEADPHONE” or “SPEAKER” lights up in the display.
*Before changing the output, turn the volume to the minimum and take off theheadphones or earphones from your ears.
❹ GAIN button
Press the GAIN button to change the ampliﬁer gain setting to LOW GAIN or HIGH
GAIN. The corresponding GAIN indicator lights up in the display.
LOW GAIN is recommended for the beginning of use. In case that you feel a lackof sound level due to the headphone’s or speaker’s efficiency and sensitivity,change to the HIGH GAIN.
*The volume knob position where HD53N exceeds the maximum output power
varies with the connected devices and input sources. When the sound is distorted
the power may exceed the maximum already. In this case, change the gain setting
to LOW GAIN or decrease the volume.
❺ INPUT selector button
Press the INPUT button to select an input from the balanced XLR or unbalanced
RCA. The corresponding indicator lights up in the display.
*Before changing the input, turn the volume to the minimum and take off theheadphones or earphones from your ears.
❻ VOLUME knob
Turn the VOLUME knob clockwise to increase the volume, and turn the knob
counterclockwise to decrease the volume.
*Due to the Intelligent Gain Management (IGM) volume control system, small
sound still comes out from headphones or speakers even at the minimum volume
knob position. To mute the sound completely, stop the playback of the connectedsource device.
*Due to the potentiometer character, the sound level of the both channels may beunbalanced in a very small range of just the starting point. Passing through thestarting point by increasing the volume a little more, the channel balance should be
perfect soon.
10Rear Panel Functions

Headphone Amplifier

Model: HD53N

CEC株式会社
CEC Co., Ltd., Japan

Made in China

RIGHT
RCA INPUT❶LEFTXLR INPUT

❷

RIGHT

SPEAKER

LEFT

❸

❹

❶ RCA Input
Line in audio signal input jacks equipped with unbalanced RCA connectors.
Use interconnect RCA cables to connect the RCA input to external sources
with RCA line output, such as CD player, tuner or tape deck.
*Phono and digital sources cannot be connected to the RCA input.

Connect the interconnect cablein the correct directionaligned for the signal path

❷ XLR Input
Line in audio signal input jacks equipped with balanced XLR connectors. Useinterconnect XLR cables to connect the XLR input to external sources with
XLR line output, such as CD player, DVD player or DA converter. Due to afull balanced circuitry design the balanced XLR connection is recommended
11for better sound quality. Pinning: 1=Ground, 2=Hot, 3=Cold.
*Phono and digital sources cannot be connected to the XLR input.

Connect the interconnect cablein the correct directionaligned for the signal path

❸ RIGHT / LEFT SPEAKER output
Power ampliﬁer output terminals for the right/left speakers. The red terminal
is for (+) the black one is for (-). Speakers with 4 ohm to 8 ohm impedance
can be connected by using banana plugs, spades or wires.
Note: Before connecting or disconnecting speakers turn the HD53N’s power
OFF.

Wires

SpadesBanana Plugs❹ AC LINE
Connect the provided AC power cord to the AC LINE inlet.

12Cautions Regarding Handling• Never connect the speaker output terminals to any ground. Both speakerterminals carry an active signal due to the full balanced circuit design of
HD53N.
• Be careful when connecting active subwoofers or similar devices to the

speaker terminals. A short circuit to the ground may result in damage to
HD53N or a broken fuse.
•The DC voltage at the speaker and the balanced headphones output

terminals is not 0 when measuring related to ground. However, the differential
DC voltage from (+) to (-) terminals is nearly 0 and thus harmless to speakers
and headphones.
• Audiophile amplifiers produce heat! Make sure to leave enough spacearound HD53N (at least 15cm) for keeping the air circulating. Make sure you
never cover the air vents on the top and bottom plates, which could result inan overheating. It is recommended to use HD53N in a low-dust environment.
• In case of overheating (over approx. 65℃ ) HD53N will cut off the operating

power automatically. In this case it is suggested to put the main power switch
to “OFF” position. Otherwise HD53N will power ON again after cooling down.

Maintenance• HD53N requires no periodic maintenance and contains no user-serviceableparts. Contact your dealer or an authorized CEC service center for inspection
and repair in case of malfunction.
• If the surface of the HD53N enclosure is soiled, wipe with a soft cloth or use

diluted neutral cleaning liquid. Be sure to remove any ﬂuid completely. Do not
use thinner, benzene, alcohol, chemical cloths or bleaching agents as thesemay damage the surface of the HD53N enclosure. Also avoid using aerosol
insecticides near the unit.
• If dust should have accumulated on the unit, remove it with stick tape (e.g.

Scotch tape). Make sure not to touch the enclosure with any tools or otherhard parts.

13

Troubleshooting
If you suspect a malfunction of the unit, please check the following chart
before calling your dealer.

No power• Check the connection at the both ends of the AC power cord.
• Make sure there is power at the wall outlet.
• Check the power switch position.

No sound• Check the connection from the external source, e.g. CD player.
• Check the operation of the external source, e.g. CD player.
• Check the connection to the headphones or speakers.
• Check whether the matching input is selected.

INPUT indicator continues blinking and the unit is not ready for use•Turn HD53N off and unplug the AC power cord from the outlet. Wait for aminute, plug the AC power cord back in and turn HD53N on again. Check allplugs on the front and rear panel are properly connected.

Humming noise• Check the pin plugs are connected adequately.

Distorted sound• Decrease the volume level.
• Check that input signal does not exceed 2Vrms(RCA) and 4Vrms(XLR).
• Check all plugs are connected adequately.

Service Contact Preparation
In case you need to contact the service center please prepare the following
information.
• Model name and serial number• Purchase date
• Dealer name and contact information• Description of the unit’s problem

14

Speciﬁcations
Frequency Response:

20Hz – 20kHz, +0/-0.25dB

S/N Ratio:-103dB Headphone LOW/HI (Volume 50% max. power / A-weighted)-110dB Headphone Balanced (Volume 50% max. power / A-weighted)

THD:

0.06% Headphone LOW/HI (1Vrms input / 0dBu output)
0.009% Headphone balanced (1Vrms input / 3dBu output)
0.03% Speaker 8 Ohm (2Vrms input / 10W output)

Rated power:2 x 1.15W (32) Headphone LOW
2 x 0.25W(32) Headphone HI
2 x 4.7W(32) Headphone Balanced
2 x 13W(8) Speaker

Load impedance:

16 Ohm – 2k Ohm Headphone, 4 Ohm – 8 Ohm SpeakerGain:

HI / LOW (Selectable)

Input terminals:

1 x balanced XLR, 1 x unbalanced RCA

Headphone output:

1 x balanced XLR (0 Ohm)

(Impedance)

1 x 6.3mm Jack (10 Ohm) for best control

Speaker output:

1 x Balanced

1 x 6.3mm Jack (120 Ohm) for sound tuning
AC power Line:

AC120V/230V, 50/60Hz (Speciﬁed on rear panel)Power consumption:

23W Headphone drive, max. 50W Speaker drive

Dimensions:

Approx. 218(W) x 354(D) x 58(H) mm (Incl. knobs, terminals and legs)

Weight:Approx. 3.2kg

Accessories:

AC power cord, Owner’s manual

Color:

Silver

NOTE: Design and speciﬁcations are subject to change without notice.
NOTE: Illustrations on the owner’s manual may deviate from the actual unit due to design
improvements.

0906-A