Woo Audio WA22 User manual

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WOO AUDIO WA22
Fully Balanced Class-A Stereo Headphone Amplifier
Owner’s Manual
Please review this manual before operating your WOO AUDIO™ product.

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Important Safety Information
CAUTION: These amplifiers are shipped without the vacuum
tubes installed. It is necessary to install the tubes first. The tubes
must be installed correctly or serious damage that is not covered
by the warranty will result.
Turn off immediately in the event of malfunction
Should you notice smoke or an unusual smell coming from the
equipments, turn it off immediately. Continued operation could
result in injury.
Do not disassemble
High voltage circuit. Touching the product’s internal parts could
result in injury. In the event of malfunction, the product should be
repaired only by a qualified technician.
Keep out of children
Failure to observe this precaution could result in injury.
WARNING: Failure to follow these instructions could result in
fire, electric shock, or other injury or damage.

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Table of Contents
IMPORTANT SAFETY INFORMATION 2
TABLE OF CONTENTS 3
OVERVIEW 4
QUICK INSTALLATION 5
OPERATION 9
COMPATIBLE TUBES 11
FAQ - FREQUENTLY ASKED QUESTIONS 12
WARRANTY AND SERVICE 13
REVIEWS 14
PRODUCT SPECIFICATION 15

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Overview
Thank you for choosing a Woo Audio product. The WA22 is a finely hand-crafted
amplifier that delivers uncompromised performance and superior listening experience.
Point-to-Point wiring
True balanced topology
All tubes. No semi-conductors in the entire signal circuitry
Soft start tube protection circuit
One 5U4G rectifier tube
Two 6SN7 drive tubes, one per channel
Two 6AS7 / 6080 power tubes, one per channel
DACT CT2 balanced stereo stepped attenuator
One balanced XLR input
One single-ended RCA input
One mono 3-pin headphone output (left and right channel)
One 4-pin stereo headphone output
One TRS headphone output (1/4”)
High and low impedance headphone output
Die cast full aluminum enclosure and knobs, anodized finished

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Quick Installation
What’s in the box?
①WA22 amplifier
②One matched pair of 6080 power tubes
③One 5U4G rectifier tube
④One matched pair of 6SN7 driver tubes
The actual tubes may look different.
Compatible tubes may be included instead of the ones illustrated above.
Power cord and interconnection cable are not included.

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Installing the tubes:
Note: avoid oil or smudge on the tube glass; clean hands before installation.
1. Find the correct tube for the socket. There is a label below each tube socket that
indicates a standard tube for the amplifier. For example, a 6080 tube should
install on the “6080” labeling socket. You MUST use the compatible tube or
serious damage may occur to the amplifier. See Compatible Tubes section for all
the approved direct substitute tubes.
2. Align the tube guide pin to the socket as below.
3. Hold the tube base firmly then squeeze it into the socket slowly. Be sure to apply
force perpendicular to the tube socket; never insert the tube at an angle. Apply
slight rocking motion for the tube, which is harder to insert; never apply circular
motion. Apply pressure from the top of the tube if needed.
Tube to tube
Tube socket guide pin indicator
Guide pin shows on the
bottom of a tube.
Do no insert a tube at an angle
Insert a tube perpendicular to
the socket.
Hold base firmly.



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4. Check installation. The tube pins should be inserted fully into the tube socket
receptacles.
Selecting AC voltage:
WARNING: failure to select the correct voltage will result in damage of the amp.
Installing the power cord:
Plug the power cord into the AC inlet. See ①in the below diagram. The AC inlet socket is a
standard IEC type. You will need to obtain the correct type for your region.
Installing the source input:
Plug the RCA interconnection cable into the RCA connectors; see ③in the below diagram. Or,
plug the XLR interconnection cable into the XLR connectors; see ④in the below diagram.


U.S.
European
U.K.
Switch to label “115” for
AC100 to 125V voltage.
Switch to label “230” for
AC210 to 240V voltage.

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Replacing the fuse when needed:
The fuse is located on the same unit of the AC inlet.
Back panel diagram:

①AC Inlet with fuse box
②Voltage selection switch
③RCA connectors
④XLR connectors
⑤RCA, XLR selector
Insert a small flat
screwdriver into
the fuse door
which located on
the AC inlet.
Release the fuse
door by pulling it
out.
The fuse holder is
released from the
AC inlet.
The fuse is held by
a clip.




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Operation
DO NOT
oTurn on the amp before properly installing ALL tubes.
oUse tubes that are not approved by Woo Audio.
oTurn on the equipment without checking the correct AC voltage setting.
oRemove any tubes or the DC cord while the amp is operating.
oTouch tubes (extremely hot) after warm-up.
oLeave the amp running unattended. To use the amp safely, please allow it to cool
down for every 8 hours of continuous play time.
DO
oPlace the amp away from any wireless or frequency-emitting devices, such as
mobile phones, PDAs and radios, to avoid noise interference.
oKeep away from water or excessive moisture.
oTurn off the amp if its sound is abnormal.
oAllow a minimum of 2 inches of air clearance for heat dissipation.
oAllow approximately 5 minutes of warm-up.
oAllow the tubes to cool down before replacing them.

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Turning the amplifier on:
1. Turn the volume knob ①to the lowest position.
2. Insert a headphone into either ②,or③,or④output.
3. Turn the power switch knob ⑤from OFF to HI or OFF to LO position. Then, the power
LED will pulsate for approx 20 seconds.
4. Observe that all tubes light gradually.
5. Wait until the LED ⑥ becomes solid and let the tubes warm up for at least 1 minute
before turning up the volume.
Front panel diagram:
①Volume control
②3-pin XLR headphone output, Left and Right channel.
③4-pin XLR headphone output
④TRS (¼” or 6.35mm) headphone output
⑤Multi-functional switch for power switch and high/low impedance selection
⑥PowerLED indicator
Break-in period:
It is recommended to allow the amplifier to operate 150+ hours so that peak performance can be
realized. An effective way to break in the amp is to run the amp normally with music playing.
Please do not leave the amp running continuously.

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Compatible Tubes
 Model#AdapterNote
Power
6080*No
421ANoGreaterpower.WesternElectricbranded.
5998NoGreaterpower.
6AS7No
6H13CNo
6N5PNo
7236NoGreaterpower.
2399No
6520No
Driver
6SN7*/GT/WGTNo
5692No
6CG7YesA9‐pinto8‐pinadapterisneeded.
6F8GYesA8‐pinto8‐pinadapterwithGridwireisneeded.
7N7YesA8‐pinto8‐pinloctaladapterisneeded.
CV181No
CV1988No
ECC32No
VT231No
Rectifier
5U4G*/BNoDirectlyHeated
274AYes DirectlyHeated,a4‐pinto8‐pinadapterisneeded.
274BNoDirectlyHeated
53KUNoDirectlyHeated
5AR4NoIndirectlyHeated
5AS4NoDirectlyHeated
5Z4NoIndirectlyHeated
5R4/GA/GB/GY NoDirectlyHeated
5U3CNoDirectlyHeated
5V4/G/GANoDirectlyHeated
5Y3NoDirectlyHeated
5Z3YesDirectlyHeated,a8‐pinto8‐pinadapterisneeded.
GZ30NoIndirectlyHeated
GZ32/33/34NoIndirectlyHeated
GZ37NoIndirectlyHeated
CV378NoIndirectlyHeated
U52NoIndirectlyHeated
U54NoDirectlyHeated
* The most current chart can be found in this document:
http://tinyurl.com/4wbv5qn

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FAQ - Frequently Asked Questions
Can I plug in 2 or more headphones at the same time?
Yes, there is no harm to the amp. However, sound quality may be degraded.
Do I have to use the correct impedance setting for my headphone?
No, you can use any setting for any headphone as long as you feel it sounds the best for
you.
If I connect the WA22 with RCA interconnects, will the amp still provide a
balanced signal to the balanced output?
No, there is no RCA to Balanced conversion in this amp. A source with a true balanced
output will work the best with the WA22.
There is abnormal sound right after turning on the amplifier.
This is normal from a cold start as the tubes are warming up to get into the proper
working state. The noise will disappear gradually.
Can I change headphone while the amplifier is on?
Yes, but you must first minimize the volume.
No sound is coming out of the headphone.
oCheck that all tubes are properly installed.
oCheck that the source is properly installed and is working fine.
oCheck that the source switch is on the correct position.
oCheck headphone connection.
There is noticeable noise coming from the headphone.
oRemove all sources from the amp to check if the noise disappears. If it does, the
noise is coming from the source.
oPlace the amp away from other electronic devices to check whether those were
causing the noise.
oPlace the amp in a different location to check if the noise is coming from the AC
line.
oRemove all tubes, clean tube pins, and then reinstall them again.
oReplace some or all tubes.
The sound is abnormal or distorted.
Replace tubes to see if they have deteriorated.
The LED and the tubes do not light.
Check if the fuse is burnt. See the Quick Installation section on how to replace a fuse.

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Warranty and Service
Woo Audio warrants this product free from defects in materials and workmanship for 1
year from the original date of purchase. The tubes are warranted for 30 days unless
otherwise stated. In the event that your Woo Audio product requires servicing, please
contact us directly to get a return instruction. If the equipment needs to be shipped back,
please use the original packaging and include a copy of the sales purchase along with a
detailed explanation of the problem(s).
Send service inquiry to [email protected]
Any modification not authorized by WOO AUDIO will void this warranty.

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Reviews
“It is transparent, particularly in that you don’t notice any treble veiling or grit as you
do with some lesser headphone amps. Bass is solid, well defined and can be very deep
with the right headphones. Tonal balance is very, very good, with no sense of treble
roll-off or brightness.” – Playback, issue 43
“Woo 22 balanced headphone amp which, with the premium tube upgrades, presents
the most effortless, immediate presentation of sound I have heard from any headphone
system, or perhaps any stereo system.” – Positive Feedback, issue 54
“The Sennheiser HD800 headphones and the Woo Audio WA22 integrated headphone
amp configured in fully balanced configuration is one of the best audio systems I have
heard. Tremble and midrange performance are as good or better than any headphone
or two-channel standalone system I have experienced. Bass is very satisfying and will
only be bettered by the very best fullrange speaker and subwoofer systems.” –
6Moon
“I have since tried HD 800’s with the prototype Woo Audio WA 22 amp (which is tube
rather than solid state amp that has variable output impedance). The WA 22 takes the
sense of vividness up a notch, mostly by making the midrange contrast level higher,
while introducing minimal if any deleterious side effects. The mostly subtractive errors
noted above are still there, but they are diminished in the overall presentation. This
gets me to the level of really, really liking the HD 800s. The HD 800s are so good that I
could easily live with them over the long haul. (page 115).” – Playback Guide to
fully sized headphones

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Product Specification
Model: WA22
Headphones Impedance: 8-600 Ohms
Input Impedance: 100 Kilo-Ohms
Frequency Response: 8 Hz - 50 KHz, -3dB
Power Output: 1500mW @32Ω
1500mW @60Ω
1600mW @120Ω
1100mW @300Ω
700mW @600Ω(with 7236 tube)
Signal/Noise: 92 dB
THD: <= 0.3%
Voltage: AC 110/220 - 240V, 50/60 Hz, switchable
External Dimension, end to end
measurement:
7" (H) x 12 (W) x 10.5" (D)
Weight: 25 pounds or 11.4 kg
Woo Audio is committed to continuously improve its products. We reserve
the right to improve the design without notice.