Hafler HA75-DAC User manual

HA75-DAC
User Guide
USB Digital Audio Converter
& Headphone Amp
Haer is a division of Radial Engineering Ltd.
1588 Kebet Way, Port Coquitlam
BC, Canada V3C 5M5
[phone] info@haer.com
www.haer.com

Table of Contents Page
Overview ................................................................................ 1
Features ..............................................................................2-3
Connect ...............................................................................4-5
Testing Your Connections....................................................... 6
Source Select Switch ............................................................. 6
Using the Headphone Load.................................................... 7
Using the Focus Control......................................................... 8
Using the Vox Control............................................................. 9
Warranty .................................................................Back Cover
Thank you for purchasing the Haer HA75-DAC headphone
amp and digital audio converter. This warm sounding tube
headphone amplier is designed to be easy to use while
providing the user with many customizable features to further
enhance the listening experience. This manual has been written
in order to provide you with all of the details so that you may take
full advantage of these extra features. As such, we ask that you
take a few minutes to read it. If you nd yourself looking for more
information, please visit the HA75-DAC FAQ page on the Haer
web site. This is where we post answers to questions from users
that are often helpful. Then, if you are still missing something,
feel free to send us an email at info@haer.com and we will do
our best to reply in short order.
HA75-DAC 'TUBE HEAD' HEADPHONE AMP
USER GUIDE

HA75-DAC HEADPHONE AMP
Haer
1
WARNING
HIGH POWER AMPLIFIER
The powerful amplier inside the HA75-DAC is designed to
accommodate all types of headphones from 8Ω to 400Ω. As we have
no way of determining the headphone impedance, the amplier is
very loud. Exposure to high sound pressure levels for an extended
period of time can cause irreparable ear damage. Please consult
your local health authority to ensure you do not expose yourself
beyond recommended limits. Radial shall not be held responsible
for using the HA75-DAC without due care or beyond recommended
legal limits imposed by your local government. Use by children is not
recommended and therefore must be carefully monitored by parents
or guardians.
CAUTION
HIGH VOLTAGE
There are high voltages inside the HA75-DAC. Before opening the unit
- It must be unplugged from the power supply and allowed to discharge
for at least 30 minutes. Touching the wrong place can cause a severe
shock. High voltages present at the tube socket will remain present
for some time after switching the HA75-DAC off. There are no user
serviceable parts inside. Only use indoors in a dry space. Do not open
unless you are a qualied technician or have experience with tubes.
OVERVIEW
The Haer HA75-DAC is a digital audio converter and tube-based
headphone amp with a number of innovative features that allow users to
tailor the listening experience to their liking. At the heart of the HA75-DAC
is a 12AX7 tube utilized for signal amplication. Tubes are preferred by
audio enthusiasts and recording engineers alike for their smooth, natural
sound, and the HA75-DAC exploits these characteristics to produce a
detailed and warm sounding output that has won the praise of many
experts in both the recording and mastering industries.
The HA75-DAC also employs high quality digital-to-analog converters
that allow connection over USB from digital audio sources such as a
laptop computer. Sample rates of up to 24bit/192khz are supported,
routing the signal through the tube-based analog circuitry. This approach
combines the best of both the digital and analog worlds in one powerful
and exible headphone amplier.

HA75-DAC HEADPHONE AMP
Haer
1. ON: Activates the HA75-DAC. It is recommended to warm up the
tube for 15 minutes to achieve thermal stability.
2. SELECT: From the front panel you can select between the analog
and the digital USB inputs.
3. FOCUS: Active matrix lets you control the width of the stereo image
to replicate listening to loudspeakers in a room.
4. GAIN: Used to adjust the volume for headphones.
5. VOX: Three position switch lets you enhance low frequencies to
suit the listening level and program material.
6. LOAD IMPEDANCE SELECTOR: Allows you to change the output
impedance to optimize performance with your headphones.
7. HEADPHONE OUTPUTS: Dual ¼” TRS outputs to enjoy the
listening experience with a friend. For best results use two matched
headphones as the impedance determines the loudness.
2
FEATURES
2 3 4 5 6 71
VOX Switch
A - Bass enhancer
Ø - Bypass / O
B - Loudness

HA75-DAC HEADPHONE AMP
Haer
3
8. POWER: ±16V 1600 mA external power supply included.
9. TUBE OUT: Add the Tube Head's warm tube character to a signal
path between a preamp and power amp if desired.
10. THRU: Un-buffered thru-puts that bypass the HA75-DAC tube
circuitry.
11. USB INPUT: Type-B USB input to receive digital audio from a
laptop.
12. RCA INPUT: Unbalanced inputs for any hi- system. Standard RCA
connectors.
13. ANALOG SELECT: Switches between RCA and XLR connections.
14. XLR INPUT: Balanced input for hi- system or studio use. XLR
inputs follow the AES standard with pin-1 (ground), pin-2 (+) and
pin-3 (-).
15. 12AX7 TUBE: Dual triode tube operates
with a B+ of about 140 Volts.
15
8 9 10 11 12 13 14

HA75-DAC HEADPHONE AMP
Haer
4
CONNECT
Connecting to and from the Haer HA75-DAC is easy. It features a USB
input for connection to digital sources, standard RCA connectors for
home use and balanced XLR-F inputs for professional use in studios.
Before making any connections, turn off your audio system. This will
prevent plug-in or turn-on transients from damaging more sensitive
components such as tweeters.
To use the HA75-DAC with a digital audio source, connect via a standard
USB type-B cable to the USB output on your computer (See Fig A).
On a Mac the HA75-DAC should automatically appear as an available
audio output device. On a Windows computer, drivers are required for
the HA75-DAC to be recognized as an output device. Please visit www.
haer.com to download the latest drivers and for installation instructions.
You can switch between the analog and the digital inputs at any time with
the front panel source select switch.
If you are connecting your HA75-DAC to a hi- system, simply take
the auxiliary output, tape monitor output or some other -10dB line level
output from your receiver or source device and connect to the HA75-
DAC analog RCA inputs (See Fig B). Make sure the input switch on the
rear panel is in the 'out' position to select the RCA inputs.
Connect the power supply. This external switching supply employs a
locking XLR connector and is able to handle input voltages ranging from
100V to 240V for use around the globe. Simply ensure the AC connector
matches your country’s power system using a standard IEC cable.
PHONO INPUT OUTPUT
Receiver
USB Type-B
HA75-DAC
(FIG A)
(FIG B)

HA75-DAC HEADPHONE AMP
Haer
5
If you are using the HA75-DAC in the studio, it is equipped with balanced
XLR female inputs that follow the AES standard with pin-1 (ground), pin-
2 (+) and pin-3 (-). These are paired with the RCA connectors. Use the
selector switch on the rear panel to toggle between the unbalanced RCA
inputs and the XLR inputs. Only one source can be selected at a time.
Also, available are two sets of RCA connectors labelled as THRU
and TUBE OUT. The THRU outputs are un-buffered and function as a
simple pass through (VOX or FOCUS will have no effect). The TUBE
OUT delivers the signal after it has been processed by the HA75-DAC.
This can be used to position the HA75-DAC in between a preamp and
power amp to add a warm tube character to the signal path. In the studio
it can be applied to recordings to 'warm-up' stale digital tracks or give
instruments and voice added character, particularly if pushed hard. Be
careful! The HA75-DAC is a powerful beast and can easily overload the
input of a mixing desk if care is not taken.
XLR Line Outputs
Record Player
Phono Stage
Power Amp Tube Out
RCA
Unbalanced
Input
(FIG C)

HA75-DAC HEADPHONE AMP
Haer
6
TESTING CONNECTIONS
Set all of the front panel knobs and switches to the start position with
the source select switch set to the input you wish to monitor, volume to
zero, focus switch off, load set to 100 Ohm, and loudness (VOX) to the
middle position.
USING THE SOURCE SELECT SWITCH
The intent is simple: let’s say you have your regular hi- source such as a
CD player or preamp connected to RCA Input and then the audio output
from a laptop computer connected to the USB input. Connecting the
HA75-DAC in between the hi- preamp and power amp using the Thru
output also lets you route the signal from your laptop to your power amp
using the HA75-DAC to select the active input and control the levels.
Plug in your headphones and then turn up the source audio system
to a low level. Slowly increase the level on the HA75-DAC using the
volume control knob. Testing at low volume will prevent damage to your
headphones and protect your hearing should a connection be faulty. If
no sound, check to make sure you have the front panel select switch set
to the appropriate input. If all seems OK, increase the volume until you
have reached a comfortable listening level.
In the studio you can use the XLR inputs to connect from your recording
system and the USB to listen to guest mixes from their laptop. Depress
the analog select switch on the back panel to use the XLR inputs, and
switch between the recording rig and the guest computer using the front
panel source select switch.
USB Input
USB Input
RCA Input
XLR Input

HA75-DAC HEADPHONE AMP
Haer
7
DUAL HEADPHONE OUTPUTS
The benet of having two headphone outputs on the HA75-DAC
means you can share the listening experience with a friend or client!
Using matched headphones is best as the impedance determines the
loudness. Otherwise there may be a substantial level difference. This is
also a great way to set and monitor the volume for someone else and
ensure it is not excessive. (See disclaimer at the front of the manual)
HEADPHONE LOAD
The HA75-DAC is equipped with a Load switch that
adjusts the output impedance that is presented to
your headphones. This can be set from 20 Ohms up
to 400 Ohms. Every model of headphones will have
its own internal impedance rating; this switch allows
you to optimize the output of the HA75-DAC to best
match your specic model of headphones.
We recommend starting at 20 Ohms and letting your ears be the judge
as you try out the other impedance settings. You will notice that some
settings will be louder than others to make sure to turn the volume down
to a reasonable level before switching to avoid damaging your ears.
FCC STATEMENT
This device complies with Part 15 of the FCC Rules. Operation is
subject to the following two conditions: (1) this device may not cause
harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation
TROUBLE SHOOTING INTERFERENCE
Should interference occur in a home environment, one or more of the
following measures can be taken:
1. Reorient or relocate the unit.
2. Increase the distance between the unit and the receiver.
3. Use double shielded audio cables.
4. Introduce a noise lter onto the AC power line.
5. Consult with the dealer or manufacturer for additional help.

HA75-DAC HEADPHONE AMP
Haer
8
THE FOCUS CONTROL
One of the particularly cool features built into the HA75-DAC is the Focus
control. This enables you to simulate the effect of listening to music in a
free air space, as if playing music through speakers in a typical room. In
essence, you can adjust the stereo image to suit.
Here’s the point: When listening to loudspeakers, the sound emanating
from the right loudspeaker will be heard in both ears, not exclusively the
right side. But with headphones, you only get the left program material in
the left ear and the right program material in the right ear. This can make
extreme 'left right' imaging sound more dramatic than it was intended,
likely pushing you away from the artist’s intended mix.
The solution is the Focus control. This is an active matrix that mixes a
mono ‘blend’ of the two channels back into the stereo image. This control
is much more precise than a typical passive mono blend. Controlling the
amount of width brings the stereo image from wide to narrow as you
increase the control from counter-clockwise to clockwise. Upon listening
– depending on the program material - you will notice a greater sense of
realism. When recording in the studio, this allows the engineer to quietly
mix as if listening to neareld monitors.
To activate, simply depress the Focus ON switch and adjust to suit.
When engaged, this will cause the volume to increase slightly as you
are now combining multiple signals together to create a new stereo mix.
Simply lower the gain control to compensate.
Listening with headphones
Narrow field
Listening with speakers
Wide field

HA75-DAC HEADPHONE AMP
Haer
9
THE VOX CONTROL
This three-position VOX or loudness control switch serves two functions.
The rst is as a traditional loudness control, the second to enhance bass.
Back in the 1970's, most integrated receivers were outtted with a
loudness switch that would enhance bass at low volumes to make up
for loudspeaker inefciency and the human ear’s greater sensitivity to
mid-range frequencies. This countered the Fletcher-Munson curves
that demonstrated how the human hearing changed based on sound
pressure levels. We felt that when listening to music at low levels, say
while reading a book, enhancing the low frequencies would enhance
the listening experience. To set the HA75-DAC’s VOX switch to normal
loudness, set the switch in the down position.
The other issue is one that has come about in recent times - headphones
with exaggerated bass that are now all too common. When comparing
headphones, the difference can be astonishing. Some have extended
high frequencies, others so much bass they can cause your head to spin.
Another problem is listening to music that may have been recorded in the
1960's or 70's that may lack bass.
Set the VOX switch in the up position to increase the bass and simulate
the effect of these over-exaggerated headphones or offset bass-lacking
mixes. This also allows the recording engineer to simulate listening to
various headphones to get a sense of how the program material will
translate.
For the purist, simply set VOX control to the middle position (bypass) to
hear the natural mix without enhancement.
VOX Switch
A - Bass enhancer
Ø - Bypass / O
B - Loudness
ABOUT THE TUBE
Most of the voltage amplication inside the HA75-DAC is done with a
12AX7 dual triode tube operating with a B+ of about 140 Volts. This tube
may be unplugged and replaced with any other brand of 12AX7 if the
user has some other preference. It is however important to note that the
HA75-DAC is biased for the 12AX7 and use with a 12AU7 or 12AT7 will
not sound good at all.
Note: High voltages are present inside the HA75-DAC. For safety we
suggest that the tube only be changed by a qualied technician.

THREE YEAR TRANSFERABLE LIMITED WARRANTY
HAFLER (A division of Radial Engineering Ltd.) (“Haer”) warrants this product to be free from defects
in material and workmanship and will remedy any such defects free of charge according to the terms
of this warranty. Haer will repair or replace (at its option) any defective component(s) of this product
(excluding nish and wear and tear on components under normal use) for a period of three (3) years
from the original date of purchase. In the event that a particular product is no longer available, Haer
reserves the right to replace the product with a similar product of equal or greater value. In the unlikely
event that a defect is uncovered, please call 604-942-1001 or email service@haer.com to obtain a RA
number (Return Authorization number) before the 3 year warranty period expires. The product must be
returned prepaid in the original shipping container (or equivalent) to Haer or to an authorized Haer
repair centre and you must assume the risk of loss or damage. A copy of the original invoice showing
date of purchase and the dealer name must accompany any request for work to be performed under
this limited and transferable warranty. This warranty shall not apply if the product has been damaged
due to abuse, misuse, misapplication, accident or as a result of service or modication by any other
than an authorized Haer repair center.
THERE ARE NO EXPRESSED WARRANTIES OTHER THAN THOSE ON THE FACE HEREOF
AND DESCRIBED ABOVE. NO WARRANTIES WHETHER EXPRESSED OR IMPLIED, INCLUDING
BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE SHALL EXTEND BEYOND THE RESPECTIVE WARRANTY PERIOD
DESCRIBED ABOVE OF THREE YEARS. HAFLER SHALL NOT BE RESPONSIBLE OR LIABLE
FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSS ARISING FROM
THE USE OF THIS PRODUCT. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, AND
YOU MAY ALSO HAVE OTHER RIGHTS, WHICH MAY VARY DEPENDING ON WHERE YOU LIVE
AND WHERE THE PRODUCT WAS PURCHASED.
www.haer.com
Haer HA75-DAC™ User Guide - Part #: R870 1303 00
Copyright 2017 Haer All rights reserved.
Specications and appearance subject to change without notice.