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All our amps come with a surprisingly good,
but still inexpensive, power supply. Any au-
diophile will tell you that the power supply
is as, or almost as important as the audio
electronics themselves. This is true. While
we think the other upgrades available for
the amps may be slightly more important,
the Desktop Supply will get every last drop
of performance out of the amp you buy.Maximum current output before a potential
loss in audio quality is 500 mA. For the best performance, we recommend one dedi-
cated DPS for each headphone amp.
1. Ground Lift
The Ground Lift seperates the audio signal ground from the power
supply ground. Usually, you will want the Ground Lift Switch to be set to ‘normal’, but
if you hear a slight buzzing noise in your system, then turn the Ground Lift Switch to
‘float’.
2. Power Entry Module
The Power Entry Module is where the Power Supply is
plugged into the wall. The power entry module can also be easily changed into other
common international voltages. Using a coin or screw driver, open the module on
the right side, and turn the voltage indicator around to read the appropriate voltage
for your region. The red window box on the power entry module indicates the current
voltage setting of your amplifier. You can easily switch the voltage between 115 VAC
and 230 VAC by carefully opening the power receptacle window housing, then simply
slide out the receptacle and reinsert it facing the opposite way until the desired voltage
clearly shows through the power module window box. The whole process should take
less than a minute!
3. Power Outputs
There are 6 power outputs on the Desktop Power Supply, and
is appropriate for use with any of the HeadRoom Desktop or Micro Lines of amps and
DACs.
Desktop Electronics Module
This little green module contains all the electronics for a Desktop Headphone Amp.
There are two 4-layer circuit boards (one each for the left and right channel) that are
connected with a series of header pins used to solder the module to the main circuit
board. This module is designed to sound great but must provide at least 20 hours of
play time on four D-cells in the Desktop Portable Amp. It uses Burr-Brown (Okay, now
TI) 2134 op-amps for the internal input buffer, crossfeed, summer, and power amp volt-
age gain stage. The output current amplifier is our version of the highly regarded Dia-
mond Buffer discrete transistor design by Walt Jung. Resistors are 1% metal thin film,
and caps in the signal chain are polyphenylenesulfide (poly film); these are MUCH
higher quality parts than you’d ever find in a typical consumer electronics product.
The Desktop portable can be upgraded to the Home module, but it will cut battery very
significantly and we don’t recommend it.
How to Connect Your Desktop Portable Amp
Electronics Module; Power Supply Upgrade
Desktop Power Supply Upgrade
1.
ground
lift
switch
3.
Power Outputs
To an Analog Source
You will need a portable cable or RCA interconnect to connect your analog
source to the Desktop Portable Amp. Plug the RCA inputs into the back of the
Desktop Portable Amp with the other end connected to the line output of your
analog source (or a headphone jack if there is no line out available.) Don’t
forget to select the appropriate input with the Source Selector Switch.
Shown to the left is a
portable CD player, us-
ing the line out of the CD
player to the analog in-
put of the Desktop Por-
table Amp.
Portable CD Player
To a Digital Source (DAC Option)
Your digital source will have either the USB, coaxial, or optical outputs. Plug
the appropriate cable into the corresponding digital input on the back of the
Desktop Portable Amp. Be sure to select ‘digital’ on the Source Selector
Switch, and the correct digital input with the
Digital Input Selector
Switch.
Most new hard-drive MP3
players on the market no lon-
ger have digital outputs, but
many existing HD players do.
This iRiver player below uses
an optical line-out, into the
optical input of the Desktop
DAC.
Portable DVD Player
The DVD player shown above uses
the optical input on the back of the
Desktop Portable Amp.
Hard-Drive MP3 Player
Desktop Power Supply
To the Desktop Power Supply
The Desktop Power Supply is a power supply
upgrade available for purchase on our web-
site. To connect the Desktop Power Supply,
you will need a power cable with 6 pin ter-
minations on either side. Connect the 5VDC
power input on the Desktop Portable Amp to
the one of the power inputs on the back of the
Desktop Power Supply. To learn more about
the Desktop Power Supply, see our section
on upgrades on the following page.
Power Entry
Module
2.
