The Micro Amp & DAC
headphone amplifier
& digital-analog converter
Owner’s Manual
Congratulations! You’ve just received the cutest little piece of hard-core
audio hardware known to the world of audiophilia. The Micro Amp and Micro
DAC are jam packed with all the sweet parts, terrific engineering, quality
manufacturing, and years of experience needed to make luscious tunes
bloom in your head. So get out your best headphones, put on your favorite
music, and prepare for the perfect pleasures of personal listening made right
between your ears.
Toll Free: 8 0 0 - 8 2 8 - 8 1 8 4
2020
Bozeman,
w w w . h e a d p h o n e . c o m
Gilkerson
MT
Drive
59715
Phone:
Fax:
4 0 6 - 5 8 7 - 9 4 6 6
4 0 6 - 5 8 7 - 9 4 8 4
Download from Www.Somanuals.com. All Manuals Search And Download.
The Micro Amp
The Micro Amp Panel Descriptions
Front Panel
Packing HeadRoom’s mobile electronics module, two nine-volt batteries, and
all the knobs and switches you need into an all but bullet proof aluminum
enclosure is pushing it a bit, but you won’t care because your head will be
thanking you for the lovely tunes.
1. Line Input The line input is where you plug in the source. Preferably the Micro
DAC; but it could be the line out of your iRiver or the headphone out of an iPod. You
will need a mini-to-mini cable to hook up your Micro Amp.
2. Headphone Out The headphone out is where you plug in your headphones.
There isn’t room for a full sized jack, but this 1/8th inch mini-plug will take the small
plug of all 1/8” headphone jacks. We also sell a short flexible Grado 1/4”-1/8”
adaptor for your big cans; and you can get a replacable Cardas headphone cable
with a mini connector for many types of headphones, call us or consult our website
for details.
3. Crossfeed Switch This switch engages the crossfeed circuit. The audio image
on headphones is often not very good; typically the image is a blob on the left, a blob
on the right, and a blob in the middle. The HeadRoom crossfeed provides the natural
acoustic cross-feed normally heard at the left and right ear as heard from the left and
right speaker. Adding back the normally occurring cross-feed signal gives your brain
enough information to build the stable and natural audio image needed to have a
quality listening experience. See pg.8 for more info on the HeadRoom crossfeed.
5.
Volume
Control
4. Gain Switch The 3-position Gain Switch accomodates various headphones’
power needs. For instance, the Low Gain setting would be used for in-ear monitors,
allowing a larger range on the volume control pot. Experiementing with your
headphones and the gain switch may help you to determine which setting you prefer.
If have any questions regarding your headphones, feel free to call and ask us.
1.
Line
Input
3.
Crossfeed
Switch
6.
2.
Power
Source
Switch
4.
Gain
Switch
5. Volume Control You never know where the volume control should be set as
different headphones often have widely different impedances and efficiencies, so use
your ears to choose your listening level, not the level on the dial. (We recommend you
choose a moderate level so as not to blow out your ears.) You also need to turn the
amp OFF or ALL THE WAY DOWN before plugging in or unplugging your headphones
to avoid short-circuiting the amp. As you turn the volume control knob clockwise,
the volume increases.
Headphone
Out
6. Power Source Switch Immediately to the right of the volume control is the
power source switch. It will run on either the two internal 9-Volt batteries or an external
power supply. If the batteries are in and external supply is attached, the only way
you can turn it off is by selecting ‘external’ and then unplugging the connector. We
offer two power supplies: the less expensive, lovingly known as “brick”, power supply
comes with the amp, the more expensive Desktop Power Supply will give you cleaner
juice, and therefore cleaner, more dynamic sound.
7.
Rear Panel
External Power Input
7. External Power Input Connect either your brick or Desktop Power Supply
here.
8. Thumb Screws To change your batteries, unscrew the screws and remove the
8.
rear panel. Orientation of 2 nine-volt batteries is indicated by the illustrations on
the rear panel.
2
Thumb Screws
3
Download from Www.Somanuals.com. All Manuals Search And Download.
The Micro DAC
The Micro DAC Panel Descriptions
The unlikely marriage of a well supported Texas Instruments USB sound de-
vice chip (to get the S/PDIF signal), Cirrus Logic’s flagship D/A converter, and
two 9-Volt batteries bears the fruit of incredibly good sound anywhere you
want to set up a personal listening station. Take a tour of the front and rear
panels and here’s what you’ll find:
Front Panel
1. Line Output The line out is the best sounding stereo-mini plug out there.
This is the signal source you plug into the input of your headphone amp. Don’t
forget to check out our Cardas mini to mini cables; they come in many flavors
. . . ok, four different lengths.
2. Optical/Coaxial Digital Input The optical input is your typical Toslink
connector. You get this input signal from the optical output of your player. Not
so many portable audio players have optical outputs anymore (call or check
our web site for recommendations), but many portable DVD players and some
hard disk drive players do. Of course, you can get this signal from many pieces
of home equipment.
3. USB Input The USB input gets its signal from a computer: laptop or desk-
top; PC, Mac, or Unix. There aren’t any portable players of any kind that have
the ability to talk to an external USB sound device . . . yet.
4. Input Select Switch If you are using both inputs select the one you
want to listen to with this switch.
3.
USB
Input
5.
1.
Line
Output
5. Power Source Switch To the far right is the power source switch. It will
run on either the two internal 9-Volt batteries or an external power supply. If
the batteries are in and external supply is attached, the only way you can turn
it off is by selecting ‘external DC’ and then unplugging the power supply from
the back of the unit. We offer two power supplies: the less expensive version,
lovingly known as “brick”, power supply comes with the amp, the more ex-
pensive Base Station One will give you cleaner juice, and therefore cleaner,
more dynamic sound.
2.
Power
Source
Switch
4.
Input
Select
Optical/
Coaxial
Digital
Input
Rear Panel
6. External Power Input Connect either of your power supplies here.
7. Thumb Screws To change your batteries, unscrew the screws and re-
move the rear panel. Orientation of 2 nine volt batteries is indicated by the
illustrations on the rear panel.
6.
External Power Input
7.
Thumb Screws
4
5
Download from Www.Somanuals.com. All Manuals Search And Download.
Connecting Your Micro Stack
Changing Batteries
Hooking up your new Micro Stack (or just one of them) is a quick and easy
process. Your source will need an analog line out, or if you are using the Micro
DAC, a digital output which could be USB, coaxial, or optical. You will need
a mini-mini cable to hook up your Micro Amp and DAC. Shown here is a 6”
Cardas mini-mini cable, available for purchase on our website.
The Micro Amp and DAC run on DC power or two 9 volt batteries. The battery
life of your Micro Amp will last approximately 15-20 hours, depending on the
impedance level of the headphones you are using, as well as the electronics
module you have (The DAC will not last quite as long). Most people have the
Micro Module, which allows for about 15-20 hours of battery life. If you have
the Desktop Module, then you should typically get around 8-10 hours of bat-
tery life.
The Micro Stack
1. Plug the mini-to-mini cable into the
line input of the Amp and line output
of the DAC. Don’t forget to select the
appropriate power source on each
unit.
To remove your 9 volt batteries, you
Micro Amp or DAC,
need to remove the rear panel. Un-
thumb screws
screw the thumb screws, and the
removed
panel will fall away from the enclo-
sure. You can also gently grasp the
panel by the center cut-out for the
power supply and pull the panel off
the unit, shown below.
Cardas
mini-mini
cable
Micro Amp or DAC with rear
panel removed
Micro Stack and
digital source
2.
Connect your digital
source to the DAC by plug-
ging in a coaxial or optical
cable into the optical/co-
axial digital input or a USB
cable from your computer
into the USB input.
Some rechargeable batteries are slightly longer than a standard 9 volt battery.
If you are using a longer 9 volt battery, slide them in allowing for the rubber
flap to fold up into the top of the enclosure, shown lower left. The Micro Amp
does not recharge your rechargable batteries.
Micro with 9 volt
alkaline battereis
Micro with 9 volt
rechargeable batteries
3. If you are only using the
Micro Amp, then connect the
source to the amp using the
(preferably) line out or head-
phone jack of your player to the
the line input.
Micro Amp
and source
4. Plug your headphones into
the 1/8 jack on the front of the
Micro Amp. Adjust the volume
on the HeadRoom amp.
When using standard alkaline batteries, or standard size rechargeable bat-
tereies, pull up the small rubber flap and slide the 9 volt battery in. The bat-
tery will slide completely into the enclosure and the rubber flap will hang
down in front of it, shown upper right.
6
7
Download from Www.Somanuals.com. All Manuals Search And Download.
What is the HeadRoom Crossfeed?
Electronics Modules for your Micro Amp
The Micro Module
Imagine you are listening to a pair of speakers. If you turn off the left speaker,
both ears hear the sound from the right speaker. But because the left ear is
slight farther away than the right ear, it hears the speaker’s sound slightly
after the right ear; about 300 microSeconds. This time difference is called the
“inter-aural time difference” and it is the main thing your brain listens for in
order to tell where to place sound left-to-right.
This little red module contains all the electronics for a Micro 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 two 9-Volt batteries in the Micro
Amp. It uses AD822 op-amps for the internal input buffer, crossfeed, sum-
mer, and power amp voltage gain stage. The output current amplifier is our
version of the highly regarded Diamond 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 Micro Amp can
be upgraded to the Desktop Module. The result will be an approximate halving
of play time and moderate improvement in sound quality. If you will be using
this amp largely in a portable mode, we suggest sticking with the stock micro
module as its better sounding by far than any portable source (accept maybe
the Micro DAC) and saving batteries is a good thing.
But in headphones if you turn off the left channel, only the right ear hears the
sound. In headphones, if there is any sound that is only in the left channel, or
only in the right channel, then only that ear hears the sound. This is not natu-
ral, and you brain becomes fatigued trying to figure out where sound is com-
ing from when only one ear is hearing it. This tends to create an audio image
that is a blob on the left, blob on the right and a blob in the middle.
HeadRoom amplifiers cure the problem by allowing you to cross-feed a little
of the left and right channels across to each other through a short time de-
lay using the crossfeed switch. The usefulness of the circuit varies depending
on what type of recording you are listening to; mono and binaural recordings
need no processor at all. Old studio recordings that have instruments panned
hard left or right, benefit greatly from the processor. Live and classical record-
ings miked from a distance benefit somewhat less, and can often be listened
to without the processor quite comfortably.
Desktop electronics module
Micro electronics module
30 degrees
off axis
The crossfeed switch in
HeadRoom amplifiers al-
low you to cross-feed a
little of the left and right
channels across to eacho-
ther through a short time
delay.
Desktop Electronics Module Upgrade
The Micro Amp can be upgraded to the Desktop Module. This little green mod-
ule 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 con-
nected with a series of header pins used to solder the module to the main cir-
cuit 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 voltage gain stage. The output current amplifier is
our version of the highly regarded Diamond 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.
Far ear
hears
slight delay.
Near ear
hears sound
first.
Plain
With
Headphones
HeadRoom
8
9
Download from Www.Somanuals.com. All Manuals Search And Download.
30 Day Guaranty & Warranty
Exchanges & Returns
HeadRoom 30 Day Guaranty
Equipment Exchanges
Unless specifically stated otherwise, all HeadRoom purchases come with a
30-day satisfaction guaranty in order to give you the opportunity to evaluate
your purchases. We’re happy to provide you with the opportunity to refund or
exchange your product, but to keep costs down we do have a few conditions.
Products must be returned to us within 30 days of the date you receive the
product. So make sure you try your purchase out right away! Products must be
in “as-new” condition. This means that they’re in pristine cosmetic condition,
functioning perfectly, and include ALL materials (plastic bags, warranty cards,
tie wraps, etc). In other words, please send products back exactly as you re-
ceived them. If a product is returned within the 30-day return period, but is not
in “as-new” condition, we will charge you a 15% restocking fee plus any labor
and materials required to return the product to “as-new” condition. Sorry, but
after your 30 day trial, products are no longer exchangeable or refundable.
If you’re having trouble with a headphone amp or system, please contact us
first to troubleshoot the problem. You can email Sales, (sales@headphone.
com) or call 800.828.8184. If we can fix it while you’ve still got the product,
everyone’s happy!
If you would like to exchange your purchase for another item, you have two
options. You can simply purchase the item you want, and send the item you
don’t want back for refund within 30 days of the original purchase (don’t for-
get to fill out the back of the Return & Exchange card and include it with your
return). We will refund your credit card after we receive the item. Or, you can
send your product back as an exchange, and indicate the product you would
like on the Return card. We will adjust your credit card accordingly and ship
you the new item. Replacement products are shipped to you as soon as pos-
sible, typically within 3-5 days provided the replacement item is in stock.
Defective Equipment Exchanges
In the uncommon event of receiving a defective product, contact us and we
will ship out a replacement product to you at no cost as soon as possible,
typically within 3-5 days provided the replacement item is in stock. You will
receive the replacement item along with a return shipping label and a card to
include with the defective item to return to HeadRoom. Important: Fill in your
name and original invoice number of your order on the card and return the
item to HeadRoom within 2 weeks. If we have not received the product after 2
weeks (allowing shipping time) we will charge your credit card the amount of
the defective item. Please understand that we enforce this policy as an incen-
tive for customers to get defective equipment back to us as soon as possible.
Mico Amp & Micro DAC Warranty:
The HeadRoom Micro Amp and DAC are warrantied for two years. If anytime
within the first two years of your purchase you have a problem with your Micro
Products, you can return it for repairs under the terms of our 30 Day Guaranty.
HeadRoom is the only authorized service center for HeadRoom products, ei-
ther in or out of warranty. If a unit is under warranty, there is no cost for the
repair labor, parts, or shipping from HeadRoom back to you (i.e., You’re re-
sponsible for paying the shipping charges to get the product to us).
Shipping Products back to HeadRoom
Please ship products back in the original shipping box (or another that is com-
parable); please don’t send headphones back in JUST the headphone box,
as it’s a sure bet that they will no longer be in “as-new” condition when we
receive them! We HIGHLY recommend that you ship returns using an insured
and “signature required” delivery method—we can’t be responsible for lost or
damaged packages. Finally, don’t forget to include the completed Return &
Exchange card and WRITE YOUR NAME on the outside of the box!
Out of Warranty Repairs
Non warranty repairs are assessed at an hourly rate of $50 per hour plus parts,
and are only conducted on HeadRoom products. If the cost of the repair is
over $100, we will call you with an estimate. If you have an older HeadRoom
amp that is out of production, we may not be able to repair the amp, however
please contact us and we will let you know if we are able to. When we receive
the equipment, we will initiate repairs and upgrades within 1-2 weeks and
return the unit to you. The customer pays for shipping to HeadRoom and we
pay for return shipping. Please refer servicing to HeadRoom factory authorized
personnel as HeadRoom is the only authorized service center for HeadRoom
products, either in or out of warranty. Tampering by persons other than Head-
Room factory authorized personnel is discouraged and will void your warranty.
HeadRoom will not accept warranty claims for damage resulting from accident,
misuse, neglect, abuse or failure to follow instructions of operation.
Return Products to:
Contact Us:
HeadRoom
Attn: Returns
2020 Gilkerson Drive
Bozeman, MT 59715
Toll Free: 800-828-8184
Phone: 406-587-9466
Fax: 406-586-9484
10
11
Download from Www.Somanuals.com. All Manuals Search And Download.
|