HeadRoom BlockHead User manual

The BlockHead Owner’s Manual 1
The BlockHead is the world’s first and only commer-
cially available fully balanced, double dual-mono,
mono-block headphone amplifier. While it’s finesse
and depth of imaging are a significant improvement
over anything we’ve previously experienced with
dynamic headphones, it’s the BlockHead’s Adam’s
apple wobbling bass reproduction and eye blinking
impact that have us re-thinking everything we
thought we knew about headphones.
obsessed headphone geeks at your service.
www.headphone.com
Headphone Amplifier
HeadRoom Corporation
The BlockHead Owner’s Manual

2800.828.8184 www.headphone.com
A Tour of Your HeadRoom BlockHead Amp
2. Gain
Switch
3. Processor
Switch
1. Volume
Control
7.
LED
1.
6.
5.
4.
3.
2.
4. Filter
Switch
6. The
Headphone
Jack
5. Phase
Switch

The BlockHead Owner’s Manual 3
1. The Volume Controls. Big, beautiful, anodized, and aluminum. They feel and
sound as good as they look! Increase the volume for each channel by turning the
knobs clockwise.
2. The Gain Switches. The 3-position Gain Switch accomodates various head-
phones’ power needs. For instance, the Low Gain setting would be used for
Grado headphones, allowing a larger range on the volume control pot.
Experiementing with your headphones and the gain switch may help you to deter-
mine which setting you prefer. If have any questions regarding your headphones,
feel free to call and ask us.
3. The Processor Switches. When switched toward PROCESS, the Audio Image
Processor is engaged for normal stereo headphone listening. In the OFF position,
the Processor is bypassed for listening to mono or binaural recordings. (These
switches should be in the OFF position when using the headphone amp as a
preamp.)
4. The Filter Switches. The filter switch is used to compensate for the warming
action of the processor. In the center position there is no filter in the circuit;
generally this is preferred. But if the processor is causing too much bass or
blurring of the central image, a mild high frequence boost filter can be turned on.
The “bright” setting accentuates the highs at about 3 kHz; with the “brighter”
setting the filter starts an octave earlier and catches some of the upper mids.
Basically, set it to what ever sounds best to you.
5. The Phase Switches. Audio sources will commonly invert the phase on a
recording. Use this switch to correct the problem.
6. The Headphone Jacks. The Neutrik headphone jacks on The BlockHead
clamp down tightly for optimum signal transfer. They will accomodate both a
1/4” and well as XLR connectors- although the XLR connectors are certainly the
recommended jack for use with the BlockHead.
7. The LED. The LED simply indicates if your unit is on or off.
About your Blockhead amp...

4800.828.8184 www.headphone.com
1. Power
Switch/ DC
Input 3. Line In
4. Ground
Lift Switch
5.
Crossfeed
Out
2. Voltage
Indicator
6.
Crossfeed In
BlockHead Rear Panel
3.
5.
6.
4.
2.
1.

The BlockHead Owner’s Manual 5
1. The Power Switch & DC Input. 1 is on, 0 is off. When the amp is on, the
glowing red LED on the front of the unit tells you so.
2. Voltage Indicator. In most cases, the voltage indicator should read ‘115
volts’ for use in the U.S. However, your voltage can be easily adjusted to 230 v. for
foreign use; call us for details on how to do this yourself.
3. Line In. Plug your source into these left and right channel inputs.
4. Ground Lift Switch. For normal use, the Ground Lift Switch should be on
‘float’.
5. Crossfeed Out.
6. Crossfeed In.
Sennheiser 600’s
with Custom XLR
Cables
The crossfeeds ennable the audio image processor to
work with the BlockHead. Use the supplied 1ft.
Dimarzio cables to loop one block to the other.
}
Rear Panel...
Since the BlockHead is a fully
balanced amplifier, you must have balanced
outputs on your headphones. Currently,
Sennheiser 600’s and Grado RS1’s are
availabe with fully balanced cables. You
also have a choice of what kind of cables
you would like to use; both Clou Cable of
Germany and Cardas Cables of USA
manufacture fully balanced headphone
cables. Just give us a call, 800.828.8184,
for more information!

6800.828.8184 www.headphone.com
Headphones share a common connection on the non-driven side of the driver
elements. You can see this by looking at a headphone plug; the left channel
connection is at the tip, the right channel connection is the ring, and the common
connection were talking about is the remainder of the plug shaft, called the sleeve.
The problem is that the summed left and right channel return current will develop a
signal across the series resistance of the common return path, which muddies the
stereo presentation on headphones with cross-talk. (When evaluating headphones,
one thing you can look for is having the join of the left and right common return at the
plug rather than within the headphones.) It is this headphone connector found on all
headphones that makes it impossible to drive the return side of the headphone
coils with the separate left and right inverted signals of a fully balanced amplifier.
What’s so special about a fully-balanced headphone amp?

The BlockHead Owner’s Manual 7
HeadRoom has managed to overcome this problem by convincing Clou Cables and
Grado Labs to build custom headphone cables. The BlockHead’s machined aluminum
front and rear panels hold together two enclosures which house the completely
separate left and right audio channel electronics (hence mono-block). Each non-
inverted and inverted audio channel has completely separate electronics and power
supplies all the way back to separate Avel-Lindburg toroidal transformers (hence
double dual-mono). Yes, this amp has four transformer, four power supplies, and
four audio channels. The amp comes standard with all sorts of sweet stuff like: high
performance Burr-Brown 627 audio op-amps (see the June ’01 Stereophile for a
very intelligent discussion about high performance audio op-amps), very low
temperature coefficient .1% metal film resistors and matched polyphenoline-sulphide
film capacitors in the signal path; Nobel potentiometer, Neutrik connectors, three
step gain control for volume control optimization of various efficiency headphones,
three step filter control, HeadRoom psychoacoustic processor circuit, and much
more. And optionally available stepped attenuators and further audio electronic
component upgrades are available, call us for details.
about the Blockhead...
How about another helpful feature: The BlockHead can double as a very good
sounding, fully balanced preamp. Make sure the Processor and Filter switches are
in the OFF position when listening through speakers to avoid goofing up your imag-
ing and frequency response. Because the BlockHead is a fully balanced unit, it is a
good idea to call us on the details of how to hook up the BlockHead to your source.
Using Your Amp as a Preamp

8800.828.8184 www.headphone.com
Despite this lack of
acoustic data, you
mind attempts to
laterally locate
sounds. The result
is a troubling
blobs-in-the-head
sonic image. Your
brain ends up frus-
trated and fa-
tigued.
Your amp has a processor because it makes headphone listening much more natu-
ral. When listening to speakers, you hear both the left and the right signals in both
ears. Not so with headphones. When you stick a pair of speakers directly to your
ears (i.e., headphones), you lose the spatial/acoustic cues your mind needs to
locate sounds in space.
Why Does Your Headphone Amp Have a Processor?
without HeadRoom with HeadRoom

The BlockHead Owner’s Manual 9
more about the processor...
The Audio Image Processor solves this problem. Analog filters are used to take an
attenuated signal from each channel, slightly delay it(about 300 microseconds,
depending on the frequency), and feed it to the opposite ear. This is the acoustic
information your mind needs to create a believable audio image in you head. This
added information eases the burden on your brain by spreading out the clumped
image in your head. Ahh, sweet relief.
How can the processor be tested?
If you have already tried out the Processor, you have probably noticed that there
isn’t a huge difference in the sound when switching the Processor on and off. If you
would like a more obvious demonstration of the effect of the Processor, just unplug
one of the line inputs to The BlockHead and listen for a few moments with the
Processor off. Now switch the Processor on and hear the difference. [ pause for
experimentation ] See, it really is doing something dramatic.
Upgrading your BlockHead
The stepped attenuator is an available upgrade for our high-end
headphone amplifiers. We use the Nobel potientiometer
on our high-end amps, and its performance is very
good—but not perfect. In order to elevate the per-
formance of our reference products to as near
perfection as possible, we use a stepped at-
tenuator. The stepped attenuator uses a range
of discrete resistors switched into the circuit to
attenuate the signal. We start with a Swiss made
Elma 24-position switch. Then we disassemble it
and remove the stock circuit boards and replace
them with our custom made boards which allows
us to mount the precision thin film resistor right on the contact
boards. The gold plating on the contacts on these boards is about 4 times thicker
than on normal contact boards. The result is, what we believe to be, the finest
stepped attenuator in the audio world today.

10 800.828.8184 www.headphone.com
How to Hook Up Your BlockHead Amp
On the back of your BlockHead amp you will find 6 inputs. Two inputs are from your
source, one for the left channel and one for the right.
The other 4 connectors are for wiring the crossfeed circuit, ennabling the HeadRoom
processor. the two 1-foot Dimarzio Interconnects included with the amp are for this
purpose. It doesn’t matter which interconnect is used for either side. For more
information about hooking up your BlockHead amp to other sources, please consult
www.headphone.com in the ‘Reading’ area, or give us a call at 800-828-8184. We’re
happy to help!
The BlockHead amplifier carries a five-year parts and labor product warranty. If you
have any problems with your headphone listening system, please first call us at 1-
800-828-8184. We will try to diagnose the problem over the phone, which can save
both of us considerable time, effort and money. If the equipment must be returned
for repair, we will authorize a return for you. HeadRoom is the only authorized
service center for HeadRoom products, either 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 responsible for paying the shipping charges to get the
product to us). For units out of warranty, repairs are billed on a time and parts
basis, plus shipping costs. When we receive the equipment, we will initiate repairs
quickly (usually within three working days) and return the unit to you, or call you with
an assessment of the problem.
Crossfeed
Source Inputs
Five-Year Product Warranty