Pass XP-12 User manual

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pass®
XP-12 Owner’s Manual

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WARNING
Water and moisture: This device should not be used near water ( as per example, near a bath-
tub, washbasin, kitchen sink, laundry tub, wet basement or swimming pool ). Care should be
taken such that objects do not have the opportunity to fall, and that liquid is never spilled onto
or into the device enclosure through openings.
Power Sources: This device must be connected to a mains power source in strict accordance
with the supplied product owners manual. Please verify that the AC mains voltage specified
in the product manual matches those requirements indicated on the unit and the AC volt-
age provided to your location by the power company. The product MUST be connected to a
MAINS socket outlet with a protective earthing connection.
Power Cords: Pass Labs provides a power supply cord that meets all legislated requirements
for the market in which the product was originally sold. If you choose to substitute an af-
ter-market product we urge you to choose one that is fully safety rated by the necessary local
authority.
Power supply cords should be routed so that they are not likely to be walked on, abraded, or
pinched by items placed on or against them, paying particular attention to cords where they
enter plugs or exit from a device. Never under any circumstance insert a cut or damaged
power cord into a mains power socket. Cables should never be connected / disconnected
with equipment powered up. Failure to heed this warning may damage or destroy equip-
ment.
Ventilation: Power-amplifiers run warm, but you should be able to place your hands on them
without discomfort. You must allow for this heat in installation, by providing for free air circula-
tion around the product. Leave a minimum of 6” of space around the amplifier. The ventila-
tion should not be impeded by covering the ventilation openings with items, such as newspa-
pers, table-cloths, curtains, etc.
Other Warnings:
No naked flame sources, such as lighted candles, should be placed on the apparatus; This
amplifier is suitable for tropical climates under 2000m and ambient temperatures of 40 degrees
C or less.
Servicing: To reduce the risk of fire, electrical shock or other injuries, the user should not at-
tempt to service the device beyond that which is described in the operating instructions. All
other servicing must be referred to qualified service personnel.
For Units With Externally Accessible Fuse Receptacle: Unplug the device from all sources of
power before changing or inspecting any fuse. Replace fuse with one of same physical size,
type and rating as that specified by the manufacturer for that product.
Country Specific Warnings:
China: For use at altitude 2000m or lower.
Norway: Apparatet må tilkoples jordet stikkontakt.
Sweden: Apparaten skall anslutas till jordat uttag.
Finland: Laite on liitettävä suojakoskettimilla varustettuun pistorasiaan.
Denmark: Apparatets stikprop skal tilsluttes en stikkontakt med jord, som giver forbindelse til
stikproppens jord.
Trademarks: “Pass”, “pass”, “Pass Labs”, “Pass Laboratories”, Supersymmetery”,
“Aleph”, and “Zen” and are all registered trademarks of Pass Laboratories, Inc., and
all rights thereto are protected by law.

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Introduction:
At Pass Labs we don’t change our products unless we feel that the changes are
significant improvements over previous versions. Because of this we see typical
product life spans of seven to eight years.
We are constantly working on and listening to new things and increasing our
knowledge of circuits and components on sound. Eventually we find some things
worth putting into production because they are significant enough. That time has
come with a new series of preamplifiers.
The new XP-12 starts with a new power supply. It uses an efficient toroidal design with
both an electrostatic and Mu metal shield along with vacuum impregnating and
epoxy fill. This gives us a very quiet transformer both electrically and mechanically.
The power supply circuitry itself is also lower noise and has additional filtering, a little
more complicated but worth it.
The XP-12 uses the single stage volume control borrowed from the Xs line preamp. This
gives us one hundred 1 dB steps with lower noise and distortion while removing some
signal path parts.
The gain circuitry continues to use our favorite transistors from Toshiba but has a larger
higher biased output stage similar to the Xs preamplifier auto bias. This makes longer
and multiple cable runs easier to drive and gives us the advantage of simplifying our
single ended output circuitry while increasing performance.
Overall this makes for a quieter more neutral, musical and versatile control center for
your system.
Thank you for purchasing this preamp. It is my sincere hope that you will enjoy its
sound as much as we do.
Pass Labs

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Setup:
Please read and understand the operational instructions and safety issues associated
with this product. We go through great effort to make a soundly engineered, and
superbly performing product of lasting durability.
We understand that things infrequently go wrong, if you have any questions or
problems please contact either your dealer or the factory, we are here to support the
product and you, the user.
As with all audio electronics the power cable should be the last thing attached and
the first one removed any time you hook up or remove equipment from the signal
chain.
The preamplifier’s voltage and current rating are indicated by affixed tag on the rear
of the preamplifier. The preamplifier typically draws 30 watts during operation. Please
verify that the indicated voltage requirement of this preamplifier is consistent with the
utility voltage at your location.
We have provided a standard IEC AC power cord that fits into the IEC 320 line
receptacle at the rear of the preamplifier chassis. The preamplifier is equipped for
operation with an earth ground provided by the users AC outlet. Do not defeat this
ground.
There are a total of five inputs. Two of the five inputs are balanced XLR only. The
other three inputs are single-ended only. There are two pairs of outputs, one pair
balanced, one pair single-ended.
On the XLR connectors, pin 1 is grounded, pin 2 is the positive signal, and pin 3 is
the negative signal. The RCA connector’s ground is in parallel with pin 1 of the XLR
outputs and the RCA hot is fed from an independent summing junction that maximizes
the X circuit benefits. The RCA, single-ended, outputs are buffered from the balanced
outputs. You may use both the single ended and balanced outputs at the same time.
On the XLR, pin 1 is ground, pin 2 is positive, and pin 3 is negative.

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Operation:
In use the XP-12’s front panel controls and alphanumeric display are quite straight
forward, and intuitive. We encourage you to become familiar with their operation
prior to establishing any input connections with this unit.
After the all the inputs and outputs are connected and double checked, you can
now turn on the preamp by means of the power switch located next to the AC inlet.
The left most button on the front panel is Mute. Pressing this button toggles between
mute on and mute off. Mute on removes signal from the output of the preamp.
The front panel mode switch cycles the preamplifier display through 2 different levels
and off. These two functions are as follows: Bright, Dim and Off. Using any functions
with the display “off” will momentarily bring the display back up to its dim setting.
The two Select switches (designated by left and right pointing arrows) select the
active input, 1 through 5.
Input 5 is unique in that it is linked with the Home Theater (Unity Gain) function. (The
HOME THEATRE FUNCTION is discussed at length later in this manual.) The two select
arrows logically control selections of the various inputs to the preamplifier.
Before selecting the theatre pass through (pass thru) option, it is imperative that the
input device on input number 5 has its gain set to minimum. Failure to follow this
precaution could result in a volume level intolerable to both ears and speakers. (The
standard 2 volt source component, with the pre-amp set to 0 dB, will drive most power
amps to full rated output.)
As an added precaution when “pass thru” is selected the volume ramps upto 89. This
is to prevent nasty surprises when “pass thru” is selected accidentally. The ramp up
sequence can be stopped at any time by hitting any button on the remote.
The theater pass through function bears special attention, this function is only
available as direct access through the hand held remote control. This function is
associated only with input number 5 and has two positions selected with the “pass
thru” button on the remote; those two positions, on and off. This function is useful in
that it allows the preamplifier to function as a unity buffer (0dB gain at volume step
89) for use with components that best function with their own volume controls, such as
surround processors.
When the right-front and left-front outputs of the processor are routed through input
5 of the XP-12 (with the gain of the XP-12 set for Unity), the volume will be under full
control of the processor and the XP-12’s action will be totally transparent. When the
user chooses this setting the software sets the XP-12’s gain to the unity gain setting,
regardless of how it was previously configured.
When at Unity both left and right level controls on the XP-12 will have a displayed
value of 89 (0 dB), You may also set any input to unity (0 dB) by selecting low gain and
setting the volume at step 89.
We have designed this product, so that the volume setting of the preamplifier will

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always revert to the values in the temporary register as you exit from Pass Through.
With the rarest of exceptions this is a very safe transition, very infrequently will the
normal chosen level be higher than 0 dB.
The electronic volume control allows greater than 70 dB range and is driven by a
micro-controller that reads the optical encoder serving as a front panel volume
control. In this manner tracking of the volume of the two balanced channels is
possible with accuracy unavailable on any ordinary volume control, assuring precise
level steps and high common mode rejection in balanced circuits.
Note: The way the volume control is designed, you may need to be at step 40 or 50
before you can hear anything.
Don’t be afraid to turn the volume up to 60, 70, 80 etc. The volume control is an
attenuator so the higher up you use it the more of the original signal is used.
Wayne Colburn’s exceptional volume control in conjunction with the fluorescent
display gives the user ability to replicate volume levels with absolute accuracy in steps
of roughly 1 dB.
We recommend the use of the balanced output mode where possible. Balanced
input to power-amplifiers will typically retain the character of the input mode,
but offers less distortion, less noise, more gain, and more voltage swing, without
compromising the sound.
With balanced operation, the common mode rejection of the preamp reflects
the intrinsic common mode rejection of the topology, the matching of the gain
devices, and the matching of the attenuator channels. In this case we have been
able to keep the total mismatch to about .1%, for a common mode rejection of
approximately -60 dB.
The input system of the preamplifier will exhibit full common mode noise rejection
with passive balanced sources, where the negative input is connected to ground
at the source through the appropriate source impedance. This allows adaptation
of unbalanced sources to balanced operation with passive cable connections in a
manner that achieves the noise rejection of active balanced sources.
The use of a micro-controller allows all of the preamplifier functions to be repeatable
and accurately controlled. The micro processor only controls the functions of the
preamplifier. At no time does any of the input or output signal come into contact with
the digital control signals. The digital circuits are powered by a power supply that is
isolated from the analog supply. Should it ever be necessary to update the software
that controls the functioning of the preamp only the socketed micro processor need
be changed.
Muting relays, which delay connection during turn-on and shut off the output when
insufficient power supply is available to maintain regulation, guard the output of the
preamplifier and offer protection to the power-amplifier and loudspeakers.

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This remote is designed to operate several pieces of Pass Labs
electronics, not all of the functions available on this remote will
be applicable to your Pass Laboratories XP-12.
Power: is not used with the XP-12. This is used on other products
and has no effect on this product.
Mute: pressing mute once will quiet the pre-amplifier outputs;
pressing mute a second time will return you to the previous
volume control setting
Input Selection: Pressing. 1,2,3,4,5 will immediately move the input
selection to that input selection; volume and balance settings will
not be disturbed.
Volume: Pressing the increase (^) button or the decrease (v)
button will shift the volume setting 1dB, holding a button down
will increase or decrease the level until such time as you either
release pressure on the button or reach the limits of the volume
control.
Balance: Pressing balance left (<) or balance right (>) will
increase the level in the left or right speaker, depending upon
which button is pushed.
Tape:is not used with the XP-12. This is used on other Pass
preamps and has no effect on this product.
Pass Thru: Pushing this button twice, sets the pre-amplifier to
volume step 89 (0 dB) and input 5. As an added precaution when “pass through”
is selected the volume ramps upto 89. This is to prevent nasty surprises when “pass
thru” is selected accidentally. The ramp up sequence can be stopped at any time by
hitting any button on the remote. The button must be pressed again to exit “Pass Thru”
and unlock the other command selections.
Display: The default setting for the display is “bright”, pressing the display button
once changes the display to its “dim” or “low intensity” setting, pressing the button
a second time selects “off” for the display. When “off” is selected any other
control function will cause the display to indicate product operational status for
approximately 7 seconds and then the display will once again blank. Pressing the
display button a third time cycles back to a “bright display”
Ext amp on: Selection of “Ext Amp On” applies 12Vdc to a two conductor 3.5mm
TS (tip-sleeve) connector on the rear of the XP-12 control chassis. This is intended to
supply a trigger voltage that will turn on associated equipment such as power amps.
As per convention + voltage is applied to the tip contact and - voltage is applied to
the sleeve contract. Check the owners manual of your pre-amp to see if this function
in compatible.

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Maintenance:
Leave it on or turn it off: The XP-12 is designed to be left on all the time. The exception
to this might be a case where the preamp will not be used for an extended time - in
that case it can be turn off.
Cleaning: The finish can be damaged by harsh cleaners and abrasive cloths. We
find a damp soft cloth works best. You can also use a mild solution of windex or white
vinigar but be careful to avoid the acrylic wndow. The acrylic window should only be
cleaned using “plastic cleaner & polish”.
Remote batteries: The two AAA batteries should be replaced every six months at
least. The batteries are located under the remote back. This is held in place with four
4-40 phillips flat head screws. Please note the polarity of the batteries, putting them in
wrong could cause damage.
Replacing the fuse: The fuse should only be replace with the same type and size as
indicated on the rear. Audio Specialty FUSE: NOTE: The “Overload” and “Time Delay
characteristics” will differ slightly (due to the different metallurgy of the fuse elements)
between commercial grade and audio grade fuses. We can’t guarantee that
your audiophile grade fuse, won’t blow at a different in-rush current threshold, than
your stock commercial fuse. Use of other than approved fuses, may invalidate your
product warranty and result in product damage.
XP-12 Specs:
Power consumption 30 Watts
Gain 9.3dB Balanced
Frequency response: +/- 0.05 dB 10Hz to 20KHz, -1dB @ 100KHz
Crosstalk > 100dB
Residual Noise 15uV 10 – 30Khz
THD < 0.001 @ 1V 1Khz
Dimensions: 17”w x 12.5”d x 4”h
Weight: 20lbs
How to replace the fuse:

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Warranty Information
We go through great effort to make a soundly engineered, and superbly performing
product of lasting durability. But we also understand that things infrequently go
wrong, if you have any questions or problems please contact either your dealer or the
factory, we are here to support the product and you, the user.
All Pass Laboratories products purchased new from an authorized Pass Laboratories
dealer in North America are covered by a transferable, limited 3-year warranty.
This warranty includes all parts and labor charges incurred at the factory or factory
specified repair facility, exclusive of any subsequent or consequential damages.
Damage due to physical abuse is specifically excluded under this warranty.
For this warranty to apply the customer is responsible for returning the product
unmodified to the factory within the specified warranty period. The customer assumes
all responsibility for shipping and insurance to and from the factory or a factory
specified repair facility. The conditions and stipulations of this Pass Laboratories
warranty only applies to units originally sold new through an authorized dealer.
Warranty on factory repair is 60 days and covers only the scope of the original repair.
Non-North America customers should consult with their original Pass Labs dealer or
distributor for warranty repair instruction prior to contacting the factory or shipping
product to the factory for repair.
Non-North American product must be returned to the country of origin for warranty
service. Foreign distributors are only required to offer warranty service on Pass
Laboratories product that they have imported, verifiable by serial number.
Please note: Conditions of warranty service and customer rights for product
purchased outside the United States may vary depending upon the distributor and
local laws. Please check with your local distributor for specific rights and details.
Any modifications to Pass Laboratories products that have not received written
factory approval nullify all claims and void all provisions of the warranty and liability
by the maker or authorized distributor. Should a modified product be returned to
the factory for repair the owner will be required to pay all necessary charges for
the repair in addition to those charges required to return the product to it’s original
configuration.
In the case of safety issues, no product shall be returned to the customer without
those safety issues being corrected to the most recent accepted standards.
Removal or alteration of original Pass Labs serial numbers voids the factory warranty.
Product with altered or missing serial numbers will be suspect as counterfeit or stolen
product.
Pass Laboratories will not repair or in any way indemnify any counterfeit or cloned
product. Pass Laboratories does not offer products in voltages intended for
international markets either to authorized Pass Labs dealers or to third parties located
in the United States or Canada.

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pass®
Pass Laboratories Inc.,
13395 New Airport Rd.,
Suite G, Auburn, CA 95602
530.878.5350
passlabs.com