Pass Labs XP-30 User Manual

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TM

November 25, 2011

XP-30 Owner’s Manual

XP-30 Owner’s Manual

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Introduction

In an area of electronics where it is often thought that everything
that can improve the sound has already been done, where other
designers are concentrating on mechanicals and eye-candy, we offer
better sound.

The XP-30 is the best preamplifier line stage ever made by Pass
Labs. By extension it is possibly the best line stage ever made. It
is the result of several years effort by Wayne Colburn and staff at
Pass Labs and has undergone numerous designs, redesigns, revisions,
more revisions, adjustments and tweaks; more than any preamp
product with the possible exception of the XP-25 phono stage.

Measurably the XP-30 generates less noise, less crosstalk, less
distortion. It delivers greater dynamic range, gain, output voltage
and output current. This is not why it is a breakthrough product.

We value technical excellence, but it is always the sound that is
paramount. Many audio products have measured spectacularly well
but have not gone down as classics because they have not delivered
subjective qualities that keep listeners happy beyond the occasional
initial excitement. With this uppermost in mind we set out to create
a new preamplifier that simply invites you to listen. We want you to
anticipate listening to your entire record collection, again and again.

As part of the process in developing the XP-30 we began by
uniformly upgrading the playback systems of our listening group.
We do not do AB or ABX testing – our people live with prototypes
as long as they like in their own system, and only one component
gets changed at a time. This allows a close duplication of our
customer’s experience and makes it easier to hear differences over
extended time, with our focus remaining on the quality of the sound.

Several set of prototypes were evaluated and refined over a period of
three years. This period also saw the final development of the XP­25, and its presence allowed us to work in as much synergy between
the components as possible. Several different power amplifiers
also participated, including XA.5 amplifiers, prototype “Concept”
amplifiers, SITs, and even tubes.

In the end everyone agreed on the sound - music flows through the
XP-30 with greater ease, spatial development and dynamic contrast
than anything else we have heard. Wayne even managed to fit in
a couple of my requested features – enhancements for bi-amping,
and enough gain and voltage swing that the XP-30 can drive power
amplifier output stages all by itself. Me, I wrote this introduction
because Wayne was too modest to. - Nelson Pass

XP-30 Owner’s Manual

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Description

The XP-30 is a modular preamplifier consisting of one control /
power supply chassis and additional gain chassis, each containing the
analog circuits of a single channel. The XP-30 is meant to typically
be used as a two-channel product, but you can use the control chassis
to serve up to six channels.

Each channel individually provides master and slave outputs. The
relative level between the master and slave outputs of each channel
is adjustable by a knob on the front panel of each individual gain
chassis. If you have ever wanted to bi-amp your loudspeakers,
you might appreciate that this feature allows easy use of different
types of amplifiers for the low vs the high frequencies, adjusting
the relative levels as needed. If you need big power and control on
the bottom but want the sweet character of tubes on the top, you
may wonder how you ever got along without this. Or why other
companies don’t offer it.

It is even useful when the same types of amplifiers are used –
typically without the full load on each amplifier the subjective balance
still needs minor tweaking.

All connected gain chassis respond to the master level adjustment on
the main control chassis through a completely new volume control
covering a range of 100 dB in precise 1 dB steps.

Both outputs of each channel are offered as single-ended and
balanced outputs having the same gain and impedance and both may
be used simultaneously with no degradation.

There are five (5) regular inputs, a special home theater bypass input
and tape input for those needing any side loops for recording or
signal processing.

The control chassis also supports a mono function between the
separate different analog stage chassis.

The power supply in the control chassis is large enough for
somebody else’s power amplifier. It contains a pair of highly
efficient, low-noise Plitron transformers in dual mono topologies,
emi filtering, large capacitance reservoirs, and of course the isolation
that comes with being in a different chassis from the analog gain
stages.

XP-30 Owner’s Manual

Something else that was on Nelson’s wish list – the ability to drive an
amplifier output stage by itself: Do you require a preamplifier deliver
a fraction of a volt to the power amplifier or peaks in excess of 50

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volts to a balanced no-feedback follower output stage?

The XP-30 is fully capable of both tasks at once. The internal gain
of each stage can be boosted another 16 dB via an internal jumper
and the preamp can serve as the low source impedance front end to
the new generation of Class A power followers. Don’t laugh – they
already are for sale, and there are more coming your way. If you
have an XP-30 you won’t have to buy a new preamp...
The output impedance of each output is quite low and thus able to
better drive long cable runs or cables with greater capacitance or
amplifiers with low input impedances.

XP-30 volume control is totally new and sonically unique. It’s
measured performance - distortion, bandwidth, noise, and resolution
is beyond reproach. It preserves the dynamics and detail of the
music passing through it, and scales this performance over its 100 dB
attenuation range.

Wayne Colburn has further refined his thinking of how the active
circuit should serve the music. Like Nelson, Wayne looks at parts
and sees not applications but potentials. The XP-30 uses a new and
more advanced version of the gain modules that have been popular
in Pass products for the last ten years. It has lower distortion and
wider bandwidth than its predecessor and also features a dramatically
higher input impedance. This improved version of our symmetric
topology sounds so exquisite that that it has also been adopted in the
new “Dual Chassis Amplifier” prototypes. Pass Labs has made large
purchases of discontinued Toshiba Jfets and Mosfets to support
production of this new gain stage for the next ten years.

XP-30 Owner’s Manual

Each of these efforts have contributed to a preamp that is more
resolving, dynamic, spatially accurate and closer to the real joy that is
music.

To summarize:

The XP-30 is a time machine, offering a greater “look-back” at the
original musical performance and conveying additional insight to the
artist’s creative intent. The XP-30 will help you rediscover the joy of
your record collection.

It’s measured performance is our best yet.

It has some features that will help you get more out of your system
– things that you may not yet appreciate.

The XP-30 is the preamplifier that we built for ourselves.

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