PassLabs Rushmore Owners manual

RUSHMORE OWNERS MANUAL

Revision 0.3 May 13, 2004

INTRODUCTION

Pass Labs is pleased to introduce the “Rushmore” loudspeaker system, the first loudspeaker
designed as a commercial offering for Pass Labs by legendary analog designer Nelson Pass. The
“Rushmore” represents 30 years of gestation and over three years of intensive development,
revision and thoughtful listening by Nelson Pass and the staff at Pass Labs. This is an
exceptionally dynamic and tonally balanced active four-way listening system featuring a 15 inch
woofer, 10 inch lower midrange, 6 inch upper midrange and a 4 inch ribbon tweeter. Fit, finish and
build quality is exceptional, and like all Pass Labs product it represents the labor of a few very
dedicated technicians and talented craftspeople.

We believe this to be the most sonically and technologically advanced listening system available
to the consumer today. We also believe the “Rushmore” loudspeaker system makes sense for
today’s lifestyle choices and conveys a tangible and palpable value to the high-end audio
experience. This loudspeaker system minimizes your hardware and cabling concerns thus allowing
you to concentrate on the delightful sonic experience of instrument and voice. The “Rushmore” is
a very sophisticated and complete system that invites you to look past the technology, and feel
entertained both visually and auditorially.

This unique listening system contains four independent purpose-built low wattage amplification
packages plus a Nelson Pass designed four-way active electronic crossover within each
loudspeaker. Each driver receives amplification from it’s own carefully tailored amplifier using Pass
Labs proprietary circuit topologies. Each amplifier has performance characteristics, which have
been optimized to best suit the assigned driver. Three 10 watt single ended Class A amplifiers
power the two midrange and top end driver, and a 40 watt Aleph-X Super-Symmetric amplifier is
dedicated to powering the woofer.

The careful integration of high efficiency speaker drivers and four low wattage class A amplifiers
has given practicality to a full range “Class A” driven loudspeaker, unique in the ability to deliver
approximately 120 dB of exceptionally wide bandwidth acoustic energy at low levels of acoustic
distortion. No longer is the sonic magic of “Class A” restricted to powering your favorite tweeter.
“Rushmore” brings this amplifier magic to a dynamic nine-octave loudspeaker system.

PHILOSOPHY

The mantra of Nelson Pass and Pass Labs in the design of “Rushmore” has been the Zen-like
pathway of “Synergy and Harmony”. Nelson started this particular design by speculating what

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characteristics a loudspeaker would posses if the production values of product now revered as
priceless classics from the golden ag e of audio were still in vogue. Pass Lab s proc ured every
speaker driver available that even remotely looked like it held promise of inclusion into the
“Rushmore” project. Special emphasis was given to locating speaker drivers which excel at
articulating infinitesimal details and have a warm, spacious, easy character. Prospective drivers
were sourced from both the professional and consumer market, ultimately only paper cones and
ribbons would be chosen. Although much attention was lavished on horns, domes and alternative
materials none had the sonic character we desired.

Each driver underwent thorough evaluation and numerous test enclosures until it’s full potential
was realized and documented. Drivers were then evaluated in conjunction; seeking those special
combinations that mutually complemented one another resulting in a refined top to bottom
balanced presentation of sound.

Evaluation of individual components has been a thorough and a thoughtful application of
technology and taste, the eventual mate of the individual pieces we believe represents a collective
far greater than the sum of the selected parts. To achieve this exquisite synergy the passions of an
audiophile and lover of live music have been carefully weighed against the thoughts and
experience of a brilliant analog designer. Nelson’s years of serious listening and patented
groundbreaking designs give credence to the audiophile perception that not all products which
measure well convey the magic and romance that the recording engineer and artist hope to
capture. “Rushmore” bridges the gap between product with spectacular performance and product
with stellar specifications.

ELECTRONICS

The precise matching of the four high efficiency loudspeaker drivers and the four independent
channels of amplification has been significantly enhanced and refined by the four channels of
Rushmore’s internal active crossover. Inclusion of the Nelson Pass designed active line level
crossovers have allowed “Rushmore” to overcome the non linearity and high distortion products
inherent in the technology utilized by other manufacturers in virtually every passive crossover ever
produced.

Foregoing the frailties of passive crossovers in favor of active crossovers, quad amping and very
high efficiency drivers makes Rushmore a very different listening experience.

For the listener this translates to a more refined spatial sound stage, increased awareness of
micro-detail and overall greater approximation of sonic reality. “Rushmore” invites and conveys
musicality even when listening outside of the ideal focal spot. With multi channel formats, listening
at the central point of focus is always preferred, but unlike some products, “Rushmore” does not
demand this; freeing you to listen to “Rushmore” casually as well as seriously. This ability to
convey music outside of a very narrow listening field was a Pass Labs acceptance criterion for this
product, because we believe that music should be an integral part of your life, rather than an
exercise in sedentary isolation. Rushmore successfully banishes the necessity of listening critically
from one rigidly defined sweet spot, letting music fill the entire roo m.

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The high efficiency woofer and midranges in this all-new listening system operate with phase­coherent single-pole crossover characteristics to beyond 6 kHz, and there is a single-pole
equalization curve applied on the extreme bottom end of the woofer. To optimize Rushmore’s
versatility individual amplifiers are provided with sufficient level trimming to tailor Rushmore’s in
room response to best suit your listening environment. To allow the greatest freedom in choice of
source components, and control electronics; inputs to “Rushmore” are provided for either single
ended or balanced sources, and input impedance have been made compatible with either solid
state or tube source electronics. “Rushmore” has been made user and auxiliary equipment
friendly by inclusion of trigger circuits that allows it to be controlled by other home entertainment
electronics.

The gated Fast Fourier response curve of this listening system is truly outstanding, with a usable
frequency response from approximately 20Hz to 40kHz. Each of the four drivers has a measured
sensitivity of nearly 100 dB referenced to 1 Watt at 1 Meter. This above normal sensitivity gives the
“Rushmore” system superb expression of micro and macro dynamics. Within “Rushmore” there is
sufficient Single-ended “Class A” amplification to routinely achieve 120 dB peaks with negligible
acoustic distortion. The high sensitivity of this system offers low level resolution previously enjoyed
only by those people fortunate enough to have experienced the very finest horn systems. Retrieval
of transient detail by “Rushmore” rivals that of legendary electrostatic systems. Characteristically
unlike either horn or electrostatic the “Rushmore” is tolerant and adaptable; allowing it to integrate
into rooms rather than dominating and strictly dictating placement of itself, the listener and
everything else within the listening environment. “Rushmore” strives to be a very different
audiophile experience and to the greatest extent possible fits your world rather than requiring that
you adapt your world to complement its acoustic behavior.

MECHANICAL

The infinite baffle enclosure for this system is structurally stabilized and visually enhanced by a
massive four foot high heat sink at the rear of the speaker, elegantly curved and rendered wood
sides and beautifully machined and polished stone tops, bottoms and fronts. Each piece is a
product of “Old World” construction values that invites tactile exploration and is a delight to the eye.

For many years the material of choice for loudspeaker enclosures has been an engineered wood
material known as MDF (medium density fiberboard); MDF has some real engineering advantages
for speakers, not the least of which is it’s exceptionally low cost and ease of machining. At Pass
Labs we felt that there had to be a better way to achieve the mechanical advantages of MDF in a
more durable and aesthetically pleasing material. To achieve this we acquired the services of
craftspeople versed in the art of piano manufacturing to teach us the century old techniques of
constructing concert grand pianos, we then applied that highly refined craft to speaker building.
We believe the magic of this type of construction is valid for speaker cabinets for the very same
reasons that it is valued as the only accepted choice for constructing fine musical instruments.
These techniques and materials require a very labor-intensive approach to construction, which we
believe is truly justified by this product.

The curved wood side-panels are meticulous formed from many thin layers of engineering grade
apple wood, alder and spruce glued to each other under heat and pressure. The visual layer is

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cherry, each piece chosen for a combination of attractive color and grain. To surpass the
resonance damping qualities of MDF we bond the engineering ply to materials with significantly
different physical properties. For this task we chose highly polished stonework and anodized
aluminum.

The tops bottoms and fronts of “Rushmore” are constructed of quarried Amphibolite. This granite­like stone has its origins in deep ocean earth crust where it has been subjected to millenniums of
tremendous pressure and very slow cooling from the molten state. Under the influence of nature’s
forces this quarried material has evolved with great beauty and considerable stability. Bonding of
stone and wood have created a beautiful structure that addresses the needs of form and function.

We take pride in presenting a product that showcases natural materials in their most
complementary form and in a way that serves our engineering requirements synergistically.
Materials are closely matched into sets, but we believe that part of the charm of “Rushmore” comes
from the subtle uniqueness inherent to these natural materials. Cherry in particular is a fascinating
dynamic material, it’s color and character continually respond to changes in light, for this reason it
has long been coveted as a material for fine furniture.

This product has been art-engineered to elegantly enhance your décor, the “Rushmore” will
become a visual and sonic focal point in your home or studio that you will delight in auditioning and
displaying.

Each speaker weighs approximately 250 lbs., and measures approximately 50 inches high, 18
inches wide and 28 inches deep.

UNPACKING

Due to the unusual mass of these loudspeakers, we urge you to follow our instructions for
unpacking and positioning. Not only does the possib ility exist for d amaging the speake r finish, it is
also quite possible that mishandling could result in damage to your health, architecture and
domestic tranquility. We have given considerable thought to engineering the packing of these
speakers, anticipating that you use the built in features of the shipping containers as an aid to
unpacking and setup. Please consult the enclosed diagrams, relax, enjoy yourself and enlist help.

This product is extremely heavy and will require more than one person to unpack and position it
safely. These loudspeakers must be moved by appliances and supported by structures that were
designed with these loads in mind.

When moving and unpacking Rushmore, we recommend you wear sturdy closed toe shoes to help
avoid personal injury in case of accident. Please observe the normal rules of good posture when
lifting heavy objects to avoid strain. Remove any rings and bracelets to avoid damage to the
surfaces of the product. Don’t unpack this product alone, enlist help; find two sturdy people. Better
yet, get your dealer to do it for you.

Study the description and drawings carefully before attempting this task. Have a plan and make
sure everyone helping knows what that plan requires of them.

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