Speaker User Manual

2
SR-1 Owner’s Manual
The SR-1 (Son of Rushmore) is the successor to the Rushmore
loudspeaker system produced by Pass Labs between the years 2003
and 2008. The design goals are similar, but product is different.
The Rushmore aimed for high dynamic contrast and control with
very low distortion. This was achieved with the finest quality
“strong motor” drivers intimately coupled to single-ended Class A
amplifiers. Each driver (deep bass, midbass, midrange, and high
frequency ribbon) operated over a limited frequency band tailored
to its strengths by a passive filter at the input of each of the four
amplifier channels. The high efficiency (98+ dB/watt) cone drivers
also had very high power handling (up to 400 watts), and the ribbon
tweeter extended from the top octave and far beyond the audio
range.
The result was a stunning display of clarity and dynamics. With
each speaker driver enjoying its own amplifier and operated at small
percentage of its capacity, the control was precise and the curtains
of distortion parted to reveal phenomenally subtle inner detail. They
were accurate and musical. They kept their detail and dynamics at
loud and soft levels. Made from Gabro (a deep-sea granite) and
piano-formed Cherry layers, they weighed just under 400 pounds
each and cost a small fortune.
It’s six years later and we no longer make the Rushmore – the cost of
parts, material, processes and shipping have skyrocketed. In this time
we have developed its successor, unimaginatively christened SR-1.
The SR-1 is also a four-way system, and the target is still high
dynamic contrast, control and very low distortion. Realizing
that most customers already have favorite amplifiers or want the
opportunity to experience different electronics and cables, we
designed it with an internal passive crossover.
Having a network mediate between the amplifier and driver is not
without its problems. The loudspeaker drivers no longer have access
to source with a high damping factor, and the variable impedance of
Introduction