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
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