Eisen Audio was hired to design and build a rackmount distribution amplifier for a touring sound system, the heralded Despacio Sound System.

This box accepts three different kinds of stereo input sources, scales their levels, sums to L-C-R, and feeds eight transformer-balanaced output amplifiers, each capable of driving hundreds of feet of cable to the individual powered speaker stacks.

A key-switch activates silent opto-mute circuits, so that the speakers don’t “pop” during changeover. This was crucial, because the speaker stacks are operated without any compression, limiting, nor overload protection in order to maintain the highest fidelity.

Given just two weeks notice and a modest budget, we were able to draw and have fabricated a custom front panel and PCB, while reusing our NLA System 8000 chassis, and fortunately we had a stockpile of Jensen output transformers on hand. Two identical units were constructed so that the tour had a backup and/or the larger system could be split into two rigs.

Design/build goals included:

– utmost reliability
– ability to be powered from any mains voltage across the globe
– transparent sound quality
– quiet operation
– ground isolation

NonLinearAudio (nonlinearaudio.com) is a manufacturing brand of Eisen Audio, co-owned by John Klett of Tech Mecca, Inc.