Dahlquist DQ LP-1 excellent condition- Rare!

This ad is for a one owner Dahlquist DQ LP-1 Active / Passive crossover in excellent condition.
SN: 0821
The Dahlquist DQ-LP1 is a unique line-level crossover which combines an electronic Low-Pass filter with a passive High-Pass filter.
The LP1 is intended primarily for integrating a subwoofer into an otherwise full range loudspeaker system. It may also be used to bi-amplify a single loudspeaker system where the crossover point is tunable from 40 to 400 Hz.

As with other electronic crossovers, the LP1 is connected between the preamplifier and the two power amplifiers; one amplifier feeds the main speaker, the other drives the subwoofer(s).

The active Low-Pass section, which feeds the subwoofer amplifier, is continuously variable from 40 to 400 Hz and provides a cut-off rate of 18db per octave. This steep slope is achieved through a non-ringing, staggered arrangement of 6-12-18 db/octave slopes, preserving bass transients. Distortion is exceptionally low, measuring 0.005% THD.

Of particular importance in a device of this type is the performance of the High-Pass section which feeds the main power amplifier. Any distortion introduced in this stage will noticeably degrade the important middle and upper frequencies. In order to avoid such degradation, the 6db/octave High-Pass section of the LP1 is purely passive and can be set for any desired crossover frequency by inserting a capacitor and/or resistor into the terminals provided on the LP1's printed circuit board.

The front panel frequency control does not effect the High-Pass frequency. Push-button switch S1 allows complete passive defeat of the High-Pass section and muting of the low frequency section to instantly restore the system to single amplifier operation.

This combination of active and passive circuitry insures the sharp cut-off and tuneability required to best integrate a subwoofer with a loudspeaker. The Owner's manual (not included) provides instructions for the hook-up and tuning of the LP1, including an easy to use chart showing the appropriate combination of resistors &/or capacitors to achieve a variety of crossover points.
Buyer pays shipping, insurance, and paypal fee if used.
Thanks.