The D/A-1 was a digital to analog converter using FET analog circuitry. Data filtering in the D/A-1 is done by a digital linear phase filter. This filter was chosen because offered very low ripple, and an imposing 100 dB of rejection of the stop-band. It also handles the final error correction. Other filtering systems tended to sound much harsher.

Data Conversion is accomplished by a bit-stream DAC chip. Bit-stream chips offer the most musical performance, especially in the critical mid and high frequency ranges, contributing to the D/A-1’s smooth, extended highs. 

Analog filtering is done in the final stage of the D/A-1. This stage is a low-pass filter, designed to remove high-frequency (supersonic) artifacts of the conversion process. The analog stage is a second-order Bessel filter and buffer circuit using jfets, tin-oxide resistors, and all polypropylene and polystyrene capacitors.

The power supplies in the DA/1 are critical to the overall design. Separate discrete, regulated power supplies power the output filter and the analog circuits in the DAC. These power supplies use polypropylene and polystyrene exclusively. Separate power transformers, and a shielded compartment isolate the analog stage from the digital circuitry.

Specifications:
Sensitivity: 1.0VRMS output at 0dB(maximum output)
Band-pass: 5Hz to 20KHz, +0. -.5dB
Hum and Noise: better than 92dB relative to1.0V output
Distortion: less than 0.05% THD
Phase: 0, 180 degrees of phase shift, switch selectable
Inputs: BNC and RCA Coaxial, TOSlink optical, ST Glass optical optionally available
Output: BNC
Mechanical: 19” Wide X 3.315” High X 14 3/8” Deep
Weight: 16 lbs.