Digital to analog audio converter box
To keep hum and other spurious signals from contaminating the audio, I'd recommend using the optical connector instead of the coaxial (if you can find the necessary fiber-optic cable) a coaxial hookup can pick up or radiate noise that may then leak into the audio outputs. Using the optical input, our spectrum analysis showed absolutely no power-line components above the unit's inherent noise level, which itself was extremely low. The distancing of the power module from the converter circuitry made possible by its 6-foot cord is probably partly responsible for the DAC-in-the-Box's extremely low hum output. Power enters the unit from a small modular power supply through a triple-conductor mini-phone connector. A front-pan-el LED lights when the circuitry has locked onto the incoming data. Audio Alchemy says that the DAC-in-the-Box will accept digital signals with sampling rates between 30 and 50 kHz, a range that covers all consumer digital formats.
The optical connector is of the standard Toslink variety. The audio outputs are standard gold-plated phono jacks, as is the coaxial digital connection. And that's about it, apart from miscellaneous chips and other parts tying together the principal integrated circuits (known in the business as "glue" circuitry), the analog output amplifiers, and the de-emphasis network (for playback of digital recordings made with pre-emphasis). The filter gets its input from a standard digital-inter-face chip. A single dual-channel eight-times-over-sampling digital filter drives both DAC's with 18-bit data. These chips are of the traditional "ladder" or "R-2R" variety, not the newfangled 1-bit type.
And it is by far the least expensive outboard D/A converter we have encountered.Īctually, "DAC-in-the-Box" is somewhat of a misnomer, since the device contains two separate 18-bit integrated-circuit D/A converters, one for each channel. It's a neat, even cute little device that hooks up to a standard digital output with either a coaxial cable or an optical connector. If you have doubts about the performance of the digital-to-analog converters (DAC's) in your CD or laserdisc player-because they are too old to have benefited from recent improvements in DAC design, or because they incorporate some signal processing of dubious value-you might consider replacing them with Audio Alchemy's DAC-in-the-Box (DITB, for short).