DOSBox Staging 0.83: Covox and LPT DAC Variants Explained

DOSBox Staging 0.83 documents several emulated parallel-port digital-to-analog converter (DAC) devices. This guide summarizes the documented device choices and the default filters that the official manual associates with them. It is a source summary drawn from the official documentation, not a hands-on tested procedure.

What Covox variants are

Covox variants appeared in the late 1980s as inexpensive ways to get digital audio output from a PC. They were small DAC devices, far simpler than a Sound Blaster, and consisted of a dongle that plugged into the parallel port, also known as the LPT (Line Print Terminal) port. They could play back digitized sound and speech at quality considered decent for the era, and are sometimes called LPT DAC devices for that reason.

Documented device options

The manual lists the following values for the parallel-port DAC device selection, including the default.

Default filters per device

The manual documents a default filter for each DAC device and the equivalent filter setting. The Disney Sound Source uses a 2nd order high-pass at 100 Hz plus a 2nd order low-pass at 2 kHz, equivalent to hpf 2 100 lpf 2 2000. The Covox Speech Thing and Stereo-on-1 are each documented with a default 2nd order low-pass at 9 kHz, equivalent to lpf 2 9000.

Turning the DAC filter off

The manual section covering the parallel-port DAC filter documents an off option. It does not document a specific default value in the excerpt collected for this guide, so consult the manual for the current default before changing it.

Scope

The documented behavior above applies to the parallel-port DAC devices described in the DOSBox Staging 0.83 manual. Confirm your version against the manual before relying on these values, and use the manual as the authority for any settings not covered here.