Covox Speech Thing

The Covox Speech Thing (also known as Covox plug) was a computer accessory for outputting digitized sounds. It is a primitive 8-bit-D/A-Wandler ( a R2R ladder ) in the form of an adapter plug that is connected to the printer port of the PC and thus provides an analog output.

The circuit was marketed around 1986 for around USD 70 per piece. However, since the installed parts cost only a fraction of the finished plug and the circuit is very simple to construct, Covox plugs were soon built themselves of many DIY enthusiasts in different variations - one of which is shown here.

The plug was up in the 1990s, widely used since then correct sound cards were still very expensive. Also in the demo scene, he was quite popular.

, The structure requires the use of accurate resistors having a tolerance of ≤ 1 %. Due to the use of the printer port, it is not possible to simultaneously print and output sound. Conversely to hear when printing loud creaking and rattling, as the print data on the Covox connector are output as sound. Nevertheless, the Covox plug is superior to the system speaker qualitatively far and still offers a cheap way to help old computers to good sound.