 Based on scaling tests done in 1968, and detailed audio work against the LS5/8 – a large "Grade I monitor" already in use at the time – and with live sources, the BBC Research Department developed the LS3/5, which became the famous LS3/5A that was used from 1975 to much of the 1990s and beyond by the BBC and audiophiles alike.In the late 1960s JBL introduced two monitors which helped secure them pre-eminence in the industry.The 4320 was a direct competitor to the Altec 604 but was a more accurate and powerful speaker and it quickly made inroads against the industry standard.