auraflyer,
Even on the BAC 1-11 circa 1980 (UK-registered), the CVR had 5 channels:
each pilot's mic "hot", i.e, live even when pilot not transmitting on radio or intercom;
input to each pilot's headphones (mono);
area microphone.
Quality of audio was excellent (playback by AAIB, Farnborough). Area microphone(s) may not be as good as the others.