Mono-a-Mono removes scratches, distortion (due to wear-and-tear, for example), and tape or surface noise from stereo recordings of mono sources. It can be used to enhance digital recordings of old records (whether 78, 45, or 33 rpm, shellac, acetate or vinyl), audio tapes (reel-to-reel or cassette), or even cylinder recordings, provided only that the playback and digitisation of the signal has been performed in stereo, but the original source was mono.

A simple muting algorithm removes the most obvious clicks, and then the unwanted components are removed using a high-order adaptive linear filter. In this way, almost all the unwanted sounds are rendered inaudible, and there are very few cases where any noticeable artefacts are introduced.

In this original “mono enhancer” mode, Mono-a-Mono suppresses any signal components which are present only in the left, or only in the right, channel of a stereo recording. If the original source was mono, this has the effect of removing any noise or distortion introduced during playback, or due to wear-and-tear of the recording medium.

Mono-a-Mono now includes an alternative “vocal remover” function, which instead suppresses those components which are common to both left and right channels of a recording. This mode is most usefully applied to recordings which were originally mixed into stereo form in the studio – so if the vocals have been placed centre-stage, with instruments to either side, Mono-a-Mono can remove almost all the vocals, leaving just the instruments. Unlike many other “vocal removers”, Mono-a-Mono will be just as effective if the vocals were placed off-centre, or if the left and right playback chains are not perfectly matched.

And yes you’re right; Mono-a-Mono is a rather naff name for a program, but it’s meant as a pun. If “Mano-a-Mano” means “hand-to-hand”, Mono-a-Mono could mean “mono-to-mono”. Forget the fact that “mono” actually means “monkey”. In fact, forget monkeys altogether. Mono-a-Mono, the program, works on sounds recorded in mono, but replayed and digitised in stereo. It then produces a mono output, as close to the original (mono) source as possible. So it starts with a mono signal, via a stereo recording, and ends up as a mono file. Hence “mono-to-mono”.