At our organ club earlier this month we had a local lad (well, he was in his early 30s) come and play piano. This is unusual for us, as we usually have one of the professionals playing, and they bring their own organ, or keyboard with pedals .. and have a couple of loudspeakers up on poles. But I had heard this lad playing a couple of times before, on a Grand Piano. He does all the arrangements for our Operatic Society, and plays for whatever Pantomime we have over Christmas. He also playes at a couple of music schools in London. And I thought he was absolutely brilliant! So I put the word about the club that although we didn't have a professional coming, we never-the-less had a superb pianist on the agenda.
I asked the organiser how they were going to get a Grand Piano up on the stage in the Football Club where we held our meetings, and she said they couldn't do that .. but that he would bring his own equipment. Which he did, a keyboard with a Sustain Pedal. Just the ticket, and a lovely sounding keyboard piano.
But .. (you knew there was a 'but' coming, didn't you?) ..
.. he had one single speaker (about 1' 6" across) and had it connected to his keyboard via a Mono output. I reckon, as all his playing came from straight in front of us from the one speaker, with high notes and low notes all mixed up and indefinable from each other. A very 'hollow' sound, and not a happy experience!
And then I thought, of course, every time I have heard him play he has played a 'real' piano. Whether a Grand or an Upright, the longer strings for the bass notes are to the left, the hammers for the middle notes come from the centre, and the high notes come from the shorter strings on the right. In other words, when listening to a real piano you are sort of listening 'in stereo'. So why didn't he take a stereo output from his keyboard? There are several schools of thought on this, which are explained in the YouTube videos that follow.
First, lets take a look at how a 'real' piano might be recorded to get a stereo recording. Of course to record a 'real' piano you need mikes, and these are positioned in this video roughly where your ears are, as that is where you 'hear' the piano you are playing. The video is definitely in stereo, and you can hear left and right predominance when he speaks (and at one point he clicks his fingers too). When he plays the piano, the sound is as your ears would hear it, and notes are not particularly 'panned' to the left or the right. And the piano sound is in stereo, as indicated by the waveform I have put underneath.
Here is the recording of the piano bit he played .. as MP3.
Maybe do a right-click to open this up in a New Tab
'Live' piano recorded in stereo using mikes
.. and below is the waveform of the piano being played. Clearly in stereo as indicated by the green volume bars, and by comparing the left and right channels of the waveform.