We transfer and remaster a lot of tapes. Those tapes are all 50 years old or even older. They are degraded and need a lot of TLC. Unfortunately – the channels on the tapes degrade differently.
In other words – the left and right channels not only need different “treatment” – but are also different in volume. In order to make those tapes sound “right” we not only have to restore the audio, but also the stereo “image”.
We do that with the best instruments available – our ears. Only when the sweet spot clicks – the “image” is right.
So here’s the story.
While I was restoring a tape I closely listened to and adjusted the stereo channels. After what I thought to be perfect work I transferred the digital audio to our dedicated listening room. We have better acoustics, better speakers and equipment there to enjoy the sound. But I couldn’t enjoy it the way I thought. And it didn’t matter how much a moved on the chair – there was no “clicking” stereo image. None.
But why?
It took me a while to find out. Somebody had swiveled one of the studio speaker just a tiny bit and they were out of alignment. And while I adjusted the stereo image to match my ears – I completely misadjusted the audio for the “real world” . I had to start over.
But first I had to re-position the speakers so that the stereo image was correct on my working place. How do you do that? Well – you create a test signal and invert one channel. Than you play it and located the spot where you hear the volume of the test signal change significantly. This is the right position for the perfect stereo signal. If you don’t like the spot, you have to move or swivel your speakers and find the listening position again.
Want to try it yourself? Here’s the test audio (1 Minute, 400hz)
Download Test File
For now .. that’s all folks.