I received an email from Andrew Pearson of the British Library providing some hints in reducing noise during playback on the Studer A807 tape machine. He would be interested in hearing from people who had other ideas and people who had either successes or failures attempting his techniques.
Please remember that these modifications are provided “as is” and neither Andrew Pearson nor Richard L. Hess (owner of this site) can or will accept any responsibility for any damage, loss-of-use, or any other incident relating to this information. You may contact Andrew at Andrew(dot)Pearson(at)bl(dot)uk
RE: Clock and other digital noise on the Studer A807
I managed to reduce the 9.6kHz contribution by moving a wiring loom from the capstan servo board away from the audio boards. I discovered that sliding the audio board assembley out past the capstan board caused the interference to pass from mainly channel 2 to channel 1, as that board became closer, and discovered the source of noise in the J1 connector – ‘M3-9600’ signal. I redirected the loom up towards the spooling motors and made about 9dB improvement, although in some cases the 28.798kHz became slightly worse. However, that’s much less objectionable than the audible whistle from the 9.6kHz.