Hi Ray,

I think what you are referring to is the 'CHORD' sound, which is normally active below the Split Point, until you start the Auto Accompaniment playing.
You can confirm this by pressing 'Program Menus' > 'Sound' > 'Part Setting' and use the Up-Arrow button to scroll through all the sounds allocated to the different parts (Right1,Right2,Left, Parts 1 through 16, Bass Pedal) an finally CHORD. This sound is generally set to an Electric Piano by default, but you can change it to any other sound you wish....
You can also set its volume to a lower level or even effectively turn it off by setting the volume to '0'.
Having set the sound and volume of the CHORD part, you can save this setting in Panel Memory along with all the other settings which you would normally include, in Panel Memories.
When you load another file from SD Card or Floppy Disk, the settings for the 'CHORD' sound will change to the sound which was present, when the file was originally saved.

Hope this answers you question Ray