Related Clues:

• Tone start
• Stereo predecessor
• Stereo precursor
• Pre-stereo sound
• One (Pref.)
• California lake
• The 'M' in MSG
• Less than bi-
• Plane or rail variety
• Stereo counterpart
• One beginning?
• Uni- relative
• The 'M' of MSG
• With 69-Across, what each set of letters in parentheses represents
• One-track