pure low frequency drone only, single continuous d

pure low frequency drone only, single continuous drone layer, no melody, no notes, no plucks, no tonal phrases, no instruments, no musical performance, constant sustained tone, sub bass to low mid drone texture only, static pitch or extremely slow micro drift only, no rhythm, no pulse, no pattern, no events, no changes, ultra minimal ambient bed, sleep noise drone, loop perfect texture, very long sustain, seamless loop design, dark warm soft tone, no attack, no transients NO kalimba NO piano NO plucked sounds NO melody NO notes NO phrases NO arpeggios NO rhythm NO percussion NO strings NO violin NO pads with motion NO lead sounds NO flute NO wind NO ethnic NO world instruments NO ornament NO expression NO bright tones NO high frequencies NO sparkle NO evolving textures sound texture only, not music