Thanks again to all but still no luck I'm afraid. Tried the culomin_mp file which still didn't work whether I was using an Android tablet, windows phone or windows PC, then tried playing around with volume levels. I realised that if the volume is high, (on any device) the tones from the file sound high pitched and screetchy. I can get them to sound like the normal tape tones by turning the volume (on the playing device) right down. I thought that might have done it but the programme name never appears, both machines (Atari 400 and 130XE) still find nothing. It seems like I have to turn the volume down to stop the sound corrupting in some way, but because of that the volume is too low for the poor old Atari to recognise anything. Not sure what else to try at this stage, very strange. I have no problem playing .tap files into my ZX Spectrum with the same Android tablet.