We are digitising 60 year old reel-reel tapes. For this we are using an Akai DS40000 Mk 2 deck, a Behringer USB digitiser, and Audacity. This is all connected to a Toshiba Qosmio G32 running Ubuntu (Linex). The tape plays smoothly with no sticky-shed or squealing. The recording was originally aired by the BBC on FM in the 1970s. The timeline is BBC Transmission > Radio FM Receiver > Reel-Reel recording > Playback on same tape deck > Behringer digitiser > Audacity > Saved as FLAC file. However the resulting digital recording has strange intermittent 'warbles.' It is as though the tape was momentarily caught on something. This is an example. Yes - some do like this kind of music!!! But it is the quality of the digital recording that is of concern. Any ideas please as to cause? http://www.mediafire.com/download/zq9d615mr84jn05/Larmona_-_Yetties__%28warble%29.flac Thank you - Chris B.