I listened to the clip and then read all the following comments. I had exactly the same thought as Ted. Most of the burbles start with an increase in pitch which indicates a slowing down during recording. My thought was an overly wide tape catching in the guides, but reel flanges or other annoyances could cause it. If this is near the end, this type of damage might also be introduced by the tape extruding into the hub's threading slots, but then it is more frequent and doesn't have the pronounced increase in pitch. Since Jamie offered, it would be interesting to see what he can do with it. Obviously, the bias will be distorted in the same way. Cheers, Richard On 8/26/2016 4:06 PM, Ted Kendall wrote: > Sounds like the tape was catching on a spool rim or in guides on > recording, causing a momentary slowing of the tape, and then releasing, > causing a bounce of tape against head. Note how the initial pitch > disturbance is upwards, indicating a slowing of recording speed. I fear > you're stuck with it. > > > On 26/08/2016 20:48, CJB wrote: >> 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. >> > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > -- Richard L. Hess email: [log in to unmask] Aurora, Ontario, Canada 647 479 2800 http://www.richardhess.com/tape/contact.htm Quality tape transfers -- even from hard-to-play tapes.