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
> 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?
> Thank you -
> Chris B.
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