On 8/26/16 4:39 PM, Richard L. Hess wrote:
> 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.
The warbles show up quite clearly in a spectrogram (I'm using Izotope
RX5). Each warble starts with a sudden upward change in pitch, followed
by a damped sinusoidal pitch oscillation with a period of about 40
milliseconds. Immediately following the initial pitch change, there
appears to be a slight loss of tape to head contact for about 10
milliseconds (there's a brief dropout which affects only frequencies
above about 2 kHz). Sure does look like the tape was jamming in the
recorder. If this was happening during playback, a) the initial pitch
jump would be down, not up, and b) I think you'd see a very obvious
mechanical disturbance of the tape break arm.
-- John Chester
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