[4candles]

Originally Posted by Five

Okay I had a look and a listen. There's almost no activity above 16kHz, just a slight bit of noise. Using better FA shows quite a steep drop at 16kHz just like the SA is showing. The frequency response is sawed off right at 16kHz in a way that doesn't look like nr. I now believe this is a webcast/mp2 broadcast that's been thru a very clean analog stage which has added that tiny bit of noise in the highs. In terms of sound there's some slurring audible in the sibilants which is typical of FM and lossy but the sound is maybe a bit too nice for a typical RM webcast. I would make note of this information in the .txt file and trade it as a "best available source" most likely SBD>?>?mp2>?FM>unknown (most likely analog) transfer>FLAC

Why doesn't anyone research these things? KCRW broadcasts a 128kbit/s live MP3 stream (which isn't archived). IMO, this is the most likely source.

If the "taper" made the common mistake of recording the webcast by simply pressing record in a sound editor (instead of capturing the original MP3 data), then he/she was recording the analogue sound inside the soundcard - which would add the "tiny bit of noise in the highs" you describe.

But what I'm interested to know is the effect of analogue stages on MP3 compression. i.e. if you take an MP3 file and pass it through an analogue generation what does the spectral analysis look like?