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The unfiltered pilot tone was a problem when recording FM radio onto tape, beating against the bias tone and confusing Dolby NR into thinking there was constant
by LeoPanthera 2y ago
The unfiltered pilot tone was a problem when recording FM radio onto tape, beating against the bias tone and confusing Dolby NR into thinking there was constant sound.
High-end cassette decks had an "MPX Filter" which was a sharp 19kHz filter before the recording system.
- CliffStoll 2y agoYou betcha! And FM broadcasts have a high-frequency pre-emphasis, which adds something like 10dB of boost to audio high frequencies. This is to reduce high frequency noise that occurs in analog FM systems. Radio receivers have a matching de-emphasis high-frequency cut. Indeed, both vinyl phonographs and audio tape systems employ similar pre-emphasis and de-emphasis. It's the RIAA curve for phonographs. Not sure what the standard is for mag tape.
- bux93 2y agoFor mag tape, it's different Dolby NR schemes.
- egorfine 2y ago> confusing Dolby NR Accidental DRM even before the "D" came to be.