Dolby Noise Reduction system

Baseball-Man-79 wrote on 6/15/2025, 9:40 PM

I have reel to reel tapes that are encoded with Dolby B. Some even have the calibration tone. I no longer have the Dolby decoder to recover the original music. Is there anything in Sound Forge or Audio Cleaning lab that can emulate the Dolby decoder? I was told that the music just sounds overly bright and decreasing the treble will reverse most of the Dolby effect. Is this true?

Comments

johnebaker wrote on 6/16/2025, 3:07 AM

@Baseball-Man-79

. . . . I was told that the music just sounds overly bright and decreasing the treble will reverse most of the Dolby effect. Is this true? . . .

Partially, the reduction in treble would give an approximation of the true Dolby De-emphasis improving the brightness.

Audio Cleaning Lab has the Cassette NR-B decoder which simulates the decoding of Dolby B + C noise reduction if a Dolby player is not available in the Mastering options, the option is found in MultiMax, Special functions,

Alternatively any multiband equaliser can be used to approximate Dolby B noise reduction with the following settings as a starting point, they may need adjusting depending on the amount of deterioration, ie loss of high frequencies, in the tape recordings.

150 Hz 0 dB

300 Hz -2 dB

500 Hz -4 dB

1kHz -6 dB

2kHz -8 dB

4kHz -10dB

Above 4kHz maintain the -10dB (flat line)

HTH

John EB
Forum Moderator

Baseball-Man-79 wrote on 6/16/2025, 4:54 AM

It seems to be working well in combination with the Cleaning function. Sounds good for a 50 year old tape.

johnebaker wrote on 6/16/2025, 4:09 PM

@Baseball-Man-79

Thanks for the feedback.

. . . . Sounds good for a 50 year old tape . . . .

Out of curiosity, would this be a felt backed tape, I would not expect a standard non backed tape would last that long?

John EB

Baseball-Man-79 wrote on 6/17/2025, 3:35 AM

The time period that I was working with reel-to-reel tape was 1972 - 1979, after I got out of the Navy. The tapes are standard 3M Scotch 150 by 3M. Stored in a dry basement for the last 42 years. I got a used tape deck a couple weeks ago and decided to digitize my collection. I digitized my record collection in 2004 using Sound Forge XP 4.0. (which I still use today.)