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Cassettes recorded with wrong bias and eq settings
Old 1 week ago
  #1
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Thomas W. Bethe's Avatar
 

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Cassettes recorded with wrong bias and eq settings

We got some cassettes in to transfer/restore that were recorded using the wrong EQ and Bias settings. They all sound very "harsh" and bright and even though they never go above about -6 dBU they all sound distorted. Any suggestions? Thanks in advance.
Old 1 week ago
  #2
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Hi Thomas,

Bias affects the linearity of the recorded waveforms. Once the waveforms are distorted I'm not sure how you could ever reverse that distortion in a linear way.

EQ seems like it should be easy to fix - but, again, you don't know what they started with and the bias issue adds to that - as well as tape age, etc.

Finally, if these tapes have noise reduction on them your job is very, very hard. Levels and EQ will be all over the place and even harder to set to get decoding to work right.

I would suggest that you "remaster" these tapes to make them sound as good as possible without attempting to restore the unknown original sound. I think that's about the best you can do (and the most time effective).
Old 1 week ago
  #3
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loujudson's Avatar
Izotope RX. After doing the best renafer youcan, Azimuth and all.
Old 1 week ago
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Thomas W. Bethe's Avatar
 

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Quote:
Originally Posted by Nonlinear View Post
Hi Thomas,

Bias affects the linearity of the recorded waveforms. Once the waveforms are distorted I'm not sure how you could ever reverse that distortion in a linear way.

EQ seems like it should be easy to fix - but, again, you don't know what they started with and the bias issue adds to that - as well as tape age, etc.

Finally, if these tapes have noise reduction on them your job is very, very hard. Levels and EQ will be all over the place and even harder to set to get decoding to work right.

I would suggest that you "remaster" these tapes to make them sound as good as possible without attempting to restore the unknown original sound. I think that's about the best you can do (and the most time effective).
Thanks for your input...much appreciated.

What a mess...I used RX6 and the azimuth correction from this plugin Stereo Tool 8.40 and some FAB Pro-Q2 and got it to sound much better. The big problem was that this was a dub of a reel to reel mono tape done in the 1960's and whoever did the transfer never checked the bias or eq settings on the cassette recorder. The Azimuth corrector in stereo tool was working overtime. (By the way a nice plugin for azimuth correction)

I found this site dealing with cassette transfers and restorations cassette tape restoration which had some nice insights into cassette transfer problems.

Seem to be getting more and more of these "problem" tapes including one that someone used both Dolby and dbx noise reduction...I don't think I will ever get that one to sound good. They used an external dbx processor and the Dolby on the cassette and thought that the dbx was some kind of single ended noise reduction unit.

Analog is a wonderful medium, too bad it gets so badly screwed up when someone does not pay attention to what they are doing.

Again thanks!
Old 1 week ago
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Perhaps you've already been up this tree, but fancier Nakamichis (and likely many others) allow you to manually select playback EQ settings and NR on the fly. Won't fix distortion from the bias but may get you closer.
Old 1 week ago
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Brent Hahn's Avatar
 

Quote:
Originally Posted by Thomas W. Bethe View Post
... this was a dub of a reel to reel mono tape done in the 1960's and whoever did the transfer never checked the bias or eq settings on the cassette recorder.
If this started out mono, you're not fooling around with trying to fix azimuth errors between left and right... right? You're just using one channel, right? Silly question, of course you are.
Old 1 week ago
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DAH
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Am I wrong that nonlinear processing which the under/overbiasing is cannot be undone?
Old 6 days ago
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Quote:
Originally Posted by Brent Hahn View Post
If this started out mono, you're not fooling around with trying to fix azimuth errors between left and right... right? You're just using one channel, right? Silly question, of course you are.
If you can get good azimuth stability, adding L+R will give better SNR. All other things working as expected...
Old 6 days ago
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Originally Posted by DAH View Post
Am I wrong that nonlinear processing which the under/overbiasing is cannot be undone?
You are right!
Old 6 days ago
  #10
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Thomas W. Bethe's Avatar
 

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Quote:
Originally Posted by Greg Reierson View Post
If you can get good azimuth stability, adding L+R will give better SNR. All other things working as expected...
THANKS!

I had not thought of that.
Old 6 days ago
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Quote:
Originally Posted by Greg Reierson View Post
If you can get good azimuth stability, adding L+R will give better SNR. All other things working as expected...
Big if. And it looks to me like tape hiss is the least of OP's worries. But you could be right. Tom -- which way does it sound better? Single track or a combo?
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