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How to Clean up Cassette to Digital, Need Help
cupelix
post May 3 2003, 00:27
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Thanks in Advance for any help one of you might offer.


I am far from an Audio Pro, yet have been trying to take some old cassette tapes and restore the sound quality they originally had, and enhance it even. As for this file in particular it seems to have lost its high's and mids. When I run it through a simple EQ plugin I just dont get the clarity I need, it just sounds worse.


Here is the steps I took in recording this tape.

#1 - Used a brand new Sony Tape deck , with preamp mixer and got the sound quality as close to 0 DB as I could (as reccomended by many audio recording sites I have read). I recorded at 44.1 hz, 16 bit through my SBLIVE card. I saw no loss in quality from tape to digital.

#2 - I then loaded Wavlab and watched the spectrum analyser and saw the highs and some mids were very low. I tried to raise this up in value but it just made the sound even more distorted than it already was.


I have many tapes like this I would like to restore, re-master (or whatever the term is). I have attached this file (in original .wav format) and uploaded it to the alt.binaries.sound.mp3 newsgroup. The topic is called:

"Sound Pro's can you give tips on how to fix this Audio File? Email - Trick@lvcm.com"

You can also download the .wav file clip at - http://www.lvcm.com/trick/badwav/badwav.wav


Any help on cleanup (what software/settings to use), examples , web links on fixing this sorta of stuff is GREATLY appreciated!!!! Heck if someone wants to clean it up themselves and email it back with the steps you used to do it, that would even be better.

This advice would be Pricessless, thanks again in advance to anyone who can help this audio newbie.

Email - trick@lvcm.com


Thanks,

Trick


PS - I have read about the CEDAR system, is this hardware based only???
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2Bdecided
post May 7 2003, 17:19
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I think the same name has been applied to different tapes in different countries, and at different times. I can also remember three different brands going from good to poor over the years, without changing the name of the tape.


Re: Dolby B. You can be sure, especially if it's a pre-recorded cassette, that there's less high frequency information coming from the tape than the Dolby circuits are expecting. There was a tape deck a few yers ago which allowed you to tweak the frequency reponse before the Dolby circuits to compensate for this. Very useful in theory, but it never worked as well as I hoped in practice.

IIRC there have been various discussions Re: digitally simulating dolby de-emphasis over at the Cool Edit forums, and none of them got anywhere.

I usually have Dolby on, but boost the high frequencies afterwards. Depends on the tape really.

Getting the azimuth right is 100x more important than everything else, as has already been mentioned.

Cheers,
David.
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knutinh
post Oct 17 2013, 07:56
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QUOTE (2Bdecided @ May 7 2003, 17:19) *
IIRC there have been various discussions Re: digitally simulating dolby de-emphasis over at the Cool Edit forums, and none of them got anywhere.

Is the problem that the algorithm itself is poorly documented, or is the problem that a hardware circuit have access to absolute levels etc that are hard to get right in an external digital simulation?

I would think that re-implementing a 70s circuit like that in MATLAB should be easy if proper documentation is available. I don't know what improvements to expect, though.

Might be interesting to "train" the software Dolby decoder by comparing some real-world cassette output to that of a CD assumed to be based on the "same" master. Or "train" it based on the cassette output response to a known stimuli recorded to tape 2 minutes earlier (using Dolby encoding).

-k

This post has been edited by knutinh: Oct 17 2013, 07:58
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2Bdecided
post Oct 17 2013, 12:47
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QUOTE (knutinh @ Oct 17 2013, 07:56) *
QUOTE (2Bdecided @ May 7 2003, 17:19) *
IIRC there have been various discussions Re: digitally simulating dolby de-emphasis over at the Cool Edit forums, and none of them got anywhere.

Is the problem that the algorithm itself is poorly documented, or is the problem that a hardware circuit have access to absolute levels etc that are hard to get right in an external digital simulation?
No, the problem is that you're replying to a post of mine from 10 years ago wink.gif I've since found a solution...
http://www.hansvanzutphen.com/tape_restore_live/
...though I like your training idea. You don't need a specific CD though - just record test signals to a tape, which is what that guy did. The response of Dolby en/decoders is surprisingly complicated and AFAIK not perfectly documented.

Cheers,
David.
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Posts in this topic
- cupelix   How to Clean up Cassette to Digital   May 3 2003, 00:27
- - dreamliner77   JUst a thought If you are recording the wav's...   May 3 2003, 00:41
- - TwoJ   Hi Cupelix PSS - Cedar is a company that does aud...   May 3 2003, 01:49
- - Pio2001   24/96 soundcards should bring nothing for recordin...   May 3 2003, 02:17
- - cupelix   Thanks for the helpfuls replies guys. In response ...   May 3 2003, 02:49
- - TwoJ   Sorry Pio2001 - I didn't mean to imply that sw...   May 3 2003, 03:18
- - woody_woodward   This topic is fascinating to me. I've done se...   May 3 2003, 06:19
- - Andavari   I'm interested in what the results would and w...   May 3 2003, 06:48
- - JeanLuc   QUOTE (Pio2001 @ May 3 2003 - 01:17 AM)1-I sh...   May 3 2003, 09:37
- - Pio2001   QUOTE (cupelix @ May 3 2003 - 04:49 AM)As far...   May 3 2003, 14:39
- - cupelix   I dont know if any of you bothered to download the...   May 4 2003, 00:36
- - woody_woodward   I tried downloading the WAV from your original pos...   May 6 2003, 19:15
- - Xenion   Nakamichi Tapedeck + Nakamichi High Comp II => ...   May 6 2003, 19:21
- - Mac   I want to have a go with your file, but I also rec...   May 6 2003, 22:09
- - _Shorty   usually when it doesn't state which type of Do...   May 7 2003, 02:56
- - DickD   First, I'd agree that you should leave some he...   May 7 2003, 13:25
- - JeanLuc   QUOTE (Pio2001 @ May 3 2003 - 01:39 PM)An MA-...   May 7 2003, 14:43
- - 2Bdecided   I think the same name has been applied to differen...   May 7 2003, 17:19
|- - knutinh   QUOTE (2Bdecided @ May 7 2003, 17:19) IIR...   Oct 17 2013, 07:56
|- - 2Bdecided   QUOTE (knutinh @ Oct 17 2013, 07:56) QUOT...   Oct 17 2013, 12:47
- - gleib   QUOTE (Pio2001 @ May 3 2003 - 05:39 AM)QUOTE ...   May 7 2003, 18:48
- - raynault   I do A LOT of Tapes, mine are all voice. First u...   Oct 16 2013, 05:26
|- - pdq   QUOTE (raynault @ Oct 16 2013, 00:26) Fir...   Oct 16 2013, 13:33
- - 2Bdecided   As neither tapes decks nor soundcards universally ...   Oct 16 2013, 14:20
- - AndyH-ha   There is nothing in the signal path to vary the le...   Oct 16 2013, 22:01
- - raynault   Usually the "pre amp" in the tape player...   Oct 24 2013, 17:40
- - 2Bdecided   QUOTE (raynault @ Oct 24 2013, 17:40) Dav...   Oct 25 2013, 09:54


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