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Wow and flutter on cassette tape + loss of high frequency



 
 
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  #1  
Old December 5th 08, 09:11 AM posted to rec.audio.tech
Phillip[_3_]
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Posts: 4
Default Wow and flutter on cassette tape + loss of high frequency

Hi there. I'm wondering whether there is any work around at all,
software or otherwise, to repair the sound of a cassette tape, that
was recorded on a tape deck a while ago and had this bad sound since
the beginning (to the fault of the deck's head or something else)...
the tape is actually in good condition itself. Anyways, the sound of
the music on the cassette is what I guess is "wow and flutter" - as
well as some loss of high frequency. I don't think I have that deck
anymore what was used to record that tape...I just remember that the
head of that deck was quite dirty...
Sometimes, at a beginning of a song, possibly after another pause in
recording, the sound is very rich and "normal" for about 3 to 4
seconds, then drifts off into a more muffled sound with wow and
flutter.
I've read a bit about azimuth adjustment, but I think that's only to
increase the high frequency on a cassette recorded on another deck,
nothing to do with wow and flutter??

Is there anything that I can do, either with a deck or software (very
willing to try that out) to gain high frequency OR reduce the wow and
flutter? I've been restoring cassettes and records to mp3 for quite a
few years now.

Thanks!
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  #2  
Old December 5th 08, 12:42 PM posted to rec.audio.tech
Mark D. Zacharias[_3_]
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Posts: 23
Default Wow and flutter on cassette tape + loss of high frequency


"Phillip" > wrote in message
...
> Hi there. I'm wondering whether there is any work around at all,
> software or otherwise, to repair the sound of a cassette tape, that
> was recorded on a tape deck a while ago and had this bad sound since
> the beginning (to the fault of the deck's head or something else)...
> the tape is actually in good condition itself. Anyways, the sound of
> the music on the cassette is what I guess is "wow and flutter" - as
> well as some loss of high frequency. I don't think I have that deck
> anymore what was used to record that tape...I just remember that the
> head of that deck was quite dirty...
> Sometimes, at a beginning of a song, possibly after another pause in
> recording, the sound is very rich and "normal" for about 3 to 4
> seconds, then drifts off into a more muffled sound with wow and
> flutter.
> I've read a bit about azimuth adjustment, but I think that's only to
> increase the high frequency on a cassette recorded on another deck,
> nothing to do with wow and flutter??
>
> Is there anything that I can do, either with a deck or software (very
> willing to try that out) to gain high frequency OR reduce the wow and
> flutter? I've been restoring cassettes and records to mp3 for quite a
> few years now.
>
> Thanks!


I've read your post twice and still cannot tell if the tape is recorded that
way or if your current player is at fault.

When you say,

"Sometimes, at a beginning of a song, possibly after another pause in
recording, the sound is very rich and "normal" for about 3 to 4 seconds,
then drifts off into a more muffled sound with wow and flutter."

Do you mean that the same passage may sometimes play OK past the point where
the sound would muffle? If so, I would say it was not the recording deck
skewing the tape while it was recording, rather that your playback deck is
the problem.

On the other hand if you mean a pause and restart by the recording machine,
then yes, the recorder was skewing the tape, the recording is bad, not much
can be done. This is not an alignment problemon the playback deck, but a
slight tweak to the alignment might reduce the effect, though there might
well be a tradeoff in high frequency response. How bad depends on how well
the two decks matched up in the first place.

A knowledgeable tech or technically inclined amateur might be able to tweak
it in real time while copying; this would take a bit of practice and a
couple tries. You could use headphones while making the adjustments.


Mark Z.


  #3  
Old December 5th 08, 03:49 PM posted to rec.audio.tech
Richard Crowley
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Posts: 4,172
Default Wow and flutter on cassette tape + loss of high frequency

"Phillip" wrote ...
> Hi there. I'm wondering whether there is any work around at all,
> software or otherwise, to repair the sound of a cassette tape, that
> was recorded on a tape deck a while ago and had this bad sound since
> the beginning (to the fault of the deck's head or something else)...
> the tape is actually in good condition itself. Anyways, the sound of
> the music on the cassette is what I guess is "wow and flutter" -


Seems unlikely that a "head problem" would cause wow and
flutter. If you are not sure what it is, post a sample online
somewhere and let us hear it.

> as well as some loss of high frequency.


Maybe a "head problem" but just as likely a tracking problem.

> I don't think I have that deck
> anymore what was used to record that tape...I just remember that the
> head of that deck was quite dirty...


Dirty heads would affect playback more than recording.

> Sometimes, at a beginning of a song, possibly after another pause in
> recording, the sound is very rich and "normal" for about 3 to 4
> seconds,


Do you mean when it was recorded or upon playback today?
Does it always happen in the same place regardless of where
you start and stop today? If it is a playback artifact today,
then you may have a chance at recovery. But if it was recorded
onto the tape, then it is what it is.

Can you "diddle" the tape path (like with a cotton swab or
something) during playback to make a differential diagnosis?

> then drifts off into a more muffled sound with wow and
> flutter.


Are you saying that these brief episodes of clarity are free
of wow and flutter? That seems pretty unusual.

> I've read a bit about azimuth adjustment, but I think that's only to
> increase the high frequency on a cassette recorded on another deck,


Part of it may be azimuth, but more likely tracking.

> nothing to do with wow and flutter??


Probably nothing to do with wow or flutter. Unless it is "scrape
flutter"

> Is there anything that I can do, either with a deck or software (very
> willing to try that out) to gain high frequency


Fixing the HF loss problem will almost certainly be a mechanical
fix when you play back the cassette on your machine today. This
is not the kind of thing that is typically fixable with software.

> OR reduce the wow and flutter?


If it really is wow and/or flutter, we have heard of a technique
that uses background hum to gague the instantaneous error
and apply correction (software based). Dunno if this is
commonly available, though?


  #4  
Old December 6th 08, 02:37 AM posted to rec.audio.tech
Phillip[_3_]
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Default Wow and flutter on cassette tape + loss of high frequency

Mark, thanks for the reply. The tape was certainly recorded that
way ;-)
Sorry about that - I did mean a pause and restart by the recording
machine.
  #5  
Old December 6th 08, 02:42 AM posted to rec.audio.tech
Phillip[_3_]
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Posts: 4
Default Wow and flutter on cassette tape + loss of high frequency

Thanks for the reply Richard!
> Do you mean when it was recorded or upon playback today?

When it was recorded, as it's not at the player's fault (it sounds the
same on other decks).
> Does it always happen in the same place regardless of where
> you start and stop today?

It happens in the same place, regardless...
> ...then you may have a chance at recovery. But if it was recorded
> onto the tape, then it is what it is.

Sounds fair enough.
> Are you saying that these brief episodes of clarity are free
> of wow and flutter? That seems pretty unusual.

That's pretty much what it is - and these brief episodes of clarity
are related to the pause and restart of the recording deck (sounds the
same on other decks with playback).

If you're interested in hearing part of a song where you can hear all
parts of the problem, I'll upload it. But it does make sense however,
that since all is at the recorder's fault, no luck. It's not a rare
gem or anything though...

Cheers!
  #6  
Old December 6th 08, 06:27 PM posted to rec.audio.tech
David Matthew Wood[_2_]
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Posts: 11
Default Wow and flutter on cassette tape + loss of high frequency

In article
>,
Phillip > wrote:

> Mark, thanks for the reply. The tape was certainly recorded that
> way ;-)
> Sorry about that - I did mean a pause and restart by the recording
> machine.


The machine was restarted at the beginning of every song? If so, then
yes, you might be able to get more highs by realigning the heads in the
machine you're using to play it back with. It takes a second or so for
things to "stabilize" after the head is engaged, hence it sounding good
for a second or so at the beginning of the recording.
Whether it sounds better or worse after the first couple of seconds,
depends on how the two decks were aligned to begin with.
Of course if the tape path in the recording machine was dirty, that can
certainly increase the chances of misalignment.

In practice, I have found it very rare to have two tape decks aligned
the same way, and the slightest bit of misalignment will have a dramatic
effect on the high frequencies, ESPECIALLY if Dolby NR is being used.
For this reason, if I am doing any tape to CD transfers, I will first
listen to the tape and realign my deck by ear to get the best results.

A trick I use to make this easier, is to combine left and right from my
tape deck so that I'm listening to the tape in mono. That way,
misalignment will show itself in the form of phase cancelation.

Try this: play the tape normally, and then while playing it, switch to
mono and then back to stereo again. If you hear a drastic change in the
overall sound quality (other than normal stereo separation, of course),
it is definitely an alignment issue.
  #7  
Old December 12th 08, 04:33 AM posted to rec.audio.tech
don ward
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Posts: 16
Default Wow and flutter on cassette tape + loss of high frequency

The obvious but often overlooked is the simple little pressure pad....
if its hard or missing you could get a lot of the symptoms you
describe.
Pick up some 25 cassettes at local thrift store in screw housings and
replace the pad and the little spring holding it in place.
dnward
 




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