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Old 12-31-2011, 08:49 PM
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Old movies and TV shows: audio "bleeding through"?


I'm watching the Twilight Zone marathon on Syfy and noticing something that I've noticed with other shows and movies of a certain age: If there's a quiet moment followed by dialogue or especially loud sounds, you can very often hear a faint "echo" of the coming audio a few seconds before it actually happens.

I'm sure I'm describing this badly, but to the extent that you can understand what I'm talking about, what causes this?
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Old 12-31-2011, 10:29 PM
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It's called print-through. http://en.wikipedia.org/wiki/Print-through
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Print-through (sometimes referred to as bleed-through) is a generally undesirable effect that arises in the use of magnetic tape for storing analogue information, in particular music.

The proximity of layers of tape on the spools of a cassette or reel to reel tape causes a weak imprint of magnetic information to be transferred to adjacent layers, effectively shifting a copy of the signal backwards and forwards along the tape. This can sometimes be heard as pre- or post-echo. [1] Thinner tapes (designed for longer running times, since more tape can be held on the same spool) are more prone to the effect than thicker tapes, and tapes held in storage for a long period or exposed to a weak magnetic field can show pronounced print-through. Digital tapes are not affected in the same manner as the imprint is generally too weak to change the state of bits recorded on adjacent layers of the tape.
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Old 12-31-2011, 10:37 PM
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Hit enter too soon.

I had an LP set (Handel's Messiah, Hermann Scherchen conducting, 1954, monophonic) with that echo in a couple of spots. Yes, the master tape itself had print-through. It was still there on the CD reissue because even with digital techniques it's impossible to remove without affecting the main sound.

(On that recording there are actually a couple of rough spots in the performance and editing as well. I wonder what problems there were prior to pressing the record, but I can't find any detailed information.)

Last edited by rowrrbazzle; 12-31-2011 at 10:39 PM.
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Old 01-01-2012, 06:47 AM
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I've always wondered about that part near the end of Whole Lotta Love (Led Zepplin) if that was tape bleed-through or done on purpose. I tend to think bleed-through. It's where Plant is slowly wailing "Way down inside...Woman...You need it...Love...." or whatever he sings.
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Old 01-01-2012, 06:53 AM
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Yes, I've been noticing this for a long time, and for whatever reason it's worst with Twilight Zone. I'm thinking that, especially in the case of voices, it could be removed by a process similar to the removal of vocals in Karaoke.
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Old 01-01-2012, 09:54 AM
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Thanks for the answer!

It's sad to think that if this print-through is present on the broadcast copies of the show, then it's likely also present on the DVDs. I'd like to think, like panache45, that since it is most noticeable during silences, they should be able to mute it better.
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Old 01-01-2012, 11:13 AM
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I used to notice that a lot during my old reel-to-reel days. I used really long (and therefore thin) reels.

As for the Zep song, I always assumed that was deliberate. At the very least, I'm guessing it was accidentally caused, but deliberately left in. It certainly works for the song.
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Old 01-01-2012, 11:15 AM
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Thanks for the explanation, people! I'm watching the Twilight Zone marathon, too, and I was getting pretty distracted by that strange, ghostly audio effect I was calling a "pre-echo" (which, as it turns out is a fairly accurate and oft-used term for this phenomenon). Very cool to see a good number of others seeking out the explanation for this weird effect at the same time and to see wiser parties being there to so quickly educate the rest of us. I'm starting to like this Internet thing! Viva la informacion!
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Old 01-01-2012, 12:11 PM
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Quote:
Originally Posted by campp View Post
I've always wondered about that part near the end of Whole Lotta Love (Led Zepplin) if that was tape bleed-through or done on purpose. I tend to think bleed-through. It's where Plant is slowly wailing "Way down inside...Woman...You need it...Love...." or whatever he sings.
I think that was caused when Plant sang a scratch vocal track when the whole band played live in the studio, and he overdubbed the new vocal that you hear. The ghost sound is Plant's voice picked up by mics on the drums and guitar and bass amplifiers.

To minimize the effects of print-through in the studio, we kept the taped wound "tails-out."
You had to rewind the tape before using it. The print-through would then happen after the original sound and be masked, rather than a pre-echo sound. Studio tape in the '70's and '80's had a thicker plastic base, AGFA 468, AMPEX and 3M tape stocks, to help with the issue.
We also recorded at faster speeds, usually 30 IPS (inches per second,) so the errors were minimized.
The tape speed of cassettes is 1 7/8 IPS. Most home reel-to-reel recorders used 3 3/4 and 7 1/2 IPS speeds.
Running at 30 IPS, a roll of tape lasted for 16 minutes. You had to record over a take of a song, or buy another roll of tape if you wanted to keep your options open when deciding to mix later.

Ah, the good ol' days.
Happy new year all!
David
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Old 01-02-2012, 08:48 AM
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Growing up in the 70s and watching a lot of TV I started noticing this (definitely in Twilight Zone), and thought I was either psychic or crazy! When I tried to explain it to other, less observant people, they tended to think the latter...
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Old 01-02-2012, 07:10 PM
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Originally Posted by banjoDavid View Post
To minimize the effects of print-through in the studio, we kept the taped wound "tails-out."
I once worked under a Production Director who believed that gravity influenced print-through, so insisted that we shelve all our reels horizontally rather than vertically to minimize its effect. It sounded ridiculous to me but I went along with the practice just to humor him. Thankfully he never made us rewire the studios with Monster cable or paint the edges of all our CDs with green Sharpies.
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Old 06-08-2019, 08:52 AM
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Format?


Cool to notice the echo (both pre- and post- on this current episode of Twilight Zone I'm watching: S1E36 "A World Of His Own" at about 18:33 on the word "No!") and then find this old post.

I'm trying to decide if this print-through happened on the original production tape (Nagra type reel-to-reel, I'd guess), which seems unlikely, as the audio would've been transferred to film after only a few days or weeks -- or on the film archive (35mm?), which wouldn't make sense, would it, because I thought the audio track was optical on that format (though I may be thinking of 16mm film I saw as a kid in school)? Though that would sure have potential for long-term storage. OR -- could it have happened in a later videotape archive?

Anyone?
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Old 06-08-2019, 08:57 AM
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Quote:
Originally Posted by campp View Post
I've always wondered about that part near the end of Whole Lotta Love (Led Zepplin) if that was tape bleed-through or done on purpose. I tend to think bleed-through. It's where Plant is slowly wailing "Way down inside...Woman...You need it...Love...." or whatever he sings.
It was in the original pressings, so it was clearly deliberate. Not likely a problem with master tapes, since it takes time in storage to develop.
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Old 06-08-2019, 09:55 AM
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Quote:
Originally Posted by banjoDavid View Post
I think that was caused when Plant sang a scratch vocal track when the whole band played live in the studio, and he overdubbed the new vocal that you hear. The ghost sound is Plant's voice picked up by mics on the drums and guitar and bass amplifiers.
No, that was very much by design. They reversed the audio, added echo and reversed it again. They invented this technique (or so the story goes), called Reverse Echo, which shows up in other places, albeit not as noticeable.

https://en.wikipedia.org/wiki/Reverse_echo
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Old 06-08-2019, 11:41 AM
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Nowadays, I'd think that they'd be able to fix this digitally in some at least partially automated fashion. Of course, they'd have to care enough to do it, but I bet that could happen on some darling old shows when they get special rereleases.
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