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Re: [ARSCLIST] De-clicking



Hi Doug:

Thanks for the further info. I had never heard of this oxide-scraping technique until today.

Now you have me curious, so a followup. How come you'd be working with old tapes from Davies and Towers instead of their source disks? Are there cases where an old disk-to-tape transfer is preferable to going back to the disk, or is it more likely the case that the original disk is lost or destroyed?

Finally, like I said I only did the tape method very little and have done almost all of this kind of work in the computer. I learned from standing over Art Shifrin's shoulder when he was working on some problematic disk transfers. For loud ticks and pops in spoken word, it's usually OK to just zoom in far enough to grab the microsecond of waveform and zap it. I was surprised in one case that I zapped 50 such waveforms, spending a solid 4 hours at it, and it eliminated all of ... 1.5 seconds from the program time! In a half-hour spoken-word program, this is undetectable. When it comes to music, it's not so simple. I've found that human beings' own time-counting is "musical" (ie non-robotic, ie imprecise) enough that some of these ticks and pops can be zapped, especially in pauses. Where it doesn't work is in percussion notes or even a fast stacatto (sp?) of any acoustic instrument. Back when I first got into computer-aided audio, I would select the tick/pop waveform and reduce its level to something lower than the surrounding music and that usually made it quiet enough to not be detrimental to the listening experience. Then Art taught me how to write out short ticks and pops by learning how to recognize what the correct waveform SHOULD be and simply writing it in using the pencil tool in Soundforge. This works great with what I call a linear disturbance -- ie when the needle doesn't jump the groove but merely rides over a scratch or piece of crud or little vinyl zit. When the needle jumps the groove like with a gouge or a big vinyl zit, all bets are off because there is no underlying music to mimick. I try to avoid records in that bad shape but sometimes you get 'em. After years of doing this, I've come to the conclusion that the most natural-sounding solution is just reduce the pop waveform to the level of the accompanying music. Any listener to a disk transfer will know that the medium is mechanical and thus there will be surface noises on even the best examples. That said, I'd love to see the waveforms coming out of a laser turntable on similar surface injuries. I would guess they'd be similar because a gouge or a big vinyl zit is a manufacturing or handling error that actually destroys part of the groove, so there can by fact be no underlying music to patch in. By the way, I know a musician would cringe at this, but there have been a few cases where the players so carefully replicate a phrase in its repeated passage that I've been known to "loop" the undamaged phrase over where there was a bad surface injury. The only time this has worked is when the phrase is repeated so perfectly that there is no time-shift. Some musicians are amazingly accurate with this, and yet don't sound robotic like a synthesizer.

-- Tom Fine

----- Original Message ----- From: "Doug Pomeroy" <pomeroyaudio@xxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Friday, July 27, 2007 8:28 PM
Subject: Re: [ARSCLIST] De-clicking



Hi Tom,

I assume the reference to "Jack" is a reference to Jack Towers.
He will tell you he got the oxide scraping technique from discussions
with the late John RT Davies. I have worked with some of John's tapes,
and I can report his scraping was VERY carefully done.  I have also worked
with some of Jack's tapes, and I have to say Jack usually took off too much
oxide, producing an obvious dropout; I had to fix lots of these, using
crossfades, or by careful deletion of part of the audible silence.

doug pomeroy

From: Tom Fine <tflists@xxxxxxxxxxxxxxxxxxx>
Reply-To: Association for Recorded Sound Discussion List              <ARSCLIST@xxxxxxx>
To: ARSCLIST@xxxxxxxxxxxxxxxx
Subject: Re: [ARSCLIST] De-clicking
Date: Fri, 27 Jul 2007 19:52:44 -0400

Hi Parker:

I'm sorry, I misunderstood what you were describing. Now I understand. That would absolutely work, but what an art form! Wow, I wonder what Jack experimented on to learn the art.

-- Tom Fine

----- Original Message ----- From: "Parker Dinkins" <parker@xxxxxxxxxxxxxxxxx>
To: <ARSCLIST@xxxxxxxxxxxxxxxx>
Sent: Friday, July 27, 2007 8:14 AM
Subject: Re: [ARSCLIST] De-clicking


on 7/26/07 8:06 PM US/Central, Tom Fine at tflists@xxxxxxxxxxxxxxxxxxx
wrote:

But if you do Jack's method, you're left with the same problem as Terry -- a
microsecond of blank space, which is just as noticeable and annoying as the
click.

By scraping off only the precise moment of the click, you're in effect creating a high speed fadeout and fade-in. It's audible, but less annoying than the click itself.

There's an overview of analog and digital de-clicking at
http://www.cedaraudio.com/intro/declick_intro.html - but without a
description of manually scraping off the oxide.

--
Parker Dinkins
MasterDigital Corporation
Audio Restoration + CD Mastering
http://masterdigital.com


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