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Old 22nd November 2020, 17:03   #21  |  Link
Ghitulescu
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Originally Posted by neil wilkes View Post
This is from a rip of the US Vinyl version of 'Smallcreeps Day' by Mike Rutherford.
It does not appear on the UK version of the same album, so had me absolutely baffled.
In vinyl reproduction there are lots of parasitic resonances.
If both (US+UK) albums have been played and digitised using the same hardware, then it can only be the master and a faulty filter/renderer (in the duplication chain), or, an overmodulated vinyl (but this would usually cause many harmonics which are missing). A lot of "analogue" vinyls originate nowadays from digital masters.
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Old 25th November 2020, 16:40   #22  |  Link
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Quote:
Originally Posted by Ghitulescu View Post
In vinyl reproduction there are lots of parasitic resonances.
If both (US+UK) albums have been played and digitised using the same hardware, then it can only be the master and a faulty filter/renderer (in the duplication chain), or, an overmodulated vinyl (but this would usually cause many harmonics which are missing). A lot of "analogue" vinyls originate nowadays from digital masters.
I know this only too well (the last point) sad to say.
I can get the details of the chain used, but it's not the chain otherwise the UK version would look the same so the cutting head theory looks to me like the best solution so far.
It's absolutely looking like a modulated signal.....
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Old 25th November 2020, 16:42   #23  |  Link
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Do you know what equipment and software was used to create this analogue to digital back-up?

And... What audio format is the digital back-up? And what is it's sample-rate and bit-depth?
Will get this information (it's not my rip - I got involved when I was asked what the heck it was, as the ripper had never seen anything like it before.
Sample rate & bit depth is 24-bit 96kHz....
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Old 25th November 2020, 16:43   #24  |  Link
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BTW:
Thanks to everyone who has chipped in here - it really is appreciated.
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Old 27th November 2020, 18:28   #25  |  Link
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It's absolutely looking like a modulated signal.....
It was a time when the companies amused themselves with all kind of copy-protection (prevention) methods. One of these used such signals amongst which 22kHz was a favourite. Such a parasitic signal would affect the Dolby system (like the pilot tone of FM Stereo).
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Old 3rd December 2020, 13:39   #26  |  Link
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Quote:
Originally Posted by Ghitulescu View Post
In vinyl reproduction there are lots of parasitic resonances.
If both (US+UK) albums have been played and digitised using the same hardware, then it can only be the master and a faulty filter/renderer (in the duplication chain), or, an overmodulated vinyl (but this would usually cause many harmonics which are missing). A lot of "analogue" vinyls originate nowadays from digital masters.
I was thinking EMF during capture could be another reason; even if the filters are working properly internally, the AC input is still the wild wild west, along with any other cables laying about. It might be worth making a second capture just to see if it's baked into the record at the same timestamps. If not, then problem solved. If so, well, too bad the recording engineer didn't catch it.
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Old 13th December 2020, 14:11   #27  |  Link
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It seems that we have found the cause of this odd signal - it turns out to be a Black Light lamp near to the setup!
Turn this off & the signal goes away, turn it back on & it returns.
So the above from foxyshadis seems to be on the mark - EMF during capture, probably caused by cheap, nasty screening of the PSU on the Blacklight or the bulb itself (probably not the bulb as the wavelength of the UV is 365nm, and that is far, far too high a frequency when converted so to my mind this must leave the PSU (AC is 100-120 @ 50/60Hz with a 13watt output).

So mystery solved - and many thanks for all your input in this thread.
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Old 13th December 2020, 15:33   #28  |  Link
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Interesting...

It's just reminded me about this: https://www.bbc.co.uk/news/uk-wales-54239180
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Old 15th December 2020, 22:48   #29  |  Link
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Ah, so it wasn't cut into the groove.
And I had assumed perfect capture conditions, not a SMPS close by.
22kHz fits the bill, and the US mains ripple modulation pattern too.

Just today a Neve preamp copy (NV73) came in for repair and what do I see:
A bloody SMPS to get +24V out of +-16V, sitting close to the precious µV-sensitive Microphone preamp, input transformer, physically touching the output pot. Photo anyone ?
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