DC Offsets are inherent in many early converters, and PCM F-1 tapes have offsets from the converters that need to be fixed. On F-1 recordings that have been transferred digitally, you can see the zero crossings move if you zoom in vertically during silent passages. 

I have some early CDs that have DC offsets that vary from one track to the next, resulting in soft clicks as they come and go. 


-----Original Message-----
From: Association for Recorded Sound Discussion List <[log in to unmask]> On Behalf Of James Perrett
Sent: Tuesday, April 27, 2021 9:55 AM
To: [log in to unmask]
Subject: Re: [ARSCLIST] [EXTERNAL] Re: [ARSCLIST] iZotope RX7 quesiton

It may also be worth pointing out that real DC offsets are very rare in my experience as most analogue to digital convertors are AC coupled.
Asymmetric waveforms where one side of the waveform is larger than the other are often mistaken for DC offsets. Brass instruments often produce these asymmetric waveforms.


On Tue, 27 Apr 2021 at 12:45, Gary A. Galo < [log in to unmask]> wrote:

> Thanks, Tim. I've used the ones in Audacity, Adobe Audition, as well 
> as my regular editor, Sound Forge. I want to recommend a few offset 
> removal programs for my upcoming ARSC conference presentation. If the 
> hum removal in RX can't be disabled, then RX won't be a good choice 
> for this application. I just want to make sure I haven't overlooked something.
> Best,
> Gary
> Get Outlook for Android<>
> ________________________________
> From: Association for Recorded Sound Discussion List < 
> [log in to unmask]> on behalf of Tim Gillett < 
> [log in to unmask]>
> Sent: Monday, April 26, 2021 9:20:41 PM
> To: [log in to unmask] <[log in to unmask]>
> Subject: [EXTERNAL] Re: [ARSCLIST] iZotope RX7 quesiton
> This message did not originate from SUNY Potsdam or one of its trusted 
> senders. Do not open attachments, click on links, or provide your 
> credentials if the source is suspicious.
> Hi Gary,    I'm not sure about RX but Audacity has a DC offset
> correction tool in the Normalize tool where  the Normalize function 
> can be optionally unchecked.
> Cheers, Tim.
> ----- Original Message -----
> From: "Association for Recorded Sound Discussion List"
> <[log in to unmask]>
> To:<[log in to unmask]>
> Cc:
> Sent:Tue, 27 Apr 2021 01:01:06 +0000
> Subject:[ARSCLIST] iZotope RX7 quesiton
>  Hi Everyone,
>  Does anyone use the DC Offset removal tool in RX7? It's part of the 
> DeHum module, but I can't seem to find a way to turn off the hum 
> removal and just run the DC offset removal. Does anyone know if it's 
> possible to do this?
>  Thanks,
>  Gary
>  Gary Galo
>  Audio Engineer Emeritus
>  The Crane School of Music
>  SUNY at Potsdam, NY 13676
>  "Great art presupposes the alert mind of the educated listener."
>  Arnold Schoenberg
>  "A true artist doesn't want to be admired, he wants to be believed."
>  Igor Markevitch
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*       James Perrett
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