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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: macdaddy on October 24, 2010, 06:19:18 AM

Title: ad2k+ input polarity
Post by: macdaddy on October 24, 2010, 06:19:18 AM
I see that the ad2k+ has what seems to be a hardware manufacturing error on the xlr inputs (pdf link (http://216.92.198.120/sites/default/files/documents/ad2402-96-manual.pdf), p 18 describes the error); a set of custom cables fixes this for the end user...

Do the sonic branded ad2k+ also have this hardware issue, or were they manufactured as a different batch, without this hardware issue..? The manual I linked above is the benchmark manual, and not the sonic one, which is why I ask (don't want to use the wrong cables)...

Thanks.
Title: Re: ad2k+ input polarity
Post by: tedyun on October 24, 2010, 09:50:39 AM
I have a Sonic-branded AD2K+, and I believe it has the polarity inversion error.

I have two recordings of a show from my V3 (polarity corrected): 1. digital output to MTII and 2. analog out to AD2K+

When I took the two recordings and aligned them, you could hear the resulting merge cancel each other out.



I see that the ad2k+ has what seems to be a hardware manufacturing error on the xlr inputs (pdf link (http://216.92.198.120/sites/default/files/documents/ad2402-96-manual.pdf), p 18 describes the error); a set of custom cables fixes this for the end user...

Do the sonic branded ad2k+ also have this hardware issue, or were they manufactured as a different batch, without this hardware issue..? The manual I linked above is the benchmark manual, and not the sonic one, which is why I ask (don't want to use the wrong cables)...

Thanks.
Title: Re: ad2k+ input polarity
Post by: Myco on October 24, 2010, 11:32:01 AM
I've never noticed this with my Sonic branded deck, i'll have to look into it.
Title: Re: ad2k+ input polarity
Post by: tedyun on October 24, 2010, 11:57:09 AM
I'm not sure if a polarity inversion can produce an audible difference (which explains how it went undetected in their production models). Apparently, there are audiophiles out there who say they can hear a difference, but then again, people say they can hear a difference between things like cryo-treated speaker wires vs. normal speaker wires.


I've never noticed this with my Sonic branded deck, i'll have to look into it.
Title: Re: ad2k+ input polarity
Post by: Myco on October 24, 2010, 02:32:20 PM
True, but thank you both for bringing this up though. I hadn't heard of this previously. I don't know that I'll do anything about it or not because I haven't heard anything in my recordings, and no one has brought it to my attention, but still not a bad thing to check it out.
Title: Re: ad2k+ input polarity
Post by: OFOTD on October 24, 2010, 02:49:12 PM
The polarity problem affected both Benchmark AND Sonic branded units.  It is listed in the owners manual for both products.  A cable fixes that on the fly or you can fix the issue in post.

Really the only time you will run into audible problems is when you attempt to mix/matrix with other tracks.   Two channel and you're fine.  More than two and you have to fix the polarity issue.
Title: Re: ad2k+ input polarity
Post by: macdaddy on October 24, 2010, 03:33:04 PM
The polarity problem affected both Benchmark AND Sonic branded units.  It is listed in the owners manual for both products.  A cable fixes that on the fly or you can fix the issue in post.

Really the only time you will run into audible problems is when you attempt to mix/matrix with other tracks.   Two channel and you're fine.  More than two and you have to fix the polarity issue.
This is what I thought, but it is nice to make sure.
Title: Re: ad2k+ input polarity
Post by: it-goes-to-eleven on October 24, 2010, 04:12:19 PM
I'm not sure if a polarity inversion can produce an audible difference (which explains how it went undetected in their production models).

Yes, by all means, spend thousands of dollars, sweat every detail you can control, and then ignore the polarity.... :P

It determines whether the speaker thrusts forward to produce a positive pressure wave, or goes backward. On a symmetric wave, like a sine wave, it probably does not matter.  Some sources, horns in particular, tend to produce very asymmetric waves.   I don't think those can be reproduced correctly if the polarity is wrong, though I have not done listening tests.

Fortunately it can be easily corrected in post.
Title: Re: ad2k+ input polarity
Post by: tedyun on October 25, 2010, 01:31:47 AM
I made adapter cables which reverses the polarity on the analog-in's, so my future recordings will be kosher (though I still can't hear the difference!).

What is the best way to invert the polarity in post?


I'm not sure if a polarity inversion can produce an audible difference (which explains how it went undetected in their production models).

Yes, by all means, spend thousands of dollars, sweat every detail you can control, and then ignore the polarity.... :P

It determines whether the speaker thrusts forward to produce a positive pressure wave, or goes backward. On a symmetric wave, like a sine wave, it probably does not matter.  Some sources, horns in particular, tend to produce very asymmetric waves.   I don't think those can be reproduced correctly if the polarity is wrong, though I have not done listening tests.

Fortunately it can be easily corrected in post.
Title: Re: ad2k+ input polarity
Post by: it-goes-to-eleven on October 25, 2010, 01:48:56 PM
Many/most of the editors have an Invert option.

Title: Re: ad2k+ input polarity
Post by: OFOTD on October 25, 2010, 02:11:46 PM
In SoundForge it's  Process > Invert/Flip