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polarity different on iMac and UA-1EX

 
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craig



Joined: 13 Nov 2006
Posts: 13

PostPosted: Tue Jun 08, 2010 11:52 am    Post subject: polarity different on iMac and UA-1EX Reply with quote

I have been reading this forum for a while and learned quite a bit. Hopefully someone can help me with the following:

I am finally getting around to digitizing some LPs. I was doing some testing to decide whether to use the built-in AD converter in my iMac or the Edirol UA-1EX USB interface I have. So far the recorded signals (from one of the Audio Obstacles test LPs) seem pretty similar. One thing I noticed is that the polarities of both channels of the waveform recorded with the audio in port are inverted relative to those recorded with the UA-1EX. I am not sure which is correct (I sort of suspect the built-in is correct). I am using a standard dual RCA-dual RCA cable from my receiver to the UA-1EX and a standard dual RCA-mini-plug from the receiver to the iMac audio in so I doubt the problem is caused by cable mis-wiring. Has anyone else seen this problem? Does the USB driver (I have the UA-1EX set to use the "advanced" driver) invert the signals? Is there anyway for Amadeus to automatically correct the polarity (other than manually using Effects->Stereo Utilities->Invert Phase)?

Thanks
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CDJonah_alt



Joined: 15 Mar 2007
Posts: 378

PostPosted: Tue Jun 08, 2010 5:02 pm    Post subject: polarity different on iMac and UA-1EX Reply with quote

Not quite sure why one should care if both channels are inverted. Or
more exactly, I don't think it matters at all.

Chuck

craig wrote:
Quote:
I have been reading this forum for a while and learned quite a bit. Hopefully someone can help me with the following:

I am finally getting around to digitizing some LPs. I was doing some testing to decide whether to use the built-in AD converter in my iMac or the Edirol UA-1EX USB interface I have. So far the recorded signals (from one of the Audio Obstacles test LPs) seem pretty similar. One thing I noticed is that the polarities of both channels of the waveform recorded with the audio in port are inverted relative to those recorded with the UA-1EX. I am not sure which is correct (I sort of suspect the built-in is correct). I am using a standard dual RCA-dual RCA cable from my receiver to the UA-1EX and a standard dual RCA-mini-plug from the receiver to the iMac audio in so I doubt the problem is caused by cable mis-wiring. Has anyone else seen this problem? Does the USB driver (I have the UA-1EX set to use the "advanced" driver) invert the signals? Is there anyway for Amadeus to automatically correct the polarity (other than manually using Effects->Stereo Utilities->I
nv
Quote:
ert Phase)?

Thanks




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Sonic Purity



Joined: 10 Nov 2007
Posts: 82
Location: Pasadena, California, U.S.A.

PostPosted: Tue Jun 08, 2010 6:22 pm    Post subject: Re: polarity different on iMac and UA-1EX Reply with quote

CDJonah_alt wrote:
Not quite sure why one should care if both channels are inverted. Or
more exactly, I don't think it matters at all.

Chuck

craig wrote:
Quote:
I have been reading this forum for a while and learned quite a bit. Hopefully someone can help me with the following:

I am finally getting around to digitizing some LPs. I was doing some testing to decide whether to use the built-in AD converter in my iMac or the Edirol UA-1EX USB interface I have. So far the recorded signals (from one of the Audio Obstacles test LPs) seem pretty similar. One thing I noticed is that the polarities of both channels of the waveform recorded with the audio in port are inverted relative to those recorded with the UA-1EX. I am not sure which is correct (I sort of suspect the built-in is correct). I am using a standard dual RCA-dual RCA cable from my receiver to the UA-1EX and a standard dual RCA-mini-plug from the receiver to the iMac audio in so I doubt the problem is caused by cable mis-wiring. Has anyone else seen this problem? Does the USB driver (I have the UA-1EX set to use the "advanced" driver) invert the signals? Is there anyway for Amadeus to automatically correct the polarity (other than manually using Effects->Stereo Utilities->I


I’ll respectfully disagree. While i have not heard differences myself, years ago i read some convincing articles that absolute polarity does matter, for which unfortunately i have almost no references. The issue is asymmetrical waveforms, such as human speech and some instruments. Apparently, with millennia of evolution hearing human voices in one polarity, it is easier to understand them in the correct polarity. I expect this would especially be the case with other sounds causing sonic distractions. Apparently the words can be understood at a lower sound level with the correct polarity. I also recall some discussion of things like bass drum thumps being different experiences when “blowing” vs. “sucking”.

I dealt with this in a different context (radio station, D.J. headphones) years ago, in an article Polarity Matters. That was more a case of relative (bone conduction vs. headphone) vs. absolute (discussed here) polarity, yet some bits of information here and there may be relevant to this discussion (and it references a Mix magazine Stephen St. Croix article on absolute polarity—the only reference i still have).

I’ve not explicitly compared USB A-D vs. Mac built-in A-D polarity as craig is studying. I recall testing my Power Mac 8600/300 DAW’s built-in and finding it polarity correct (this is a vague memory), yet nothing else/more recent. Craig may want to contact Edirol with information on his Mac and OS, and see if they have anything useful to say.
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craig



Joined: 13 Nov 2006
Posts: 13

PostPosted: Tue Jun 08, 2010 6:39 pm    Post subject: polarity different on iMac and UA-1EX Reply with quote

It actually does make some difference (speaker cone compresses air in
one case, rarefies it in the other). As with most aspects of
acoustics, some people are more sensitive to it than others. There
is apparently some carelessness, perhaps because the effect is fairly
minor, among equipment makers, recording engineers (and device driver
writers?) about getting it right. Of course it becomes a bigger
problem when there are several tracks and the different tracks are
recorded with different polarity conventions.

Craig


On Jun 8, 2010, at 12:51 PM, Charles Jonah wrote:

Quote:
Not quite sure why one should care if both channels are inverted.
Or more exactly, I don't think it matters at all.

Chuck

craig wrote:
Quote:
I have been reading this forum for a while and learned quite a
bit. Hopefully someone can help me with the following:

I am finally getting around to digitizing some LPs. I was doing
some testing to decide whether to use the built-in AD converter in
my iMac or the Edirol UA-1EX USB interface I have. So far the
recorded signals (from one of the Audio Obstacles test LPs) seem
pretty similar. One thing I noticed is that the polarities of
both channels of the waveform recorded with the audio in port are
inverted relative to those recorded with the UA-1EX. I am not
sure which is correct (I sort of suspect the built-in is
correct). I am using a standard dual RCA-dual RCA cable from my
receiver to the UA-1EX and a standard dual RCA-mini-plug from the
receiver to the iMac audio in so I doubt the problem is caused by
cable mis-wiring. Has anyone else seen this problem? Does the
USB driver (I have the UA-1EX set to use the "advanced" driver)
invert the signals? Is there anyway for Amadeus to automatically
correct the polarity (other than manually using Effects->Stereo
Utilities->I
nv
Quote:
ert Phase)?

Thanks




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Unsubscribe / change settings at http://two.pairlist.net/mailman/
listinfo/forum_list


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