Why do I see a stronger left channel?

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Midranger
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Why do I see a stronger left channel?

Post by Midranger » 29 May 2012 06:26

I've been ripping a lot of 12" disco singles. I've noticed that a clear majority of them always look like the left channel is substantially hotter. Here's an old Crown Heights Affair 12" that shows what I am seeing.

http://i.imgur.com/n0rLb.jpg

When I first started doing this I thought there might be something wrong with my turntable causing a channel imbalance but then I would occasionally rip some LPs and noticed that the channels usually look much more equal. Some LPs show a hotter left channel but I would say it's a minority whereas 90 out 100 12" singles look like the image above.

Can anyone tell me what I am seeing exactly? I've read a bit about things like mid side mastering, making the bass mono and other mastering trivia that make me suspect I'm seeing something like that rather than a problem with my hardware or ripping process.

Jim Leach
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Re: Why do I see a stronger left channel?

Post by Jim Leach » 29 May 2012 13:50

Difficult to say for sure.

If ALL records were hotter in one channel (as mine are) then there is an equipment issue to be addressed (phono preamp in my case).

if it is not all recordings that are affected, then it could very likely be the way the recording was done.

Best test is to find a digital version of the same material you have on vinyl (for the exercise- I understand you are ripping vinyl that is not available otherwise) and compare the image.

In my case I adjust the balance of the preamp to compensate when I spin vinyl. I am planning a full gut and rebuild of the phono pre and should get the probem sorted out then.

jake

Re: Why do I see a stronger left channel?

Post by jake » 29 May 2012 14:18

If everything is balanced properly, it must be the anti-skate. The groove size difference between LP's and 12" singles may be letting the difference appear more in 12" format. I would try using zero anti-skate, and then try anti-skat usual setting PLUS 1, see what the difference is. Balancing issues drive me crazy.

Midranger
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Re: Why do I see a stronger left channel?

Post by Midranger » 29 May 2012 23:41

Thanks for the input. In regards to anti-skate settings, I've taken screenshots of some various settings. These are all line-level captures from the tape-out of my Onkyo A-9555 with no gain applied. I see the same behavior regardless of cartridge/headshell used as well.

A standard new LP with my normal anti-skate setting of 1.75g:
http://i.imgur.com/p0rp1.jpg

12" single with normal anti-skate setting of 1.75g:
http://i.imgur.com/tfFEO.jpg

12" single with 0g anti-skate:
http://i.imgur.com/zXsS6.jpg

12" single with 2.75g anti-skate:
http://i.imgur.com/UTHIz.jpg

12" single with 3.75g anti-skate:
http://i.imgur.com/FpHBe.jpg

My anti-skate definitely works as evidenced by how the arm behaves on a single-sided record. I think the photos above should show why I was wondering if this was not something to do with how these singles were mastered or cut.

Another thing I would point out is that when I listen to these records, either the original vinyl or my digitized copy, I don't detect that the left channel sounds louder or that there is a channel imbalance. Imaging seems like it is pretty much what it should be, it just looks like there is noticeably more stuff in the left channel.

Hanuman
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Re: Why do I see a stronger left channel?

Post by Hanuman » 30 May 2012 23:33

If they're 45rpm singles you're doing then do a test capture at 33rpm to see what happens to the levels then. I'm not suggesting this as a workflow, only to remove one variable for the comparison with the regular LPs. The (linear?) scale of a waveform display can a tad misleading. Whats the difference in dB left-to-right?

Midranger
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Re: Why do I see a stronger left channel?

Post by Midranger » 03 Jun 2012 01:50

Hanuman wrote:If they're 45rpm singles you're doing then do a test capture at 33rpm to see what happens to the levels then. ... The (linear?) scale of a waveform display can a tad misleading. Whats the difference in dB left-to-right?
Thanks for the suggestion. Using Audacity, here are two captures of the same record(a 45rpm 12inch single) done at both 33rpm and 45rpm with the waveform displayed in both the default waveform(linear?) and waveform(dB).

33rpm waveform:
http://i.imgur.com/I6Rahh.jpg

45rpm waveform:
http://i.imgur.com/jONHPh.jpg

33rpm waveform(dB):
http://i.imgur.com/KIJOTh.jpg

45rpm waveform(dB):
http://i.imgur.com/wwb8Xh.jpg

The difference doesn't seem to appear as dramatic with the dB display but it's still noticeable. What do you think?

This isn't a showstopper kind of thing for me but I am just trying to understand what I am actually seeing..

bpbutler
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Re: Why do I see a stronger left channel?

Post by bpbutler » 03 Jun 2012 02:33

It looks like all they're doing is changing the vertical scale from a linear to dB scale, but not changing the vertical axis to a log plot. This isn't very useful.

From the linear plots, I estimate you have about a 3dB difference, which is about half power in one vs the other.

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Re: Why do I see a stronger left channel?

Post by alanchamberlain » 12 Jun 2012 19:44

is it possible that too much anti-skating has been applied for a long time which could result in the stylus wearing down more on the right side? Rega arms are notorious for being inaccurate - for a 1.5 grammes stylus weight usually a 0.5 anti-skate setting is about right. I think what you are experiencing is what probably (and unknowingly) happened to me although I have no exact data to bear this out. I only remember that when I bought a new cartridge left and right channels were virtually identical regarding volume.

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Re: Why do I see a stronger left channel?

Post by Midranger » 14 Jun 2012 03:17

alanchamberlain wrote:is it possible that too much anti-skating has been applied for a long time which could result in the stylus wearing down more on the right side?
No. The above screenshots are all from a new Nagaoka MP-110 with less than 40 hrs on it. I can reproduce the same thing with my Ortofon OM3E, Shure M44-7 or Shure Whitelabels. I did speculate that perhaps some of these records had been played a ton with the anti-skate set to 0(not an uncommon practice with DJs) and worn out on one channel as a result but I don't think that is likely either as I can also demonstrate the same behavior with minty records that I acquired sealed. It happens across different turntables, soundcards, phono preamps etc. If it were gear-related I would think I would see consistent behavior across all records.

Again, this isn't with all of my 12" singles, just a majority...60-70% perhaps. It really makes me think it is something with how they are mastered but I don't actually know what it is yet.

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Re: Why do I see a stronger left channel?

Post by Alec124c41 » 14 Jun 2012 03:21

Out of curiosity, try switching the left and right phono leads, and see if the graph changes.

Cheers,
Alec

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Re: Why do I see a stronger left channel?

Post by Midranger » 14 Jun 2012 04:41

Alec124c41 wrote:Out of curiosity, try switching the left and right phono leads, and see if the graph changes.
Phono leads reversed:
http://i.imgur.com/oqbO5.jpg

All the screenshots you above in this thread happen to be from this 1976(first year of commercially available 12" singles) pressing:
http://www.discogs.com/Crown-Heights-Af ... se/1112733

Here's another example but from seven years later. This is a record I got sealed and has been played maybe 10 times max. http://www.discogs.com/Sylvester-Tell-M ... ease/99079

http://i.imgur.com/g8And.jpg

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Re: Why do I see a stronger left channel?

Post by hey_homes » 25 Jun 2012 11:22

I'm glad to see this thread as I have exactly the same issue. I've been ripping a few tunes and every single one is slightly louder on the left.

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Re: Why do I see a stronger left channel?

Post by ripblade » 10 Jul 2012 23:22

One possibility: A cartridge's channel balance is usually uneven in the sub-bass region, which could account for the unequal voltage swings shown on the waveform display. Although it may look hotter on one channel, the difference could be entirely subsonic.

Is the channel balance in the midrange ok?

Another possibility is if the phono stage uses ac coupling capacitors, one or the other may be of a lesser value, resulting in uneven sub-bass channel balance.

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Re: Why do I see a stronger left channel?

Post by EdAInWestOC » 11 Jul 2012 02:44

Do you have a test record? If you have something that has calibrated signals of a known amplitude it would be very easy to say that you have an equipment issue.

It looks like it could be a phono preamp or tonearm wiring issue but you are using records with unknown recorded amplitudes. I agree that it looks wrong but you cannot be sure unless you have a test record. You have a lot of unknowns using the records you have tried.

After you verify with a test LP then I would start substituting equipment to see where the problem lies. Until then you are guessing.

Good Luck,
Ed

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Re: Why do I see a stronger left channel?

Post by Alec124c41 » 11 Jul 2012 03:18

Have you tried this with a mono record? There is no guarantee that signal strength will be equal on a stereo recording. If you have a bass on the left and a rhythm guitar on the right ...

Cheers,
Alec

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