DIGITAL Channel Error Samples: Phase Inversion and LFE Delay

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HomerJAU

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To help those wondering about issues in the recent 'Elliot Scheiner LFE Issues' thread and whether they can hear a difference with fixes applied, here are 3 short 30 sec samples to compare:

Beck: Sea Change (BDA) has two issues:
1. Front Left and Front Right channel are Phase Inverted
2. LFE channel is 8ms delayed

I have fixed each issue and uploaded small (14.7MB) files for testing and education (Fair Use). To limit size I first resampled the first album track from 192kHz to 48kHz. I've also trimmed out a 30 sec chunk between 10s and 40s and used just that section.

File 1: The original mix (untouched)
File 2: Front Left and Front Right Phase Inverted fixed (LFE issue remains)
File 3: Both Phase Inversion and LFE delay are fixed.

NOTE: Fair Use claimed - These 30 sec samples are for test and education purposes only


Please post your test listening results in this thread.

Comparing 1 vs 2 will show whether Channel Inversion can be heard by you on your system
Comparing 2 vs 3 will show whether LFE delay can be heard by you on your system

(BTW: Beck: Sea Change SACD has same issues as the BDA - The DVDA has no issues)

Here's the original waveform prior to applying fixes:

1614637861469.png
 
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timothyemerson

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Thanks for posting this. This is one of my go-to demo tracks for tight, deep bass (and a discrete surround mix)!

I can hear differences between all 3 files:
File 1. Sound(ed) fine up until now!
File 2. Tighter and deeper bass. This is my favourite of the 3.
File 3. This appears to have the least amount of bass of the 3. Like someone cranked down the sub.

Next question: Can the File 2 fix be done in Audacity and if so, do I apply it to the entire album, and... how? :)
 

HomerJAU

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I’m pretty sure you can invert channels in Audacity. Invert FR and FL only. You need to do one file at a time.

If you have Windows then Music Media Helper’s Remix Channels tool has an Invert Phase option than can update all the album tracks (files) in a single command, much easier and faster.
 

timothyemerson

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I’m pretty sure you can invert channels in Audacity. Invert FR and FL only. You need to do one file at a time.

If you have Windows then Music Media Helper’s Remix Channels tool has an Invert Phase option than can update all the album tracks (files) in a single command, much easier and faster.
Thank you sir!

I managed to wrangle it in Audacity. If anyone wants to know what I did:
1. Open the 5.1 FLAC in Audacity.
2. Click the Select button in the blue section to the left of the channel for the Front Left - this highlights the squiggly area.
3. Click Effect in the top menu.
4. Select Invert - it'll then apply the invert/inversion.
5. Do steps 2-4 for the Front Right channel.
6. Export audio as usual.

One day I'll download MMH and learn all about how much time I could have saved!

I gave The Golden Age a spin and good gravy, that bass. Looking forward to giving the full album a spin tonight. I gotta say, this is all pretty exciting.
 

mkt

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This is fascinating. I didn't expect to notice a difference but the additional (excessive?) bass in #2 really stands out. #3 is not as strikingly different as #2 but a little better than #1 to my ear.

I'll have to take a look at my flac files for this album.

Thanks for sharing the samples!
PS. I am using bass management.
 
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humprof

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I listened on my secondary system, which borrows an old pair of home-built floor-standing 3-ways for the rears. (Not a great match for the small bookshelves in front, but they're what's available.)

With the phase inversion corrected, I could definitely hear an improvement. But the LFE correction made no difference, probably because of those 12" woofers in the rears are carrying at least as much bass as the actual sub.
 

timothyemerson

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I had a decent listen to Sea Change last night and after about a song and a half, the inverted RF/LF bass started sounding weird and was just too much. I ended up having to drop the sub about 9dB. After flicking between the inverted and original, I ended up preferring the original. It's not like the original was lacking at all!
 

HomerJAU

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I was thinking theres plenty of bass in the fronts and rears, hence turning down your sub wouldn’t make a lot of difference. I was thinking if set to ‘small’ your AVR was routing bass to your sub.
 

timothyemerson

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I was thinking theres plenty of bass in the fronts and rears, hence turning down your sub wouldn’t make a lot of difference. I was thinking if set to ‘small’ your AVR was routing bass to your sub.
Yeah, I had to really drop the sub quite a bit but there was still a heck of a lot of thump coming from the fronts and it just sounded strange after a while - like when you get a sub for the first time and mess with the phase. Initially, one setting might sound alright but after some time, you prefer another setting.
 

fthesoundguy

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Just had a go at these and the differences are huge! When its fully correct, the kick drum sounds so lovely and makes the original sound anemic. If I ever get around to getting this disc, I will definitely be ripping it and making these corrections. Thanks for the files too, its always nice to actually hear what people are explaining.
 

HomerJAU

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My copy of the SACD doesn't have the inverted front channels, but it does have the offset LFE.

Here's my SACD ISO ripped with my PS3 in 2009. This is the same as the waveform @steelydave sent me last week. It has inverted FL & FR.

@sjcorne Is it possible your capture was from a previously fixed file?

BeckSC-SACD.PNG
 

sjcorne

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@sjcorne Is it possible your capture was from a previously fixed file?

I did the capture from my own copy of the SACD over a year ago--no alterations aside from .FLAC conversion & tagging. I suppose I could pull out the disc and rip it again to confirm, but I was under the impression that only the Blu-Ray edition had the phase inversion problem.
 

steelydave

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Interesting, I guess there must've been a "secret" remaster/correction of the front channels on the SACD - I'm guessing they must've done it around the same time they released the DVD-A in 2004, because the polarity of the front channels is correct there, too.
 

HomerJAU

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Did the SACD ever get a second release? Mine was one of my first SACD purchases so I presume first release.
 
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