DIGITAL The LFE bug

[The Rang]

The sub setting on my Marantz SR7000 allows for a 10db boost, not sure if this happens before or after BM though.

Plus I'll need to check and see if that 10db boost is universal or if I can set each input independantly.

It's really only an issue for me when I use the 5.1 analog outputs from my Denon 3930....I can remember to double check the sub settings

 

[Ge Someone]

LB-V posted a link in another thread to a great, thorough article. It explains the history of LFE and the home cinema version of it and the reason for the 10dB boost.

here is "The Misunderstood 0.1 LFE Channel in 5.1 Digital Surround Sound".

quote: "home (Dolby Digital) equipment is pre-set to play LFE data 10 dB higher than a main channel (or 10dB higher than the bass from a main channel)." -- emphasis by me.

At least it made some details clear to me.

 

[leevitalone1]

I have the same disc and I also must lower bass to 3 or 0, ( analog 5.1 inputs
to my Itegra), so its the disc. just a very instense production freq. wise

Since found Itegra does manegment for all digital but for MC analog it's done at the device.
a quality unit helps that issue. need to upgrade to get my dsd correct.

 

[Franklin]

This is interesting. I'm listening to the Rumours DVD-A and it is really lacking in bass when I use the high res analogue out. Dolby Digital, and it's fine. Other discs I have seem to sound fine, so I'm a bit puzzled.

 

[wavelength]

This is interesting. I'm listening to the Rumours DVD-A and it is really lacking in bass when I use the high res analogue out. Dolby Digital, and it's fine. Other discs I have seem to sound fine, so I'm a bit puzzled.

There is plenty of bass for me using oppo 105 analog out.

 

[Franklin]

Must be my player, which has needlessly complicated bass management :-(

 

[leevitalone1]

Must be my player, which has needlessly complicated bass management :-(

see post 22. what player do you have?

 

[Franklin]

...

 

[ssully]

It's 2019 and I'm back to scare you about the LFE bug again, and SACD rips in particular.

We're moving beyond physical media. Ponder the case of digital files with LFE, in 2019. They might be
lossy DTS, AC3...
lossless MLP, DTS-MA HD, DolbyTrueHD... and DSD (and its relative DSF)...

any of which might have been converted to WAV (PCM), and thus maybe FLAC too...

All (but one*) of these are supposed to be recorded such that the LFE channel is down 10dB in level, and they expect the AVR to give their LFE a +10dB boost, after decoding, but before any bass management.

But 5.1 and this whole LFE -10dB offset stuff began with Dolby (and then DTS) and for awhilein back in the Oughts, and referring here to digital transmission to the AVR (i.e., over HDMI), only Dolby (and DTS) data got proper LFE boost, and only if they were decoded to PCM in the AVR. AVRs were too dumb to realize that incoming PCM LFE (from player-decoded DD, DTS, and from DVDA) also needed the boost. Some of them also seem to have been doing the boost *after* bass management, a terrible idea.

Stipulate that by now , AVRs are smart enough to do this right. AVRs now (and for quite some time) just bass boost all LFE (hopefully BEFORE bass management). So you can stream a raw DTS file as .dts, or stream a decoded DTS file as .wav, and the AVR will do the right thing: boost the LFE by +10dB. Ditto all the lossy and lossless flavors of DD and DTS, Bluray and DVDA too. (NB: The 'right thing' assumes those files were recorded with the proper -10dB LFE offset in the first place...**)

So what about SACD? Why does anyone like this stupid format? Here's another reason to hate it. It was the only one* whose official spec said NOT to apply the -10dB offset to its LFE, leave it full-range. That always messed things up....I'm told SACD players eventually got around it by lowering their *PCM* LFE outputs by -10dB (AFAIK all players had to option of converting DSD to PCM before HDMI output..some cheaper ones *only ever* did that). And maybe (I don't know if this is true, maybe) some AVRs got smart and when they saw raw DSD incoming, they 'knew' not to boost its LFE? But ha ha too bad , because it seems some SACDs do NOT adhere to Scarlet Book spec, and *did* lower their LFEs. That would mess up raw DSD LFE output from such 'DSD smart' AVRs. They'd work perfectly on 'DSD dumb' AVRs.

And now that we can rip SACDs and stream them as data files to an AVR, do you see the issue in 2019?
- If the SACD followed Scarlet Book spec, you either need an AVR that is smart about DSD data, or you need to convert the rip to PCM and lower that LFE by 10dB. (The recent versions of foo_input_sacd, btw, have an option to lower LFE by 10, leave it 'as is', or raise it by 10...that also applies to creating a PCM file from the DSD.)
- If the SACD doesn't follow SB spec, the LFE is already lowered correctly (I hope), so you need an AVR that *isn't* DSD-smart, or, just convert the DSD file to PCM (that does the trick whether your AVR is DSD-smart or DSD-dumb).

But...how can you know which spec was followed? You'd have to compare the LFE of the DSD version to the same mastering in DD, DTS, or DVDA. Fun! And expensive.***

I say, better not to have an LFE at all on music discs, really, and especially not on SACDs!

And of course, problem solved in 4.0.





*two really, if you count first generation DTS music discs, which had full-level LFE, but even they corrected it , I've read

**I suspect one or two DVDAs I've heard fail here

*** on another thread I'll show a recent comparison I did of a Genesis DTS 96/24 DVD , to its SACD counterpart. Spoiler: the DSD (converted to PCM) LFE 'as is', was the same level as the decoded DTS LFE. Think of the implications.

 

[humprof]

It's 2019 and I'm back to scare you about the LFE bug again, and SACD rips in particular.

We're moving beyond physical media. Ponder the case of digital files with LFE, in 2019. They might be
lossy DTS, AC3...
lossless MLP, DTS-MA HD, DolbyTrueHD... and DSD (and its relative DSF)...

any of which might have been converted to WAV (PCM), and thus maybe FLAC too...

All (but one*) of these are supposed to be recorded such that the LFE channel is down 10dB in level, and they expect the AVR to give their LFE a +10dB boost, after decoding, but before any bass management.

But 5.1 and this whole LFE -10dB offset stuff began with Dolby (and then DTS) and for awhilein back in the Oughts, and referring here to digital transmission to the AVR (i.e., over HDMI), only Dolby (and DTS) data got proper LFE boost, and only if they were decoded to PCM in the AVR. AVRs were too dumb to realize that incoming PCM LFE (from player-decoded DD, DTS, and from DVDA) also needed the boost. Some of them also seem to have been doing the boost *after* bass management, a terrible idea.

Stipulate that by now , AVRs are smart enough to do this right. AVRs now (and for quite some time) just bass boost all LFE (hopefully BEFORE bass management). So you can stream a raw DTS file as .dts, or stream a decoded DTS file as .wav, and the AVR will do the right thing: boost the LFE by +10dB. Ditto all the lossy and lossless flavors of DD and DTS, Bluray and DVDA too. (NB: The 'right thing' assumes those files were recorded with the proper -10dB LFE offset in the first place...**)

So what about SACD? Why does anyone like this stupid format? Here's another reason to hate it. It was the only one* whose official spec said NOT to apply the -10dB offset to its LFE, leave it full-range. That always messed things up....I'm told SACD players eventually got around it by lowering their *PCM* LFE outputs by -10dB (AFAIK all players had to option of converting DSD to PCM before HDMI output..some cheaper ones *only ever* did that). And maybe (I don't know if this is true, maybe) some AVRs got smart and when they saw raw DSD incoming, they 'knew' not to boost its LFE? But ha ha too bad , because it seems some SACDs do NOT adhere to Scarlet Book spec, and *did* lower their LFEs. That would mess up raw DSD LFE output from such 'DSD smart' AVRs. They'd work perfectly on 'DSD dumb' AVRs.

And now that we can rip SACDs and stream them as data files to an AVR, do you see the issue in 2019?
- If the SACD followed Scarlet Book spec, you either need an AVR that is smart about DSD data, or you need to convert the rip to PCM and lower that LFE by 10dB. (The recent versions of foo_input_sacd, btw, have an option to lower LFE by 10, leave it 'as is', or raise it by 10...that also applies to creating a PCM file from the DSD.)
- If the SACD doesn't follow SB spec, the LFE is already lowered correctly (I hope), so you need an AVR that *isn't* DSD-smart, or, just convert the DSD file to PCM (that does the trick whether your AVR is DSD-smart or DSD-dumb).

But...how can you know which spec was followed? You'd have to compare the LFE of the DSD version to the same mastering in DD, DTS, or DVDA. Fun! And expensive.***

I say, better not to have an LFE at all on music discs, really, and especially not on SACDs!

And of course, problem solved in 4.0.





*two really, if you count first generation DTS music discs, which had full-level LFE, but even they corrected it , I've read

**I suspect one or two DVDAs I've heard fail here

*** on another thread I'll show a recent comparison I did of a Genesis DTS 96/24 DVD , to its SACD counterpart. Spoiler: the DSD (converted to PCM) LFE 'as is', was the same level as the decoded DTS LFE. Think of the implications.

Ouch. Just when I thought I'd sorted this out, courtesy of Bob Pariseau's old AVS post (which somebody posted recently in another thread)...

 

[Frogmort]

It's 2019 and I'm back to scare you about the LFE bug again, and SACD rips in particular.

We're moving beyond physical media. Ponder the case of digital files with LFE, in 2019. They might be
lossy DTS, AC3...
lossless MLP, DTS-MA HD, DolbyTrueHD... and DSD (and its relative DSF)...

any of which might have been converted to WAV (PCM), and thus maybe FLAC too...

All (but one*) of these are supposed to be recorded such that the LFE channel is down 10dB in level, and they expect the AVR to give their LFE a +10dB boost, after decoding, but before any bass management.

But 5.1 and this whole LFE -10dB offset stuff began with Dolby (and then DTS) and for awhilein back in the Oughts, and referring here to digital transmission to the AVR (i.e., over HDMI), only Dolby (and DTS) data got proper LFE boost, and only if they were decoded to PCM in the AVR. AVRs were too dumb to realize that incoming PCM LFE (from player-decoded DD, DTS, and from DVDA) also needed the boost. Some of them also seem to have been doing the boost *after* bass management, a terrible idea.

Stipulate that by now , AVRs are smart enough to do this right. AVRs now (and for quite some time) just bass boost all LFE (hopefully BEFORE bass management). So you can stream a raw DTS file as .dts, or stream a decoded DTS file as .wav, and the AVR will do the right thing: boost the LFE by +10dB. Ditto all the lossy and lossless flavors of DD and DTS, Bluray and DVDA too. (NB: The 'right thing' assumes those files were recorded with the proper -10dB LFE offset in the first place...**)

So what about SACD? Why does anyone like this stupid format? Here's another reason to hate it. It was the only one* whose official spec said NOT to apply the -10dB offset to its LFE, leave it full-range. That always messed things up....I'm told SACD players eventually got around it by lowering their *PCM* LFE outputs by -10dB (AFAIK all players had to option of converting DSD to PCM before HDMI output..some cheaper ones *only ever* did that). And maybe (I don't know if this is true, maybe) some AVRs got smart and when they saw raw DSD incoming, they 'knew' not to boost its LFE? But ha ha too bad , because it seems some SACDs do NOT adhere to Scarlet Book spec, and *did* lower their LFEs. That would mess up raw DSD LFE output from such 'DSD smart' AVRs. They'd work perfectly on 'DSD dumb' AVRs.

And now that we can rip SACDs and stream them as data files to an AVR, do you see the issue in 2019?
- If the SACD followed Scarlet Book spec, you either need an AVR that is smart about DSD data, or you need to convert the rip to PCM and lower that LFE by 10dB. (The recent versions of foo_input_sacd, btw, have an option to lower LFE by 10, leave it 'as is', or raise it by 10...that also applies to creating a PCM file from the DSD.)
- If the SACD doesn't follow SB spec, the LFE is already lowered correctly (I hope), so you need an AVR that *isn't* DSD-smart, or, just convert the DSD file to PCM (that does the trick whether your AVR is DSD-smart or DSD-dumb).

But...how can you know which spec was followed? You'd have to compare the LFE of the DSD version to the same mastering in DD, DTS, or DVDA. Fun! And expensive.***

I say, better not to have an LFE at all on music discs, really, and especially not on SACDs!

And of course, problem solved in 4.0.





*two really, if you count first generation DTS music discs, which had full-level LFE, but even they corrected it , I've read

**I suspect one or two DVDAs I've heard fail here

*** on another thread I'll show a recent comparison I did of a Genesis DTS 96/24 DVD , to its SACD counterpart. Spoiler: the DSD (converted to PCM) LFE 'as is', was the same level as the decoded DTS LFE. Think of the implications.

I'm not sure I have a better understanding now than I did before your explanation about LFE levels, but I do appreciate the effort. I'm not even sure if the guys in charge of that decision understand all of the time. I've heard many albums that sound neutered on the bottom end, and many that sound overloaded too.

 

[ssully]

Ouch. Just when I thought I'd sorted this out, courtesy of Bob Pariseau's old AVS post (which somebody posted recently in another thread)...

BPs post here , particularly regarding the Pentatone SACD test disc, was one of the sources for my post.

His AVSF post you link to is about analog connection from player to AVR. Mine is entirely about digital. I entirely abandoned analog cabling with relief as soon as HDMI 1.1 (DVDA capability) became available -- over a decade ago. I haven't even used a disc player in years, except to rip. Using HDMI simplifies and opens up so much more comprehensive control over sound, by allowing unitary DSP for *all sources*, that I can't fathom why anyone would stick to analog.

 

[humprof]

BPs post here , particularly regarding the Pentatone SACD test disc, was one of the sources for my post.

His AVSF post you link to is about analog connection from player to AVR.

Yeah; it was the latter sections of that post (especially the section about the LFE Channel and "sub boost") that I was implicitly alluding to. Glad to know about Bob's website and the specific post you cited, though.

Mine is entirely about digital. I entirely abandoned analog cabling with relief as soon as HDMI 1.1 (DVDA capability) became available -- over a decade ago. I haven't even used a disc player in years, except to rip. Using HDMI simplifies and opens up so much more comprehensive control over sound, by allowing unitary DSP for *all sources*, that I can't fathom why anyone would stick to analog.

I understand the convenience of ripping (and the wisdom of backing up), and I do have a couple of TB worth of stuff on a hard drive that I play through a laptop connected to my AVR via HDMI. But I still enjoy popping a disc in the Oppo, too. And while uniform DSP would be great, my understanding of the advantage of analog connections for the disc player is that this ensures the audio signal is processed with the Oppo's DAC rather than the AVR's. In my case, anyway, the Oppo's is way better.

 

[ar surround]

I say, better not to have an LFE at all on music discs, really, and especially not on SACDs!

And of course, problem solved in 4.0.

I think you answered your own question regarding LFE on SACD and came up with the solution. I've always considered the LFE as just what its name says...Low Frequency Effect...and meant for that function in movies and TV.