Q. about bass management when creating DVD-A

I have been using the Adobe Audition 1.5 scripts for SQ and QS decoding and burning the files to DVD-A with DVD-A Solo. Everything sounded fine until this past weekend, when I picked up a copy of Enoch Light's "Brass Menagerie 1973." This is a fun album , but it caused me to notice something that I hadn't before. There are a few points on this album where the entire band suddenly emanates from only one of the rear speakers. And when that happens, the bass management in my system checks out, and nothing comes out of the subwoofer until the sound returns to the front speakers. First of all, is that normal? Second, is there some simple way to create a .1 channel of the low frequencies from the four channels of a quad recording? Maybe creating 4.1 rather than 4.0 DVD-Audio discs might be the best solution.

J. D.

Are yuo sure your settings on the dvd-a player places the rear speakers as "large"?

winopener said:

Are yuo sure your settings on the dvd-a player places the rear speakers as "large"?

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My settings are for all five of my satellite speakers as small.

J. D.

If they are not ullrange, there's no way you can get it.
If they are fullrange, set it to "large".

I've tried summing the 4 mono files, then EQ'ing the thing dropping everything over 80Hz, but have never been happy with the muddy results.

you might try AUDIO CONTROL (THE RICHTER SCALE SERIES THREE) for help with bass management/trainman92

Bass Management is often misunderstood in pretty much the same way that the LFE channel is often confused with a SubWoofer.
Bass Management is used when your system does not have full-range speakers attached and will divert audio from the main channels to a subwoofer using a very steep slope (around 48dB/Octave).
It is most commonly used in Sub/Satellite systems, where the main channels are fed into bookshelf type speakers that just cannot handle any bass response at all - and it is futile to try & second-guess what any individual system is capable of handling.
For this reason, when creating a multichannel disc for general release, you should leave the 4 main channels as they are - full range - and not use any form of bass redirection at all in authoring as the end users system will handle theredirection itself - and additionally, you cannot possibly know what the crossover frequency is on other peoples systems.
Creating a dedicated LFE channel is a very difficult task indeed, and we will come back to this later. For now, though, if you have - for example - a 4 channel recovery from Audition decoded SQ using the superb script, when making the DVD-A whatever you do leave all 4 channels as full range in the authoring.
If you are using a sub/satellite system, as long as it is correctly set up & properly calibrated, it will automatically redirect the bass frequencies the speakers cannot handle to the Subwoofer.
If you are using a full-range system, then again leave it all "as is" on the 4 main channels, and you will have the decoded files "as mixed".
With all 4 main channels full range, the Subwoofer is no longer acting as a bass driver, but instead as a proper Sub, and extending the bass response of your main system down to as low as 15Hz on some setups - but with SQ Quadraphonic, there is nothing there at these frequencies apart from turntable rumble.
If your Authoring setup is not full range, then you have to come up with a solution to the bass management issue.
If you have Steinberg's Nuendo, there is a life saving feature included called the Control Room. This will allow you to have a separate output buss for listening to your work, whist leaving the main output buss alone. What this means in the real world is that I can set up a 4.0 mix, or a 5.1, and have everything running ful range to export, but if I am using my nearfield monitors (not full range, but going to 50Hz at -3dB) I can insert a Bass Management plugin into the Control Room path so that I am monitoring correctly, with the frequencies the nearfileds cannot handle going to the Sub - but the actual output when I export the final mixdown is going out full-range.
Without a control room, you can still set things up correctly (assuming there is no crossover network in the speakers, of course) using the same Bass Management plugin - but you will need to remember to turn it off before exporting the mix.

LFE Creation.
This is difficult to do, and I have met very few people who can get it right. There is at least one member here who has it down to a fine art (I won't name names, as he knows who he is).
The problems you are facing when doing this are essentially these:
1 - Phase. Are you adding Bass response to the original track or diverting from the mains? If the former, the signal absolutely must be 100% phase coherent or you will get problems caused by cancellation, or even doubling - ending up with either a very thin sounding mix or else one that is simply muddy & booming all over the place.
2 - Altering the mix.
Bass Management is used for playback - if you have the BM set to subtract everything below, say, 80Hz & divert to the Sub, then you are removing bass response from the original mix - and those purists who do not use an LFE will find that there is simply no low bass at all in their playback version.
Not good.
If adding extra bass, then you are once again hitting the problem mentioned above in (1).
The ideal solution, if you absolutely MUST add an LFE channel, is to do so in such a way that the extra punch is there if required but also if you turn the LFE off it should not affect the original balance of the mix.

Some of the old Quad material is just mixed very light on the bass, and short of carefully creating your own LFE channel, there is little you can do about this. Reason things were sometimes mixed bass-light was to get more music on the original vinyl, as bass energy in vinyl is translated to sideways motion/movement in the groove on the record, and the wider this movement - the less material you can fit onto the record.

I hope this helps a little, but if you are going to be creating DVD-A from SQ, then you really should not be trying to do this with a Sub/Satellite setup in an ideal world. We don't live in one of those though - so compromise is the way.
If you want to attempt creating your own LFE channel, be prepared to make a fair few coasters whilst getting it right - but if you have Nuendo's Surround Edition, there is a useful tool called the "LFE Splitter" that is designed to get you in the right area for this.

Neil, thank you for that detailed response.

J. D.

neil wilkes said:

Bass Management is used when your system does not have full-range speakers attached and will divert audio from the main channels to a subwoofer using a very steep slope (around 48dB/Octave).

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..and also when you have no subwoofer, but there's LFE information in the source. Bass management will route it to the 'full-range' speakers you *do* have (usually front L/R).

Some early players -- and who knows maybe some current ones ...failed to implement this 'other' facet of bass management well.

For this reason, when creating a multichannel disc for general release, you should leave the 4 main channels as they are - full range - and not use any form of bass redirection at all in authoring as the end users system will handle theredirection itself - and additionally, you cannot possibly know what the crossover frequency is on other peoples systems.

Click to expand...

Agreed! Now, if only we could get all surround music engineers to agree too...

ssully said:

..and also when you have no subwoofer, but there's LFE information in the source. Bass management will route it to the 'full-range' speakers you *do* have (usually front L/R).
Some early players -- and who knows maybe some current ones ...failed to implement this 'other' facet of bass management well.

Click to expand...

Eek - I wasn't aware of that! That is not good, really it isn't.
What players do this??

ssully said:

Bass management will route [Low Frequency Enhancement channel] to the 'full-range' speakers you do have (usually front L/R).

Some early players -- and who knows maybe some current ones ...failed to implement this 'other' facet of bass management well.

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Yup, my player (not a real early one) will not do that (through the analog outs).
But thank God, I can do that on my amp. So I'm able to hear all of the information from the x.1 discs.

neil wilkes said:

That is not good, really it isn't.

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But it is! That is when you have no separate subwoofer (and the mains can handle the low bass freqs ). Besides, (in my case) it can be switched off and LFE channel sensitivity can be adjusted (although in 5 dB steps).

Ge Someone said:

But it is! That is when you have no separate subwoofer (and the mains can handle the low bass freqs ). Besides, (in my case) it can be switched off and LFE channel sensitivity can be adjusted (although in 5 dB steps).

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I disagree - strongly.
This type of recombining would only work if the LFE content was subtracted from the main channels.
If it was derived independantly, with the main channels being full-range (the correct way to mix in 5.1) then summing LFE back into the L/R channels will give too much bass, and quite possibly phase problems as well.

I dunno, I think there is enough low frequency information on just about any record, including SQ records, to make an LFE channel a worthwhile consideration. Generally, even really good full range speakers don't offer flat low frequency performance down to levels that can be found on LPs, even if the music has been compressed for mastering.

The real argument against a dedicated LFE channel on a legacy conversion is that it's just way too easy to fuck it up. There is just too much variability in this area for there to be even a remote chance of having it work correctly on every system where the disc might be played.

The number one pitfall I see is creating an LFE channel for a sub-optimal system. By sub-optimal, I mean any system that does not have five full-range, properly calibrated speakers in a 5.1 setup. If you create an LFE to sound good on a sub-optimal system, you can be guaranteed of shitty performance on virtually any system.

So, if you're converting/mastering from a sub-optimal system, save yourself the hassle and not bother with an LFE channel. But if your only audience is yourself, knock yourself out. It can be a lot of fun! Just never upgrade your system or you'll have to do it all over again...

neil wilkes said:

I disagree - strongly.
This type of recombining would only work if the LFE content was subtracted from the main channels.
If it was derived independantly, with the main channels being full-range then summing LFE back into the L/R channels will give too much bass, and quite possibly phase problems as well.

Click to expand...

I hope it's OK to agree to disagree

What you describe is more the headache for the engineer(making the mix), not the listener . Indeed the separate LFE is a tricky thing. The mixing engineer should (at least in theory) check the mix (after monitoring on a full range set) also on a Satellite/Sub set-up (small speakers) and also folded down to stereo (perhaps switching back and forth between 5.1 and 2.0 a few times?).
In the last two scenario the low freqs are also combined, first one in the sub, second one in the main pair. Phase problems can be detected this way and should be dealt with.
Even when using the LFE channel with a sub the low frequencies are also combined, only this time "in the air". There can be phase cancellation too and more problematic, because on one spot it's different than on another spot.

Because of all this the routing, of the .1 Low Frequency Enhancement channel to capable mains, turns out to work quite good once the right level is dialed in.

All this extra work (and choices) for the mixing/mastering engineers would be unnecessary if, for music, 5.0 would be used. At the listeners side bass management could take care of what is optimal for that set-up. On this part (in fact on most of the rest) I certainly agree with Neil and Cai.
But for some reason the fashion is 5.1, as it is the standard for movies (where .1 is used as Low Frequency Effect channel)

[On Topic] the problem of the original question seems to be flawed bass management. Creating a .1 channel is a workaround, doing what your bass management should have done. Only such a disc will not be ideal on other playback systems.
[/On Topic]

Ge Someone said:

I hope it's OK to agree to disagree

What you describe is more the headache for the engineer(making the mix), not the listener . Indeed the separate LFE is a tricky thing. The mixing engineer should (at least in theory) check the mix (after monitoring on a full range set) also on a Satellite/Sub set-up (small speakers) and also folded down to stereo (perhaps switching back and forth between 5.1 and 2.0 a few times?).
In the last two scenario the low freqs are also combined, first one in the sub, second one in the main pair. Phase problems can be detected this way and should be dealt with.
Even when using the LFE channel with a sub the low frequencies are also combined, only this time "in the air". There can be phase cancellation too and more problematic, because on one spot it's different than on another spot.

Because of all this the routing, of the .1 Low Frequency Enhancement channel to capable mains, turns out to work quite good once the right level is dialed in.

All this extra work (and choices) for the mixing/mastering engineers would be unnecessary if, for music, 5.0 would be used. At the listeners side bass management could take care of what is optimal for that set-up. On this part (in fact on most of the rest) I certainly agree with Neil and Cai.
But for some reason the fashion is 5.1, as it is the standard for movies (where .1 is used as Low Frequency Effect channel)

[On Topic] the problem of the original question seems to be flawed bass management. Creating a .1 channel is a workaround, doing what your bass management should have done. Only such a disc will not be ideal on other playback systems.
[/On Topic]

Click to expand...

Disagree? You want to disagree?
Yep - that's absolutely fine.

LFE is a contentious thing in music authoring. The recommendation from the Record Producers Guild is actually to leave it alone & mix in 5.0, and if you do decide to mix to 5.1 then to treat the 5 main channels as full-range come hell or high water - you simply cannot even begin to second-guess consumer grade sub/satellite setups that are designed for DVD-Video playback and not music playback.

The .1 channel should be considered not as a subwoofer or bass channel, but as the acronym says - Low Frequency Effects. It was originally intended to be there so the bass response in small speaker systems could be extended down to around 20Hz, sometimes even lower. Where all the problems begin to creep in is in the typical "Home Cinema" speaker setup that is often - at best - 2 full range main L/R speakers, often floorstanders. Then a limited response Centre channel (hell, it's only for dialogue and we all know that proper music engineers hate using a centre channel, don't we?) and even more limited rear speakers as all they carry is ambience.
This type of thinking & setup is 150% wrong for music playback, be it DTS-CD, DVD-Video, DVD-A or SACD. Setups for Audio should all be full-range across all 5 channels - or you are simply not hearing the music as it was mixed. I have long thought that this is the main reason multichannel music gets such a pasting from so many people - they simply do not have the right speakers.
When I were a lad, the speakers were considered the single most important part of our stereo setups. If you had the wrong speakers, you could have the finest amp/turntable in the world and it would still sound like crap. These days, speakers seem to be an afterthought for most people, who often buy according to how they will look, or worse still, how little space they will take up & if they can be hidden from view.
This is bad. Very bad.

Creating an LFE is not easy. When you are mixing from multitracks, it is a lot easier to do. When you are creating an additive LFE from an old Quad mix, it is almost impossible to get it right so that it sounds equally good across the board, and this is because of Bass Management, the fact that most people do not know how to set up bass management, and tend to leave their players on the factory default settings.
If you know what you are doing, an LFE can be created from a Quad mix.
I only know a couple of people who can do this reliably (and no, I am not one of them).
When mixing from a multitrack, it's easy.
What is hard is trying to ensure that the end user hears the mix as you intended it to be heard. And on a sub/satellite system, this is never going to happen.

In short - avoid where possible. Unless you
A - know what you are doing, or
B - really, really want to.:sun

neil wilkes said:

Disagree? You want to disagree?
Yep - that's absolutely fine.

LFE is a contentious thing in music authoring. The recommendation from the Record Producers Guild is actually to leave it alone & mix in 5.0, and if you do decide to mix to 5.1 then to treat the 5 main channels as full-range come hell or high water - you simply cannot even begin to second-guess consumer grade sub/satellite setups that are designed for DVD-Video playback and not music playback.

The .1 channel should be considered not as a subwoofer or bass channel, but as the acronym says - Low Frequency Effects. It was originally intended to be there so the bass response in small speaker systems could be extended down to around 20Hz, sometimes even lower. Where all the problems begin to creep in is in the typical "Home Cinema" speaker setup that is often - at best - 2 full range main L/R speakers, often floorstanders. Then a limited response Centre channel (hell, it's only for dialogue and we all know that proper music engineers hate using a centre channel, don't we?) and even more limited rear speakers as all they carry is ambience.
This type of thinking & setup is 150% wrong for music playback, be it DTS-CD, DVD-Video, DVD-A or SACD. Setups for Audio should all be full-range across all 5 channels - or you are simply not hearing the music as it was mixed. I have long thought that this is the main reason multichannel music gets such a pasting from so many people - they simply do not have the right speakers.
When I were a lad, the speakers were considered the single most important part of our stereo setups. If you had the wrong speakers, you could have the finest amp/turntable in the world and it would still sound like crap. These days, speakers seem to be an afterthought for most people, who often buy according to how they will look, or worse still, how little space they will take up & if they can be hidden from view.
This is bad. Very bad.

Creating an LFE is not easy. When you are mixing from multitracks, it is a lot easier to do. When you are creating an additive LFE from an old Quad mix, it is almost impossible to get it right so that it sounds equally good across the board, and this is because of Bass Management, the fact that most people do not know how to set up bass management, and tend to leave their players on the factory default settings.
If you know what you are doing, an LFE can be created from a Quad mix.
I only know a couple of people who can do this reliably (and no, I am not one of them).
When mixing from a multitrack, it's easy.
What is hard is trying to ensure that the end user hears the mix as you intended it to be heard. And on a sub/satellite system, this is never going to happen.

In short - avoid where possible. Unless you
A - know what you are doing, or
B - really, really want to.:sun

Click to expand...

Agreed on all counts-although I've never tried to to create LFE from an
(original) quad recording.
Personally, I don't even use the LFE track for encoding MLP or DTS (music).
I only have to please myself, anyway.

regards
boondocks

neil wilkes said:

I disagree - strongly.
This type of recombining would only work if the LFE content was subtracted from the main channels.

Click to expand...

Dedicated LFE content isn't coded in the main channels. I' m talking about data that is ONLY encoded in the LFE channel. THis is how the LFE channel was intended to be used originally : for bass frequency 'effects' that aren't encoded in other channels. This os more a 'movie' thing than a music thing, but stupidly, music mixers have been allowed/encouraged to put data into the LFE channel. 'Standard' LFE should also be encoded at -10dB compared to the other channels, as per Dolby Digital spec, then boosted 10 dB at decoding.

Such data is actually intended to be directed to loudspeakers optimize for low freqency output (eg subwoofers) but if one is lacking, it should be sent to the mains. Otherwise it's simply *lost*.


To me this is all terrific reasons why DVD-A /SACD mixders shouldn't put ANYTING in the .1 (LFE ) channel. Let that be filled by bass management only!

ssully said:

To me this is all terrific reasons why DVD-A /SACD mixders shouldn't put ANYTING in the .1 (LFE ) channel. Let that be filled by bass management only!

Click to expand...

Hear, Hear.
Been saying this for years now.
LFE is an effects channel, and all 5 channels for both DVD-A & SACD should be mixed as full-range. IE, 20Hz to 48KHz at sample rates of 96K, otherwise 20-24000 if at 48KHz.

Very Fascinating info here. I am of the belief that I too HATE the center channel for multichannel music (It ruins the sound field of the other 4 channels) and forget the .1 channel for music. I've worked with digital audio since 1991 when Opcode's Studio Vision came out with digital audio recording option in it's midi program.

I am of the belief that I too HATE the center channel for multichannel music (It ruins the sound field of the other 4 channels) and forget the .1 channel for music.

Click to expand...

Opposite here - I prefer a genuine Centre Channel when it is there. For me it anchors the field, and this is as it should be. Sorry, I just do not understand why anyone would want to use a phantom centre when we have a real one available that allows us to move sound into it's desired space rather than using EQ & reverb to try & shoehorn 3 channels into 2.
What I don't like is an artificially generated centre channel from old Quad - where an album was mixed for 4 channels, it was mixed for 4 channels & not 5. or 5.1.