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[flac.rules]

I have done some measurements to back up my claims. The measurements are done with a pro grade sound level meter. I did all the measurements at the same location with 50 Hz and 63 Hz sines, in WASAPI mode (two frequencies, just in case local nodes should somehow mess up the result). The end of the story? JRSS upmixing boosts the subwoofer-channel 7-8 dB (oddly enough not 10 db) compared to just running in stereo. It would be very nice if someone could look into this. Also, any ideas on how to test this with native 5.1-material? I want to check if the program handles this correctly also. Attached is a screen shot of my settings. EDIT: how do i attach files in this forum?

[Matt]

Double-check DSP Studio > Output Format > Subwoofer settings.

You can make a pink noise file with Media Editor, play it, and use DSP Studio > Analyzer to see the levels of the output channels.

I just tested this and the output levels look correct.  The subwoofer is -10 dB compared to L / R with 'Something outside of Media Center will make the subwoofer +10 dB (standard calibration)' enabled.  With that unchecked, the subwoofer matches the L / R level.

If 'Analyzer' shows matching levels and you're getting different readings with your sound meter, it means your receiver or subwoofer amplifier is adding a gain or not calibrated for the computer's input.

[flac.rules]

How can i see what is which channel in the analyzer? I have "something outside of media center will make the subwoofer 10 dB enabled. I can attach a screenshot of my settings, but i don't seem to be able to attach stuff to posts?

[Matt]

How can i see what is which channel in the analyzer?

There's no legend (yet).

However, the highest line is the sum of all the channels.

The two lower channels are L and R.

The subwoofer should be obvious since the high frequencies are removed.

Each vertical hash is 3 dB.

[flac.rules]

I have done further investigations. The problem is not apparent when the crossover is set at for instance 100 Hz. (even at a signal well below 100 Hz, for instance 50 Hz) However if i have the crossover-setting at "all frequencies", the level is too high. This confuses me, as even if you set "all frequencies" the receiver itself should just crossover the signal at the required frequency.

[mojave]

The "all frequencies" setting sends the full range signal to the subwoofer channel. If you are using a receiver, it will see this as the LFE channel and will not apply a crossover to it. You will then get additional output because the subwoofer and speakers will be playing the same frequencies (at least as high as the sub can play).

If you only listen to two channel sources, you can use the bass management in Output Format. However, if you have both 2 channel and multi channel (5.1, 7.1) sources, then you want to use bass management in Room Correction. You then use "silent" in Output Format. You could also set up two zones:  one for 2-channel and one for multi-channel playback. The 2-channel zone would use the bass management in Output Format the the multi-channel playback could use the bass management in Room Correction.

Attach files by using "Additional Options" when posting to the thread.

[Matt]

Also, remember that Subclarity might attenuate pink noise.

If you're calibrating using pink noise, disable Subclarity (DSP Studio > Output Format).  For real content, I really like Subclarity.

[mojave]

Also, remember that Subclarity might attenuate pink noise.

How can we remember that when this is the only description of Subclarity you have given? 

It allows quick impacts like thumps and hits to pass through, but filters out long rumbles.  The goal is to remove drone from bass guitars, etc. from the subwoofer line while keeping tight hits from bass drums and other low bass. 

Subclarity is one of my favorite recent improvements to the audio engine.  I had always wanted something that did this, but wasn't sure it was possible.  In my opinion, it works and sounds really good.

[flac.rules]

The "all frequencies" setting sends the full range signal to the subwoofer channel. If you are using a receiver, it will see this as the LFE channel and will not apply a crossover to it. You will then get additional output because the subwoofer and speakers will be playing the same frequencies (at least as high as the sub can play).

If you only listen to two channel sources, you can use the bass management in Output Format. However, if you have both 2 channel and multi channel (5.1, 7.1) sources, then you want to use bass management in Room Correction. You then use "silent" in Output Format. You could also set up two zones:  one for 2-channel and one for multi-channel playback. The 2-channel zone would use the bass management in Output Format the the multi-channel playback could use the bass management in Room Correction.

Attach files by using "Additional Options" when posting to the thread.

Sorry for late reply, I have been away.

Why wouldn't it apply the crossover to it? Normally receivers apply the crossover to both the LFE-channel and the mains channels as far as i know? It just takes the LFE-channel adds 10 dB, lumps that together with the main, and then after all that, uses the crossover, an redirects all content below the crossover frequency. And why would i use silent for output to the sub? Besides, i don't think tats the problem here, i get 10 db additional, not 3 db, as a summing would indicate, and i get the 10 dbs also well belo the range of my speakers (at 50 Hz for instance).

After looking at the analyzer, it seems (a bit difficult to say), that the sub -level out from the program is the same with 150 Hz crossover, as with "all frequencies", but why would the receiver add 20 dB to the signal in that case? This is a bit of a mystery for me.

[flac.rules]

Seems like any crossover except "all frequencies" fixes the problem, just to be absolutely sure, the crossover is considering the LFE-channel? If the crossover is 80 Hz, 50 Hz will be sent to the LFE, and 100 Hz to the mains? (so in theory it should not make a difference at all when you have digital input, as the receiver will send any content below its crossover to the sub, regardless of if it originated in the mains or the LFE)

[Matt]

Seems like any crossover except "all frequencies" fixes the problem, just to be absolutely sure, the crossover is considering the LFE-channel? If the crossover is 80 Hz, 50 Hz will be sent to the LFE, and 100 Hz to the mains? (so in theory it should not make a difference at all when you have digital input, as the receiver will send any content below its crossover to the sub, regardless of if it originated in the mains or the LFE)

The crossover for the subwoofer in DSP Studio > Output Format makes no changes to the mains.

You should use DSP Studio > Room Correction if you want to cross-over or redirect speakers.

[mojave]

If you are using the crossover setting in Output Format, the frequencies below the crossover frequency are sent to the subwoofer channel. The other channels are still full range. The combined bass from the other channels and the subwoofer channel could be louder than it should be. You can go to Room Correction and use the bass management to remove bass in the other channels below the crossover frequency when using JRSS for music.

When using JRSS for movies, you want to use "move" instead of "remove" in bass management or you will lose the effects that are encoded in the main/surround channels.

Edit:  Set the crossover in Output Format to "silent" if using the crossovers with "move" in Room Correction.

[flac.rules]

The crossover for the subwoofer in DSP Studio > Output Format makes no changes to the mains.

You should use DSP Studio > Room Correction if you want to cross-over or redirect speakers.

That makes no sense? Why is that the default? When would you want to output the bass twice when MC is upmixing a stereo signal? That would boost the bass +3dB.

[mojave]

I just saw that we discussed this back in June of 2010.

JRSS was developed before MC had bass management. The benefit of doing a crossover in Output Format is that the subwoofer channel is created from just the original left and right channel. With those that use Dolby Prologic IIx or DTS Neo, the surround channels are created and then the subwoofer channel is made by redirecting the bass from all these channels. This makes the subwoofer channel to not have as good of quality because the matrixed channels are also included.

A solution would be for there to be no crossover setting in Output Format and for JRSS to leave the subwoofer channel blank. Users should just use the bass management in Room Correction. I would get rid of the "remove" option in bass management since it would no longer be needed.

For music and TV shows, bass management could detect if there was a blank LFE channel. If so, then it would create a bass channel from just the front two channels (regardless of crossover setting for the surrounds) and follow the "move" or "copy" for all the channels.  If there was an LFE channel already present, like in movies, then it would route bass from all channels to the LFE channel following the bass management settings. This method preserves the quality of the subwoofer channel for two channel sources and 5.1 channel sources that have just a stereo encoding (like TV shows). It also allows for just one setting to be used for all music, movies and TV shows.

[flac.rules]

I dont get it, whats the problem of just sending the frequencies to the sub in such a way that the sound below the crossover is not elevated +3dB? I really see absolutely no use for adding +3dB, just make the default way output format works different?

[audunth]

I just want to clarify a few things, and see if I understand this correctly.

First of all, everybody should read this paper from Dolby explaining the concept of the LFE channel and how it should NOT be confused with the subwoofer channel: http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/38_LFE.pdf , even though I'm pretty sure most of you guys here already understands this.

Now, as I understand it, MC has all the options for everybody to route (or not route) the bass however they like.

For those with a (not ancient) home theatre receiver, the receiver itself has adequate speaker levelling, delay settings and bass management and thus MC's Room Correction is not needed (of course you still may wanna let MC handle it for various reasons if you know what you're doing, but the receiver is usually easier to set up). Also, in this case if you upmix to 7.1 (and optionally stereo to 2.1), you'd wanna set the subwoofer to silent to get correct reproduction. And you leave Room Correction unchecked in MC.

As a side note, I believe the label "Room Correction" is wrong and misleading, since room correction usually refers to frequency/timing correction to compensate for the effect the room has on the sound, like room nodes etc. "Delay, Levels and Bass Management" or "Speaker Management" is really what it is, and has very little to do with actual room correction.

Modern receivers work like this (correct me if I'm wrong):
When you select a speaker as "small", the bass below the crossover frequency is removed from that speaker and redirected to the subwoofer. The speakers set to "large" in the receiver's setup plays their bass itself. Usually the receiver also has an the option to double the bass from ALL speakers to the sub. The LFE channel is MADE for the subwoofer, so the LFE channel is, like Matt says above, just passed on to the subwoofer. The crossover isn't for taking away high frequencies from the sub, it's for moving bass from the small speakers to the sub below a certain frequency. The LFE channel contains nothing above 120 Hz, but it may contain sounds above the crossover that is still intended for the subwoofer (and if the receiver removed sounds above the crossover it would not play the movie as the sound mixers intended). The LFE channel may or may not be routed through a low pass filter, depending on the receiver. So making MC make a LFE channel with full frequency is not something you want, unless you use the subwoofer's own crossover filter.

I myself use the above option, let MC upmix to 7.1 while leaving stereo alone (mix stereo to 2.1 with sub set to silent) and let the receiver handle the bass management. This way I don't have to turn on and off the bass management on the receiver when listening to other sources, like FM radio or satellite receiver. I plan to incorporate FIR filters made with Audiolense when I get around to it, and then I'll have to let the FIR filters or MC take care of bass management, since the bass management will have to be taken care of before or during the sound correction.

Then you have those who connect the computer's sound card directly to a multichannel power amplifier (or via an external DAC/sound card), and lets MC handle levels, delay and bass management. MC's bass management also lets you choose exactly which bass goes to which speaker as I see it. To get correct reproduction, also here the sub output should be set to silent in Output Format for signals that don't have a LFE channel.

I agree "Silent" should be the default choice.

Then you of couse have those who bypass all MC's DSP options and output the untouched audio track (DD/DTS or whatever) to the receiver or surround processor and let it handle decoding, upmixing and everything else. That's also an available option in MC.

So what's missing? With all the settings right for correct reproduction, is the bass still too loud?

As I said above, please correct me if I have misunderstood something, as I'm not a professional, just an enthusiast who gets most my information by looking it up on the internet and discussing with knowledgeable people on forums like this (and of course real people in the real world ). And I hope this post doesn't confuse people even more


EDIT: Found another great article that goes into the deep of bass management: http://www.ultimateavmag.com/content/bass-management-and-lfe-channel
This article suggests that the LFE channel mostly runs through a low pass filter, but not always, and also that any movie might contain full frequency sound in the LFE channel, so therefore it would generally be a good idea to apply the subwoofer's own low pass filter, if it has one, for the safety of the sub at high volumes. Unless you test and verify that the receiver actually has a LFE low pass filter (should be doable with MC). Just set it well above the highest crossover frequency of any of the other speakers, so the two filters won't interfere with each other.

[flac.rules]

Well, setting the LFE-track as silent is fine, an as you said, should work fine since the basse below the crossover is outputted to the sub anyway. However i still don't understand why JRMCs default behaviour is to duplicate all frequency content below the crossover set in MC (thus elevating theese frequencies 3 dB), why is this the default, and when would it be useful?

[audunth]

I agree, it's strange that doubling the bass and making a full frequency LFE signal is default. In my opinion, there should even be a warning when selecting full frequency, since sending a full frequency signal to the sub could potentially damage it at high levels.

The only application of the setting as I see it is if you WANT the bass to be doubled and you don't have that option in the receiver, and you're using the subwoofer's own low pass filter.

[Matt]

The default JRSS settings are designed to create a good sounding LFE channel for a subwoofer, and to leave the main speakers alone.  And in my opinion, the subwoofer created for stereo content by JRSS sounds great.

If you want bass redirection (i.e. removal of bass from the mains), it can be enabled in Room Correction.  As mentioned above, picking 'Silent' for the JRSS subwoofer output is appropriate here if energy neutrality is your goal.

It's possible that the option to "Move bass to subwoofer" should act like "Remove bass below crossover" when dealing with a 2.0 to 5.1 upmixed signal from JRSS.  But this is not clear cut.  For example, I think for audio a cross-over around 60 Hz sounds best for a subwoofer.  But my mains and surrounds use a different cross-over (as required by their design), so energy neutrality is not possible if I want the 60 Hz subwoofer crossover.  So then I have to decide between what I think sounds best (60 Hz) or energy neutrality.

[audunth]

Of course the default full frequency setting might sound good on a given system, and I don't doubt it sounds good on your system, Matt. However, I would think many MC users are also playing music through other sources like FM/DAB radios, satellite/cable receivers, even ol' fashioned CD players or turntables, and have their amp/receiver set up to sound good with all sources, that's why I think the "correct" sound should be default. Also, in my opinion it makes more sense that the most correct, neutral setting be default rather than the one that sounds best on a given system. Most audio systems sound better corrected with an equalizer or more advanced room correction that almost all new receivers have, but it's still off by default.

For example, I think for audio a cross-over around 60 Hz sounds best for a subwoofer.  But my mains and surrounds use a different cross-over (as required by their design), so energy neutrality is not possible if I want the 60 Hz subwoofer crossover.

As most subwoofers can play well above 100 Hz, even up to 200 Hz, the crossover frequency is not set according to the subwoofer's properties, but mostly to the speaker's and room's properties. Very few systems will sound the best they can if the crossover is set to the same frequency for the surround and front speakers, unless they are identical speakers. So I'm not sure I understand you here, it sounds like you think all speakers have to have the same crossover frequency, which I'm 100% sure you don't, since MC's bass management lets you choose a different crossover for each speaker, even the steepness of the low pass/high pass filters.

[mojave]

But this is not clear cut.  For example, I think for audio a cross-over around 60 Hz sounds best for a subwoofer.  But my mains and surrounds use a different cross-over (as required by their design), so energy neutrality is not possible if I want the 60 Hz subwoofer crossover.  So then I have to decide between what I think sounds best (60 Hz) or energy neutrality.

Since you aren't using the same crossover on mains and subs for when using JRSS, you are either overlapping your frequencies (60 Hz sub and < 60 Hz mains) or you have a gap in your frequency response (60 Hz sub and > 60 Hz mains). Can you share your actual settings, please, in Room Correction?

I don't know what the default setting is for the crossover in Output Format when JRSS is selected since I haven't done a fresh install in a while. I would recommend that it be "Silent" instead of  "All frequencies" if it isn't already.

[Matt]

Since you aren't using the same crossover on mains and subs for when using JRSS, you are either overlapping your frequencies (60 Hz sub and < 60 Hz mains) or you have a gap in your frequency response (60 Hz sub and > 60 Hz mains). Can you share your actual settings, please, in Room Correction?

That was my point.  I can choose between energy neutrality (no gaps / overlaps) or better sound (with gaps / overlaps).  There are some interesting possible technical reasons for this as it's a complex topic, but I don't think it's necessary for us to pick a side.

If you want simple 2.0 to 2.1 / 5.1 / 7.1, just enable that number of channels in DSP Studio > Output Format.  The defaults (60 Hz subwoofer cross-over, Subclarity, etc.) will sound good.

If you want energy neutrality, configure DSP Studio > Output Format to output a silent sub.  Then use DSP Studio > Room Correction to move bass from the main speakers to the subwoofer.  Using Room Correction requires some manual configuration, and as such, is not a default setting.

[mojave]

I would like to expand on what I said earlier:

A solution would be for there to be no crossover setting in Output Format and for JRSS to leave the subwoofer channel blank. Users should just use the bass management in Room Correction. I would get rid of the "remove" option in bass management since it would no longer be needed.

For music and TV shows, bass management could detect if there was a blank LFE channel. If so, then it would create a bass channel from just the front two channels (regardless of crossover setting for the surrounds) and follow the "move" or "copy" for all the channels.  If there was an LFE channel already present, like in movies, then it would route bass from all channels to the LFE channel following the bass management settings. This method preserves the quality of the subwoofer channel for two channel sources and 5.1 channel sources that have just a stereo encoding (like TV shows). It also allows for just one setting to be used for all music, movies and TV shows.

Would it be helpful to have one more choice in Room Correction? You could put the heading "Speaker" and have its crossover and slope. Then you could have the heading "Subwoofer" with its crossover (where Routing is currently) and have its crossover and slope. Then move Routing down a line. You could also put a check box that says "Make crossovers the same frequency." If this is selected, the sub crossover would automatically be the same a the speaker crossover and you would have energy neutrality. If this wasn't selected, then you could have the speakers and subwoofer overlap in frequency which could result in improved sound depending on room and speakers.

These changes have several benefits:

• The user doesn't have to try to understand why there is a crossover setting in both Output Format and Room Correction
• For most users, they can use one set of setting for music and movies. With the current method, Bass Management in Room Correction needs to not be used with a crossover (and move option) if one is already using the crossover in Output Format. Otherwise you will get redirect bass twice.
• The slope selections make more sense since they would now have a heading (speaker or subwoofer). Unless you have followed some of the threads, you really wouldn't know whether they apply to the sub or speaker.
• Some like to have their mains/surrounds and subs overlap for movies, too. This would allow for that possibility.

Finally, in the bass management section of the Sub tab, instead of the greyed out bass management options it would be nice to have two options there:  a checkbox to link settings for mains and a check box to link settings for all channels. This would allow one to set the left speaker and the right would have the same bass management settings. Or one could easily change bass management settings for all their speakers.

[audunth]

Okay, Matt, I think I understand what you meant before, that your mains and surrounds have a different crossover than your subwoofer. I thought you meant your mains have a different crossover than your surrounds.

Well, with all due respect, I think you're confusing crossover with low pass filter (LPF) and high pass filter (HPF). The way bass management work is that the crossover is the frequency where the HPF is applied to the speaker and the LPF is applied to the sub. This is always at the same frequency for the sub and the speaker, in MC's bass management configuration as well as in every receiver/surround processor on the market. You can apply a different filter (dB/octave) for the speaker and sub, but the frequency is always the same, because overlap or gap would sound terrible, unless intentionally done to compensate for a dip/peak in the room frequency response, but that's way more effectively done with a parametric equalizer. Also, an equalizer is a more effective way of creating a dip/peak at a certain point to increase or decrease a given frequency to your liking.

So, the definition of crossover is: A combination of a high pass filter and low pass filter both working together with the same cutoff frequency. You'll also find crossover filters (mostly analog passive) inside speakers with more than one driver.

Now, the "crossover" in the Output format page is for the JRSS-created LFE channel. It is not a crossover, but a low pass filter, and has nothing to do with bass management. A fake LFE channel is under no circumstances is necessary to get good sound and it should therefore be disabled (silent) by default, like all other sound-fiddling options. (I'm not saying it can't sound good in a particular system/room where the circumstances are just right, but it might sound like crap in another setup, and there are much better ways to achieve good sound in any setup).

I would also like to see an image of your Room correction page settings, Matt.

Oh, and let me repeat my suggestion to rename the "Room correction" options page to "Speaker management". What this page does has nothing to do with room correction.

Digital room correction (or DRC) is a process in the field of acoustics where digital filters designed to ameliorate unfavorable effects of a room's acoustics are applied to the input of a sound reproduction system. Modern room correction systems produce substantial improvements in the time domain and frequency domain response of the sound reproduction system.

The fundamental principle of bass management (also called LFE Crossover) in surround sound replay systems is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of handling it, whether the latter are the main system loudspeakers or one or more special low-frequency speakers (subwoofers).

[mojave]

So, the definition of crossover is: A combination of a high pass filter and low pass filter both working together with the same cutoff frequency. You'll also find crossover filters (mostly analog passive) inside speakers with more than one driver.

Analog crossovers don't always use the same crossover frequency and neither do speakers that use active crossovers.  Even the limited crossovers between speaker and subwoofer in most speaker's bass management will use different frequencies due to differnt slopes on the HPF and LPF. Selecting "80 Hz" in the settings means that the HPF and the LPF sum at 80 Hz to produce an even frequency response.

Matt knows what a HPF and LPF since he has them available in the Parametric Equalizer. I really don't have a problem with calling it a crossover in Output Format. Whenever you work with active crossovers, the HPF or the LPF is also called a crossover. However, I do agree that Speaker Management is probably a better name than Room Correction.

[Matt]

Now, the "crossover" in the Output format page is for the JRSS-created LFE channel. It is not a crossover, but a low pass filter

I agree.  Cutoff frequency or low-pass frequency would be a more accurate term.

A fake LFE channel is under no circumstances is necessary to get good sound and it should therefore be disabled (silent) by default, like all other sound-fiddling options. (I'm not saying it can't sound good in a particular system/room where the circumstances are just right, but it might sound like crap in another setup, and there are much better ways to achieve good sound in any setup).

JRSS is a sound-fiddling option.  It is off by default, but when enabled, it attempts to make good sounding 5.1 or 7.1 from a 2.0 source.

[Matt]

The benefit of doing a crossover in Output Format is that the subwoofer channel is created from just the original left and right channel. With those that use Dolby Prologic IIx or DTS Neo, the surround channels are created and then the subwoofer channel is made by redirecting the bass from all these channels. This makes the subwoofer channel to not have as good of quality because the matrixed channels are also included.

This is an important point, because real-world listening tests show that JRSS gives a cleaner subwoofer than redirection.

A solution would be for there to be no crossover setting in Output Format and for JRSS to leave the subwoofer channel blank. Users should just use the bass management in Room Correction. I would get rid of the "remove" option in bass management since it would no longer be needed.

I think this is too complicated for many users.  It's good that we support bass redirection, but it's not something I'm ready to force on everyone for v16.

For music and TV shows, bass management could detect if there was a blank LFE channel. If so, then it would create a bass channel from just the front two channels (regardless of crossover setting for the surrounds) and follow the "move" or "copy" for all the channels.  If there was an LFE channel already present, like in movies, then it would route bass from all channels to the LFE channel following the bass management settings. This method preserves the quality of the subwoofer channel for two channel sources and 5.1 channel sources that have just a stereo encoding (like TV shows). It also allows for just one setting to be used for all music, movies and TV shows.

This is a little like what I posted above.  Basically, for simulated channels (i.e. the surrounds when doing 2.0 upmixing), "Move bass" would become "Remove bass".  Energy neutrality gets a little complicated here since JRSS is adding energy by adding speakers, but I think it would just be a matter of accounting for the total energy in the 5 or 7 speakers vs the 2 speakers being used to build the subwoofer.

To sound as good as JRSS, I think the subwoofer would need an optional final low-pass filter and/or subclarity.

[flac.rules]

This is an important point, because real-world listening tests show that JRSS gives a cleaner subwoofer than redirection.


I think this is too complicated for many users.  It's good that we support bass redirection, but it's not something I'm ready to force on everyone for v16.

Frankly, I think its unnecessary complicated that the default settings are not energy neutral. I understand the solution proposed, but why is the default not energy neutral? I feel i have a pretty good grasp of how this works in receivers and with the LFE-channel, but I was not prepared for the mixing to change the spectral balance, why should I, and why is that the default? I go to lengths to get a good sound from other sources (movies and two-channel sources), why would I want the spectral balance to change? Especially when its very unclear from the settings that it actually does. And why is it desirable for other users? In some select few cases i guess it can sound better, just as boosting all low frequency content by +3dB could sound better in some systems, but that seems pretty random?

[audunth]

I agree with Elvis here. On any piece of AV-equipment on the market, energy neutral settings are the default. If you turn on 7.1 upmixing on any receiver, it doesn't change the tonal balance, and people doesn't expect it to do that in MC either. A developer at Yamaha don't take a receiver prototype home, adjusts it so it sounds good in his listening room and then makes that the default setting.

Mojave: I don't know the exact technical details, I'm just saying you don't set the crossover frequency specifically for the sub (you can't do that with MC's bass management either, that's why the crossover choice is greyed out in the sub tab), you set a crossover for each speaker (or pair/group of speakers) and it automatically makes the sub play the frequencies below the crossover for each speaker.