Bass in LFE vs Individual Channels

[Vladimir Filevski]

Google says this

As usual, AI is wrong.

This is right:

"Bass management" in an AVR is an optional crossover that allows the regular bass from the other channels to be re-routed to the subwoofer.

 

[techsamurai]

LFE+main is a setting that most don't really need. If your mains go to below 50hz something to consider. We can talk more if people are interested, but it is quite a bit of niche.

Not the point of the discussion but here are my settings for my 5.1:

L+R : Full Range (towers 38hz min)
Center 60hz (small center inside a BDI cabinet)
Surrounds : 80hz (bookshelves)

Audyssey always recommends all speakers to Full Range for past 20 years with 6 AVRs (Audyssey MultEq and XT32) but I reduce it manually for dialogue clarity on the center and to give more power to the mains.

LFE: LFE+Mains I might have set that manually - maybe I should check it off.

I have a different set up for 2 channel playback: 40hz and LFE+Mains

 

[Oddball]

Well, we are all on a journey, so trying different things is part of it. Only you can say what is the right setting after all. Should measure reasonably well, but at the end choice is up to your preference.

Every system is different so we all need to do best we can with what we have. I can say that if people are really picky, having DLBC or Audy MultiEX-X will help them tune the system to what they really would like to hear. But then, I do remember hundreds of hours that I have spend just understanding what is it that I actually like to hear. Discovering your preference across multiple systems is probably the most time demanding thing in the business.

 

[Daverz]

I see stuff in the LFE channel on some SACDs (so just for music, no video). I wonder what the intent of the mastering engineer was there?

I have a "DIY" 4 channel setup with the channel routing done by CamillaDSP into a Moto Ultralite Mk5. I have a digital crossover that sends the low frequencies on channels 1 & 2 to left and right subwoofers, respectively. Currently I just ignore the LFE. I think my other options for the LFE are

1. Attenuate the LFE (how much?) and route to channels 1 & 2 (that is, before crossover is applied)
2. Send it directly to subs, no lowpass.
3. Like 2, but apply lowpass first.

 

[Kal Rubinson]

I can say that if people are really picky, having DLBC or Audy MultiEX-X will help them tune the system to what they really would like to hear.

And DL-ART provides more opportunities.

 

[Oddball]

And DL-ART provides more opportunities.

That is what we keep hearing - and eagerly awaiting reviews that would substantiate that.

And there is a very down to earth question how much will ART lower ones hardware requirements. DBAs and Trinnov waweforming have been around for a while but take a lot of the budget and space. ART - you tell us how it fares in that respect if your NDA is not too strict.

EDIT: Also - had a couple of practical ART questions in this thread and you might be one of the few that could answer - even without being close to breaching your NDA.

Dirac ART is now running on beta FW for Denon Xx800H AVRs!

I just want to share a new press statement. Greets, mike https://www.dirac.com/blog/dirac-announces-that-dirac-live-active-room-treatment-is-coming-to-denon-and-marantz-devices-to-unlock-next-generation-room-correction-capabilities/?srsltid=AfmBOop8iUdDQSbCo6BVqdoJSGam3zThPyFtKCG5PbsXAMl1ZO5lw_6G

www.audiosciencereview.com

 

[techsamurai]

And DL-ART provides more opportunities.

Not an ART expert but my understanding is that it will distribute bass across all speakers. Will it use the bass from the individual channels and/or the LFE?

Would that not require a significant number of subs positioned around the room and or tower speaker for LCR (obviously since 70% of sound) and surrounds?

 

[Chrispy]

The LFE NEVER goes to the regular speakers.

The "LFE" is the "point one" low frequency effects channel on a DVD/Blu-Ray. I don't think it's supposed to go over 80Hz but on the disc it's just one of 6 (or more) channels. It's a separate channel that's not included in the stereo downmix so without a surround decoder and a subwoofer it's lost.

"Bass management" in an AVR is an optional crossover that allows the regular bass from the other channels to be re-routed to the subwoofer. Your AVR may have settings for "large" main speakers, which means the regular bass isn't re-routed to the sub (so the sub wouldn't be used at all with regular stereo music), "medium" which has a lower crossover, or 'small" which has a higher crossover.

If you don't have an AVR your stereo preamp or receiver may have a crossover and a subwoofer output, but it's technically not an LFE. Or the sub may have its own pass-through crossover, or you can have a separate crossover, etc.

Not true. Sometimes LFE can be sent to mains, particularly with a few new avrs/pre-pros from what I've seen. Can even be adjusted as to how much. Not something I'd particularly look for as important otoh.

 

[techsamurai]

Not true. Sometimes LFE can be sent to mains, particularly with a few new avrs/pre-pros from what I've seen. Can even be adjusted as to how much. Not something I'd particularly look for as important otoh.

That would be interesting - do you specify the channel or set of channels that would handle it or is it sent to all of them including the height channels?

AVR: Hey, overhead in-ceiling speaker, you've just been promoted to a subwoofer!

Speaker: I'm not designed for that! I can only handle frequencies over 120hz.

AVR: Just shut up and do your job! (Jolts speaker with 100 watt shock)

 

[Chrispy]

Seems another example of how bass managment vs treatment of LFE is different.....let alone the various settings used like LFE+MainDouble Bass etc. Mostly user errors.

 

[Vladimir Filevski]

@techsamurai
Summary:
1. LFE channel is separate channel/recording, which content is not present in front L-C-R and surround channels/recordings. You need an active subwoofer to take full advantage of the LFE channel.
2. If L-C-R loudspeakers are small and can't reproduce low frequencies from their channel content, AVR Bass Management System can redirect all L-C-R bass contents to the subwoofer, below some user-defined frequency (... 80, 100, 120 Hz, ...). User must manually set this option. So, all L-C-R bass content will be mixed with LFE channel content and delivered to the subwoofer.
3. If you don't have subwoofer, AVR Bass Management System can redirects LFE content to the front channels. User must manually set this option. Unless you have really big bad front loudspeakers, you have to settle with very modest SPL output.

 

[Oddball]

LFE+Main has been around for a while. Depending on the settings, one might achieve similar results as with traditional crossover approach, or could create an area of overlap between the subs and large speakers that get the full range signal. I would not dismiss it as user error, but it is certainly additional challenge - and requires large speakers and adequate amps.

Sending LFE signal to other speakers can be done with Trinnov, Storm and as of recent D&M gear. On Trinnov you can slice it and dice it pretty much any way you want with full support from Optimizier. On Storm you will need extra bass management module ($2K) and it will not work with Dirac, so it will require custom PEQ setup.

On D&M, you need to designate your speakers as large which means they will get full range signal and none of that channel's signal will be sent to subs (absent LFE+Main). This will not work with Dirac though. Then you can adjust the level of the LFE signal per pair of speakers from -20dB to 0dB. While it might sound scary, Audyssey will take care of the scary part. So if e.g. your LR go down to 30hz, it will follow the EQ curve for the mains also when sending LFE so 20hz LFE signal will be reduced as you have requested with your curve. So rolling off steep is recommended for using this feature.

There is also such feature as directional LFE, but that rarely works, so not going to get into that.

 

[Vincentponcet]

Are you saying that 20hz-60hz can be localized?

I didn't say that. I'm talking about spl

 

[techsamurai]

On D&M, you need to designate your speakers as large which means they will get full range signal and none of that channel's signal will be sent to subs (absent LFE+Main). This will not work with Dirac though.

So what is really happening when I set my LR to Full Range and LFE to LFE+Main?

I know the channels' bass for LR goes to the channels but what about the LFE? What does LFE+Main do?

Denon's answer is very confusing and it seems that LFE+Main is the recommended setting.

We recommend using LFE+MAIN if you normally playback both movies and music.

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support.denon.com

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support.denon.com

 

[GXAlan]

Are you saying that 20hz-60hz can be localized?

No. BUT the second order harmonic distortion of that 60 Hz signal can be localized.

Simple test. Take a subwoofer at modest level, stand close somewhat close to the sub just play a movie with real LFE content, muting all channels but the sub. Pick a scene with a lot of active content. While standing still, turn around and see if there is a difference when facing the front or rear wall. Real LFE content is nice stress test to include IMD but the effect works with test tones too.

Now increase the volume and step further away from the sub. You are roughly level matches. Now do the same test.

When you start to hit the distortion limits of the subwoofer, you will add localization. It is my opinion that the sound quality doesn’t change too much between low and high distortion bass, which is consistent with the CTA-2010 arguments that you can have 10 or 20% THD without it being offensive when it comes to bass. However, it is also my opinion that there is a difference in localization with higher distortion…. Which is not a “sound audibility” perspective but an immersion perspective.

The other practical way is to try two different subwoofers. I have an approximately 1500 cubic ft room where I am 3m from the main subs. I use an 18” PSA S1813M and 15” Earthquake Supernova Luminous. These subs are seemingly overkill, but it allows the subs to work at a much lower level of distortion and increases immersion by reducing localization.

I also have an Earthquake Sound CP-8 slim sub. That has a lot of output and a lot of distortion. It’s a good choice when you have to choose between zero subwoofer and a budget subwoofer that’s small, but there’s clearly a difference. I ironically have my smallest sub in my biggest room (for aesthetics).

Last, the LFE channel itself is mixed to 120 Hz.

 

[Kal Rubinson]

Not an ART expert but my understanding is that it will distribute bass across all speakers. Will it use the bass from the individual channels and/or the LFE?

One has options to control most of those variables.

That is what we keep hearing - and eagerly awaiting reviews that would substantiate that.

The DL-ART that I use is still in beta.

 

[darth]

Ignoring Genelec specific fluff, I learnt a bit about about this from these pages

Bass Management System - Genelec.com

Bass Management System handles multichannel low frequency content.

www.genelec.com

https://support.genelec.com/hc/en-us/articles/360013339960-What-is-the-LFE-1-Channel

Architectures shown here

https://support.genelec.com/hc/en-us/article_attachments/360011472099

 

[techsamurai]

Take a subwoofer at modest level, stand close somewhat close to the sub just play a movie with real LFE content, muting all channels but the sub.

How do you mute channels? I guess I could yank out the cables but that requires moving the cabinet which has near invisible wheels (believe it or not) but is still a workout.

No. BUT the second order harmonic distortion of that 60 Hz signal can be localized.

I didn't even know there were 2 orders of harmonic distortion. My old AVR could only crossover at 60hz as the bottom and I remember thinking it had pros and cons when I introduced it and set the crossover to 60hz - it wasn't a complete victory for the sub as I was expecting. Since I was limited to 60hz, I believe I finally went Full Range for the L+R for music as the sub didn't seem to provide the same quality as the speakers when playing some songs. I suspect the localization, timing, decay, or some other attribute were affecting the sound even at those low frequencies and 15 years of listening without a sub made it fairly easy to detect. I doubt I'd notice now as I'm used to the sub's sound. I'd notice it being off probably which I did one day when the volume was -10db by accident.

 

[Oddball]

So what is really happening when I set my LR to Full Range and LFE to LFE+Main?

I know the channels' bass for LR goes to the channels but what about the LFE? What does LFE+Main do?

Denon's answer is very confusing and it seems that LFE+Main is the recommended setting.

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support.denon.com

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support.denon.com

LFE+Main would send full range signal to large speakers and then one has option to pick a point where signal from these channels will be sent to the subs. D&M has quite a chunky choice of 40/60/80hz and then in 10hz increments and this is a low pass filter where sub/s gradually pick up. Again, Audy will still work to protect your speakers and roll them off according to their curve so that full range is not necessarily going to break the speakers.

This does not have anything to do with LFE per se. LFE channel will be played by the subs. LFE distribution is where one can send LFE to large channels.

It is questionable what are the good circumstances to use this setup. I can definitively use it with LR reaching to 30hz and 300Wpc of Bryston amps per channel. My surrounds are not that capable but still go down to 50hz and have 125Wpc Rotel amp support so it still makes sense. But I still choose to reinforce the low end with subs phasing in at 60hz. It is a mess, but in a good way. Then put on top of it LFE distribution and a headache becomes a migraine.

 

[Vladimir Filevski]

It is questionable what are the good circumstances to use this setup.

Agreed. I would say LFE+Main is unnecessary option for OP and for many others.