Home Theatre Speakers - do you really need a sub, if you have full range?

[dlaloum]

All it does is disable bass management for front speakers. LFE still only send to the sub out.

Don't know whether that is the case with current AVR's - but in past generations, I have run 4.0 setups before and the LFE channel was redirected to the Front L/R.

LFE definitely was redirected - intention of "double bass" settings is to direct the LFE channel into the front L/R in addition to the sub - that is its whole reason for existence....

 

[sarumbear]

Don't know whether that is the case with current AVR's - but in past generations, I have run 4.0 setups before and the LFE channel was redirected to the Front L/R.

LFE definitely was redirected - intention of "double bass" settings is to direct the LFE channel into the front L/R in addition to the sub - that is its whole reason for existence....

I stand corrected.

I tested this on a friend's AVR-X2200W and indeed when selected as LFE+Mains, LFE is mixed to the front pair.

 

[Jon AA]

Unless you tested this with all the major audio codecs it's unfortunately not valid. If you just used REW or whatever, then you're sending PCM audio so it's valid for that.

LFE behaviour with no subwoofer is different for the DD+ decoder, DD decoder, and then different again for the multi-stream codecs like TrueHD/Atmos, which afaik prevents audio engineers from even trying to include the LFE in the stereo mix.

Well, the Atmos test disk was actually the next thing I tried--in both TrueHD and DD+, same results. The same test tones in DD+ downloaded from the internet in an MP4, same results. The Auro3D test disk, same results. The Omnimic test disk which is generic DD I think, same results. In short, I can't find a source in which the LFE does not play. I do have a DTS:X test disk, but it doesn't have an LFE test tone...but based upon how my floor shook with the demo material at very moderate volumes, I'm going out on a limb and saying it must have been playing LFE with those as well (I know, that's real "scientific!" ) . In short, until somebody can find a codec, source or any way possible to keep the LFE from playing through at least the L&R speakers, I think I'm on safe ground saying it's not possible for it not to play with these units.

This discovery is very useful though! It's actually even worse than I thought. On top of the inconsistent LFE downmixing issue, this makes a multi-channel system without subs pretty pointless IMO. Only having the L/R involved limits you to two LFE sources with no placement flexibility, no matter how many floorstanders you've got.

Unfortunately (or fortunately?) I need to walk that back a bit. I seem to have accidentally discovered this is setup dependent. I decided to give things another quick listen yesterday and I thought I was losing my mind--I was getting LFE from the surrounds! I *think* I tracked down the discrepancy--in my haste in turning off the subs and setting the speakers to large (in the on screen menu--not the proper way), I had somehow accidentally shut off the back surrounds giving a 5.1 base layer. I don't know why they'd think you want LFE from the surrounds in a 5.1 but not a 7.1, but that seems to be the case. I didn't spend a bunch of time testing though, so I'm not going to be definitive other than saying it may be possible in some setups to have the LFE coming from both the fronts and surrounds. At no time did the center channel ever play LFE.

So in the end, as far as I can tell, with these units you will always hear the LFE channel being played, even without a sub. But it's obvious they are not designed to do that as well as possible, or they'd play it through all the speakers you set to large.

 

[sarumbear]

This is why I have a separate subwoofer that is fed with the LFE signal only. I treat it as its name Low Frequency Effects, not music, not dialogue. Just the effects and as such I am happy if such low frequencies are coming from a flat frequency response speaker or not. I don't think the rumble or an explosion sound needs to be equalised.

 

[Sancus]

So in the end, as far as I can tell, with these units you will always hear the LFE channel being played, even without a sub. But it's obvious they are not designed to do that as well as possible, or they'd play it through all the speakers you set to large.

So after reading your results I went and tested it myself. You're right, you do get LFE in some configs with some codecs, so I'm wrong that you won't consistently get LFE in any circumstances. However, there is a big caveat.

Here are my results:

LFE? Yes or no.	2.0	3.0	5.0
Atmos/TrueHD(same behaviour)	No	Yes	Yes
DTS 5.1	Yes	Yes	Yes

In all cases, when surrounds were enabled, I got LFE from the surrounds. I also NEVER got LFE from the center.

So it seems that a surround setup with no sub will at least work. However, stereo folks are out of luck, as none of the newer Dolby codecs will ever downmix the LFE. And that's a large portion of newer content.

I do have a DTS:X test file, but it's a silly little flying orb that activates multiple speakers. I honestly cannot tell when the LFE is activated or not activated. Maybe if I low-passed my Genelecs to eliminate all other sound I could get it to work, but honestly I don't care that much. The file is here for anyone who wants to try.

I should note that there are a lot of different ways to mix content in the object-based codecs(Atmos and DTS:X) using a combination of objects and bed channels. So there is unfortunately no way to 100% confirm that this works consistently with all available content. Other brands of receivers may also not work this way.

I still think no-sub setups are going to perform a lot worse than multi-sub setups.

 

[Jon AA]

This is why I have a separate subwoofer that is fed with the LFE signal only. I treat it as its name Low Frequency Effects, not music, not dialogue. Just the effects and as such I am happy if such low frequencies are coming from a flat frequency response speaker or not. I don't think the rumble or an explosion sound needs to be equalised.

That's sure an interesting way of doing it. A lot of multichannel music uses the LFE channel, if you listen to a lot of that I don't think one unequalized sub is going to give the best results.

Here are my results:

LFE? Yes or no.	2.0	3.0	5.0
Atmos/TrueHD(same behaviour)	No	Yes	Yes
DTS 5.1	Yes	Yes	Yes

Interesting, I never tested 2.0. That's definitely a flaw for movie watching on a 2.0 system.

I still think no-sub setups are going to perform a lot worse than multi-sub setups.

I definitely agree with that. Subs are good....

 

[sarumbear]

That's sure an interesting way of doing it. A lot of multichannel music uses the LFE channel, if you listen to a lot of that I don't think one unequalized sub is going to give the best results.

That’s how you listen at a cinema, that’s how they auditioned when post-producing the film and that’s how surround sound was invented as: a separate speaker for every channel.

To me it’s not interesting but the expected way.

 

[DonH56]

I did not read the whole thread, sorry, but here is my old "why subs?" post from ages ago. I first added a (DIY servo) sub to my system back around 1980 or so and have had them in pretty much every system of mine since.

---

I use subs, and have for decades, for all the usual reasons:

- Very (perhaps extremely) few "large" speakers actually play well below 40 Hz let alone 20 Hz. They distort heavily when presented with large bass signals (which most are -- see Fletcher-Munson) and driving them down low robs headroom for higher frequencies and causes distortion well above the fundamental signal frequency (harmonic and nasty intermodulation). Subs typically enable the mains to operate with much lower distortion.

- Very rare is the room setup such that the best place for stereo imaging and soundfield is the best place for the subs (or deep bass drivers) to counter room modes and such. Having independent subs provides placement options to smooth the in-room response. It is almost impossible to counter a null without subs (typically must move the MLP or change the room's dimensions though there are purpose-built panels that can also work). This is one of the things that led me to subs despite having quite capable mains.

- Powered subs offload the main amplifiers of the need to provide deep bass energy, providing more headroom and cleaner sound from the amplifiers.

- Music (let alone action movies) often contains deep bass content even if it is not real obvious. Kick drums, tympani, organ, sure, but also piano hammer strikes, plucked strings, beat patterns from instruments playing together, etc. May not really notice when they are there but usually obvious when they are taken away. Having subs fill in the bottom octave or three can make a difference.

- Purpose-built subs can provide high output cleanly at relatively low cost. The amplifiers and drivers need only cover a fairly limited frequency range so have fewer constraints upon them than woofers in a full-range system.

I do prefer main speakers with fairly deep bass and always have. Crossovers are not brick walls so a fair amount of energy still comes from the mains an octave below the crossover frequency. Higher-order crossovers allow you to reduce the overlap, but I still like having the capability. I have never really understood the idea of running "passive" bi-amping as implemented by an AVR (sending full-range signals to multiple channels and letting the speaker's crossovers separate frequency bands -- wastes amplifier headroom and seems to me of little benefit). Nor do I agree with the "plus" setting putting subs and mains in parallel; again, my idea has always been to isolate the two for the reasons above.

My first sub was a DIY design using an Infinity IRS woofer with my own control box to provide the crossover and a servo circuit using the second voice coil of the woofer. I had a Hafler DH-220 around so also incorporated a circuit to bridge it for use as a subwoofer amp. It worked well and the -3 dB point was ~16 Hz. I now run four small (F12) Rythmik subs using a similar (but updated) servo design with my Revel Salon2's and am happy with the result.

FWIWFM/IME/IMO/my 0.000001 cent (microcent) - Don

 

[Jon AA]

That’s how you listen at a cinema, that’s how they auditioned when post-producing the film and that’s how surround sound was invented as: a separate speaker for every channel.

Which has absolutely nothing to do with anything. In the mix you stream or have on disk at home, you have no idea how little or how much they decided to put into the LFE channel. Some music disks put nothing in there, others seem to put a great deal of the recording in there.

Don't get me wrong, I'm very open to the concept of full range speakers around the room, or local bass management crossing speakers to subs near them--but that only applies to the speaker channels. The LFE channel contains no spatial information by design. In tracks that rely upon it heavily, if you can't reproduce it well you will be missing out.

If you really have full range speakers around the room or multiple subs, what exactly do you think you're gaining by not spreading the LFE around and properly equalizing it? Honestly it sounds like a waste of a Trinnov to me. I have heard some pros say they like to mix the LFE hotter to the subs on the front stage, but all spread it around. A single, unequalized sub for the LFE is a strategy I've never heard of. Probably for good reason.

 

[sarumbear]

Which has absolutely nothing to do with anything. In the mix you stream or have on disk at home, you have no idea how little or how much they decided to put into the LFE channel. Some music disks put nothing in there, others seem to put a great deal of the recording in there.

Don't get me wrong, I'm very open to the concept of full range speakers around the room, or local bass management crossing speakers to subs near them--but that only applies to the speaker channels. The LFE channel contains no spatial information by design. In tracks that rely upon it heavily, if you can't reproduce it well you will be missing out.

If you really have full range speakers around the room or multiple subs, what exactly do you think you're gaining by not spreading the LFE around and properly equalizing it? Honestly it sounds like a waste of a Trinnov to me. I have heard some pros say they like to mix the LFE hotter to the subs on the front stage, but all spread it around. A single, unequalized sub for the LFE is a strategy I've never heard of. Probably for good reason.

I think you missed my point. I was advocating the use of subwoofer for LFE channel.

 

[JoachimStrobel]

I have 6 Canton RCL, they do 18Hz easily, Diraced. For Multichannel music all is fine as there usually is no LFE channel. For movies there is always a LFE channel, not for music but other stuff. Mixing that into other channels is tough to do. For the correct level and balance it would have to be done into all 6 channels, causing phase problems. And I have seen only setups where the LFE is merged into the mains. So I bought a low cost subwoofer for those LFE sound snippets. That sounds great for what is is. I guess nobody will do a contest on with system a gun fire sounds most melodic. I guess I miss the point about all those multisub setups with advanced Dirac stuff aiming for high fidelity in gun sound reproduction.
I got my loudspeakers for a good price as their production was stopped. But I see the problem should want to upgrade. I probably read all those threads multisubs again then …..

 

[Jon AA]

Well, for lovers of large speakers all over the room, the new Denon/Marantz units are going to make you happy with movies (possibly music too).

LFE Distribution
Adjusts the amount of LFE signal sent to the large floor speakers.

Off (Default): Floor Speakers do not play LFE signals.

–20 dB – 0 dB Adjusts the amount of LFE signal sent to the large floor speakers.

This setting cannot be set when the “Front”, “Center”, “Surround”, “Surround Back”, and “Front Wide” settings of “Speaker Configuration” are all “Small”.

From what I can tell from the manual, this option is available even if you do have subs. LFE+Main might become significantly more useful--one can still do a manual crossover in MQX and have their large speakers contribute to smoothing the bass over that frequency for LFE (and possibly other speakers?). It's unclear exactly how it will work just from the manual, (they seem to combine bass managed material and LFE material at times in the terminology), but these are some pretty sophisticated bass management options that I didn't ever think I'd see from D&M.

 

[sarumbear]

Well, for lovers of large speakers all over the room, the new Denon/Marantz units are going to make you happy with movies (possibly music too).


From what I can tell from the manual, this option is available even if you do have subs. LFE+Main might become significantly more useful--one can still do a manual crossover in MQX and have their large speakers contribute to smoothing the bass over that frequency for LFE (and possibly other speakers?). It's unclear exactly how it will work just from the manual, (they seem to combine bass managed material and LFE material at times in the terminology), but these are some pretty sophisticated bass management options that I didn't ever think I'd see from D&M.

LFE+Main was always available but not with variable level. That is a new option.