• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Are there 2.1 systems with real LFE processing?

Tommy2D

Tommy2D

Active Member
Hi guys, I generally prefer active speakers over a receiver plus passive speaker combination. I had a pair of decent stereo bookshelf speakers (Edifier R200DB), connected to my TV (using optical), and I was generally pleased.

I did some reading about how the LFE channel typically isn't processed by a 2.0 amp. I used a 5.1 DTS test feature on a Bluray and found that my speakers would simulate the center and LR/RR but the LFE was in fact completely silent.

I really enjoy watching movies at home, but I'm not really interested in a full surround setup. However, I did feel like I might be missing some enjoyable effects on the LFE channel. So, I picked up the Edifier S350DB "2.1" system. It definitely has nice bass coming from the subwoofer but it appears that its internal amplifier is actually 2.0/stereo. When I use the same 5.1 test feature, the LFE channel is dead silent. I even tried connecting the S350DB directly to my PS4, using all audio options (LPCM, Bitstream, etc.) and the results were the same.

My question now is...Are there 2.1 active systems with a 2.1 integrated amplifier that will process the LFE channel? Or am I just missing the boat, somehow?
 
Last edited:
Register to hide this ad
The ".1", or LFE channel, is a separate, discrete channel in a dolby digital recording. It does not exist in a stereo recording. ".1" is often misapplied to a stereo system with a subwoofer.

The best you can get is a summed mono channel which you can hook up to a powered sub woofer with level and crossover controls. It's been done for many years, and quite successfully.
 
Last edited:
If you're playing discs (such as Blu-ray, Ultra HD Blu-ray), then the Oppo universal players' (e.g., UDP-205, BDP-105, BDP-95) line-level subwoofer connection will work. I use Oppo players in 2.1 and 4.2 systems.

Otherwise, perhaps an HDMI DAC will serve your needs, such as Essence Evolve II-4K. (I have no experience with this unit.)
 
botrytis said:
NO That is your answer. LFE is only part of Dolby digital surround.
Click to expand...

Yes, I understand that the LFE is a discrete channel, which stereo amplifiers discard.

However, if powered speakers have a sub and an optical connection, why couldn't they also include internal processing to decode the LFE channel from the optical source and process it? I suspect that there are some soundbar+subwoofers, designed for home cinema, that do this using either optical,digital coax or HDMI input. I just wish that there was a reliable product indicator about whether a powered speaker set actually includes LFE processing.
 
Tommy2D said:
Yes, I understand that the LFE is a discrete channel, which stereo amplifiers discard.

However, if powered speakers have a sub and an optical connection, why couldn't they also include internal processing to decode the LFE channel from the optical source and process it? I suspect that there are some soundbar+subwoofers, designed for home cinema, that do this using either optical,digital coax or HDMI input. I just wish that there was a reliable product indicator about whether a powered speaker set actually includes LFE processing.
Click to expand...

The LFE isn't "discarded" in a stereo setup, the LFE was added to create another channel, not the other way around.
 
Last edited:
Grenadeslio said:
The LFE isn't "discarded" in a stereo setup, the LFE was added to create another channel, nog the other way around.
Click to expand...

I understand the concept. The LFE is a specific channel for very low frequency effects; I've read articles and white papers on it (https://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/38_LFE.pdf). Unless I totally misunderstand: for 5.1,the source sends all six channels and the receiver decodes and decides how to process that information. There has to be some handshake, encode/decode process at play.

My question is: if a AV receiver can decode all channels appropriately, why couldn't the integrated circuity of a 2.1 system? After all, can't you use a 5.1 receiver with just L/R speakers and a sub and still enjoy the LFE channel?
 
(sigh) Look, you ARE getting the information from the LFE channel. It's folded into the two channels and the sub takes the lows it can handle from them.

What you bought is simply a glorified sound bar. I'm sure they could manufacture exactly what you want but it seems you are the only one demanding this so there's no economic rationale for anyone to manufacture it.

If this really, really bugs you then get a Dolby AVR and connect only the right and left speakers and the subwoofer and don't run it in stereo. Of course, you'll lose the center and surround info but you'll get your precious LFE.
 
Last edited:
You should pay attention to answers that have been previously posted (#8, #9, #10).

Once again: Two channel stereo does not have an LFE channel. It has two channels (left and right) period. There is no such thing as 2.1 stereo.
 
You purchased a "2.1 set of speakers" - 2 speakers and a sub. Just because your speaker system is marketed as a "2.1" system doesn't mean it will decode anything. It will only internally pass the low frequencies (L+R summed) to the sub and pass the mid to high frequencies (L+R stereo) to the 2 speakers.


EDIT: you should look into a soundbar+sub system for TV/video viewing/listening.
 
@JoeESP9,I read the responses.
@imral3: I suspect that soundbar + subs will also not process the LFE channel.

@the skipper I appreciate you multiple posts from what I have read, the information from the LFE channel is not folded into the L/R channel. It's discarded, in part because sound engineers do not want to overtax stereo speakers that may not have large woofers. I've also read that some AV receivers DO provide the option to achieve what you are describing, through settings (you're essentially telling the system, yes my substantial stereo speakers will not blow out from bass heavy effects).

I'm not sure where the frustration is coming from here. I personally don't think that is crazy to want the full low frequency effects, from a movie, if your system has a sub or even stereo speakers with large woofers. I don't see how lacking a center speaker, and two surround sateilletes should prevent the reproduction of low frequency cinematic effects.

As you said: perhaps there is no market, but I would suspect that most people don't realize that they are missing part of the experience.

https://hometheaterhifi.com/editorial/the-misunderstood-01-lfe-channel-in-51-digital-surround-sound/

One reason not to send a subwoofer the LFE channel alone is that there may not be anything on it or there may not be an LFE track at all. When coming out with the DVD format, it was important that consumers be able to always see and hear the program, without extra hardware like 5.1 decoders. This is why there is always an AC-3 or PCM soundtrack: Either can be played by any DVD player. Even a 6-channel AC-3 mix can be played without a 6-channel decoder because of the DVD player’s internal downmixer. This takes the soundtrack and downmixes it to a 2-channel Pro Logic output. Important is the fact that the LFE channel is not part of this downmix and gets discarded. Production facilities know that unless they provide a dedicated two channel soundtrack, nothing important should be exclusively put in the LFE channel: Depending on the playback system, it may not be heard. When done right, essential information (which can include deep bass) will be put in the screen channels.
 
As you asked, I fixed the title of your thread with a question mark, and I also prefaced it with "Are there"
From the responses you have gotten so far, I would Say "no, there are not"

Most people will either use a surround system, typically 5.1, or a 2 channel stereo system.
I don't believe anyone is really chasing a 2.1 channel system market for TV or movie use.
No frustration here - I have a 7.1 system set up downstairs, and a 2 channel music system upstairs.
 
Tommy2D said:
I suspect that soundbar + subs will also not process the LFE channel.
Click to expand...
Most (if not all) soundbar systems have the necessary decoding technology built in. These are designed for playback of TV and/or movie soundtracks. The speakers you bought are just that, speakers, plain and simple.
 
@hjames . Thanks for editing the post title. Is that a Mod only function (I didn't see the option for a title edit)?

I suspect that you're correct; I'm probably part of a nano-market in terms of interest. Eventually, I'll probably just break down and get a 5.1 AV receiver setup for home cinema use. This just irks me a bit, on a technical level, because I suspect that it would be easily achievable as long as the active speakers accept a digital input and have sufficient low frequency production. Maybe there's a product designer knocking around here that might have some additional insight. IMHO: It just seems like a lost opportunity when producing 2.1 active speaker sets. I do accept that even an extra few dollars to produce a feature, for a very small audience, is often a losing proposition.

@JoeESP9 With the right amp/receiver, it seems like you can decode and mix the LFE into stereo speakers. "On the flip side, you don’t need a subwoofer to hear the content of the LFE track. If your mains are of substantial mettle, and you don’t have a sub, bass management can usually re-route the LFE to your fronts." https://hometheaterhifi.com/editorial/the-misunderstood-01-lfe-channel-in-51-digital-surround-sound/
 
@imral3 Anything's possible, but aren't soundbars are just a form factor of active/powered speakers? A soundbar has drivers packed into a plastic box along with a circuit board. This unit just has the tweeters and mid-range drivers in satellites instead of a bar. They are not passive speakers (what I'd call speakers plain and simple). The have the same inputs as most soundbars+subs (Optical, Digital Coaxial, RCA...I'll grant that there's no HDMI input).

I agree with that you that soundbars are certainly marketed as a TV audio solution, so perhaps there are some out there that do a better job of signal processing and bass management for surround sources. Thanks for your feedback.
 
Tommy2D said:
@imral3 Anything's possible, but aren't soundbars are just a form factor of active/powered speakers? A soundbar has drivers packed into a plastic box along with a circuit board. This unit just has the tweeters and mid-range drivers in satellites instead of a bar. They are not passive speakers (what I'd call speakers plain and simple). The have the same inputs as most soundbars+subs (Optical, Digital Coaxial, RCA...I'll grant that there's no HDMI input).

I agree with that you that soundbars are certainly marketed as a TV audio solution, so perhaps there are some out there that do a better job of signal processing and bass management for surround sources. Thanks for your feedback.
Click to expand...
I'm not being dismissive when I say the Edifier speakers are only speakers. Just stating fact, as these contain no surround decoding internally.

EDIT: Edifier makes several surround systems with built in decoding technology.
 
Keep in mind your "subwoofer" won't be able to handle true LFE range since it goes from 3 to 120 hz. How far down do you think that little sub can go with any authority? It's only rated down to 40 hz, and doesn't specify a db range. Add to that that the LFE* is only supposed to provide that visceral effect one feels during action scenes.

* Low Frequency Effects
 
Last edited:
@imral3 I didn't take any offense or feel dismissed. I was just fleshing out the terminology. I tend to think of any speakers with optical/digital coaxial input as having some level of digital signal decoding capability. They at least have to include some kind of DAC to decode the pulses from the digital inputs to convert into usable sound waves to amplify and send to the speakers. That said, you're completely correct that different speaker sets will have support for additional codecs.

@ckoenig70 That looks like a pretty slicky pre-amp; I definitely like the dials to configure the crossovers.

Side note: The BluRay that I'm using to test the LFE channel is a DTS 5.1 recording. I'll have to see if any of my other DVDs have test programs.

New Question: Is there a way to do a channel test using a sound file, on a computer? I'm 99% percent sure that YouTube converts all of its content to stereo, so any test vids there would be useless.

Thanks for the interesting conversation, thus far.
 
You must log in or register to reply here.
Back
Top Bottom