LFE Downmix into 2.0 on Ultra

[tabata]

Hi @WiiM Team and @WiiM Support ,

I’m trying to create interest for a feature that:

1) isn’t provided elsewhere
2) would be super valuable to many users, even many who don’t even know it yet
3) that WiiM is uniquely capable of providing on existing hardware, and given their engineering talent
4) is actually about providing audio features and performance (rather than, say, all of the attention on the VU meters lately)

Please, please, please offer the ability to downmix LFE from multichannel sources into 2.0 output on the Ultra.

Before anyone goes any further, if you have a very bass-capable system that currently does not receive LFE: 1) Stream the Severance opening title theme on Spotify or Tidal Connect, 2) go onto your TV or streaming player and play the same theme by watching the start of an episode. The Spotify/Tidal version has the LFE mixed into the 2 channels, and it is incredible. It makes the hair on the back of my neck stand up. The video streaming version is very meh. Convinced? I certainly am.

Currently, anyone without a full-sized AVR cannot get a downmix of LFE into 2.0. AVRs are very expensive, large, and completely overkill for this task.

The Wiim Ultra no doubt has the processing power and the app control ability to offer the option of taking a 5.1 signal via HDMI, break it down, and add LFE to the L+R.

Before anyone starts saying, “but Dolby white papers say the LFE channel should be ditched in a 2.0 downmix.” Great, thanks, but that’s dumb! There are many full range speakers or sat+sub combos that would benefit by this, and that’s why so many AVRs offer downmixing the LFE into the 2.0. My system is a perfect example, and there are many others like it, and I don’t think people know how much information they’re missing on the LFE. WiiM would be heroes.

Or maybe the counter-argument is, “but you have to understand the LFE is a bass-boosted signal, often 10db higher than the mains, and that creates issues for combining them into one output.” Ok, but that’s completely surmountable. The Ultra has very powerful digital signal processing to manage that and prevent clipping. It could even offer a slider in the app for users to attenuate the LFE signal in relative terms to the mains so that we could fine tune the signal for the next device in the chain.

To be clear, I do not want the LFE broken out and put on the subwoofer output of the Ultra. That would completely defeat the purpose for me. I have a miniDSP SHD 2x4 processor that is vital to my system that would be downstream of the Ultra. In my 2.2 system, the SHD handles independent stereo time-alignment for my two subs, my HPF and LPF crossovers, gain structure for my power amp, delays, Dirac Live correction, etc. It can only take a 2 channel input. The downmixed 2.0 with LFE needs to be available on the digital optical and coax outputs of the Ultra (huge, huge preference for digital output here), or on the two channel RCA outputs if for some reason that is the only workable method.

I already own the Ultra in a different 2.1 music-only system where it is my sole preamp (and where I’m using the Ultra’s sub output), but I would absolutely 100% buy another Ultra for my 2.2 home theater system simply for it to perform a single task: taking a multichannel source and adding LFE to the 2.0 output. That’s how bad I want it, and how limited the options are elsewhere.

So many people don’t know what they’re missing because they aren’t even aware of what’s being stripped out, or even if they are aware it’s happening, they downplay the difference it would make. This is a chance for WiiM to offer something unique and that opens people’s eyes. I think experiences like that are the core of WiiM’s appeal, and why I’m such a fan. Thank you!

 

[tabata]

I came up with a workaround for my system that I’m pretty pleased with myself about, and the bottom line is that if you have (very) large mains or any sort of 2.1 system that doesn’t currently get the LFE signal (e.g. WiiM Ultra currently, optical out of your TV, etc. — you can test with 5.1 test videos on Youtube), you do not know what you are missing. WiiM would be doing a huge service to offer LFE downmixing as an option.

I looked around Facebook Marketplace and found an Emotiva UMC-200 processor for $150. It’s an ancient, low budget 1080p AV pre-pro from 2012, but it has Dolby Digital and DTS via ARC (it can’t do DD+ over ARC, just like WiiM Ultra currently). With the right settings enabled, it downmixes LFE into 2.0 because that’s been a common feature in the AV world for a long time. It has LFE level trim as well, like I described wanting in the above discussion.

The UMC-200 is as small and slim as it gets for this type of device, which was vital for me, but you could do the same with one of those massive double-height AV Processor or AVR units. They were way expensive and overkill for a project that is already using a full-size enclosure that used to route entire 7.1 home theaters as a glorified HDMI audio extractor which you can get for $50 and smaller than a pack of cigarettes. But hey, breathing new life into vintage gear is cool, and those extractors don’t have the LFE.

Last thing on the features, and @hgo58 will appreciate this, the ARC connection disappears when the unit is on standby. So if my kids or a house guest grabs my Roku Ultra remote and fires up a show — I don’t leave the big system remote lying around — they get the TV speakers and that’s just fine. It’s like the UMC-200 isn’t there. But as soon as I fire up the full system and UMC-200, the ARC registers with the TV and it grabs the signal. That’s exactly how some of us want the WiiM Ultra to behave (as an option — always-on ARC should be available too).

The only downsides are 1) it only does DD over ARC and DD is more compressed than I would like to see in 2025, and 2) I have to use the built in DAC and analog RCA outs to get the 2.0 LFE downmix, but this unit has decent preamp measurements over HDMI input (ASR, Audioholics, and Sound & Vision all tested this thing — optical and coax inputs don’t perform well but HDMI is clean) and I’m getting dead silence when nothing is playing, so probably good enough.

I’m not getting any signal overload problems with the LFE folded in, and my crossovers in the miniDSP handle all of the routing. I’m on LR 24db/oct HPF and LPF filters, both set at 90hz. It’s a proper 2.2 setup with stereo routing and separate timing for the subs. The LS50s have no idea any of this stuff is happening and their excursion is just fine. The subs are going wild.

So much of the home theater experience is the LFE that I think this is a big deal. I can do without surround sound, honestly. It’s cool, but I’ve never had a room where it made sense to install it and I don’t mind that sounds aren’t swirling all around me. But I can fit a couple subwoofers in this room and the effect is huge. If you are using optical out from your TV or letting the WiiM Ultra handle it right now, you are losing a ton of atmosphere and impact from TV shows and movies.

@WiiM Support I’d happily switch this whole thing over to the WiiM Ultra, especially if DD+ 5.1 could somehow be included to get some better bandwidth, just to upgrade from the Mini and have a smaller, sleeker device handle this operation than a low-end, secondhand AV processor from the first Obama administration. I also assume that with the Ultra I would be able to route this digitally, which isn’t something the UMC-200 does and that would allow me to preserve the digital signal all the way until the miniDSP DAC. Think about it, please!

System, outside of the UMC-200, for reference:

Sources:
WiiM Mini
Roku Ultra (2024)
Samsung S90D QD-OLED 65” (2024)

Preamp and amp:
miniDSP SHD
NAD C298

Speakers
KEF LS50 Meta
2x SVS SB-1000 Pro

 

[rccarguy]

"you can test with 5.1 test videos on Youtube), you do not know what you are missing."

Youtube doesn't have LFE channel. If you want to test discrete 5.1, use a DVD with DD or DTS mix. Preferbly DTS as it has higher bitrate. Or use a BD movie ideally as that is lossless HD audio so higher quality

" that if you have (very) large mains"

I have large mains that go down to 32hz and using 300W amplifiers. I wouldn't recommend directing LFE to that, you could damage them

But yeah stereo and AV doesn't really mix, not optimal that a stereo amp chucks away LFE, doesn't decode DD/DTS

 

[tabata]

"you can test with 5.1 test videos on Youtube), you do not know what you are missing."

Youtube doesn't have LFE channel. If you want to test discrete 5.1, use a DVD with DD or DTS mix. Preferbly DTS as it has higher bitrate. Or use a BD movie ideally as that is lossless HD audio so higher quality

" that if you have (very) large mains"

I have large mains that go down to 32hz and using 300W amplifiers. I wouldn't recommend directing LFE to that, you could damage them

But yeah stereo and AV doesn't really mix, not optimal that a stereo amp chucks away LFE, doesn't decode DD/DTS

You absolutely can test for receiving an LFE signal from YouTube. There are 5.1 channel-by-channel test videos and you can test you’re getting surround downmix and the LFE.

I think with a trim level you would be fine with regular big mains. You bring down the boosted peaks of home theater and it just becomes normal bass. The point is some bass sounds and atmosphere are only going to the LFE channel and having the track completely disappear is way worse than just attenuating it and sending it through the mains.

 

[tabata]

And I basically retract my “very large mains” comment if there’s an LFE trim setting. People are already doing crazy things to their speakers with hip hop and EDM. We don’t need to think of this as a limited use case only for people with enormous towers.