Dolby vs. DTS vs. Auro Upmixers

Upmixer Face-off: DSU vs. Neural:X vs. Auro-3D

As part of my testing of the flagship Denon AVR-X8500H A/V receiver, I finally have access to all three of the competing immersive sound upmixer formats and was able to run a comparison to see exactly how they each work on a normal movie soundtrack.

My prior A/V receiver, the 2014 Denon AVR-X5200W, was a Dolby Atmos model released prior to the introduction of DTS:X. In addition to being unable to decode actual DTS:X soundtracks (which defaulted to the DTS-HD Master Audio 7.1 core instead), the receiver also lacked the corresponding DTS Neural:X surround upmixer. Its support for DTS upmixing was limited to Neo:6, which topped out at 7.1 channels of sound. As such, in order to fill the height speakers in my room when playing a non-Atmos soundtrack, I had no choice but to use the Dolby Surround Upmixer (DSU). I didn’t have much complaint with this, as DSU generally does a good job. Still, I’d been curious to see what the competition did differently.

A couple years ago, our site’s Michael S. Palmer made his own comparison between DSU and Neural:X, which suggested that Neural:X was more aggressive and louder in panning sound effects to the height speakers. Whether this is desirable may be a matter of personal opinion. Not only did I want to check that out for myself, the X8500H affords me a couple of advantages that Michael didn’t have at the time: 1) I can run six height speakers in a 7.1.6 configuration rather than be restricted to 7.1.4, and 2) the X8500H also comes standard with the third-party Auro-3D upmixer, which was previously a $199 add-on expense (that I doubt many users paid for).

The Test

After installing the X8500H, I configured the receiver for 7.1.6 format, designating my three pairs of height speakers as Front Height, Top Middle, and Rear Height respectively. Then I performed an Audyssey calibration to adjust the volume levels and apply EQ.

Of the three upmixers, only DSU utilizes all three height pairs. Both Neural:X and Auro-3D are limited to 7.1.4 processing, ignoring the Top Middle speakers. (Auro-3D can be configured for 5.1.6, but I did not test that this time through.) On the other hand, although it fills more speakers with sound, DSU only actually decodes height information as a single stereo signal, using the entire left side of the room (all speakers) as one channel and the entire right side of the room as the other, with no distinction between front and rear. (Note that this only applies to DSU upmixing, not to native Dolby Atmos soundtracks, which have fully discrete sound from every speaker.) In their favor, both Neural:X and Auro-3D have four distinct upmixed height channels, front and rear on both the left and right.

My go-to demo for upmixing is the DTS-HD Master Audio 7.1 soundtrack on the Blu-ray edition of ‘Spectre‘. The opening teaser action sequence has a huge crowd of thousands of people on the ground shouting and cheering during the Dia de los Mueros celebration in Mexico City while a helicopter does acrobatic stunts above them. I started by watching the scene with all three upmixers. In all cases, I could hear the sound of the helicopter moving around above my head, which is especially effective when it pans from one side of the room to the other (left to right or vice versa). While there were some differences, they all sounded more similar than not.

To get a better sense of what each upmixer really does, I then disconnected my subwoofer and all of my speakers except the height channels. The results I got after replaying the scene were interesting:

DSU – It was very startling to me just how few of the helicopter sounds emanated from the height speakers in this scene. Almost none, in fact. Those sounds almost entirely remained in the ground level speakers, but they image extremely well, enough to fool me into thinking that the sounds were above my head. Mostly what DSU drew upward were the diffuse noises of the crowd shouting and cheering, which filled the whole room through the entire scene even when only using the height speakers.

DTS Neural:X – This behaved almost exactly the opposite of DSU. A great many helicopter sounds came from the height speakers, often very loudly. Meanwhile, crowd sounds were hardly drawn upwards at all. Logically, this would seem to make sense (the crowd is on the ground and the helicopter is above), but I still expected more of the ambient crowd noises to fill the heights. Neural:X is the only of the three upmixers to have prominent drop-outs where no sound at all came from the height speakers during this scene.

Auro-3D – Auro fell somewhere in between the other two. It had a fair number of both crowd noises and helicopter sounds in the heights. The crowd noises were roughly equivalent to what DSU did but with more helicopter sounds. Those helicopter sounds were not nearly as loud as Neural:X.

I then reconnected my subwoofer and all my other speakers. Regardless of what I learned about how much the height speakers were actually working, the helicopter still seemed to buzz above my head using all three sound formats. It was indeed loudest up there with Neural:X, but it was plenty convincing with the other two as well. As I said earlier, the overall sound of the scene was largely similar regardless of which upmixer was chosen.

The Conclusion

It seems to me that each of these three processors has a different philosophy for how to upmix audio from a standard channel-based soundtrack into an immersive system. The Dolby Surround Upmixer primarily focuses on drawing ambient and atmospheric sounds into the height speakers while leaving most discrete sound effects in the original ground channels. DTS Neural:X does the opposite, pulling sound effects upward while leaving ambient sounds below. It also applies a decided volume boost to the height speakers compared to the other formats. Finally, Auro-3D appears to simply copy the ground channels into the heights, expanding the soundstage vertically with a little reverb added to give the heights some separation.

The lack of Top Middle support in Neural:X or Auro-3D didn’t prove to be much of an impediment. Both imaged sound above my head fairly well using just the Front Height and Rear Height channels. At the same time, I hardly noticed that DSU did not have discrete front and rear effects, likely because the types of sounds it pulls upward don’t rely on that kind of precision.

Which of these does a better job of upmixing will be a matter of personal preference, and may also vary depending on the content. With its volume boost and focus on discrete sound effects, Neural:X is perhaps the showiest of the three upmixer formats. It really wants you to know that it’s working. As a result, it can have more of a “wow” factor than the subtler DSU. At the same time, Neural:X risks being too aggressive and loud, which can be distracting. Its focus on sound effects also means that it risks erroneously drawing inappropriate sound effects that are intended to stay at ground level (like, for example, cars driving) above the listener. Auro-3D can also have this problem, whereas DSU takes a more cautious approach and is more likely to leave the sound effects where they started, instead keeping its heights constantly active with atmospheric effects.

Auro-3D essentially creates walls of sound, as if each of the speakers on the ground were taller and extended to the ceiling. This can be quite effective in some circumstances, especially music, but in my opinion is less useful for movies because it cannot provide true separation where some sounds leave the ground and only appear overhead. Conversely, that type of separation can be a detriment for music. When watching a concert, you don’t want the sound of a flute or violin to appear isolated above your head, which can sometimes happen with DSU. In those circumstances, Auro-3D shines.

Ultimately, even despite their differences, all three of these upmixers are pretty good at what they do. With all speakers playing on both the ground and height levels, they’re all liable to have quite similar net effects. The best course of action is to play around with all of them and default to the one that you find most engaging for the broadest variety of content.

Dolby Gets Petty

All of this testing of upmixers may unfortunately be complicated by recent news that Dolby has reportedly mandated that its licensing partners prohibit cross-upmixing of Dolby-encoded soundtracks with competitor processors. In other words, if you watch a movie or other content with a Dolby Digital or Dolby TrueHD soundtrack, you’ll be restricted to only using the Dolby Surround Upmixer, and cannot apply DTS Neural:X or Auro-3D upmixing to it.

There is no technical reason or limitation for this. Cross-upmixing works fine on current A/V receivers. Although certain 2015 processors from Denon and Marantz did block cross-upmixing in this manner for a time, that was later resolved with a firmware update that re-enabled the feature.

Right now, it’s not clear whether this mandate will only apply to upcoming products, or whether owners of existing A/V receivers and processors should worry about currently active features being taken away during firmware updates. Until that’s cleared up, it may be wise to disconnect those units from their internet connections and avoid making firmware updates.

In the event that cross-upmixing is blocked, viewers watching movies on Blu-ray or Ultra HD discs can switch their players to outputting the soundtracks in PCM 5.1 or 7.1 form rather than Bitstream. Unfortunately, this workaround is unlikely to work for TV and cable broadcasts or streaming, where the receiver boxes typically limit PCM output to just basic stereo sound.

To be frank, this seems like a major dick move to me, done for no apparent reason other than to spite the competition. At present, DTS has not imposed a similar limitation on its own soundtracks, but I wouldn’t be surprised to see that company retaliate in kind, blocking DSU from use on Blu-rays with DTS-HD Master Audio sound. In the end, it’s the consumers who will hurt the most from this. I hope the powers-that-be at Dolby rethink this decision.

Which Surround Sound Upmixer Do You Prefer?

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  1. Csm101

    I’ve gotten to the point where I just us my Neural X for all of my upmixing needs. It’s simpler that way. Hopefully Dolby won’t screw that up.

    • Abe

      Thank you for posting this article Josh.
      Just got one of the new Denons and still need to spend time with all these settings.
      Perfect timing.

  2. William Henley

    I haven’t gone height yet, but I tend to use Neo 6 for classical music, and ProLogic for movies. When listening to pop stereo music or rock, I forget what they call it, but it is pretty much where it mirrors the front speakers to the sides and back.

    I have had to turn off surround sound upmixing if I am watching something off the internet that only has a stereo track that has been highly compressed (for example, pulling up an older clip from Britain’s Got Talent on YouTube). It will try to send the audience to the back speakers, which would be fine, but there is significant clipping in the sound, which makes the audience sound like they are canned from a 50s sitcom, so rather than adding depth, it actually pulls you out of the experience and realize just how bad older sound compression in internet videos was.

  3. When you were switching between the upmixers did you change the Amp Assign? (Speakers/Manual Setup/Amp Assign) I have the Denon X7200WA and have found that you will get a very different effect depending on which assignment you have enabled. The main difference is whether you have your heights set to Dolby Atmos which sets the speakers as all ceiling mounted. Dolby content is mixed to amplify the sounds in those speaker locations.
    If you have your assignment set to Auro-3D you can choose between ceiling mounted or traditional heights. If you have ceiling mounted you won’t notice a major shift between the assignments, but if you have traditional heights you’ll hear a much more definitive channel separation with both Auro-3D and Neural:X because the upmixers are truly trying to put sounds at the appropriate height.
    My personal preference for things like video games that are not natively in Atmos I set my assignment to Auro-3D and I get very good channel separation in all directions. For non-immersive files I find the Auro-3D sounds really good. After reading this article I’ll go back and re-evaluate that.

    Setup: Denon X7200WA, Klipsch Reference Premier RP-280f (FR, FL, RR, LR), RP-450C (C), RP-160M (FRH, FLH, RRH, RLH), Definitive Supercube 6000 (sub)

    • Josh Zyber

      My height speakers are configured as Front Height, Top Middle, and Rear Height for all three formats. This is appropriate for where the speakers are physically located. The front pair are pretty far forward in the room, above my front towers. Similar for the back.

      If you switch your amp configuration when changing audio formats, you also have to re-run Audyssey every time. Audyssey wipes out your settings any time you change speaker configuration.

  4. Warner

    Thanks for posting this. As an audio person I love these type of discussions. I am way more into audio than video will go 4K soon just to get access to more atmos and other 3d sound.

  5. C.C.

    I do enjoy your HT articles quite a bit….
    But I am flabbergasted that you are not running (at the very least) DUAL Subs.

  6. Great article very interested in your comments around Auro and music playback. I love multi channel music playback, previously owning a lexicon with Logic 7 music which was the best Upmixer for music I’d heard. Not impressed with Dolby or DTS for upmixing 2 channel music sounds really unnatural. But have been told that for music Auro is fantastic for upmxing music.

    • Josh Zyber

      I’m not much of a music listener, so I don’t know how much help I can be in that regard. My comments in this article were based on the music that appears in movie soundtracks.

  7. Pedram

    I’ve always been curious as to how these up mixers determine what sound effects to send to the height channels. How does it know that rain or helicopter sounds come from above, whereas car sounds our voices don’t?

    I haven’t really discriminated between the two up mixers I have (DTS or Dolby), but based on your review I’m going to lean towards Neural:X more now because I really want to be reminded that I have ceiling speakers. Thanks for the article.

  8. David

    It may sound crazy, but Lost Boys has some good Atmos height speaker action, via DSU up-mixing; especially during the intro with “People are strange.”

  9. Jeff

    I have the Marantz 8805 processor and have been playing around a bit as well with the various options. I need to do a bit more experimenting, but I am leaning towards the Auro upmixer at this time. I do however have the recommended Auro speaker layout with front height, center height, surround height, and a single voice of God directly overhead. I also matrix in a rear center height to close the circle on that array. I also have 4 speakers in the classic Atmos locations as well, so it is pretty easy for me to go back and forth between the two. I was using Dunkirk as a demo, and I found the room a bit more immersive using The Auro upmixer. I also watched the non Atmos mix of Black Panther and was pleased by what specifically went to the voice of God speaker. I need to play around a bit more with only the overhead amps going to gain that perspective as well.

  10. Jeff

    Update on the last comment…

    I did a shootout today, but added a twist. I compared the 3 up-mixer options, but at the same time, compared various speaker setups along with them. I have identical direct firing speakers all aimed at the main listening position. Top front, top rear, front height, rear height, center height, surround height, and voice of God. Plus to make things interesting, I have 3 matrixed channels as well, with one being a rear center height matrixed from the two rear height channels, and the other two matrixed in between front and rear heights on the left side and right side. I was leaning towards the Auro using their suggested layout, but got adventurous and brought in rear height instead of surround heights. I then added in the three matrixed channels which brought the total to 9 height channels. 3 on the front and back walls in duplicate positions and then 3 up the middle with center height, VOG, and the rear center height matrixed channel. Took awhile to tweak things in, but was blown away by the effect. When I heard a subtle pigeon come out of the VOG by itself as the bird was directly overhead, I knew I stumbled on to something. I watched 3 movies today and was grinning from ear to ear with how every inch of my ceiling had sound at 1point or another with effects panning from side to side and front to back. I know this is not an easy setup to realistically duplicate, but if you can do it, it is well worth it as their is a lot of 5.11 and 7.1content out there waiting to be upmixed.

  11. Al

    The one crucial problem or flaw with this article is that you didn’t test the upmixers on a Dolby TrueHD track, as well. If you would have, you would have noticed that the DSU upmixer is much more effective at adding top/height effects to a TrueHD track, just like Neural X more effectively adds top/height effects to DTS HD tracks. The best way to use the upmixers is to use the one that is built to cooperate with the actual audio track you’re listening to.

  12. Al

    You’re arguing something that is well known and irrelevant. It doesn’t apply to what I’m informing you of. The fact still remains. The DSU is more effective with Dolby TrueHD tracks. And Neural X is more effective with DTS tracks. I’ve done A-B comparisons with all of my other speakers except for the ceiling speakers unplugged, with numerous audio tracks.

    • Josh Zyber

      That’s not possible for a couple of reasons. The lossless compression codecs do not change the underlying audio mix. If you encode the same soundtrack with both codecs (as has happened on a handful of Blu-rays), they will decode with identical results. Also, the upmixing occurs after the audio is decoded to PCM. The compression codec used makes no difference to that.

      It you seem to be getting better results upmixing DTS MA tracks with Neural:X, that’s most likely a consequence of the simple fact that DTS dominates on Blu-ray, and therefore most of the best movie soundtracks happen to be encoded with it. You would need to compare the exact same soundtrack encoded with both formats. And you would need to compensate for the volume difference since DTS doesn’t use DialNorm and is almost always set for a louder default.

      • Al

        That’s very interesting, and good to know! I’m happy to have a better understanding of the whole process. You should check it out for yourself. It’s quite interesting that the DSU has been much more effective with Dolby TrueHD tracks. You’re explanation of DTS-HD tracks dominating blu-ray mostly accounts for this, but could it really just be coincidence that on the limited number of TrueHD tracks, the DSU upmixer has worked much more effectively than it typically does on DTS tracks?

        • Josh Zyber

          I would need to know what movies/scenes you watched, and what seemed better about them with one upmixer vs. the other.

          Ultimately, all of this stuff is highly subjective. If one upmixer sounds better to you with certain types of content, you should use the one you prefer.

          • Al

            I pretty much just went through and found any TrueHD tracks that I could, and then listened with only my ceiling speakers plugged in. What I noticed is that the DSU was pulling proper elevation effects up to the ceiling speakers, on these tracks, when I had often felt that it didn’t when implemented on DTS tracks. Think of what you said about the helicopter in Spectre… On most DTS tracks, I observed the same thing, when using the DSU. Sounds that should be coming from overhead (that the upmixer should be pulling up to the ceiling speakers) didn’t end up making it to the elevation speakers. However, on almost every TrueHD track I listened to, if a something on screen was occurring overhead, the DSU upmixer would effectively pull that up to the elevation speakers. I guess it’s just a case of those audio tracks being mixed in superior fashion. Somehow, the DSU knew that those sounds needed to come from above, on those particular tracks; whereas, on many DTS tracks, the DSU did not know that certain sounds should be coming from above.

  13. Benji

    WTF? This article is based on the experience from ONE blu-ray, one DTS-HD 7.1 mix? I’m with Al on this, you should have tested several different blu-rays, each with a different audio format:

    LPCM 5.1
    DTS-HD 5.1
    DTS-HD 7.1
    Dolby TrueHD 5.1
    Dolby TrueHD 7.1

    and a DVD with DD5.1

    Then, this article would have been more relevant. As it is, all this tells us is how Spectre performed with the different upscalers.

    I clicked on the headline hoping to find out something relevant, but, this was rushed and incomplete…disappointing.

    • Josh Zyber

      Did you mean DTS Neural:X? The DTS IMAX mode is only intended to be used specifically on content authored with an “IMAX Enhanced” metadata flag (of which there are only two nature documentaries, currently).

      • M-Easy

        Nope. I mean DTS IMAX. If you force your PS4 to play DTS. When on PS4 my receiver reads IMAX DTS + Neu:X. This mode seems to force more sounds into the height channels. The bass is about the same as PCM, which I used to game in.

  14. GTO

    sometimes DTS Neural X from movie are not difference between front and rear top speakers (only stereo). And from games DTS Neural X doing sound in top speakers only from rearspeakers. I have question, its normall or not?

    • Josh Zyber

      That doesn’t sound normal. If you have an x.x.4 setup, Neural:X should give you discrete sounds in the Top Front and the Top Rear speakers.

      The exception to this would be if you have exceeded the DTS 11-channel limit. If you have 9 speakers (7.1 + Front Wides) on the ground layer, DTS will only allow you to use 2 heights. Or it will give you 4 heights but not send any signal to the Front Wides.

  15. GTO

    i have 7.1+4 top speakers (top front and top read). I notice that:
    if i play 2.0: top speakers playing 360°
    if i play 5.1: top speakers playing sound only between sur. back speakers (45°)
    if i play 7.1: top speakers playing sound only between side speakers(180°)

    I talk only about DTS Neural X.

  16. Les

    Using Denon AVR-6400H. Compared available upmixes on A Nightmare on Elm Street (1980s) streamed via iTunes on AppleTV 4k. Note sound is streamed 5.1 L-PCM. Auro-3D had the best results. Note the choice of
    1: Multi-in + Dolby Surround
    2: Multi-in + DTS Neural X
    3: Auro-3D
    The key difference between the first 2 choices and the 3rd is that Dolby and DTS upmix by adding additional rear and ceiling channels while also playing the original 5.1 L-PCM, hence the multi + choice of upmixes. Although there are subtle additions such as assisting ambient sound transitioning from surround right, to rear right, to rear left, to ending in surround left as the beginning theme music/chimes during Tina walking in boiler room, the fact that 5.1 PCM (multi) is always active creates a quick jump of musical notes from right to left with Dolby doing minor assisting in activating rear channels and DTS doing a slightly better assisting in highlighting said notes in rear channels. Auro-3D does the best job by taking the entire L-PCM code and converting and upmixing it to Auro-3D. This made a clear highlight of ambient music notes transitioning from speaker to speaker and eliminating an ambient note being heard in say a right surround speaker when it was moved to the right rear speaker, preventing the L-PCM from making a sudden move from right side to left side. Auro-3D made a smooth transition of said notes from right to left by moving to the appropriate speakers clearly note by note as the transitioned original notes were removed to new speaker location instead of being kept in its original location that would interfere with appropriate upmixing use of the additional rear channels.
    I only tested upconversion of L-PCM audio, commonly used on streamed media, not Dolby or DTS media being upconverted, not yet. In addition to said movie upconverted to smooth and clear transition using Auro-3D, I also noticed the music/effect at the main title appearing on screen was placed all around listener, making you feel it was more in your face and surrounding you, even with ambience from behind using rear speakers. The Dolby and DTS upmix did not envelop the listener and restricted the experience at the front speakers, creating a distance between the listener. This makes sense since as before, Dolby and DTS add channels, but don’t mess with the original 5.1 L-PCM, whereas Auro-3D converted the original L-PCM to new locations and intensity, creating a clear and superior listening experience. This test was done 10/24/20 and for years I always used Denon’s Multi+Dolby upmix, not realizing how superior the experience was changing the upmix to Auro-3D. Again, I have yet to test Auro-3D upmix for content that uses Dolby or DTS as original sound format instead of L-PCM as original sound format.

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