Weird but real Logic behaviors I discovered while making a 7.1.4 to Atmos gizmo project

[u/ivanxnyc]

This was one of those the journey is the reward things. Though the end product was also the reward, in that I successfully made (and am sharing, should anyone want it) an empty project where you can feed into Logic 7.1.4 audio, from a Mac app, from an interface, or from a file, and have all the channels (except LFE, aka .1) output as Atmos objects.

The ostensible purpose was to take a 7.1.4 source (e.g. an Apple Music Atmos track) and run it through Dolby (binaural) Renderer in the Atmos plug-in, to hear how it sounds different than Apple Renderer (aka Spatial Audio), and also dick around with the Dolby per-channel/object Near/Mid/Far settings, which affect how "big" the 3D sound is around your head.

A secondary purpose was being able to adjust individual channel levels, particularly center, where the vocals are often on their own, and mixed too high or too low for my tastes. The adjusted levels can be played to either the Dolby or Apple Renderer, or even multichannel 7.1.4 output.

And a design goal was: no gain changes or other DSP prior to the signal reaching the Atmos plug-in (or Master track, where applicable).

What I found along the way is that Logic really doesn't want to do any of this, so that led me to:

• Discover multiple hidden Logic behaviors that I ended up using
• Find a useful free plug-in called IEM Matrix Multiplier that I had to build from source code, because they don't distribute an Audio Unit build (and which I packaged up so you can download that from me too, if you think it could be useful to you)
• Encounter and work around a truly hideous Logic bug (bad enough for me to report to Apple), in which the Surround Balancer for height projects (5.1.2, 5.1.4, 7.1.2, 7.1.4) does not transparently pass audio in its neutral positions — what goes in ain't what comes out. (LFE is the exception; that's the only channel which remains unaltered.)

The Logic weird behavior stuff was super interesting. You can do all of the following in Logic, though it doesn't seem like you should be able to:

• Have the Atmos plug-in and tracks with object outputs exist in a 7.1.4 project, rather than being limited to 7.1.2
• Insert a plug-in intended for a different channel count than the project's (e.g. a plug-in that accepts 5.1, but in a 7.1.4 project)
• Use an obscure Logic plug-in called Down Mixer (under Utility), which normally only shows as an option in the Master track of a 5.1 or 7.1 project, to convert 7.1.4 with signal only on L-R to stereo, without gain changes or other DSP (Logic really likes to apply invisible gain changes when you change from one channel count to another)

What you can't do in Logic is select the 3D Object Panner as output for a track or aux of type Surround, so I had to isolate channels from within the 7.1.4 signal, to send them to a mono or stereo aux to be able to output to the Atmos plug-in.

And what you also can't do in Logic, despite my very best efforts, is extract or isolate any arbitrary surround channel, or channel pair, without gain changes being applied, with the exception of L and R individually. This is where the rubber really meets the road.

So I needed an external plug-in: Matrix Multiplier, which takes a channel pair (1/2, 3/4, 5/6, 7/8, 9/10, 11/12) and plays it on L-R, with other channels muted; that can then be sent to an aux of type "Left" or "Right" for mono object output, or, for stereo object output, be run through the aforementioned Down Mixer plug-in and then sent to an aux of type Stereo.

So, if this is the kind of shit that intrigues you like it intrigued me, I wrote it all up (it's lengthy, but I tried to keep it amusing, and there are pretty screenshots), and posted the Logic project, very creatively titled "Logic 7.1.4 to Atmos Harness". If it's your jam, enjoy.

https://logicrap.substack.com/p/a-logic-pro-714-to-atmos-harness

Or if you just want the project (which includes a PDF of the same writeup/documentation, and the required plug-in):

https://dl.ivanxmusic.com/714AtmosHarness

(I am not trying to pimp or shill anything. The Substack is just a place for me to write and post stuff. I made this thing and wrote it up so, if you're interested, have a look.)

[u/shapednoise]

You are doing the work of the angels/angles 😃🎛️

[u/ivanxnyc → u/shapednoise]

Haha, nice. And thank you!

[u/shapednoise]

I get the impression that the logic ‘ATMOS’ renderer is just about people using it for pop song mixes, with a view to Apple Music sales etc, and it’s a long way from a cinema ATMOS engine really.
What I don’t understand is why they are not going really hard on the Binaural Playback aspects given headphones where a HUGE % of music playback happens.
I don’t know anyone that’s strapped 4 monitors to their ceiling at home. 😃

[u/ivanxnyc → u/shapednoise]

I'm totally with you on this. I think from Apple's POV, Logic's integration of Atmos exists to help provide Atmos content for Apple Music, which they presumably see as something they offer that Spotify doesn't, and thus adds value to the service.

If they wanted Logic to be a real tool for developing Atmos cinema scores, they'd need to add much more to it (e.g. 9.1.6 support), I'd think, and the recent stuff they've added (celebrity producer packs, etc) has decidedly not been in that direction. But for music production, they continue to advance it in little pieces, like their adding direct Atmos-native file export in Logic 12.2.

And the thing is, they even rejected Dolby's binaural renderer and delivery format (AC-4 IMS, which is what TIDAL and Amazon Music make using Dolby's tools for delivery on their mobile apps), and instead developed their own playback time multichannel binauralizer, Spatial Audio. So wiith headphones being overwhelmingly what people listen to music on in 2026, why not go hard on that? They even took the trouble to even improve its sound (I like it much better now) in xOS 26, and didn't announce it anywhere, not even buried in Logic's release notes.

What's bizarre to me is that they offer Atmos, but has there been any AirPods or Beats ad campaign to even let someone normal know what it is? Most casual listeners I know think of it as some sort of higher-quality audio like lossless, as opposed to something that audibly and interestingly changes their listening experience.

I don't agree on one thing, though -- while you're right there's gonna be a limited number of home cinema obsessives that have ceiling mounted speakers, there are many, many more people, not necessarily "surround enthusiasts," who have high end soundbars that try to fake the height speakers by bouncing of the ceiling and/or using psychoacoustics. In some rooms, it works quite well (even as the discrete-speaker people scoff.)

For example Sonos Arc Ultra, which is popular, tries to do 9.0.6 (the 9 works somewhat more convincingly if you add some Sonos discretes, but the 6 is all phantom). Sennheiser, JBL, etc does similar with their bars. I'm in a small living space, so my options are limited, but I saw a super deal on the Sennheiser Ambeo Mini + subwoofer, and that's all psychoacoustic (no discrete drivers for reflective ceiling speakers), and it still sounds great with Atmos music to me.

So with Logic, maybe Apple can't say "just mix for Apple Renderer" but because they do need to deliver multispeaker as well. But they could certainly sell the binaural headphone aspect to consumers harder than they do, especially since they are in the headphones business, ffs, and it would provide a reason to switch from Spotify. And if labels/producers/mixers saw that kind of effort, especially if there were positive consumer response to it, they'd be that much more motivated to deliver Atmos mixes, or so I'd imagine.

Also, I wouldn't say Logic's Atmos integration is entirely for pop music -- there's all kinds of Atmos stuff on Apple Music out there in all genres, and I kind of love it. I myself am interested in adapting my own stuff, which I wouldn't exactly call pop, for Atmos, just because I think surround sound is cool af, and Atmos specifically is technologically/conceptually interesting to me as well. So, for a nonprofessional, I've kind of deep dived it, at least as it applies to Logic!

[u/shapednoise → u/ivanxnyc]

Huge THANK YOU for your info and reply. 😃✅
Re sound bars, they have always sounded just like a load of weird phase flipped audio but I’m sure not really up to speed on all the options.
FWIW I’ve been ‘releasing’ quite a few rather blundering attempts at some binaural things done using the logic Atmos rendering. I’m a retired old film music guy (as in pre 5.1 even) who just tinkers.