Question: Are there Low Frequency Effects / other audio, post the set decoder channel count in the E4L Master Bus?

[this1self]

Hello,

I think this is the behavior I am seeing:

1. Set Decoder to Octo.
2. Set Output routings from 1 through 8 appropriately.
3. Set an Output Routing for 9/10 as well (don't leave as "No Output").

I am seeing audio from Channels 9/10, and even from more output channels after that as well.

What is the expected behavior here for the Channels after the expected max channel count?
I was curious if this is supposed to LFE and be connected to Subwoofers?

I see this note on in the documentation for the AIIRA decoder:

## Subwoofer Decoding
By default no subwoofer output is routed, but there is a basic scaffolding in place for a mono subwoofer output on the right side of the patcher. Simply connect this to an appropriate out~ outlet if you have a subwoofer in your system.

Note: It is not recommended to spatially decode subwoofer channels within the IEM plugin.

Does this mean that the Built-In E4L Decoders are decoding for subwoofers?

Real Question: What is the recommended approach + mapping for subwoofers?

Suppose I have a Quad speaker system -> each with a subwoofer and a top.
Is it better to treat them as one single speaker source?
Or should be have 8 channels in this case, 4 going to the Tops, and 4 going to the Subs?
-> Side-Question: How does one work with choosing the subwoofer crossover frequency based on the Ambisonic decoding (if there is some specific things the Decoder is doing to LFE / Low Frequency content)? Does one set the same crossover frequency that was physically set on the speakers, in the Ambisonic Decoder as well?

Thank you!

• Govinda

[mcslee]

The octo decoder does include LFE output on channel 9, which is simply an unspatialized pass-thru of the omni content (see below).

I am seeing audio from Channels 9/10, and even from more output channels after that as well.

Can you provide a screenshot of your setup and let me know where you are "seeing" this? That decoder shouldn't be able to output to any other channels, as you can see nothing is even connected to them.

Real Question: What is the recommended approach + mapping for subwoofers?

There's no single simple answer to this, it really depends upon the sound system, the room you're in, what kind of material. I'd just recommend playing around with different strategies to see what works best.

For a quad system where every channel has a top and a sub, I would probably just use a full-range quad ambisonics decoder, and then send that to each sub/top pair. I'm assuming the subs/tops in that setup probably have their own ability to daisy-chain the sub to the top with a crossover applied.

I probably wouldn't do any crossover filtering in the decoder for that kind of setup.

[this1self]

Hello, thank you very much for your response.
Apologies for my delay - we played a show at Fort Mason Center SF on August 8th and 9th, with Ableton through E4L on 8-channels of speakers (two quad layers - one on the 1st floor, and one on the 2nd floor mezzanine (light-well cutout). It was really good and well received.

We used a custom AIIRA Decoder, and input the final layout of the speakers of the venue.
It seemed to work very well.

I had a break after this intense show, and couldn't get back to my studio setup to send the screenshots over to test these extra channel information.

Now that I have run through them, I see that the issue is specifically with the Custom AIIRA Decoder.

Please see this Note here with the test results and screenshots:
https://share.note.sx/oe3xgggb

Adding the last two test's screenshots for convenience:

---

6. Quad Decoder

Screenshot of TotalMix outputs:

✅ Expected Audio Channels: 1 to 4, with LFE on Channel 5.

7. AIIRA with 4-channels

Screenshot of TotalMix outputs:

❌ Unexpected: Generating 16 channels

---

I seem to be using the latest version of E4L with 11.3.11.

Conclusion

No issues with the Envelope shipped decoders in terms of extra channel audio being generated.
Seeing issue only with Custom decoder.
Have not tried any other custom decoder Max patch outside of the e4l.decoder.example.iem.