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1st order nfc-HOA3D with 6 speakers only. Possible?

Spat
#1

Hello everyone,

I have an issue with my 3D nfc-HOA setup and can’t figure out where it comes from.

6 monitoring speakers (Focal CMS40): 4 on a horizontal square at approximately 1.73m each, and 2 at +/-90°, 45° elevation on the X axis, at 1,33m each). The room is a simple one with some passive correction.
With this setup, the high frequencies become unstable on the X axis. Also it becomes difficult to clearly locate sources when my head is right on the axis.

I am decoding everything for 8 speakers but the 2 below ones are declared at the same position as the 2 above (8 “virtual” spks -> 6 real spks with above only). The 8 speakers channels are then routed to individual room filters (which I created with the HISSTools, a toolbox for tweaking Impulse Responses) and are finally delayed and gain-corrected (done with spat.delaycalibration~ and gaincalibration~).

Decodermethod: energypreserving
decodertype: mostly maxre but I’ve yet to make up my mind on which one sounds the best in my situation. Whichever I choose, it doesn’t solve the issue.

Everything is working perfectly well, except this problem which makes it difficult to EQ and position sources near the X axis.
Does anyone have already experienced such an issue? Is the number and the characteristics of the speakers a problem with this setup? Maybe the proximity?

I hope someone can help me figure this out.
Philippe.

#2

Hi Philippe,

Could you please send a patch so that we can better understand your setup and the problem(s) ?

Also, please note that NFC is still somehow experimental
(and I doubt it can really provide significant effect with ‘only’ 6 speakers).

T.

#3

Thank you for your quick (and late) answer T. ^^

Ok so there is no real gain in using the Near Field compensation filters with such a small setup. I will try to encode with the standard HOA panning, to see it this issue disappear. Also I’ll try to sort out a part of my patchs for you to check for configuration issues…

Philippe.

#4

Hi Philippe,

cool idea with the use of so few loudspeakers. Have you found resources on the internet (different websites or…) that give you ideas for loudspeaker setups using relatively few loudspeakers (in the range around 6 - 10 loudspeakers) ?

all the best,
Lasse

#5

Hello Lassemunk,

I managed to find some advices on various website when I was planning to build my rig but when it comes to first order, you don’t really have a lot of possible speakers setups. The cube or the “double rectangle” are the only solutions I found. The second one is quite nice if you have the necessary space. But the real problem though is not the setup itself, but how you will install the speakers in the room! Is the room already equipped with everyday things? How will you fix and position the speakers at the top and the bottom of the the room? There are lots of little issues that you can’t think of when you’re making you plans. It’s a lot easier when you have a dedicated room though ^^

For listening and experimenting, I would suggest to start with a Hifi amplifier with HDMI plugs and some small passive speakers. It’s a lot easier to install and it makes the job. But when it comes to mixing, you will have to be more careful.

In my case I haven’t found the solution. It appears that the issue is coming from the setup itself, so I’ll be experimenting in 2D for the time being.

Regards,
Philippe.