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Old 07-22-2016, 02:28 PM   #1
Dannii
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Default Looking for Ambisonic Custom Speaker Array Decoder

UPDATE August 2018
For the last year or more, I've been running a 3D cube array of Auratone 5C cubes with four EV DL15W subwoofers for monitoring my Ambisonic mixes. I'm currently running the Blue Ripple Sound (http://www.blueripplesound.com/) third order cube decoder with very good results and am testing a few other decoders including the ones in the IEM Plugin Suite (https://plugins.iem.at/) which are coming along very nicely and are free.


Original post from July 2016 below....

As the thread title suggests, I'm looking for a custom speaker array Ambisonic decoder to use in REAPER on Windows 10.

I'm setting up a speaker array using 12 channels (11 full range and a sub) with a convention 5.1 array at head height (for compatibility with non Ambisonic mixing and listening), two upper front channels (above the main front L & R), two lower front channels (below the main front L & R) and two upper rear channels (above the main rear L & R). So basically a double cube without the lower two rear channels.

The Blue Ripple Sound Rapture3D looks like it would be ideal but it is VERY expensive given the Aussie dollar to British pound conversion rates.

The Gerzonic DecoPro http://www.gerzonic.net/ looks ideal too but there's no demo download (or any download for that matter) and I'm getting no response to emails I've sent.

I've seen a few utilities that also seem perfect but they are Mac only.

I have Bruce Wiggins vsts and the Ambisonic toolkit for REAPER (which are both very good) but the most I can do there is cube or hexagonal arrays in 3D format.
I've considered the cube layout but the problem there is my main mixing array is a conventional 5.1 layout at head height. If that was to form part of the cube, it would place my listening position at either the base of the cube or the top of the cube (depending whether or not the additional speakers were above or below the 5.1 array) rather than in the middle.

Does anyone know of anything I might have missed that would allow me to configure a custom speaker array?
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Old 07-23-2016, 09:39 PM   #2
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Upon rethinking all this, I might just go with setting up a 3D cube with eight speakers (Auratone 5Cs) and forsaking the traditional 5.1 mixing arrangement. It turns out I can probably emulate the 5.1 arrangement with some Ambisonic decoding already in my plugin arsenal.
I'm quite probably going to be doing the vast majority of my mixing in Ambisonic format from now on anyway and that can be easily downmixed to other formats.
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Old 07-24-2016, 04:44 AM   #3
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That's exactly the line of thought I've followed.

I started looking for a sub, even considered building one myself. Then I decided 5.1 wasn't the way to go. So I scrapped center and sub. The reasoning is that all real "mixing" will be done on four speakers anyway, as the center should only do voice and the sub would be fed a low passed sum in the end.

That's when I decided for 8 identical speakers. I only have 6. They seem to have to be identical.

And I took that down to four speakers, because my recordings won't have height information as I only start out. I hope I'll find 2 additional speakers while I'm starting to learn how to do 4 channels. And I hope adding the extra 4 channels later will be relatively simple.

Problems to fix at this stage:

- panning out of the box between front and rear. No mixers seem to have this, so I'll have to mod a mixer, or stay ITB.
- later on, panning height info, is more or less the same problem, but with 8 channels in stead of four. And that's a hardware problem, as I can find stereo pots to pan between front and rear, but 4 channel ganged faders are rare and expensive. And as I need two of those per channel for four channels, that's doable. With 8 channels, I'd need three four channel ganged pots per channel. That's going out of budget fast, with a total of 24 pots.

I've temporarily scrapped the idea of buying a mixer to mod.

Think I'll either be building my own one. Something like an 8 by 8 matrix mixer. Shure made one years ago, for line levels. But it's a rare beast. I only stumbled upon one for sale here by accident. It's too expensive for what it is (it isn't exactly high end soundwise) and it only controls levels, no eq fi.

Anyhow, the four channel setup works. As a prototype that is. I still have to review the speakers, as they aren't as identical as I would like. Have to figure out if it's the room acoustics, or the speakers.

ATM, I'm thinking about mic setup and mic building for a tetra mic, or one of the other setups.
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Old 07-24-2016, 12:21 PM   #4
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Ambisonic panning outside the box using non DSP techniques sounds like a lot of work and I'm not sure how you'd go encoding the Ambisonic information using that technique.
What if you did the panning inside REAPER, post encoding and used MIDI controllers to control the Ambisonic panning plugins?

I'm currently rearranging my speakers into a 3D cube which is a lot easier said than done!! I have seven Auratone 5C cubes and four other small two way speakers at present. Ideally, I'd like another 5C but for the initial experiments, I'm going to see if it is adequate enough to try to EQ two of the other speakers to match the 5Cs as far as possible. I could see phase issues being a potential problem though.

I did some initial testing with the cube arrangement VERY loosely arranged with four of the speakers on the floor and the other four at head height and none aligned very well symmetrically. Probably needless to say but the initial listening tests, while interesting, were far from convincing as far as spacial cues go.

This next test will be with all speakers equidistant from the listening position and with the two unmatched ones EQd as closely as possible. Hopefully that will yield substantially more convincing results.

More to come.....
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Old 07-24-2016, 01:42 PM   #5
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Quote:
Originally Posted by ReaDave View Post
Ambisonic panning outside the box using non DSP techniques sounds like a lot of work and I'm not sure how you'd go encoding the Ambisonic information using that technique.
It's simple analog level panning, but in 2D (to start with) and later on in 3D. No DSP needed, imho. I'm planning to use it for mixing in mono sources and for level control while playing back in other rooms than my own.

Quote:
What if you did the panning inside REAPER, post encoding and used MIDI controllers to control the Ambisonic panning plugins?
That's what I plan on doing. The mixer would only be an add-on and only needed for playback in other places.

Quote:
I'm currently rearranging my speakers into a 3D cube which is a lot easier said than done!! I have seven Auratone 5C cubes and four other small two way speakers at present. Ideally, I'd like another 5C but for the initial experiments, I'm going to see if it is adequate enough to try to EQ two of the other speakers to match the 5Cs as far as possible. I could see phase issues being a potential problem though.
What I've learned so far:

Speakers and mics need to be as identical as possible. On the mic side, this is less of a problem, as the mics are very close to one another. As long as the capsules are identical, you're good to go. On the speaker side, the room influence is a major problem. I haven't tried eq. I'm a bit skeptical about eq, as it doesn't do anything for reflections and I suspect it will even amplify reflections.

Most of the information is in the midrange. So, Auratones might be useful. I've been thinking about making 8 simple broadband speakers, to avoid phase problems. But I can't figure out (in my head) if phase problems would be a big worry. Ah, more experimenting to come. And atm, my listening room is just too hot, with outside temps from 25 to 30 degrees and two sides who are almost entirely glass. That's another problem too...

Quote:
I did some initial testing with the cube arrangement VERY loosely arranged with four of the speakers on the floor and the other four at head height and none aligned very well symmetrically. Probably needless to say but the initial listening tests, while interesting, were far from convincing as far as spacial cues go.
I think you need to set the upper four higher. In all my limited testing with 8 speakers, I've put the top ones close to the ceiling and the bottom ones on the floor. And that immediately revealed problem #1: the floor is tiled, the ceiling is wood and hollow. Acoustically very different.

That's why I went back to 2D with four speakers, for the time being. I need to make that work first and find another pair of identical speakers. I think it won't work with different speakers. At least, it didn't work for me, with 6 fairly identical active 2 way speakers and 2 active 3 way speakers. Same brand, same age, but the difference in mids was killing almost all placement info.

Quote:
This next test will be with all speakers equidistant from the listening position and with the two unmatched ones EQd as closely as possible. Hopefully that will yield substantially more convincing results.

More to come.....
Yes, please, keep us informed. And thanks for this thread!
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Old 07-24-2016, 06:02 PM   #6
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Well, that's MAJORLY annoying!!!! I just typed a rather long and detailed reply and accidentally hit the back button and lost the whole lot!! GRRRRR... Hate that!!

Hmmm... let me see if I can remember what I typed....
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Old 07-24-2016, 06:24 PM   #7
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Quote:
Originally Posted by cyrano View Post
It's simple analog level panning, but in 2D (to start with) and later on in 3D. No DSP needed, imho. I'm planning to use it for mixing in mono sources and for level control while playing back in other rooms than my own.
Hmm... still not sure how you're working the Ambisonic encoding. From what I've seen through experimentation so far, to pan a sound in an Ambisonic mix, the source (mono, stereo or other) needs to first be converted to B format and then manipulated with a B format panning/rotating/zooming/other plugin.
Quote:
Originally Posted by cyrano View Post
That's what I plan on doing. The mixer would only be an add-on and only needed for playback in other places.
Keen to hear about your MIDI controller experiments when you get into it.
Quote:
Originally Posted by cyrano View Post
What I've learned so far:

Speakers and mics need to be as identical as possible. On the mic side, this is less of a problem, as the mics are very close to one another. As long as the capsules are identical, you're good to go. On the speaker side, the room influence is a major problem. I haven't tried eq. I'm a bit skeptical about eq, as it doesn't do anything for reflections and I suspect it will even amplify reflections.

Most of the information is in the midrange. So, Auratones might be useful. I've been thinking about making 8 simple broadband speakers, to avoid phase problems. But I can't figure out (in my head) if phase problems would be a big worry. Ah, more experimenting to come. And atm, my listening room is just too hot, with outside temps from 25 to 30 degrees and two sides who are almost entirely glass. That's another problem too...
Are you renting where you are now or is it your own property? Maybe you could look at double glazing although that could get expensive for a large area.
Quote:
Originally Posted by cyrano View Post
I think you need to set the upper four higher. In all my limited testing with 8 speakers, I've put the top ones close to the ceiling and the bottom ones on the floor. And that immediately revealed problem #1: the floor is tiled, the ceiling is wood and hollow. Acoustically very different.

That's why I went back to 2D with four speakers, for the time being. I need to make that work first and find another pair of identical speakers. I think it won't work with different speakers. At least, it didn't work for me, with 6 fairly identical active 2 way speakers and 2 active 3 way speakers. Same brand, same age, but the difference in mids was killing almost all placement info.

Yes, please, keep us informed. And thanks for this thread!
No problemo!! Great to have your input here.

I'm actually sitting at my DAW PC, typing this reply (for the second time!!) on it while REAPER plays some B format recordings in the background on the new speaker layout and I'm thoroughly enjoying it this time!!

I ended up moving the lower ring of speakers off the floor and also moved the top ring up higher. My ear height is now right smack in the middle of the two layers. I also have all eight speakers equidistant from the listening position and have EQd the two non Auratones to match the Auratones as closely as I can. I did have to swap the polarity on them but that could be more of a signal routing issue because they are running from a different amp to the six Auratones.
The non Auratones are serving as the lower, rear pair.

Overall, the sound is FAR, FAR more convincing now and almost uncanny in 3D positioning. I had to pause a couple of times just to check that some of the things I was hearing were on the recording and not outside!

I currently have three new Auratones and four original 80s models and have them very closely matched with a little EQ. Even so, I'm contemplating either purchasing one more new one to have four new ones in one ring and four 80s ones in the other ring or purchasing FIVE new ones to have a complete set of eight perfectly matching ones. The latter option is stretching my already far stretched budget though!! I just set up a large solar/battery/multi inverter power system for my home and studio (no more electricity bills!!) and have also just purchased two new Roland JP08 Boutique synths so the bank account has taken a pretty hefty beating!

I am putting together some plans (in my head as I type!) to build a double octagon frame to mount all eight speaker to. At the moment, two are sitting on cardboard boxes, four are on tall CD racks (at the top and bottom) and two are on some Gibraltar drum hardware from my Roland V Drums kit. Quite the mashup!! Sounds great though!!
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