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Abisonic Microphones


Alejandro Reyes

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2 minutes ago, Mobilemike said:

Have you heard and used the Røde? Or are we just making random assumptions?

 

-Mike

 

IMMO is: In My Modest "Oppinion", just "Oppinion" 

 

But just making random assumptions: IMMO Rode make entry level microphones (with some nice ones like the NTG3), I don't expect anything more than this, and... I ordered one for try

 

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15 minutes ago, ramallo said:

 

IMMO is: In My Modest "Oppinion", just "Oppinion" 

 

But just making random assumptions: IMMO Rode make entry level microphones (with some nice ones like the NTG3), I don't expect anything more than this, and... I ordered one for try

 

Cool, just wanted to clarify. :)

 

And I was genuinely curious too because I don’t know anyone who has actually tried the Røde Soundfield yet. 

 

Rode does also make some nice microphones for studio recording: their NT5/NT6’s and NTR ribbons in particular are pretty well regarded in the location music world. I’m hopeful that the NT-SF1 is going to be something really cool. 

 

-Mike

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Can I ask if anyone feels there is a great advantage to using the Soundfield SMP200 Pre-amp with the SPS200? I bought a SPS200, partially and gratefully influenced by comments on this forum. I'm using it with a MixPre-6 but wonder whether there would be any benefit in terms of quality in getting the matched pre. Alternately, have been thinking about getting the direct out upgrade for my Cooper CS104 - though I realize I'd lose the ease of the 4 linked inputs. I'm using the mic for field recording, not broadcast. Many thanks. 

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10 hours ago, ramallo said:

 

IMMO is: In My Modest "Oppinion", just "Oppinion" 

 

But just making random assumptions: IMMO Rode make entry level microphones (with some nice ones like the NTG3), I don't expect anything more than this, and... I ordered one for try

 


I hope the NT-SF1 is more like the NTG3 than the NTG2!

 

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  • 3 weeks later...
On 8/1/2018 at 6:50 AM, soundmanjohn said:

However, you should note that both these microphones use a generic A-B conversion program and the Ambeo version is not that accurate, in my view. Len Moskowitz's TetraMic comes with individual calibration files for each microphone and is, to my ears, more accurate in terms of imaging and much better in terms of frequency response.

 

Len will also calibrate other tetrahedral mics like the SoundField SPS200 and deliver calibration files for use with VVMic, VVTetra or VVEncode. Or at least he used to, not sure if he is still doing that.

 

On 8/1/2018 at 8:25 PM, Stephenvit said:

Can I ask if anyone feels there is a great advantage to using the Soundfield SMP200 Pre-amp with the SPS200? I bought a SPS200, partially and gratefully influenced by comments on this forum. I'm using it with a MixPre-6 but wonder whether there would be any benefit in terms of quality in getting the matched pre. Alternately, have been thinking about getting the direct out upgrade for my Cooper CS104 - though I realize I'd lose the ease of the 4 linked inputs. I'm using the mic for field recording, not broadcast. Many thanks. 

 

While in theory, matched pre-amps are definitely the way to go, I've found that in the case of generic A-to-B conversion as it happens with the SoundField SPS200 you already lose some spatial resolution and that 1st order ambisonic is already low spatial resolution in comparison to higher order ambisonics anyway.

I think your money is better spent in sending your SPS200 to Core Sound (they're based in NJ) for calibration so that you get better B-format files. Or maybe on a HOA microphone solution, though not many exist.

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22 minutes ago, Jose Frias said:

 

Len will also calibrate other tetrahedral mics like the SoundField SPS200 and deliver calibration files for use with VVMic, VVTetra or VVEncode. Or at least he used to, not sure if he is still doing that.

 

 

While in theory, matched pre-amps are definitely the way to go, I've found that in the case of generic A-to-B conversion as it happens with the SoundField SPS200 you already lose some spatial resolution and that 1st order ambisonic is already low spatial resolution in comparison to higher order ambisonics anyway.

I think your money is better spent in sending your SPS200 to Core Sound (they're based in NJ) for calibration so that you get better B-format files. Or maybe on a HOA microphone solution, though not many exist.

 

The Harpex do a upsample the FOA to HOA, IMMO this plugin is the best investment for ambisonics.

 

Jose, have you calibrated your microphone at Core?

 

Best

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Just now, ramallo said:

 

The Harpex do a upsample the FOA to HOA, IMMO this plugin is the best investment for ambisonics.

 

Jose, have you calibrated your microphone at Core?

 

Best


I do love the Harpex plug-in, and think it is a great investment.

I did not personally get my SPS200 calibrated yet. It was my intention to do so sometime last year, and I had reached out to Len to get it done, but then I got into a string of jobs and couldn't make it happen. These days, I'm more interested in HOA so I haven't put too much mind into it.

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1 minute ago, Jose Frias said:

I did not personally get my SPS200 calibrated yet. It was my intention to do so sometime last year, and I had reached out to Len to get it done, but then I got into a string of jobs and couldn't make it happen. These days, I'm more interested in HOA so I haven't put too much mind into it.

 

I'll stay tuned about, I have my reserves.

 

I have an accident with my SPS200 and drop to the floor, I taken a measures against a DPA 4007 for evaluate the damage. I surprised about how close are the capsules and how flat are. The damage was cosmetical, but a sent to Soundfield for change the shell of a capsule, and they replaced all for a new set.

 

Best

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2 hours ago, Jose Frias said:

While in theory, matched pre-amps are definitely the way to go, I've found that in the case of generic A-to-B conversion as it happens with the SoundField SPS200 you already lose some spatial resolution and that 1st order ambisonic is already low spatial resolution in comparison to higher order ambisonics anyway.

I think your money is better spent in sending your SPS200 to Core Sound (they're based in NJ) for calibration so that you get better B-format files. Or maybe on a HOA microphone solution, though not many exist.

 

thanks very much for the info and suggestion

 

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Excuse my ignorance: 

FOA?

HOA?

I did google:

https://acronyms.thefreedictionary.com/FOA

https://acronyms.thefreedictionary.com/HOA

 

Interesting thread. Anyone using this 1:

http://brahmamic.com/products/freestanding-14mm-tetra/

 

When recording are ops monitoring signal with/out calibration applied? - ie does a beginner need a laptop in the field to be confident of how it's really going to work out.

 

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57 minutes ago, daniel said:

Excuse my ignorance: 

FOA?

HOA?

I did google:

https://acronyms.thefreedictionary.com/FOA

https://acronyms.thefreedictionary.com/HOA

 

Interesting thread. Anyone using this 1:

http://brahmamic.com/products/freestanding-14mm-tetra/

 

When recording are ops monitoring signal with/out calibration applied? - ie does a beginner need a laptop in the field to be confident of how it's really going to work out.

 

 

FOA = First Order Ambisonic. Also acronymed as 1OA.

HOA = Higher Order Ambisonic. This includes Second Order Ambisonic or SOA / 2OA, Third Order Ambisonic or TOA / 3OA, and above (4OA, 5OA, 6OA, 7OA, etc)

 

The higher the order the better the spatial resolution, which typically translates to better localisation of sound sources within the sound field reproduction, but it also means the file will be larger due to the exponential increase in channels, and it also means it will require more processing power to decode. Most video games live in the 3OA world. VR/360 videos in its current iteration started mostly as 1OA, though other formats were also available like omni binaural, but currently there's a wave of 3OA tools making its way to content creators and post production professionals.

 

Since all you need is 4 channels with mic pres (hopefully all matched with gangable parameters), quite a few field recorders offer a generic A-to-B format converter for 1OA which allows the field recordist to monitor the sound field decoded to stereo for an idea of what it will sound like later, but for the most part and if you've done this enough to understand how to work with ambisonic mics and how they get processed in post, you'll develop a workflow that doesn't require you to monitor the sound field per se, and then it's about gauging levels, making sure all inputs have matched settings, there's no wind noise, etc. So any recorder with gangable inputs will do. HOA recordings are only available through the very few 2OA mics, including the Octomic from Core Sound, or through high array microphones like the Eigenmike, and beamforming / matricing to convert to HOA like 5OA. The latter would require a laptop system to record since it's 32 channels.

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14 hours ago, daniel said:

When recording are ops monitoring signal with/out calibration applied? - ie does a beginner need a laptop in the field to be confident of how it's really going to work out.

 


What I did was a two pronged approach:
1) used a bluetooth app so I could visually monitor what is happening, and remotely start/stop (because you can't be too near the recorder, as the 360VR camera sees everywhere!)

2) took a stereo feed out of the recorder and sent to me wireless so I could monitor it with my ears as well

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8 hours ago, IronFilm said:

 


What I did was a two pronged approach:
1) used a bluetooth app so I could visually monitor what is happening, and remotely start/stop (because you can't be too near the recorder, as the 360VR camera sees everywhere!)

2) took a stereo feed out of the recorder and sent to me wireless so I could monitor it with my ears as well

I was less concerned with how I would get a signal to my ears than how useful an uncalibrated signal would be to monitor for a beginner (in this field - like myself). I'm guessing an experienced op would be able to gauge how an uncalibrated signal would transpose in PP, a beginner less so, if at all?

I image wind noise, suspension rumble, signal interference are not masked by the uncalibrated O/P but more subtle nuances of the sound and therefore where best to place the mic probably are masked to certain extent?

Maybe I'm over thinking this but I'd like to develop this as a skillset.

Are the current recorders with an 'Ambisonic Modes' calibrating the I/P signals before recording or just for monitoring? 

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15 minutes ago, daniel said:

I'm guessing an experienced op would be able to gauge how an uncalibrated signal would transpose in PP, a beginner less so, if at all?

I image wind noise, suspension rumble, signal interference are not masked by the uncalibrated O/P but more subtle nuances of the sound and therefore where best to place the mic probably are masked to certain extent?

 

To a degree. It's not so much about knowing how the sound field will sound like without using decoders, as much as it is about knowing what can present as issues when converting the A- to B-format. i.e. wind noise, suspension rumble, if there's any weird noise artifacts in any of the capsules, etc.

 

21 minutes ago, daniel said:

Are the current recorders with an 'Ambisonic Modes' calibrating the I/P signals before recording or just for monitoring? 

 

Most can do both, record and monitor the signal post processing, or record the signal raw and monitor post processing. The latter is recommended as the A- to B-format conversions in recorders use a generic algorithm, and in post you can use better conversion algorithms.

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22 minutes ago, daniel said:

Are the current recorders with an 'Ambisonic Modes' calibrating the I/P signals before recording or just for monitoring? 

 

I would presume not at all - neither. If you calibrate the response of 4 or more capsules then recorders which can gang channels with individual offsets applied (presumably the Cantar can ...) will then record and monitor 'compensated' balanced channels. Or you could do it manually with any two-gain structure (trim and fader). Or just apply the offsets in post.

 

I've never even thought of calibrating my Soundfield. Like any expensive stereo fixed array I'd expect a decent capsule match to be done for each mic in manufacture ... and it sounds a bit hi-fi enthusiast to me too. If capsules are different sensitivities then they are going to have different frequency responses, so balancing between them into a recorder is only going to be accurate at whatever was the chosen fixed frequency value (say 1kHz). If you're calibrating the freq response too ... has anyone created a nice enough superfine ultra wide spectrum EQ to balance the channels in post to bother? Referring to freq calibration in measurement applications is usually referring to just a fixed point or area, not the entire bandwidth.

 

Am I missing something obvious - or are tetrahedral mics coming out of the factory willy-nilly these days that folks think level balancing is necessary?

 

Jez

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2 hours ago, The Immoral Mr Teas said:

 

 

Am I missing something obvious - or are tetrahedral mics coming out of the factory willy-nilly these days that folks think level balancing is necessary?

 

Jez

 

In my case with the Soundfield SPS200 is unnecessary, the capsules are very very close

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3 hours ago, Jose Frias said:

To a degree. It's not so much about knowing how the sound field will sound like without using decoders, as much as it is about knowing what can present as issues when converting the A- to B-format. i.e. wind noise, suspension rumble, if there's any weird noise artifacts in any of the capsules, etc.

 

 

I agree, it is about listening (and looking! Thus why I used the wireless app as well) out for problems. And positioning the mic as close (and as consistently as possible) as you can to the camera so that perspective is accurate. You do this and you're 90% of the way there, the last 10% is just refinements. 

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2 hours ago, IronFilm said:

When I did a shoot earlier this year I'm 95% sure the producer who rang me up didn't even know what "ambisonics" is. 

Rather it is part of my job to identify what kind of shoot it is they're doing and what they need for it. 

 

Yeah, I imagine few producers know the nuances of multi-channel audio recording. No doubt you are going to bring your expertise to the project to approach the production. In the shoot you mention were you brought in for surround/immersive/3D audio recording specifically? What are the production deliverables in these projects? Raw A-format, B-format, 5.1? Other?

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5 hours ago, jon_tatooles said:

are your customers specifically asking for "surround", "3D audio", "ambisonics"? If yes, what kinds of projects? Do those who ask have any understanding of it and have they thought through the whole pipeline to the listener?

 

If it's a VR/360 video production company, they will specifically ask for "spatial audio" which seems to have become the default nomenclature for this kind of work. They may specify that they want Ambisonics, which is obviously not the only spatial audio format, but it seems to be the most widely adopted one for VR and 360. A professional VR production company would definitely understand the entire pipeline.

 

Now if it's a regular production company that is doing a VR / 360 video project, then it may be a different situation where they know very little to nothing of the workflow and pipeline, but they have some basic understanding of the language. In those cases most of the 

clients I have worked with will hire a VR sup or tech who guides them through the process and who communicates all the technical requirements for the project.

 

2 hours ago, jon_tatooles said:

What are the production deliverables in these projects? Raw A-format, B-format, 5.1? Other?

 

Depends on the project, but for most of the VR / 360 video projects my company and I work on I'm delivering to post:

- Multi-track files (sync'ed with video) with all isolated sound sources (mostly dialog or speaking parts, sometimes interesting production sound effects that can't be replaced or reproduced in post)

- Wild mono files of isolated sound sources

- Wild 1OA A-format files of room tone and ambiences

- Wild 1OA A-format files of impulse responses

 

In post, for a linear project like a 360 video we will sync the multi-track file to video. Lay down some to all of the wild sounds, add Foley and sound design as appropriate. We pan, or as we like to call it "spatialize", all of these tracks into a 3OA mix. We convert A- to B-format, and upconvert the 1OA room tone to 3OA and lay them down in the mix. We feed the 1OA impulse responses through a convolver that we use for reverb on the ISOs. Once the 3OA mix is done, it is muxed with the final 360 video for delivery to the platforms that support 360 video playback with Ambisonics (YouTube, Facebook, LittlStar, SamsungVR, etc), or it is packaged into an app for the Oculus store or Steam VR for example. If the project is interactive, then we build the audio through wwide, an audio engine that operates as middleware for a game engines like Unity or Unreal.

 

BTW, 1OA files we typically record with the MixPre-6.

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Excellent, interesting and nicely concise write-up Jose, thank you.

 

Interesting that you are mixing (and presumably delivering?) in 3OA and recording in 1OA. I don't have close to the same experience as yourself in actually working (and delivering a product) in ambisonics, yet I've known it, used it and experimented with it since a long while back. I believe Jon was perhaps referring to the end delivery format or situation in his question (which was well answered but I'm still curious). I will add my own experience that as a single point mic, if the ambisonic mic cannot be well-positioned it may well be compromised (or be not terribly good) as the source of a good or perfect 'localisation sound-scape'. This will be understood by everyone who at some time couldn't get the boom mic just outside the frame pointing at the dialogue, and is stated pretty succinctly by Soundfield who pretty much said 'position it as a mono mic to get a good result'. So even for these 'vector-soundscape' situations perhaps even ambisonics can't deliver (against the tyranny of camera position for instance). So, I'm sort of second-guessing Jon's question here in what the requirements are and how much are met by a single ambisonic mic and what else goes into a third order ambisonic mix?

 

Are you using Harpex for the final mix? And is there a strong reason for delivering in 3OA rather than 1OA? Is it just that 'one can' or do other input elements and/or delivery requirements (being what - speaker or output-wise) necessitate or benefit from the higher order?

 

Hope these questions make sense to anyone but myself! I'm actually interested in how we might be experiencing a repeat of the "locked camera" restriction of both sight and sound that disabled film in the 1930s, a previous era of great change, and my own fetish interest ...

 

Jez

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