I have a Sound Devices MixPre-6 with Rode NT-SF1. Which Ambisonics Mode is the right one for recording?

! would start with A-format, then have the Rode Plugin convert it to B format or different. Looks like A>B format converters are tailored to a specific mic, so you'd need the Rode plugin for the best result.

I have Sound Devices 788T and Soundfield 350ST and the new Rode SF1.

SF1 outputs A format. This is no problem to record on the 788T but you have no meaningful headphone monitoring. You can listen to each channel at a time, but there is no A format to stereo basic decode. The 788T has B format to stereo decode (dire tho it is). With the SF1 you are flying blind until you can get the A format signal into either the Rode plugin or something like Harpex

Record A-Format. Convert with Rode plugin.

Sound Devices just confirmed to me that the internal B Format is tailored to
the Sennheiser Ambeo.

Hi everyone,
I made a basic test with my new NT-SF1 in a quiet room (mic connected to SoundDevices MixPre 6 II at 66dB cha 1-4 linked, 192kHz 32bit)
Please, look at the following two snapshots: ONE and TWO.
I noticed 3 things:
1. Channels 2 e 4 are paired and calibrated, whilst channels 1 and 3 are completely out of balance in comparison with 2 and 4! (This happens positioning the mic in every direction, so it doesn't depend on the room.)
2. There's a strange pick around 40-50k?
3. When I make a sound (with my voice) the 4 channels “tend” to raise to the same level, that's good, but this also means that capsules have different SNR, that's bad, so that difference between the channels is much more evident in low-noisy ambients, and less evident in noisy ambients. (Not a perfect behaviour IMHO.)

Question is: in Your opinion, my mic is damaged? Or Rode does tolerate this discrepancy in the 4 channels' calibration?

Thanks in advance.

I would definitely contact Rode, they have (in my experience) good warranty-service. NT-SF1 is supposed to be a high-quality microphone and you / we should expect tight tolerances.

::
Mads

Another option..... https://www.facebook.com/permalink.p...31418576875192

Cool! Thanks a lot! Unfortunately I do not know nothing similar here in Italy...

That looks like more than calibration.

Call Rode to repair, you have a 10 year warranty.

Before you call, put a test meter on your cable assembly.
Or open the XLR ends, and look for a broken wire.

It's a good point! Thanks. But all test meters I've seen have only the plug for the XLR-side of the cable, not for the female-side of the cable (that's specific from Rode).
Can you tell me a specific test meter for Rode ambisonic cable? Thanks in advance.

Ok, it seems that my unit has a real problem, not simply calibration (and I agree, that difference between capsules' SNR isn't usual). I think I'll go for returning my unit for a refund.
Now, returning my unit means that I don't have a mic anymore: here in Europe the NT-SF1 is completely out of stock.
I have 2 possibilities:
1. Waiting a couple of months to buy a new NT-SF1;
2. Buying right now a Sennheiser Ambeo VR Mic.

I heard the Ambeo in a YT video comparison against NT-SF1, and I must say that I prefer the audio quality (especially the low-noise performance) of the Rode.
Anyway Ambeo is made with electret capsules that many people say are much better for outdoor recording (humidity, temperature...) And actually I plan to use the mic mainly for outdoor recordings (night, fog, sun...)

Question is: for my case do you recommend electret (Ambeo), or can I use safely the Rode?

Thanks in advance.

The old fashion way, a VOM, and patience!!

Here is the pinout:

I know this post is 1 year old, but I never asked, were you recoding through the amibisomics plugin aa A format. or just raw 4 channel??
Cause thats what you would see as raw.

Hi, thanks for your reply. No plugin. Raw tracks.
But why should I see that behavior in raw mode?

Without getting into phase and time orders. The tetrahedral mic array isn't as simple as 4 mics pointing in 4 directions. Think of it as a very complicated M/S array, for the lack of better explaining.

You should be looking at your recording in minimum an A Format.

If you have the MixPre 6 II the plugin is free.

Record in A format, then use the Rode software to create an immersive format, at least 5.1, then listen.

I knew plugin was for Ambeo only, possibly am I wrong?

Recording in A format is raw, recording in B format is designed for Sennheiser Ambeo only.

Record in A format, then use the Rode plugin in your favorite workstation to create any other format.

OK, I'll try. Thanks!
Anyway, it seems that plugin is not free (see HERE)...

Page 4 first line
https://cdn.sounddevices.com/downloa...Plugin8.19.pdf

Upgrade to latest firmware first


If you have a Mixpre 6 II it’s free.
Enter your serial number in the box.
Should give you a $0 invoice and allow a download

OH! Thanks man!

A disheartening update:
About 1 year ago I returned my NT-SF1 because the levels of the 4 channels were unpaired, as you can see HERE and HERE. It was a mic issue, since the levels "pattern" (3rd cha highest, 1st cha slightly lower, and 2nd & 4th are the lowest at the same level) remained the same even changing the mic position/orientation or placing the mic in different environments (only after swapping the connectors' order in the MixPre inputs, the "pattern" followed the changes consequently, proof that the problem came from the mic).
So, I returned the mic and the replacement arrived this November (after about one year), and with my great surprise, also the replacement has a similar kind of problem: the only difference is that the "pattern" is now 1st cha highest, 3rd cha slightly lower, and 2nd and 4th are the lowest at the same level (images HERE).
I wrote to Rode and they replied that I should "match the four gains digitally in the recorder settings". Well, it would be acceptable, but unfortunately it seems I can't do it in my MixPre-6 II, because after setting Ambisonic mode, all the knobs/faders (but one) are blocked/useless because all knobs are paired with the first one. So it seems I can't manually correct the channels levels individually.

At this point I have only 2 questions:

1. Is there someone else that experienced the same problem? (It would be weird I was the only one with the only two problematic mics!)

2. Anyone knows if there is a way to manually correct the channels levels individually in MixPre-6 II (in Ambisonic mode)?

Please, let me know.
Many thanks in advance.

(P.S. My MixPre-6 II is updated to firmware 8, and I use Ambisonic plugin recording in A-format. And as you can see on the screenshots I linked, the transformation to stereo format (via the Rode plugin in the DAW) results in a completely unbalanced stereo.)

Match the four gains digitally does not mean turn the knob until the levels are the same. It means if not using the plug in, the level "gain numbers" need to all match.

The sound isn't equal all around you, and trying to match levels will certainly induce problems in the matrix.

Please do some reading and research about ambisonics.

I can easily agree, nevertheless it's what SoundDevices and Rode both suggest! Rode recommend trying to adjust the individual channels levels, and SoundDevices confirms it's easily possible to record a simple non-Ambisonic 4-channels file to have the use of the 4 indipendent knobs and then use that file as A-format in the DAW-plugin.
I'm not saying it's a perfect way to do the job...
The point is that I tried two different NT-SF1 units, both with the same "unbalanced channels" issue (I made a bunch of tests to be sure of it).
Now, I honestly can't believe that I was so unlucky to buy the only two defective units, right? So my question remains: is this issue quite common in NF-SF1 units or not? Nobody else experienced that?
Please, let me know.
Thanks again.

Yes
Because sound from 4 mics won’t be equal, especially outdoors.
Sound Devices meant keep the gain equal, not as metering but as amount of gain in numbers.
For example all 4 mics would have say 50 DB of gain each.

I'm indoor...
No. I personally received their mail and they were pretty clear: in my case they referred to metering, and they agreed on the fact that my units behavior was not normal. More: I downloaded various samples of silent rooms and they had channels at the same level (metering).

OK, I'll change my question: anyone else received a defective NT-SF1?

I haven't got the NT-SF1, but I did consider getting one when it was released, so in that sense I can relate to the issues you have.

Røde seems to be proud of the consistency of their products and as far as I know ambiosonic systems need to be very accurately matched to produce desired results.
And I wonder: If Røde cannot even get the levels right between the four capsules, how about frequency response?

As I hear your description, you should not accept the issues you have, you need a replacement from Røde.
::
Mads

Another thing, you haven't ruled out the recorder, or the cable.
I left you the pinout earlier, just get an ohm meter, and test all the wires.
Only 10.

Try another MIXPRE, or check all you settings, turning ambisonics mode on doesn't override some settings.

Hi,

I know this is from 2 yrs ago,
But I am having the exact same problem....I daresay my Rodes is probably too late to return...but did you find the non ambisonic mode on the mix pre....and adjusting the gain levels equal on the inputs worked?

As the inputs certainly do not work in ambisonic mode!

I know this doesn't help those using the SD MixPre 6, but I have had ZERO issues using the NT SF1 / Zoom F6 combo with stock cable & extension cable.
I purchased mine during the pandemic to try inexpensive ambisonic recording, knowing this low cost rig likely had a higher noise floor than the high end stuff I was Jonesing for. Adding the extended cable was helpful moving the recordist farther from the primary recording zone when needed.