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Author Topic: Rode AI-Micro Ultra-compact Dual-channel Interface  (Read 13315 times)

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Offline capnhook

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #45 on: December 13, 2022, 06:27:07 PM »
Maybe a 3.5 mm female coupler and one of those 3.5 mm cables pads that they use for cameras might work to bring down the signal. 20db pad and boost in post?

Am I missing something, brother doomed?  Have you tried an attenuator cable on the input, as fireonshakedownstreet suggests?  ???
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Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #46 on: December 14, 2022, 01:24:42 AM »
yes, the problem is with the actual device, its doing something to the audio, I just tested that today and it's almost certainly corrupting the audio. The higher the input levels, the worse the corruption. Though it's not for sure yet, I am also going to test it straight into a real system with Audacity as the recording tool to see what happens there, just to rule out Android itself. But USB Audio Recorder Pro guys told me they make their own usb driver, so ideally, android is not involved, but it's hard to know with those types of closed systems.

My current guess is that the 'AI' in AI-Micro stands for their attempt to have 'smart' sound processing, and that attempt simply should be terminated with a firmware update.

It's not a question at this point of adding a pad, anything I send into that device corrupts, I verified it with an ab test against a known good usb audio device I've used previous to the Rode. Since that test was done on my home system, which can't reach those clipping sound pressure levels, I was able to see what the device does basically on its own, and it is bad. The only thing I want a usb audio ADC to do is convert the incoming analog, convert it to digital, then send that down the usb to its destination. Much more than that is going on, and their docs appear to be wrong, or they messed up the firmware, so shutting off the high pass filter in their app does not appear to be shutting it off for the 3rd party audio tool.

I can't guess what is being done on that device, but I won't trust it for anything until either they issue a real firmware fix for these issues, and make it work correctly with non Rode software, including disabling any and all active processing of the audio.

The device is also putting out roughly 10db more than my previous usb audio interface I'd used with good success, and how or why that can happen is beyond me, since both are receiving the same input signals during testing. I don't know the ins and outs of this type of device design so I don't know where the issues are really sourced, but i'm not risking any show I want to actually record on such an unpredictable device.

I'm going to test the revised setup at the same venue on saturday, that will tell me pretty absolutely if it was the rode at fault since I'll be removing that from the setup, though I may bring it and swap during a band I don't care about's set, just so I can get a really accurate comparison at the same venue on the same night.

I'll post an update after that test, but these things aren't easy to track down conclusively, but right now, most of my suspicion is on the rode, because it's doing things that should not be happening, and they are verifiable and readily measurable. It's possible that they messed up the firmware, but I don't really see how, since I tried this recording on their own app, to the same results. Which suggests this is intentional, and someone's notion of a good idea. I'm also suspecting the initial reasons they didn't answer my questions twice about this stuff is they don't actually want to admit what they are doing, though that's just a guess.

One of the really terrifying things I saw, though I have to retest to make sure, is that during a roughly 30 second test recording, it was actually actively and dynamically adjusting the compression levels, you can actually hear it happen during the section, and see it in a wave editor. I believe that's the 'AI' part of the logic, though it's just a guess. But I don't want to push my speakers that hard much more, they don't like it, and neither do I, so I may just put this device away and let other people figure it out, and use something I know works.
« Last Edit: December 14, 2022, 01:45:53 AM by doomed »

Offline fireonshakedwnstreet

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #47 on: December 14, 2022, 09:45:51 AM »
That sound awful! Thanks for your work, doomed.
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Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #48 on: December 14, 2022, 03:18:18 PM »
I'd like to do more work on this in terms of more testing, but as mentioned, neither my ears nor my speakers like being pushed to that level. I'm glad I captured the two main tests clearly however.

The more I think about this, the more I believe that the 'AI' in AI-Micro stands for a horrific notion of trying to make the device 'sound good' to amateurs. Even the higher db output level fits in with that. I believe it was John Watkinson in his The Art of Digital Audio that noted that in listening tests, users almost always think the one that is 'louder' sounds 'better'. It could have been someone else, but same level of understanding. Compression on vocals also is a trick to bring things to sound 'good' in for example a youtube streamer's voice, etc.

I will however basically know for sure after this weekend, because it will be the same venue, same sound system, similar type of music, at least close enough, and a known recording spot. If the Andrea unit delivers with the new sensitive mics a totally fine recording, then there is no doubt.

It's my understanding that in a club setting, 96 db (aka, 16 bit) is all you need from noise floor to house sound pressure level at x distance, where x is far enough away to be reasonable, that is, your head isn't stuck into the cabinets, from stage speakers.

I need to get this totally solidified by next month because a real band that rarely comes is playing, at what are sure to be challenging sound pressure levels, so this all needs to be solid by then. Actually another guy is coming earlier too, and he almost never shows up playing live anymore. Saturday's show should show me all I need however since if that gets pushed into clipping territory I will have to look into getting a pad for these mics, which is/was a suggestion I appreciated, I probably didn't make that clear.
« Last Edit: December 14, 2022, 03:59:33 PM by doomed »

Offline Ozpeter

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #49 on: December 15, 2022, 05:29:37 AM »
To be honest, mine has been in a drawer for some months simply because, well, I don't think I actually needed it, and lack of functioning stereo input for PiP mics is a bit of a dealbreaker.  But I'll see if I can test it in the next few days to see whether it too gives bad results with a beefy input.  One thought is that Android devices can be surprisingly incompatible with external stuff (eg something might be fine with one phone but not with another phone, for no obvious reason) - have you tested it with another phone at all?  Apologies if you've already mentioned that.

Offline justme

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #50 on: December 15, 2022, 05:40:53 AM »
Thank you.

Impressively solid testing and very valuable knowledge.

Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #51 on: December 16, 2022, 01:23:47 PM »
justme, I wish I could do more testing, but if I posted screen shots of the two frequency graphs from the recordings, you'd instantly see the difference. Definitely not in the faux audiophile expert realm that is, 'the sound stage is more balanced and lean yet crystaline in clarity and presence' here, it's: one sounds like the recorded source, and one sounds like crap. With the graphs showing the corruptions clearly.

Ozpeter, one thing that USB Audio Recorder Pro does is they made their own usb audio driver, probably based off the Linux kernel's normal driver is my guess, they don't use the usb audio driver of Android. This is actually quite meaningful, because if that was not the case, then it could be different Android versions shipping different or varying usb audio drivers, which would certainly result in such issues. This usb driver and logic is used on their Evolution DAW as well, so it should be working for a while, I hope.

But you are quite right that this is unfortunately not 100% knowable since Android is something of a blackbox sadly, except for the fact I have done many fine recordings with the other usb device on the same phone at high db levels without a single issue like this, when I have gain too high, the recording clips, period. I cannot make the Rode clip. I've had issues at high db levels, but they are what you'd expect from either overloaded mics or overloaded circuits in battery box or elsewhere.

One reason I don't actually think it's even worth testing the other usb recording apps for android is they are all worse, worse interfaces, worse usabilty, worse documentation, some even try to force you sign up to their 'cloud' stuff (BandLab) so I couldn't even test those at all, but I assume they are as bad or worse. The dolby one was particularly terrible, which was a bit of a surprise, that one doesn't even pretend to not do dynamic processing, in fact they brag about it, and it's clearly not something that can be disabled.

I could test another round recording straight to a real computer, same tests, but as noted, my speakers just don't like going to just below small club levels, and blowing their woofers isn't worth it to me since I already see the non ambiguous data in the recordings I tested with.

Everything points to Rode making very bad decisions about their firmware, and also to a certain NIH (not invented here) attitude towards purchasers of their AI-Micro, since none of those filters or settings should be active in the first place when not going into a Rode app.

The clear presence of a bass cut as well means I can't even trust their own docs that say clearly that if you disable high pass filter in their app, it will disable it on the device for 3rd party apps as well, which does not appear to be the case. Or they messed up their firmware, and it's supposed to work, but doesn't, it is too hard to tell to be honest, and not one of these issues should exist on what is supposed to be a quality device.

I'm keeping my fingers crossed for a few things now:
* The old usb audio interface performs as expected (and given it's coming in around 10db or so under the Rode, which is roughly the range that was being redlined with the rode, I have good optimism there). I'll know this tomorrow.

* A serious usb DAC maker, like Dragonfly, decides it's worth making a quality stereo mic input ADC. This is unfortunately a very fringe requirement, so the market is clearly not very big, but I'm going to keep my eye out, as we see with Rode, the chips are there, but all that's needed is either for them to wake up and disable all their processing and deliver clean audio via a firmware update, or for another vendor to make a stereo 24/48 capable ADC using the same chips, unless the processing is built into the chips, which I suspect is not the case. There is nothing in the tech requirements at all that makes this not possible, so it's just a matter of someone doing it, and deciding there's enough market to make it worth it.

After this experience, I think I'd definitely bump up my maximum price I'd pay for such a device however.
« Last Edit: December 16, 2022, 01:29:00 PM by doomed »

Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #52 on: December 19, 2022, 01:54:15 PM »
After the live test, I can confirm almost certainly that the AI in AI-Micro is, first, a nonsense marketing term, and second, points to processing triggered by difficult to determine events. This logic is either baked into the chips, or it's running in the operating system/audio software blob we call 'firmware', or possibly a combination of the two.

There's a few unknowns, first is if moving the gain slider to 0 is what triggers increasingly extreme processing, or if it's gain plus incoming voltage that triggers it. This can be determined by a lower volume test, which I'll do when I have the time.

In other words, if I can demonstrate to myself conclusively that the AI-Micro applies no processing at higher gain levels, say, +8-12db, then it could be used with an attenuator. Sound Professionals sells several options, which I will look into, but that would always require that you get it right to start in terms of the attenuation and the gain levels on the Rode.

I'd say tentatively if you see significant red in your recording app VU meter, you can throw away the recording, it can't be fixed, and will be a full fail.

I've done a recording with the rode at lower input levels, and found some things I found to be odd, but didn't give it much thought at the time, since I thought it might have just been the room, but now I'm not so sure, those could have been milder applications of the dynamic processing going on.

Then there's that largely inexplicable roughly 10db or so boost applied to the digital usb output, which makes no sense unless you are trying to make it sound 'louder' to the person recording it.

I believe I can nail down a few of these questions crudely, but not with certainty, because if it's a progressive action, that is, gain controlled, or gain plus input voltage controlled, that would suggest that it's always applying it to some degree.

I would not use this device for any live recording until these questions can be unambiguously resolved.
« Last Edit: December 19, 2022, 01:55:46 PM by doomed »

Offline Barry M

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #53 on: December 19, 2022, 07:32:48 PM »
I believe the AI stands for audio interface, not artificial intelligence.

Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #54 on: December 19, 2022, 08:23:19 PM »
Sounds plausible, though at least there would be an excuse for those behaviors if it meant Artificial Intelligence-Micro.

I'm slightly curious to see what it does under varying loads, so I'm going to run a few more tests on it, a/b'ing it with the reliable consistent interface, I'm actually curious to see what it does and how it does it, and if I can determine if there is a point where processing stops and straight audio comes through, or if there isn't.

Just to be sure I hadn't missed anything, I reread their main page, but nothing beyond a strong focus on podcasting etc appears.

I'm really hoping this changes (via maybe a firmware update) to be honest, because the device itself is very promising, but not as long as it tries to be 'smart' when not asked to be. But I think youtubers and podcasters are their primary target market, think dual mics in an interview or conversation setting, despite their pages mention repeatedly of 'high quality' sound etc.

Or it could just be a mistake and a failure to test adequately, hard to say really, too many unknowables which can only be determined via testing and analysis. which is kind of tedious to do, though educational.

I don't think AI was an accident in the naming though, every usb audio device out there ever has been an audio interface, but non have called themselves AI-xxxx, and none that I  know of do this type of active processing.

Simple documentation of features would remove all the guesswork, but I'll plug away at it some more, but not in a live use setting.

Offline Barry M

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #55 on: December 19, 2022, 10:41:22 PM »
Rode calls them the AI series, and yeah, that might be a marketing play on artificial intelligence, but all they talk about is audio Interfaces. The predecessor that the AI-Micro is a smaller version of was the AI-1. Nothing suggesting any intelligence in them, other than "auto-sensing" TRS and TRRS.

https://rode.com/en/interfaces-and-mixers/ai-series

Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #56 on: December 20, 2022, 01:59:49 PM »
Just a quick heads up, I was looking up the specs on the Andrea usb audio interface, and they are having an end of year half off sale, and also I discovered that they offer a stereo 1/8" mic only interface, no headphone out, no dac, with better specs. It's only $20 now (december 2022), but they only ship priority mail, at $10, so if you order 2 you'll get a much better deal. I've used their headphone/mic unit with very good success, and this one is better from what I can see. The headphone/mic one is also on sale, half off, about $20 too. You won't find a better deal than this ever on a stereo mic supporting usb audio interface that actually works.

I've never seen the 48khz supported so far on recording apps, but that may be simply because they don't know about this device, which is not common. Not that 48khz will do you any good with 20-20,000hz supporting mics.

https://shop.andreacommunications.com/usb-ma-premium-external-usb-microphone-adapter/

2 Channel Stereo
48K/44.1KHz/16K/8K
0-70°C

Supply Voltage:            4.5-5.5 VDC
Total Power Consumption:   120 mA
Bias Voltage:              2.2V via 3.3K Resistor
A/D Conversion Resolution: 16 bit
THD + N:                   -90 dB
Supply Bass Resistor:      2.2K ohm @ 3.3 VDC
Frequency Response:        20-20,000 Hz
Input Range:               0-1.25 Vms
Dynamic Range:             96 dB
Record Gain Range:         -6 to 33 dB
« Last Edit: December 20, 2022, 02:23:16 PM by doomed »

Offline doomed

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Re: Rode AI-Micro Ultra-compact Dual-channel Interface
« Reply #57 on: December 20, 2022, 02:16:08 PM »
A small update in the Røde testing. I am frankly puzzled by my latest lower volume tests. I did another a/b recording, same source, same mic position, etc, between the AI-Micro and the Andrea SB-SA. You may recall that at high db levels, the AI-Micro is delivering almost 10db more output than the Andrea, making it unusable in a live setting without an attenuator / pad, so I expected to see similar results in normal listening level tests. Such was not the case. Whereas at high db levels, the AI-Micro had much higher output than the SB-SA, at lower levels, normal listening on stereo, the AI-Micro needs much MORE gain to match the rough recording levels. This is clearly impossible if this was a linear circuit, so it clearly isn't, which was already obvious from the original set of live and test case results.

As well as some other oddities which I honestly cannot understand or explain in terms of the normalized overall db levels per frequency range.

So this device is fairly radically unpredictable, whereas the SB-SA/SB-MA act totally linearly, utterly predictable, those clearly do no clever tricks to the audio at all, and are what they claim, a usb audio interface, period.

The AI-Micro is most definitely not linear, and is doing a lot of things I cannot explain or understand, and because of this, I view it as far too unpredictable to ever use in a real live setting where the recording matters. There's also the question of the bass cut apparently kicking in after being disabled in the Rode Connect app, which is supposed to disable it in the firmware, but as far as I can tell, that bass cut also seems to activate dynamically at higher db input levels, but it's all a guess.

One thing I was testing, which I was largely able to determine, is that the bass cut is activating at higher db input levels, and is not active at lower db input levels. But I'm not going to push my gear to find what point that kicks in automatically, and if it kicks in with an off/on manner, or if it kicks in progressively.

If this is not burned into the chips of the AI-Micro, this anomalous behavior could be fixed with a firmware update, and I hope it will be one day, but as it is, when a simple test fails to show any type of consistent behavior between db levels, that just makes the rode a no go for me. For what it's worth, from what I can see in the wave forms and frequency graphs, at lower db levels, the rode requires MORE db gain, not less, to match the levels of the SB-SA, the opposite, that is, of what happened at high db levels. The wave forms and frequency graphs at lower db levels do appear to roughly match, which was not the case at higher db levels, but I'm not going to subject my system to any more of those high db tests. There's also another odd difference which I simply do not understand and can't explain, so I may need to learn a bit more about what Audacity is showing me before commenting on that part. But it should not be there, if I understand the stuff right, which is not a given.
« Last Edit: December 20, 2022, 02:22:09 PM by doomed »

 

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