weird modulation(?) on audio recording - help!

[rayw]

Audacity 2.3.3
OS X El Capitan 10.11.6
Rode NT1-A
Scarlett Solo


Hello, everybody.

Long time lurker, first time poster. I'm sorry if this is in the wrong bit. If it is, I hope someone will move it to where it's supposed to go.

I've just started audiobook recording. I've got myself a book to record and and I'm having so much trouble. I'm using a brand new (as in arrived today) Scarlett Solo/Rode NT1-A set up into my MacBook Air and I'm seeing and hearing a weird crackle on some of the recorded audio. The thing is I've heard this on another setup (my first one that turned up last week) with a Rode NT1 and AI-1 that made me call Rode and see about sending the Ai-1 back as I thought it was up the spout.

I'm at my wit's end as I thought if I replaced the mic and interface that would solve the problem, but lo and behold it's on the recording I've just made too. That means I think there's something I'm just not doing and I can't for the life of me figure out what it is, as two brand-new mics and interfaces can't be up the spout. And I can't afford both, so I've got to return or sell one on.

I know my way around Audacity in the most basic fashion as I've used it for little audio edits and fiddling over the years but this is the first time I"ve used it in anger and I'm having so much trouble with this.

Can anyone please tell me what the matter is or what I need to configure?

Today as prep for this recording session, I did a full reinstall of Audacity 2.3.3 and optimised the Mac - hard disk first aid, removeded all junk files. Got it all clean and tidy. But then this.

I've attached a screenshot of the weird waveform, it looks all torn up, and a .wav of the troublesome audio for investigation. Specifically the word 'follow', that's where I heard it and nearly burst into tears today. Which is a surprise as I'm in my 40's.

So I signed up here instead.

edits: context/typo

[Trebor]

weird modulation(?) on audio recording - please help!

If you mean the constant ~20Hz ripple, than can be removed with a rumble filter in Audacity ...

high-pass aka ''rumble'' filter.gif (112.69 KiB) Viewed 106 times

<20Hz is not audible, but you should remove it as it can interfere with processing.

[rayw]

Hello, Trebor!

Thank you! I had a think last night after I posted and I noticed that both the AI1 and the Solo were outputting at the maximum sample rates so I changed them to match the project file (44.1) and changed bit depth on the project to 24-bit and I thought that I'd sussed it, I did sound much better.

Screen Shot 2020-05-17 at 00.04.25.png (154.98 KiB) Viewed 96 times

Screen Shot 2020-05-17 at 00.09.04.png (163.93 KiB) Viewed 96 times

But after starting recording again today, I'm SURE I'm still hearing something.

So a 100hz rumble filter will clear that tearing up? I tried it on a clip and I'm not sure I can hear a difference, but maybe I've gone earblind - I've heard myself so much lately! And I'll be hearing more as the deadline is Wednesday for this!

Do these units put out this 20hz rumble you're talking about, or is it something from my recording space? Its a cupboard 4ft x 4ft x10ft (tall) that I've deadened as much as I can with with acoustic foam and blankets and earlier records have been alright, it's just since using BOTH these interfces. That makes me think that it's a problem with me and my set up.

[rayw]

...and to follow on, I did just run a 100hz rumble over my posted clip (weird follow) and I didn't hear any difference to it. Mind you, comparatively today's records DO sound much better, so maybe just giving Audacity the right incoming audio has helped...? I'm still not sure, but I'm second-guessing myself constantly at the moment.

[rayw]

...as this is about audiobook production, should I also post there?

[steve]

...as this is about audiobook production, should I also post there?

We prefer to avoid duplicating topics. The regular contributors to the forum will see your posts whichever forum board you use, so there is no benefit to duplicate posts.

Do you still require help with something?

[rayw]

I'm sorry, Steve. I'm having a right old flap. Yes. I do.

I've just done another recording using the Scarlett and althought that sounded good, the file I'm editing now doesn't, I'm sure I'm still hearing this tearing. It MUST be something to do with the way I have the interfaces set up, I thought that making the appropriate changes in the Mac MIDI settings - as I'm sure I saw in the Scarlett paperwork, but now can't see at all - would do the trick, and as I did this to both the AI1 and the Scarlett last night and they sounded fine I'm now tearing my hair out when I hear it on other recordings.

Can you see anything wrong in the screenshots I posted regards the input settings? Am I even on the right track making sure the audio coming out of the interface matches the settings for the project? I mean it seems to be common sense but I have very little experience with Audacity's deeper features aside of importing a .wav or .mp3 for tweaking; actually *recording* using Audacity seems to have me stumped. The funny thing is before the audio interfaces arrived I was using an H5 as a (somewhat noisy) interface with no trouble so I can't see what can be wrong. These should just work to feed audio into Audacity, surely? I mean they say plug and play...

Sorry if I seem a bit like I'm raving, this has had me on it's horns since Wednesday

[steve]

Can you see anything wrong in the screenshots I posted regards the input settings?

Normally Audacity should be set up to record as 32-bit float. See: https://manual.audacityteam.org/man/qua ... ences.html

I'm sure I'm still hearing this tearing.

Please post a short sample in WAV format so that we can see / hear what you are referring to.

[rayw]

Steve, thank you.

I will post a .wav when I can isolate a good example of what I think I'm hearing now. There was a sample posted initially in the post at the top of the page here, you can hear it most on the word 'follow', now I think i can still hear a smiliar thing on the records I've today but I think I'm starting to go barmy and need to edit something rather than just endlessly rerecording and getting upset.

So let me ask some questions that might help me understand more. I thought that if the interface is set to 44.1/24-bit and the project is 44.1/24, they'd be compatibale, like setting your video edit timeline to match the format of the video you're editing (I've always been more video than audio). And that was the explanation I gave myself when files sounded good last night, is that not the case with audio? Is 32-bit better? Do the project settings *matter* with an Audacity project? That sounds daft, but I mean if a device is putting out 96kHz/24 - like the AI1 was intially - will that make any difference if fed to a 44.1 project?

The 'follow' example above was from project settings of 44.1/32 with the Scarlett putting out highest sample rate, would that cause that distortion on the clip I posted at the top of the thread? If not, what? Has to be something I'm not doing right and that's what's messing with me the most.

[rayw]

Please post a short sample in WAV format so that we can see / hear what you are referring to.

here's one that just popped up, the world 'ultimately'.

ultimately.wav

(1.04 MiB) Downloaded 9 times

I mean what on earth?!

And I like dogs, but I've been doing this training book for ages and I'm going off them fast.