Crackling on live gig recording

[Jakester]

I recorded our gig last night direct from our XR18 into a program called RecAll by Audified - basically it takes the direct from desk signal with no processing and records it. 

 

Last time I tried it I got lots of stuttering which I think was down to the default buffer size being too small. 

 

This time I have no stuttering, but instead lots of crackling across all the tracks. 

 

I know the crackling wasn't present during the gig as I was wearing IEMs and I would have heard it. 

 

Apparently crackling can also be a sign the buffer is too small - but it was set to 1024 samples as all RecAll was doing was recording, with no monitoring or effects processing so I assumed that would be better for the recording. 

 

Should I have had a smaller buffer than 1024? Any other suggestions (all audio connections were fine so that's ruled out as a caused as it was across all tracks)?

[Dad3353]

1 hour ago, Jakester said:

... lots of crackling across all the tracks...

 

Any barbecue in the vicinity..? 

 

crackling
/ˈkraklɪŋ/
noun
1.
the crisp fatty skin of roast pork.

 

 

[BigRedX]

This normally occurs because the sample clocks for each digital device have not been synchronised. What connection are you using between the XR18 and your computer? The best method is to use the device with the most accurate clock to control the other(s). However, the most practical way is for the recording device to be synchronised to the one supplying the digital audio as it can usually be done using the same connection for both the clock and the audio.

 

I once spent a week removing all these clicks from 20 minutes of 8 channel audio, because I'd forgotten turn on clock synchronisation when we digitally transferred the audio from ProTools to Logic using an ADAT connection, and it wasn't possible to do the transfer again properly. Because of the way the clicks are generated they were in a different place on every track, so the only solution was to listen to each track solo'd and use the pencil editing tool to manually draw over them wherever they occurred. It's a mistake you only ever make once!

Edited July 3, 2022 by BigRedX

[Jakester]

14 hours ago, BigRedX said:

This normally occurs because the sample clocks for each digital device have not been synchronised. What connection are you using between the XR18 and your computer? The best method is to use the device with the most accurate clock to control the other(s). However, the most practical way is for the recording device to be synchronised to the one supplying the digital audio as it can usually be done using the same connection for both the clock and the audio.

 

USB from XR18 to laptop. 

 

TBH I wouldn't know how to check the sample clock synchronisation in the programme I used - the point is it's supposed to be 'plug and play' with the minimum of configuration beforehand:

 

https://shop.audified.com/products/recall

 

I certainly don't recall (boom boom) seeing a clock sync option, but there may have been one buried away somewhere. How irritating. 

[BigRedX]

Have a look in the preferences settings for RecAll.

 

Also if you are on a Mac open the Audio MIDI Setup and check the clock source for the XR18 input.

[cheddatom]

I guess RecAll would have dumped all of the wav files into a folder. Have you tried playing one of these back using a media player app rather than RecAll? I'm thinking the sound could be there for playback, but hopefully not on the actual recordings

[Jakester]

1 minute ago, cheddatom said:

I guess RecAll would have dumped all of the wav files into a folder. Have you tried playing one of these back using a media player app rather than RecAll? I'm thinking the sound could be there for playback, but hopefully not on the actual recordings

 

Yes, sadly that's where I found the crackling - I imported them into Reaper to edit into songs. 

[cheddatom]

ah, sorry! Maybe try Reaper to record next time instead of RecAll?

[Jakester]

18 minutes ago, cheddatom said:

ah, sorry! Maybe try Reaper to record next time instead of RecAll?

 

Yep, the reason I plumped for RecAll (aside from the fact I got it free!) was it was supposed to be a 'one click' solution - I find when I'm doing everything else (I'm the only one who knows how the PA works in our band!), even arming a Reaper template to record can easily fall by the wayside whereas if there's only one button to press, it *should* be straightforward. 

 

Ah well, I'll use Reaper next time. 

[BigRedX]

If the clock settings are all OK, can you let us know the following:

 

1. What make and EXACT model of laptop are you recording on to?

2. Where is this recorded audio being saved to? The system drive or somewhere else? If somewhere else how is this device connected to the laptop?

3. How many tracks of audio are you trying to record simultaneously and are they mono or stereo?

4. Are you running any other programs on the laptop while you are recording? If so what? and why?

 

The buffer size shouldn't have any impact on the recording process if you're not monitoring the recordings in real time (you shouldn't be doing this in this situation), so, it may be that you are getting a data bottleneck somewhere. While USB2 (or 3) are pretty good, laptops tend to have an number of "invisible" peripherals which can have the potential to disrupt the USB bus. For a start if you don't do it already I would disable both WiFi and Bluetooth while you are recording. 

[Jakester]

58 minutes ago, BigRedX said:

If the clock settings are all OK, can you let us know the following:

 

1. What make and EXACT model of laptop are you recording on to?

2. Where is this recorded audio being saved to? The system drive or somewhere else? If somewhere else how is this device connected to the laptop?

3. How many tracks of audio are you trying to record simultaneously and are they mono or stereo?

4. Are you running any other programs on the laptop while you are recording? If so what? and why?

 

 

1 - 2012 MacBook Pro running Catalina 10.15.7 w/8GB RAM

2 - 1TB SSD system drive

3 - On this occasion, 9 mono tracks

4 - I had an instance of XAir running too in case the iPad I was using failed, but other than usual system programmes, nothing else. 

[BigRedX]

Using a Mac makes troubleshooting  much easier since OSX has a couple of handy utilities in theOS that can tell you about how the system is configured and where and why potential problems may be occurring.

 

So check the clocking in the Audio MIDI Setup, which can be found in your utilities folder. With the XR18 inputs selected it should say Clock Source: Default. This means that you have a working synchronised clock source between the Mac and the XR18. If it doesn't let us know what it does say.

 

Then double-check that RecAll isn't over-riding this setting somewhere in its preferences. If there's an option have the XR18 supply the clock

 

Next, how full is your system drive? It is recommended that you always keep 10% free. On top of that you'll need enough space to record your audio. For a monophonic track each minute recorded at 44.1kHz 16bit is 5MB so a 45 minute set with 9 tracks being recorded will require 2GB free on top of that. If you are recording at 24bit that adds 50% to the figure, and obviously longer sets require more space. To be safe I'd want a quarter of the system drive free for recording a gig. If you have a good USB2 external drive it might be worth trying that and seeing if it makes any difference (see the advice about USB buses below, though).

 

I'd also suggest that 8GB is little low for Catalina (the OS will use nearly all of that before you run any thing else) so, if you can, upgrade to 16GB. I have a Mid 2012 MacBook Pro and adding the additional RAM is simple if you have the correct size Philips and Torx screwdrivers. The less storage access the OS is doing for house-keeping purposes the more reliable the audio recording will be.

 

Then if you are still having problems check what else is on the USB bus that you have the XR18 connected to. As I said before laptops have all sorts of additional devices that you won't necessarily know about potentially sharing the bus, such as the keyboard, trackpad, memory card reader, web-cam, WiFi, Bluetooth, (which is why all wireless communications should be turned off) etc. To see what else is on the bus have a look at USB in the System Information (Alt-Apple Menu>System Information). Check all the USB sockets on the Mac to see which one has the fewest other devices, and that's the one to use. Unfortunately the only way to see is to plug the XR18 into each, quitting a reloading the System Information program each time (it doesn't have live refresh). Also, unfortunately USB socket ≠ USB bus, so several USB sockets may all be on the same USB bus.

 

HTH

[Jakester]

Thanks @BigRedX, I will work through that very comprehensive checklist! 

[BigRedX]

BTW can you zoom in on a "crackling" waveform in Reaper and send a screen shot of it? That might help work out what the problem is. The lack of clock sync that I initially suggested manifests as pulse waves one or two samples long on the positive part of the axis.

Edited July 4, 2022 by BigRedX

[Jakester]

Right, did a dirty render of one of the worst affected tracks, and also a quick poor-quality phone vid. Also a screenshot. 

 

It's across all of the tracks, even when they're silent. I did notice that the kick was distorting a lot, and wondered if it could have been that, but not sure how clipping on one track could affect the others, and the peaks don't necessarily correspond to the kick drum. 

 

(Not me playing bass, before the comments start!)

 

 

 

 

 

 

 

 

 

 

 

[paul_5]

multi-tracking to the system disk is always risky - could be that it's just bottle-necked on the way in.

 

I used to get this when my buffers were set too low, if you don't need to monitor stuff with low latency whilst recording (like you do when overdubbing etc...) then ramp your buffer up - this is why I like to record bands 'live', they listen to each other in the room, instead of an audio interface.

Edited July 4, 2022 by paul_5

[Jakester]

 

11 minutes ago, paul_5 said:

multi-tracking to the system disk is always risky - could be that it's just bottle-necked on the way in.

 

I used to get this when my buffers were set too low, if you don't need to monitor stuff with low latency whilst recording (like you do when overdubbing etc...) then ramp your buffer up - this is why I like to record bands 'live', they listen to each other in the room, instead of an audio interface.

 

On 03/07/2022 at 16:27, Jakester said:

Apparently crackling can also be a sign the buffer is too small - but it was set to 1024 samples as all RecAll was doing was recording, with no monitoring or effects processing so I assumed that would be better for the recording

 

[skidder652003]

does the XR 18 have the ability to record direct to an SD card or memory stick?

We had one years ago so I can't remember.

 

We now use the Zoom L20 and that lets you record 20 separate tracks straight to SD or memory stick in the desk or via cable to your DAW.

[Jakester]

17 minutes ago, skidder652003 said:

does the XR 18 have the ability to record direct to an SD card or memory stick?

We had one years ago so I can't remember.

 

We now use the Zoom L20 and that lets you record 20 separate tracks straight to SD or memory stick in the desk or via cable to your DAW.

No, sadly not - that would be perfect. 

[Jakester]

Hmm, looks like you can finagle a Raspberry Pi into a USB recorder…

 

https://dikant.de/2018/02/28/raspberry-xr18-recorder/

[Jakester]

Wow, what a rabbit hole… 

 

Someone else has developed a touchscreen version…

 

https://www.z-liverec.com

[BigRedX]

13 hours ago, Jakester said:

 

Can you please zoom right in on one of those clicks so that it fills the whole window and take another screen shot?

[Jakester]

Sorry, haven't had a chance to get round to this yet, but interestingly I recorded our gig last night using the same setup but via Reaper, instead of RecAll, and it worked absolutely fine, with no clicking or background noise. 

 

It does therefore seem like it's a software issue (thankfully!) rather than a hardware one. 

[BigRedX]

In that case unless getting RecAll working is still a priority, just continue using Reaper.

 

On the basis of that update my suspicion that it is a clocking problem that is being caused by RecAll is the favourite. 

 

If you still want to resolve this then please post the zoomed in screen shot of one of the clicks and point me in the direction of the manual for RecAll.