HELP audacity multiple track crackling when during playback

Using Audacity 2.1.1

Hi there, I have used Audacity before a few years ago. Just bought myself a Rode NT1-A mic and ATH-M20x headphones, but have never experienced the problem below before.

When I record one track and play back, it comes through the headphones fine, but if I record more than one track (with the headphones plugged into to the phantom power supply) when I play back there are crackles and “jumps” throughout. If I play through laptop speakers, those crackles are still there.

However, if I record multiple tracks without the headphones plugged in, playback sounds fine, no crackles. Obviously I need the headphones plugged in so the mic isn’t picking up what has already been recorded when I am recording on top of existing tracks. I have no idea why the crackles are happening with the headphones plugged in. Can anyone shed some light and help me solve this problem? Many thanks for your help,

Note: I’ve just upgraded after reading the above message stating to download the latest audacity version. The sound is now even worse through the headphones (not just crackles, but going loud, quiet, sounding plain awful!) when recording multiple tracks.

Please help, thanks, Kat

When one plays back multiple tracks, one usually has to turn down the gain-slider

on all the tracks to some degree to avoid clipping, (which is a crackling sound).

Hi Trebor, thanks for your reply. It doesn’t seem to be making any difference, even when I turn the gain right down :frowning:

Just to add on to what I’ve already said, none of the distorted sound is happening when I listen and record just using inbuilt laptop speakers. I have just tried earbud earphones in place of the new headphones, plugged into the phantom power supply (M-Audio Fast Track) but the same thing is happening (distorted sound when more than one track has been recorded and is playing back).

Changing the gain sliders on each track isn’t making any difference, just making the tracks sound a lot quieter, still with the crackling.

I am staying within the green on the playback level too.

Any help much appreciated. I’m getting pretty frustrated and downhearted as I have no clue why this is happening :frowning: . I have used Audacity so many times in the past, with the same phantom power supply (just different mic and set of headphones) and never ever experienced this. Thanks, Kat

Ok, I’m continuing to play around while waiting for my posts to be approved and receive responses.

Latest findings:

The first track recorded is “perfect”… voice sounds like it should, no crackles.
Second track recorded (and muting the first to listen to this one) my voice sounds slightly lower and weirder. This is the track that gets the crackles. When I mute this track and play back the first track, that one is same as it originally was, “perfect”, no crackles.

I’ve actually just gone to try out a third track and now I’m getting weird noise coming through the headphones… kind of like white noise and someone is changing the channel and the other channels have white noise too… coming and going. I’ve quickly changed to earbuds and same thing is happening.

When I repeat this recording “experiment” without the headphones plugged into audio interface, and change setting to laptop inbuilt speakers, all tracks sound perfect.

It’s weird because I’m using the same mic, plugged into the phantom power audio interface for both kinds of recording.

Is it possible that the phantom power audio interface is the problem?? Could having the headphones plugged in affect what I’ve mentioned above? This makes no sense to me but is the only explanation that seems possible.

I’m off to have a break from this. Hopefully someone out there can help shed some light… :neutral_face:

I think that rules-out Audacity as the culprit.

I’ve never used “M-Audio Fast Track” interface, but apparently feeding back the first track onto the second track is possible, but can be avoided …[b]how-set-direct-monitoring-fast-track[/b]-ultra-mac.html#post8944402

Hi Trebor,

Thanks for your reply. My neighbour came over yesterday afternoon to have a look and he reckons that it’s something about the computer not being able to cope with the two-way “traffic” of both 1: the previously recorded track(s) travelling from the computer to the headphones so I can listen, and 2: the recording travelling from the mic to the computer. Obviously when I’m recording the first track, the headphones aren’t receiving anything. Why my laptop can’t cope with this two way,I don’t know, but at least there is a reason that kind of makes sense.

We have found an interim solution of plugging the headphones into the laptop rather than through the audio interface, for the time being until can work out why this is happening (which for some silly reason my brain didn’t think to do!). My neighbour said something about potentially background processes on the laptop using a lot of processing power and maybe there is a way of prioritising it to Audacity while it’s running, but I’m not sure how to do that yet. Will look into it (again any suggestions welcome).

I now realise this is not an Audacity issue now though, so not really applicable to this forum anymore. But really appreciate help you have given. Thank you :slight_smile:



That is a possibility. Computers are made as general purpose machines, not as ready made recording studios. Tweaking the computer to achieve better audio performance can give very significant improvements, though it is not easy to work out where the bottleneck is.

Some tips / suggestions are given in these articles:

increasing Audacity’s CPU priority from “normal” to “above normal” is worth a try to see if it improves matters …

[u]don’t[/u] push priority up to “Realtime”, as that can cause the computer to be unresponsive.