Crackling when I record overdub

Desktop PC running Windows 7. Audacity 2.0.1. I’m using a good quality mic, plugged into the sound card with a mini jack.

(I’ve been using Audacity for years in its various forms, and this problem has never occurred before tonight. I’ve not made any changes to the hardware setup.)

I’m singing several parts of a song, overdubbing each new part while listening to the parts I’ve already recorded on good quality headphones that don’t leak sound. The first part records fine, but when I play back the second and subsequent parts, they’re full of crackles. I’ve tried muting various parts to see where the crackling is, and it seems that every part, apart from the first, is affected in a similar way.

I’ve recorded loads of songs in this way over the years, and this has never happened before. Since I’ve still got a copy of Audacity 1.3 I tried doing the same thing using that, and the same thing happened. If it was a wobbly electrical connection or something, it would affect the first track too, wouldn’t it? Is some sort of interference happening between the tracks? I have to say I’m mystified. I’m no Audacity expert, despite using it for years - I just do fairly basic, simple things with it, (mainly multitracking songs with vocals and instruments) and this is the first problem I’ve hit, so I’m hoping that someone who really knows what’s going on can suggest something!

Thank you.


Can you post a segment of crackles? Not the original track, just one of the ones that’s damaged.

Ordinarily, we would jump right on this and say you had an underpowered machine to handle multiple directions of live sound, but you have a new machine.

…Actually, you didn’t say you had a new machine, you just said you have Win7. Did you install Win7 on a wimpy machine? Crackles is pretty typical of the machine not being able to catch its breath. Koz

Do you want the original aup format?

It’s newish - new enough to have had W7 installed when I got it. 2 years old maybe? Reasonably powerful. And I’ve done lots of these things on the same machine with the same setup since I got it, with no problems until last night, which makes me think something has changed, or gone wrong, without my knowledge. Hmm. I do have a bad habit of multitasking, and doing other things at the same time as recording music, so I wonder if I closed everything else apart from Audacity, would that help? I hadn’t thought of overloading the poor computer being a possible cause.

Haven’t got time to try anything just now as I ought to earning a living at the moment, but I’ll try later tonight and report back.



AUP isn’t a sound format. Export as WAV and try that.

Do you have Skype running while you’re trying to do production? Say hello to mum for us and then hang up. You can’t have two or more sound services running at once.

Another thing that can give crackles is speaking through a USB hub with other equipment – although that would have damaged the first track as well.


Thanks! You’ve given me enough clues to fix it now! All sorts of things that can potenially use the sound services were apparently running in the background, without my knowledge. I hardly ever use Skype, but it switches itself on automatically, so I cancelled that. Then there were one or two other things that might just have interfered too - closed them all, then tried recording a second track once again, and - HURRAH! - it’s crackle-free! (I don’t use a usb mic - it plugs directly into the soundcard with a mini stereo jack, so that wasn’t the problem.)

It’s really frustrating when you don’t know which path to go down for faultfinding, so I’m very grateful - you’ve highlighted a new path for me to explore if I have problems again. I hadn’t thought at all about other software using sound services.

Now to get back to those harmonies …



Well, as soon as I’d posted the above reply, I recorded another track … and it was full of crackling again. Decided to cut my losses and try the whole deal over again on my laptop. It works on there absolutely perfectly, although it’s an older, far less powerful machine running on Vista. So I’ve no idea what’s the matter with the desktop machine, but I might as well stick to using the laptop for recording from now on rather than spend time troubleshooting the other one.

Thanks again for the advice.