I am in the process of digitizing our vinyl collection.
I have an Audio Technica AT-LP120 with an AT95E MM cartridge. I am running Audacity 2.0.5 on Windows 2008 R2 x64 on a Core i5 with 16 GB memory. Should be enough, I would say.
Every now and then, in the middle of a track, the recording starts to flutter heavily. Normally I would think that the needle was dirty or that the needle pressure is too low. However, when I stop the Audacity recording and immediately start it again, without touching the turn table, the flutter disappears. Restarting the track does not reproduce the problem, so eventually I get my LP digitized.
Anyone any idea’s as to what can cause this?
Change the USB cable, make sure it is tight both ends and plug it into an empty USB port on the computer, not into a USB hub.
OK. I am not using an USB hub, but I will change the cable. I will let you know.
If that doesn’t help…
Make sure you are not multitasking. Don’t run any other applications, and you may have to turn-off background operations such as virus scanning. If you havea laptop, turning-off Wi-Fi is rumored to sometimes help.
Try increasing the buffer/latency - Edit → Preferences → Recording, and increase the latency.
Normally I would think that the needle was dirty or that the needle pressure is too low. However, when I stop the Audacity recording and immediately start it again, without touching the turn table, the flutter disappears.
It might be helpful to plug your turntable into your stereo (or TV, or whatever) to confirm that this is a computer/digital problem.
Usually, random “glitches” are caused by the digital data stream being interrupted. This is usually related to your multitasking operating system. Your operating system is always multitasking, even if you are only running one application… The display is getting updated, it’s checking for keyboard & mouse input, updating the system clock, and there’s a bunch of other overhead.
So… the way recording works is the audio is digitized and it flows into a buffer (holding tank) at a nice even pace. When the operating system gets around to it, it reads the buffer in a quick burst and writes the data to your hard drive. If it doesn’t get around to reading the buffer in time, the buffer “overflows” and you get a glitch. (During playback, the danger is buffer underflow where the buffer “runs dry”.)
Note that this can happen even when the background/multitasking operations only using a small amount of CPU time… Some process just has to “hog” the CPU & databus for a few too-many milliseconds and you get a glitch in your audio. (A faster computer can often help, but any modern computer is plenty fast-enough for 2-channel audio and computer speed is not the root of the problem.)
A bigger buffer creates more latency (delay). Lateny is NOT an issue when digitizing vinyl so there is no downside to a bigger buffer. (to much latency can become a big problem if you are speaking/singing into a microphone and listening to yourself on headphones.)
Changing the cable did not help.
But changing the latency DID!
Thank you for you very helpful post and clear explanation!
Glad it was fixed.
But to be clear for others, the setting to change is “Audio to buffer”. The default of 100 ms “should” be OK for most cases.
The “Latency correction” setting is for pushing back recorded tracks after overdubbing against existing tracks. That setting wouldn’t make any difference to your issue.