Why does clipping occur?

[Bainemo]

Is it Audacity? My sound card?

I'll give you some context. My current setup is a dynamic mic hooked up to a tube preamp via XLR cables. The preamp then connects to my computer using an XLR to 3.5mm jack. I have my gain set as such that my voice doesn't clip on the preamp even if I speak loudly with my mouth against the mic. Yet if it goes above 0 dB AT ALL audacity clips like mad. I can't tell if my sound card just isn't designed to handle signals of moderate or higher strength or there's some setting in audacity I'm missing. It's an onboard card, which makes me think it is in fact the card.

Is there any way to test this? Further, is there any way to set the max signal level audacity will handle before clipping it? Thanks.

[steve]

The preamp then connects to my computer using an XLR to 3.5mm jack.

If your computer is a laptop then you're pre-amp is probably plugged ino a microphone input - that would certainly account for the clipping.

[DVDdoug]

If your computer is a laptop then you're pre-amp is probably plugged ino a microphone input -

And if that's the case, be aware that most USB soundcards also have only mic-in and headphone-out. Berhinger makes a line-in to USB device, and there are lots of high-end USB audio devices with XLR mic inputs, etc.

Yet if it goes above 0 dB...

0dBFS (zero decibels full scale) is the "digital maximum". It's as high as the ADC or DAC can "count", or it's the biggest number you can hold in an integer WAV file, etc.

...audacity clips like mad. I can't tell if my sound card just isn't designed to handle signals of moderate or higher strength...

It's actually the soundcard's analog-to-digital converter (ADC) that's clipping.

... is there any way to set the max signal level audacity will handle before clipping it?

I don't know if this is true... but somewhere I read that most "everyday soundcards" don't have an analog volume control (or attenuator). if that's true, reducing the software recording-volume just alters the digital signal-level (after the ADC) and does not prevent overdriving of the ADC.

[Bainemo]

I should have mentioned that it's not a laptop and it's not a mic in jack. Desktop, line in. If I was using mic in I assume the signal would be distorted beyond recognition.

So what I understand is that audacity doesn't have a maximum signal level, but my sound card does. Therefore the only way to raise that would be a new sound card. It's certainly not a big enough deal to warrant that kind of action - more curiosity than anything. Thanks for the information.

[kozikowski]

Windows laptops generally have Headphone Out and Mic in, suitable for conferencing, Skype, etc.

http://www.kozco.com/tech/audacity/pix/ ... pSound.jpg
http://www.kozco.com/tech/audacity/pix/PCHeadset.jpg

Mic-In is Mono, very sensitive and distorts very easily.

We generally recommend the UCA202 as a USB stereo solution.

http://kozco.com/tech/audacity/pix/UCA202.jpg

..as an example.

If you know how to manage electronics, components, tools and soldering, you can build a volume adapter out of Radio Shack parts that will take care of the overload issue, but you will never get around the mono-stereo thing.

Koz

[steve]

I don't know if this is true... but somewhere I read that most "everyday soundcards" don't have an analog volume control (or attenuator). if that's true, reducing the software recording-volume just alters the digital signal-level (after the ADC) and does not prevent overdriving of the ADC.

That's partly true.
For USB sound cards, adjusting the record level on the computer does not adjust the analogue input gain. Some USB sound cards have a record volume control knob that allows you to adjust the input gain.
Internal sound cards that have a Line In connector will usually be able to cope with a reasonably large input signal - you may need to turn the gain down a bit on your pre-amp for the line in of your computer but in principle the computer sound card should be able to handle a line level output from a microphone pre-amp.

So far we don't have much information about your set up Bainemo.
In particular:
What sort of pre-amp are you using?
Which version of Windows?
Which version of Audacity?

[kozikowski]

Racing posts.

So you're doing this...

http://kozco.com/tech/audacity/pix/DesktopLine-In.jpg

That should have worked. Do you have a 20Db Boost control in your system tools? You should be able to turn down the Line-In slider in Windows Control Panels to get out of this problem. Line-In doesn't have that wacky preamplifier thing to overload.

Koz