Signal is cutted at -0,6 dB

[thyme]

Hi,

I have got a problem with Audacity and Windows.

How you can see in this picture, the signal is always cutted at -0,6 dB



In sounds distorted then.
I think this is not a problem with the gain control of my mic pre amp... if I reduce gain to not reach -0,6 dB the recording will be not loud enough...

Can somebody help me to solve this problem?

[kozikowski]

Which preamplifier and how is it connected to the computer? Be specific. Part and model numbers. Which computer?

I'm guessing you have the Line_Level output of the MicPre connected to the Mic-In of the computer. You are overloading the sound card of the computer.

Koz

[steve]

It is most likely a problem with either your sound card, or your sound card settings, or as koz says, overloading the sound card input.

(My sound card line input clips at -0.3 dB)

By playing around with your Windows Mixer settings you may find that adjusting either the input gain, or the master record level will allow you to get closer to 0dB.

Having said that, 0.6 dB is a very small amount in the scheme of things. Depending on the quality of your equipment, the dynamic range available is likely to be in the region of 80dB (between noise level and clip level) Dropping the gain so that you record at -3 dB will probably also lower the noise floor by 3dB, so you still have the same dynamic range. After you have finished your recording and editing you can use the "Normalize" effect to bring the peak level up closer to 0 dB.

I would generally advise keeping the peak level on your final mix slightly below 0 dB as some audio players do not handle 0dB very well (clip prematurely).

[thyme]

This is the Soundcard: http://www.m-audio.com/products/en_us/M ... -main.html
And this is the mic: http://www.mxlmics.com/condenser_mic/mx ... xl2006.htm
Soundcard is connected via USB...

It can not be a hardware problem, because under linux everything works well with absolutely the same settings and programs... it must be a problem with windows or any settings (driver of the soundcard is up to date...)

Mic -> Amp (Mic input)
Amp -> PC (USB)

[steve]

What we can eliminate:

Hardware (it works with Linux)
Audacity (Audacity is a slave to the computer sound system)

What's left - the drivers.
USB sound cards frequently have few or no controls for adjusting input levels. If this is the case with your set-up then you may have to live with it. As I mentioned previously, this isn't really any major problem, it just means that you will have to make sure that the input does not peak up to -0.6dB instead of watching the 0dB mark. When I record, I generally keep the peak levels at around -3 to -6 dB and there is no loss in quality, but the extra headroom can be useful to accommodate the occasional overly high peak (which can then be brought back down into the normal range using a limiter).

[thyme]

Ok I understand...

Isn't the gain control a line-in control? Look at the picture of my soundcard...

But don't you have the probleme that you amplify the recorded noise when you normalise your recording...?

[kozikowski]

<<<But don't you have the probleme that you amplify the recorded noise when you normalise your recording...?>>>

Where is your noise floor now?

The noise floor is determined by either the microphone amplifiers or the first time the analog signal hits the A/D converters. Connect all your equipment to your computer as normal and don't turn any of it on. Launch Audacity and click once inside the red record meters. That's the computer noise floor. Even poor sound cards should be in the -65 or lower range.

If you have a USB Sound device, turn that on. You are now watching the noise floor of the USB amplifiers plus the sound card. Etc. Keep turning things on up the pathway to the microphone and watch the noise get worse and worse. Those are the numbers that will never get any better. The target is a 20 dB headroom with a 60dB noise floor--so the bouncing lights with everything running and no sound is -80dB. This isn't usually achievable in practice with home equipment which is why splitting dBs is such a juggling act.

I wouldn't be trying to do any sort of live work with equipment that has any obvious shortcomings. Let's say you keep the 60dB noise floor, but are willing to sacrifice headroom a bit, you could do production with peaks at -6dB, nominal sound level at about -17 (formerly Audio CD standard). Drop down 60 from that and it's -77dB.

All these juggles are a cloud around your existing noise floor.

I once worked with a sound card that had -40dB noise floor--but only on left. Right was perfectly quiet. Fortunately, most of it was ultrasonic, so nobody knew.

Koz

[thyme]

I contacted the M-Audio support and they told me to buy an active usb hub for frictionless current supply.
I did that, but the problem is still the same...

[kozikowski]

<<<USB Hub>>>

That's actually a pretty good bet. Trying to run audio equipment from the battery power in the USB connection is sometimes less than successful. The 5 volt supply from the computer can be soft (not at 5 volts) or it can be noisy. I had a USB device once that let me hear each time the hard drive changed speeds. It produced a little whine in the sound.

I went for the instructions for the card and the microphone and there's nothing obvious odd or wrong. You don't get the clip light on the front of the M-Audio ever, do you?

I'm betting you can plug headphones into the M-Audio and everything sounds clean, right? With clipping that bad, the show should sound terrible. Did you download the latest drivers? Windows machines are such fun to troubleshoot.

Koz

[thyme]

Yes I installed the latest driver (release date: 22.08.2008, brand-new )

And I don't get the clip light on the front of the M-Audio! I'm not stupid ...