peaking at .5

[bobohank]

Hello,

I have just recently started using audacity for mostly acoustic guitar and voice recordings. My computer is a compaq Presario R3000 laptop( Microsoft Windows XP/version 2002/SP3). I'm using a couple different microphones into a M-Audio Mobile Pre USB unit, then into the computer. The problem I'm having is that the recordings peak at .5, while I understand that it would be ideal to peak at 1. The most closely related forum that I could find on Audicity said something about amplifying each track afterward. I tried this, and indeed it did then increase the track to peaking at 1, but I assume that there should be a way to initially record the tracks peaking at 1, without having to amplify every single track afterward. Any help in this department would be much appreciated. Thanks very much, Joe

[kozikowski]

You rarely want to capture peaking at 1. Live recordings are very unstable for volume control and any sound actually at 1 is distorted. The object is to peak just below one, but you do that in post, not during the capture.

But that's not your problem. You are overloading something. Do you get the clip lights on your M-Audio? Can you force the clip lights to come on (just as a test)? Yell into the microphone?

Koz

[bobohank]

Thanks for the reply,
Yes the clip lights do come on, exactly at the moments when the waveforms hit the .5 mark and flatline.

And when I said I wanted to peak at 1, I was meaning more what you were suggesting, as in, coming as close to 1 as possible without peaking.


Thanks, Joe

[kozikowski]

OK. Now my head officially hurts. Your system is overloading backwards. As the singer gets louder, the digital service is supposed to hit "1" (the Audacity bouncing light meter goes to zero) first, then, a short time later -- and still getting louder, the red light is supposed to light on the M-Audio. By the time the M-Audio red light blinks on, the digital system is supposed to be without question seriously into damage and overload.

Typically, once the USB sound device makes the digital sound signal, you don't change it until post production, days later. But maybe not. Does the input volume control in Audacity do anything? Is there a USB device listed in your Windows Control Panel, and does it have a volume control? Do any of them work?

There is the nagging voice in the back of my head that M-Audio sound equipment uses ASIO software drivers and Audacity doesn't get along with those too well.

Koz

[steve]

Typically the volume controls in Audacity have no effect on USB audio devices. The same is generally true of the Windows Mixer.

Some USB audio devices have only hardware adjustment of input level (0.0dB on the hardware should produce 0.0dB on the computer).

Some USB audio devices have a special applet (sometimes in the Sys tray near the clock, sometimes in the Windows Control Panel) that can scale the input level to provide a kind of recording level adjustment.

Some USB devices have no control at all and require that the level of the signal going into the audio device is adjusted before being fed into the device. Again 0.0dB on the sound card should produce 0.0dB on the computer.

According to the manual:

"Once setup is complete, you can control most aspects of the MobilePre
USB using its control panel.To launch the control panel in your operating
system, check the following instructions:
Windows: You should see an M-Audio logo “M” installed on the right
side of your Windows taskbar. Double click on this logo, to launch the M-
Audio MobilePre USB Control Panel."


If the input is being clipped before it gets to the USB device, then it does not matter what you do later it can not be un-clipped. For best results you should use good quality microphones of a suitable type for the recording source connected to the XLR (large 3 pin) connectors of the M-Audio Mobile Pre USB unit (with phantom power switched on if, and only if, required by the microphone).

One thing that I've noticed with some M-Audio USB devices is that they do not always initialise correctly when connected (or at boot up). To fix this you can either reboot and try again, or (better) use "Safely remove hardware" to remove all instances of M-Audio, then switch off the device for 10 seconds, then switch on again and wait for 30 seconds or so for the drivers to be reloaded.

There is the nagging voice in the back of my head that M-Audio sound equipment uses ASIO software drivers and Audacity doesn't get along with those too well.

The M-Audio device uses ASIO drivers by default, but also includes Windows (MME) drivers. Audacity does not ship with ASIO support. If the Windows drivers were not installed it would not be possible to record anything from the device.

[bobohank]

Thanks to you both for your input. Shortly after I read the replies I went away on a vacation for a week and a half, so that is the reason for the lag.
Kozikowski: Yes the input control (in the PreMobile control panel separate from Audacity) does have an affect, but however I change the settings it still peaks at .5.
Also I'm sorry for speaking imprecisely. When I said it flatlines, I meant to express that the soundwave stops at .5 and does not go above this (the line at .5 is flat) and not that it goes to zero.
Steve: I went to "safely remove hardware" and completely erased the PreMobile driver and then reloaded it. I wasn't sure if that was exactly what you where suggesting or not, but I could not find a way to re-load the drivers within 10 to 30 seconds. Anyway, it still functions the same and after reloading.
I noticed that if I keep it from peaking at .5 I can use the envelope tool to increase it to 1, but I don't know if that is a good method. Is that any different from amplifying the track to 1 afterwards.
Any more input would be greatly appreciated.
Thanks very much, Joe