Assistance with hiss diagnosis

[Gale Andrews]

And just checking, when I set the mic level in Windows, I see that the mic level within Audacity goes up/down correspondingly. So, when I set the mic level in Windows at 0, then open Audacity, it shows the mic level at 0 there too. If I keep both open and move the mic level up and down in Windows, I see the mic level go up/down in Audacity.

Correct behavior, right?

Yes, absolutely what we intend.


Gale

[kwartz]

Interestingly (for me anyway...) I recently got my hands on a Miktek ProCast. And I'm getting the same (to my ears) background hiss as I do with the Samson G Track.

Which makes me think that the hiss is being generated by:

Option 1: Environment
Option 2: Computer

I tried the ProCast on a Windows 7 32 bit machine (my normal machine is Windows 7 64 bit) and the hiss was WAY worse.

I don't really know where to go from here on identifying the source, so I'm concentrating on removing it after the fact, but thought I'd update the thread with my new developments. For posterity's sake.

[steve]

Here you go, thanks again.
Two Words.wav

The noise level during the "silence" is around -60 dB unweighted, -67 dB A-weighted, which is about normal for a USB mic. If you had a louder speaking voice, then you would be able to turn down the recording level on the G-Track, which would also reduce the noise level, so do try to keep your voice level up - speak as if you are talking to someone facing you, and not like you are talking to a lump of metal and plastic in front of your face A 10 dB increase in your voice level could give close to 10 dB reduction in noise level .

I tried the ProCast on a Windows 7 32 bit machine (my normal machine is Windows 7 64 bit) and the hiss was WAY worse.

That would be a problem. If the noise was "way worse" then something is not right - either the settings, or possibly electrical noise via the USB cable, though electrical noise usually has a "buzzing mosquito" type sound rather than plain "hiss".

[kwartz]

Here you go, thanks again.
Two Words.wav

The noise level during the "silence" is around -60 dB unweighted, -67 dB A-weighted, which is about normal for a USB mic. If you had a louder speaking voice, then you would be able to turn down the recording level on the G-Track, which would also reduce the noise level, so do try to keep your voice level up - speak as if you are talking to someone facing you, and not like you are talking to a lump of metal and plastic in front of your face A 10 dB increase in your voice level could give close to 10 dB reduction in noise level .

I tried the ProCast on a Windows 7 32 bit machine (my normal machine is Windows 7 64 bit) and the hiss was WAY worse.

That would be a problem. If the noise was "way worse" then something is not right - either the settings, or possibly electrical noise via the USB cable, though electrical noise usually has a "buzzing mosquito" type sound rather than plain "hiss".

I guess I probably would characterize it as close to buzzing mosquito on the other computer, but then I would expect to hear the same thing on my normal machine since it's using the same cable... but there could be variables here I'm not aware of (jacked up usb port on the machine?).

Thanks for the tip about talking louder. I tend to speak softly when recording, need a sign that says "Speak Up, Stupid!".

What is the difference between unweighted and A-weighted, and how do you tell within Audacity? Heading over to the manual for research now...

Thanks again for your help.

[steve]

What is the difference between unweighted and A-weighted,

A-weighted is supposed to give a better indication of how "loud" low level noise sounds. It is popular with manufacturers and sales teams because it is always a lot lower than unweighted (Z-weighted / zero-weighted). What it does is to pre-filter the sound to reduce very low and very high frequencies, as human hearing is less sensitive to these frequencies, especially when at low level.

There are a couple of experimental plugins for measuring A-weighted noise level - nothing "official" yet though. One of them is here: http://forum.audacityteam.org/viewtopic ... 454#p99454

I would expect to hear the same thing on my normal machine since it's using the same cable

Not necessarily. The other computer may be generating more electrical noise, and cables are only resistant to electrical noise from outside - if the noise is "in" the USB power voltage, then it will travel up the USB cable unhindered. Some USB devices are better than others at filtering out noise on the power supply, but if the USB power line is noisy them some of that noise is likely to end up affecting the microphone signal.