Tech: Noise reduction - filter for recording

Subject: RE: Tech: Noise reduction - filter for recording
From: Grab
Date: 31 May 07 - 10:05 AM

Re hiss, are you trying to feed a guitar pickup directly into a PC line-level input, and then cranking up the gain to get something out of it? If so, there's your trouble - as mentioned before, too little signal for the input. Get a preamp, or use a regular guitar amp and feed the line-out from there into the PC.

Recording to PC can be inherently noisy with some onboard soundcards. Some are pretty good, but some cheaper ones are crap. Also consider that the noise might not be on the recording. To rule out the recorder (PC or whatever) as the source of problems, buy or borrow a basic MP3 player that'll record and has a line-in socket. If that's noise-free, you've cracked it.

I had (still have, but it's awaiting Ebaying) an ST Audio 8-track PC recorder which had serious hiss on the headphone output. Try playing back on some other medium, like burning to CD and playing on your hifi.

Audacity and other programs do have noise-removal facilities, but they always leave the sound messed up. The only solution is a clean recording, not post-processing.

Graham.

Subject: RE: Tech: Noise reduction - filter for recording
From: Darowyn
Date: 31 May 07 - 04:56 AM

I agree with S&R. Hiss is nearly always a result of a low signal to noise ratio. Every electrical component- even a length of wire- generates noise. However, if your signal is many hundreds of times louder, you won't hear it.
One of the first things you need to learn in sound recording is called "gain staging". Briefly, it means that you must ensure that the signal going into your recorder is at a level so that the loudest sounds reach the maximum level that your equipment can record without distortion. That is the definition (in recording) of Zero dB.
Are you "playing it safe" by running lower levels. If you are recording to, say -18dB, your signal is only one eighth of what it could be.
When you turn up the playback to get back to normal levels, you will have boosted the noise eight times too.
You don't say what your recording medium is- is it intrinsically noisy- like an ancient Soundblaster soundcard or a cassette recorder for example?
The second thing- what mic are you using?
Muddy guitar sound is caused by:-
a muddy guitar
dead strings
an unsuitable mic
bad mic positioning
We need more exact symptoms before we can make a successful diagnosis.
Cheers
Dave

Subject: RE: Tech: Noise reduction - filter for recording
From: s&r
Date: 31 May 07 - 03:33 AM

Make sure that you have a good level of sound into the mics. Low sound input levels mean that everything else in the chain is wound up too high - this makes what noise there is more prominent.

Stu

Subject: RE: Tech: Noise reduction - filter for recording
From: The Fooles Troupe
Date: 30 May 07 - 08:18 PM

"'low level' background hiss"

This is usually caused by the elctronics -
cheap -> more hiss, expensive -> less hiss....

:-)

Subject: RE: Tech: Noise reduction - filter for recording
From: Bernard
Date: 30 May 07 - 03:49 PM

What recording system are you using? I record programmes for Radio Britfolk directly into a PC via an analogue mixer (Soundcraft 400B - a bit elderly, but works well!), and have no problems with background noise.

Noise problems can arise from the ambience in the room. I used cheap internal doors covered in carpet to deaden the ambience of my studio. Poor quality microphone pre-amps can hiss, too.

You should be able to get a 'clean' recording without resorting to signal processors, then do a little normalising/compression with software afterwards.

Subject: Tech: Noise reduction - filter for recording
From: GUEST,Snakes
Date: 30 May 07 - 03:01 PM

Can someone suggest good noise reduction / compression equipment ( <= $100 - $200) for recording.
I am trying to reduce 'low level' background hiss, and would also like to get a clearer, crisper sound for my acoustic guitar.