Reducing room/background/ambient noise

T

TheLemonAid

New member
Good day all,

I am as newbie here as it gets, it's my first post here. I have looked around and tried to find the answer to this question for a while now. I found some things that could get me on the track, but nothing that could really directly solve my problem. So let me get to the point:

Problem: I've been recording acoustic guitar and the song has moderat dynamically varied nature. During the quieter parts and the end when the guitar fades out, background noise penetrates through the sound of the guitar. I would like to know how to get rid of that background noise.

You probably want to know this: I record using an SEelectronics SE2200a condenser mic, going into a Presonus Firestudio Mobile interface, that's connected via firewire to my laptop and the software I use to mix and master is Logic Pro 9. I use a room in a guest house (separated from the main house in which my family and I live), in which the floor is entirely covered in carpet and all the windows have thick curtains covering them. For the rest, the room is empty, except for some wooden furniture. I've attempted to create a recording-booth, by hanging blankets inside a closet, that's where my mic is. I am facing the microphone with my guitar and I've erected mattresses behind me to minimize sound reflecting off the walls, so the mic will pick up as much dry sound as possible.

I've turned off all devices which were likely to make noise (lights, fridge, etc. I even put my laptop and interface in another room) in hope to reduce background noise during the recording stage. When I finished recording and proceeded to mixing, I was still rather disappointed by the amount of background noise and tried reducing it using the expander plugin (pretty much the opposite of a compressor), which works well but comes at a trade off in the form of audible working of the expander it self as the guitar plays.

My biggest question would be: What can I do to reduce background noise during the recording stage so it won't be much of a bother during mixing? Also, are there any plugins or mixing tricks that would help to deal with this problem?


Thank you for reading this bulk of letters and any help is hugely appreciated!


Cheers!


P.S. Keep Music Alive.
 
Are you sure this background noise is actually background noise? What I mean is, since you've eliminated as much "appliance" noise as possible, are you sure it's coming from the room into the mic? Or could it be noise from somewhere inside your recording chain (mic, cable, inter-face/pre-amp, etc....)
 
What RAMI said ^ - is it actual noise that's in the background or noise that's being generated by your system?

Also, what is the nature of the music you're attempting to record... is it just acoustic guitar, or will it have other elements. What and how many?

In terms of the fade out.... one trick I've used over the years with acoustic songs that end on a lingering chord, is to automate a low pass filter at the last chord and head it south whilst the chord rings out. You still get the effect of the fade as the volume dies, but you're slowly shelving off the higher frequencies, where most of the hiss is, assuming that's what we're talking about here - you have to be careful or your ending will sound weird, but it works for me. YMMV.
 
As RAMI and Armistice have said, the first thing is to make sure that the noise isn't inherent in your electronics.

If that checks out as okay, then think about your position in the room. Without seeing it, I'd probably sit in front of those thick curtains you mention and, if things are still not as you like, prop up the mattress you talk about somewhere behind the mic. If you're still getting noise with this much soft stuff, something funny is happening.

Finally, we didn't talk about the mic position. Don't forget that sound follows the inverse square law. If the mic is 18 inches from your guitar, try moving it to 9 inches--and, once you've adjusted the levels, you should find any room noise is only a quarter what it used to be.
 
The "background noise" could actually be formed in the recording chain, the mic I bought is second hand and the cable that I am using came with it. So, maybe the problem lies within the cable, which as I researched is not of a high quality. Furthermore, I am using a firewire 800 to firewire 800 adapter, bought at the local media-markt, this could be the source of the problem also.

Next time I record, I will look at how mic placement around the room will affect this background noise issue.

Armistice, the low-pass at the fade out does indeed help, thank you for the tip. This actually also made me realise, that the high-pass filter that comes on the SE2200a microphone, was on during the recording. Could that have something to do with the problem as well?

I've bounced a part of the fade out, so you can hear what kind of noise I am talking about.

Thank you for all the helpful replies!

Cheers!

Also, Keep Music Alive! :thumbs up:
 

Attachments

  • Background Noise sample.mp3
    244.8 KB · Views: 47
I had a listen. That hiss sounds like system noise to me, i.e. noise coming from somewhere in the recording path. In particular, it sounds like preamp noise.

How high do you have the input gain set on the interface? For me, that's the most likely culprit. I would try reducing the inut level on the interface, getting the mike a bit closer to the guitar, and playing a bit louder.

Another thing to look out for is to make sure that input levels on channels you are not using are set to zero and are not feeding into the recording.
 
So it is system noise then... that's good to know, I now know where to troubleshoot the issue.

The input gain on my interface was set so high, but not the highest so I averted clipping. But actually if I just turned the gain knob up a little, clipping would form. So, I was pretty much as high as I could go with the gain without clipping. From online tutorials, I thought this was the general guideline, but I'll try reducing the gain, moving the mic closer and playing a tad louder to see if it helps. I made sure there are no other channels feeding into the recording.

Edit: Any tips on ways to reduce system noise?

Thanks for the tips!

P.S. Keep Music Alive :)
 
TheLemonAid said:
So it is system noise then... that's good to know, I now know where to troubleshoot the issue.

The input gain on my interface was set so high, but not the highest so I averted clipping. But actually if I just turned the gain knob up a little, clipping would form. So, I was pretty much as high as I could go with the gain without clipping. From online tutorials, I thought this was the general guideline, but I'll try reducing the gain, moving the mic closer and playing a tad louder to see if it helps. I made sure there are no other channels feeding into the recording.

Edit: Any tips on ways to reduce system noise?

Thanks for the tips!

P.S. Keep Music Alive :)
Click to expand...


Do a bit of experimenting.

Plug the mike in, and change the input level, going from minimum to maximum (use headphones to monitor). Does the hiss increase as you increase the level? Or is the hiss constant.

Actually, you can try this without a mike plugged in as well.

With luck, you will find that the hiss kicks in mostly at the extreme high area. In which case, set the level to where the signal coming in (voice, guitar, whatever) is significantly louder than the hiss. Don't worry too much about the level going into the computer. You can increase this afterwards.
 
I have experimented with the system noise a lot a few days back and I was impressed by the amount of hiss produced by the circuit it self without the mic even plugged in. The room noise was actually only audible when I set the gain high on my interface. I monitored the hiss using pairs of different headphones, and some bring it out more than others. As anticipated, I found out that bringing up the higher frequencies in the EQ and compressing the track does increase the hiss as well.

I recorded some test guitar at a much lower gain level, to see how much the hiss would decrease, in comparison to the recording before. It has gotten better, but the hiss is still annoyingly present and heard over the mix.

Would changing anything such as the I/O Buffer Size or sample rates have any influence on the system hiss? Or if you have any other tips, they're all very welcome of course!

Thanks for the replies, they're very appreciated and helpful!


And also of course, Keep Music Alive! :)
 
Attached is an extract of the noise only. This is electronics noise.

On Samplitude's (excellent!) meters the noise averages -55dBFS which is a poor cassette! But is it the pre amp or the mic?

Buy an XLR plug and ideally solder a metal film 180Ohm resistor across pins 2 and 3 and re assemble (or just short 2&3 but don't run O/C. not fair). Set the system up aswas and then unplug the mic and plug in the dummy. Send us the noise.

I suspect that this is mic noise and you have a bad sample. Using an SM57 and an A&H ZED10 into a 2496 I can get a noise floor of -75dBFS. Not Abbey Road perhaps but pretty good for a home jockey? Other matters...

Buy a modest, $20 sound level meter (C scale) and then Google for the "83dB Monitoring regime".
Do not judge noise on headphones.
Watch your gain staging and are you running 24bits (44.1kHz is plenty good enough IMHO) and keeping average levels at -18dBFS?

For acoustic guitar (and speech) you really do need the quietest of quiet systems and you might like to consider a different mic. The Rode NT-1A is claimed to have the lowest self noise of any similar mic.

Dave.
 

Attachments

  • .png
    .png
    16.4 KB · Views: 38
Has it worked THIS time!?

Dave.

Whooo!-Hooo!
Hmm? Should extend past 10kHz and descend to -127dBFS (no! Nothing is that good! Feature of the system.)
 

Attachments

  • .png
    .png
    16.4 KB · Views: 35
Thanks a lot for your in-depth response! I'll try to do this when I have some time and money.

In the meanwhile, I had a friend come over to check out the hiss issue (he's a very experienced home-producer, he knows his stuff) and he came to the conclusion that it's my device that's causing the issue, i.e. that there's a problem with the device causing it to create so much hiss. So, I guess this is the risk of buying second hand products.

I've also very recently bought a microphone for €15, I didn't really need it but for the price I just decided to do it. It's a Philips Mixer Booster mic (not much about it on the internet, there was one post about it on this very forum: [I was going to post a link to that thread here, but apparently I am not allowed to post links unless I have more than 10 posts]) I might do a review of it. For now I can't, because in order to pick up anything the gain needs to be turned up super high, where the hiss from my device is unbearable. All I can say is, it's a dynamic, cardioid mic.

Thanks for all your help everyone!

Keep Music Alive
 
Yup that's it. Except, I think that the jack on the one I bought looks a little different, but that's a minor thing. For the rest it's exactly the same. Do you happen to know something about it?
 
Integral hiss in the equipment is mostly just the cumulative sound of the electrons in the components and the circuits. Some cars make more noise when they approach than others, because of the way they are built and the quality of the components used.......and the quieter cars cost more. Same principle with audio gear.

I'm going to diverge and say that I think it's your preamp. For $250 bucks you are not going to get a -90db noise floor from your preamp.

Your knowledgeable friend came over and gave you his opinion. Go the other way. Take your mic over to his place and his gear and see if he suddenly gets a ton of hiss when he plugs your mic into his gear.

Either way, for the money you had to spend, you can't get a silent recording medium. Turn the gain down, move the mic closer, and get the best SN ratio you can get with the weapons you have. Use a noise gate. When you get your guitar track mixed and you add any other parts, most of that hiss won't be noticeable anyway.
 
You must log in or register to reply here.
Back
Top