Opinions on room noise

anton · #1 06-12-2013, 10:57 PM

Hi Folks,

I was wondering if I can get your opinions on the room noise in this clip. Mics are Peluso CEMC 6's in ORTF about 8 in from the guitar. They are going into a Presonus Firestudio Mobile on my iMac.

https://dl.dropboxusercontent.com/u/.../roomnoise.mp3

We bought a place back in Feb and I again have a room to dedicate to recording and music. Im trying to outfit it the best I can so I can record a second cd.

Is the noise on this recording bad enough to think about a different setup? Through my speakers it sounds ok but when I listen through my good headphones I can definitely hear noise. I cant tell if its computer noise or just general "house" noise. I put my mics in a separate room from the computer and made a recording, but I really don't think the noise is any less.

Im willing to invest a mac mini or some sort of setup where I can have the computer in another room if thats what it takes. But I'd like to make sure its computer noise, for all i know it might be my mics or interface.

thanks

Anton

KevWind · #2 06-13-2013, 07:23 AM

Anton do you have an I Phone or Android if so there are a number of free or cheap SPL meter applications with which you can quickly and easily test system and ambient room noise. You can just sit at the recording position and check the spl level with the computer running and check it again with the computer off. The odds are ( unless you happen to have really unusually quiet rooms/house) that the ambient noise is going to be some where between 10db on the low side and much more typically 20 to 25db. Taking the computer (unless it is particularly noisy) out of equation will usually only yield about a 3-4 db reduction.
If giving the room a significant sound reduction make over is out of the question then one thing that may help, particularly when close cardioid mic'ing are portable sound baffles or gobos. There was a fairly extensive thread on here about these and a link to a DIY page on Fran Guidry's web sight.

rick-slo · #3 06-13-2013, 08:02 AM

I hear machine noise (computer I assume) and preamp or mike noise.

1. If computer you can increase distance from it, put blankets around it, etc.

2. If preamp noise try keeping the mike preamp gain level down and boost levels back up after recording is done. Most quickly you can just
check that out live with the preamp set at various gain levels and make up volume in the DAW.

Doug Young · #4 06-13-2013, 09:04 PM

That's almost certainly the computer or other environmental noise. Doesn't sound at all like mic self-noise to me. You play very quietly, a computer in the same room is going to be a killer. If you can move the computer to another room that's easiest. Get extension cables for keyboard, mouse and monitor. Another alternative is to use a silent recorder - like the Zoom. Then transfer files to the computer for editing. That's how I did my 1st CD, and it's actually a nice solution, because you can record anywhere that sounds good. But it's certainly nice to just be able to record to the computer directly, as well.

rick-slo · #5 06-13-2013, 10:57 PM

Turn up the volume Doug. There is room noise (most likely computer) and mike or preamp hiss. That said I probably could live with the mike/preamp hiss. The computer noise fairly is easy to control.

Doug Young · #6 06-13-2013, 11:10 PM

Quote:

Originally Posted by rick-slo

Turn up the volume Doug. There is room noise (most likely computer) and mike or preamp hiss. That said I probably could live with the mike/preamp hiss. The computer noise fairly is easy to control.

I didn't mean his recording was quiet :-) I've spent a lot of time with anton in the studio, I recorded his last CD. He's a pretty quiet, delicate player, so noise is going to be a bigger issue for him than for someone who really slams into the guitar. He has decent mics and a preamp, so I doubt that's a significant issue. What's sticking out for me, at least, isn't regular enough to be mic self noise. It sounds like a computer hard drive and/or fan, tho there's not enough total silent spaces to completely diagnose. But it could be both. But we know there's a computer in the room :-)

anton · #7 06-14-2013, 08:07 AM

For comparison, here is another track with my ADK A6's. Same spot in the room, spaced pair, similar preamp levels.

https://dl.dropboxusercontent.com/u/..._roomnoise.mp3

To my ear there is less extraneous noise. I tried to leave a larger passage of silence at the end.

I obviously wont be able to get the perfection of recording at Doug's place, or a professional studio here in town, but I guess my main thought is can I get it good enough.

If i boost the levels in logic during playback so the meters get closer to zero I can definitely hear more noise, especially during the silent parts. I worry that during the mixing/mastering stages when levels get raised this going to make environmental noise more apparent. Though they probably have more sophisticated ways of doing this.

Ill drag the ADK configuration into an adjacent room and see what that sounds like. That or buying something like a mac mini and placing it in another room or the closet would be the preferable option.

I appreciate everyone's thoughts.

thanks

Anton

el_kabong · #8 06-14-2013, 09:18 AM

Just curious, but have any of you had good results gating this sort of noise or will there be telltale legacies from that? It's been my intention to test this approach soonish. I've been considering some sort of isolation box for the computer too, of course, but have wondered just where the critical threshold might be. What do you figure you're getting as a noise floor?

anton · #9 06-14-2013, 09:53 AM

Gating is a little beyond me at the moment, i dont know much about that.

I'd like to build some sort of enclosure box, but the bummer is that I have an iMac, so its all one piece. Getting a new computer would mean a new monitor as well.

I've got an older Macbook, maybe Ill just put that in the other room with the interface and run the mic cables to it, so i can leave them in their current position. Then I can just drag the files onto the iMac for editing and processing.

Anton

rick-slo · #10 06-14-2013, 10:16 AM

Sounds like the prior clip - computer noise and some mike or preamp hiss.
The hiss is pretty minimal and might not be noticeable most of the time.

Gating the noise in the quieter sections would be too noticeable and artificial sounding.

Doug Young · #11 06-14-2013, 10:17 AM

Quote:

Originally Posted by el_kabong

Just curious, but have any of you had good results gating this sort of noise or will there be telltale legacies from that? It's been my intention to test this approach soonish. I've been considering some sort of isolation box for the computer too, of course, but have wondered just where the critical threshold might be. What do you figure you're getting as a noise floor?

Gating can be a little tough, since it will probably cut off the tails of quiet notes and maybe draw more attention to the issue, unless the music material is very abrupt and percussive. I have had some luck at manually tweaking tails. Adobe Audition has an EQ that you can vary in both strength and frequency with time, so I used to occasionally use that on a tail - take two filters - start with the EQ set so you have a high pass filter at 0Hz with no cut, and a low pass set at 20Khz and no cut. Then slowly decrease the frequency on the low pass and raise the frequency of the high pass, while also increasing the amount of cut as the note fades. If you just sort of follow the decay curve of the guitar, you can mostly kill the broadband noise. It's kind of a manual "gate".

anton · #12 06-14-2013, 10:23 AM

I took the above track with the ADK's and normalized it, trying to get the levels close to zero.

https://dl.dropboxusercontent.com/u/...normalized.mp3

I also eliminated the silence at either end and added some fades.

I don't know, I think it sounds pretty good to my ear. Its not perfect, especially at the fade out, but I like the tone of my guitar.

Anton

el_kabong · #13 06-14-2013, 10:30 AM

Quote:

Originally Posted by Doug Young

Gating can be a little tough, since it will probably cut off the tails of quiet notes and maybe draw more attention to the issue, unless the music material is very abrupt and percussive. I have had some luck at manually tweaking tails. Adobe Audition has an EQ that you can vary in both strength and frequency with time, so I used to occasionally use that on a tail - take two filters - start with the EQ set so you have a high pass filter at 0Hz with no cut, and a low pass set at 20Khz and no cut. Then slowly decrease the frequency on the low pass and raise the frequency of the high pass, while also increasing the amount of cut as the note fades. If you just sort of follow the decay curve of the guitar, you can mostly kill the broadband noise. It's kind of a manual "gate".

Good suggestions, I'll give it a try. Thanks Doug. Still playing around with pre-fade compression to tame transients and, hopefully, improve my gain staging a bit. Seems (to my amateur understanding) that I'd have better control over S/N with a little help from this end of the equation too, right?

rick-slo · #14 06-14-2013, 10:47 AM

Quote:

Originally Posted by Doug Young

Gating can be a little tough, since it will probably cut off the tails of quiet notes and maybe draw more attention to the issue, unless the music material is very abrupt and percussive. I have had some luck at manually tweaking tails. Adobe Audition has an EQ that you can vary in both strength and frequency with time, so I used to occasionally use that on a tail - take two filters - start with the EQ set so you have a high pass filter at 0Hz with no cut, and a low pass set at 20Khz and no cut. Then slowly decrease the frequency on the low pass and raise the frequency of the high pass, while also increasing the amount of cut as the note fades. If you just sort of follow the decay curve of the guitar, you can mostly kill the broadband noise. It's kind of a manual "gate".

I would instead just fade out the ending with the volume control. You could as you are overall gradually fading gradually increase volume of certain frequencies (those of the guitar) with an equalizer.

Doug Young · #15 06-14-2013, 11:12 AM

Quote:

Originally Posted by rick-slo

I would instead just fade out the ending with the volume control. You could as you are overall gradually fading gradually increase volume of certain frequencies (those of the guitar) with an equalizer.

Yeah, a simple fade is certainly easier. With the EQ approach, you can keep the tail going a bit longer, and in some cases, sound more natural. Just another tool.