noise questions (how much is TOO much)

[tokyofan]

Just added a new pre (Grace 101) to my Mbox and using a TLM 103 in a small closet recording booth. The new pre seems to pick up EVERYTHING including much more from the G5 fans in the next room.

During playback I can hear a little fan noise through the headphones but not the monitors. Other than trying to re-locate the G5 what else can I do? I can make a cut at 100Hz which seems to help but how much can I cut without affecting voice recordings? Would a noise-gate help? How much ambient noise (from lighting, ventilation, fans, etc.) is acceptable/manageable since a 100% quiet space is hard to achieve. Solutions?

And I just installed a powered fluorescent light in the booth which seems to give off a slight buzz. Again, can hear a bit through the cans but not the monitors. Am I asking for too much?

 

[dgatwood]

Just added a new pre (Grace 101) to my Mbox and using a TLM 103 in a small closet recording booth. The new pre seems to pick up EVERYTHING including much more from the G5 fans in the next room.

What G5 model is this?

Short, general answer to the question is that any noise is too much if you can hear it. It's only going to build up as you lay down track upon track.

If you give me more information about which G5 model, configuration, etc., I might be able to suggest some noise abatement tricks....

 

[tokyofan]

Re:

Hardware Overview:

Machine Name: Power Mac G5
Machine Model: PowerMac7,2
CPU Type: PowerPC 970 (2.2)
Number Of CPUs: 1
CPU Speed: 1.6 GHz
L2 Cache (per CPU): 512 KB
Memory: 768 MB
Bus Speed: 800 MHz
Boot ROM Version: 5.1.5f2
Serial Number: YM409LALNVQ

 

[dgatwood]

Hardware Overview:

Machine Name: Power Mac G5
Machine Model: PowerMac7,2
CPU Type: PowerPC 970 (2.2)
Number Of CPUs: 1
CPU Speed: 1.6 GHz
L2 Cache (per CPU): 512 KB
Memory: 768 MB
Bus Speed: 800 MHz
Boot ROM Version: 5.1.5f2
Serial Number: YM409LALNVQ

See disclaimer at bottom.

Hmm. I wouldn't have expected noise problems on the 1.6. It has the smaller power supply, and I don't remember hearing about any real noise problems with it (unlike mine, which is the dual 2GHz big brother of that one). Your graphics card also probably doesn't have a fan on it, which is another common source of noise problems. You're definitely outside the serial number range for http://docs.info.apple.com/article.html?artnum=86523 though not by much.

Can you identify a particular fan that's producing most of the noise? (The power supply fans and the drive bay fans seem to be popular answers to that question, judging from the message boards.) Try stopping each of the fans with a pencil (or for the power supply fans, by VERY CAREFULLY sticking a paper clip in there and holding the fans still BEFORE you turn the machine on, being careful not to touch anything with the paper clip other than the plastic fan blades and the front metal grille; wear insulating gloves if you are paranoid). See if you can narrow it down to a single fan or fan group.

If you can narrow it down to a single problem fan (e.g. a fan chattering due to bad bearings), if it's under warranty, you might be able to get Apple to take care of it at the store on the spot (power supply fan notwithstanding, since the power supply is a pain in the backside to swap on G5s... though maybe not as much on the single processor versions... not sure...). If it's out of warranty, you can find most of those fans online for not terribly much money (relatively speaking) or swap it with something of equivalent rating from Radio Shack if you're daring.

I've heard of people swapping the power supply fans with commonly available off-the-shelf parts, since some of those chattered a bit, at least with the bigger power supply in the dual 2GHz. Again, I've never heard of such a problem with the 1.6's PSU, though.

If the machine's fans are spinning up excessively (as opposed to just being noisy when they're spinning), you might be able to significantly improve the problem by taking a 3 foot electric fan, setting it at the lowest setting, and blowing it at the front of the unit. The fan speed is proportional to CPU activity and temperature. You probably can't fix the CPU activity, but improving the temperature is more fixable.

You also might read up on the problem that some people noted with the position of the thermal sensor in the drive bay being sub-optimal in some units. Normally, that would cause the fans to come on less than they should, but it's possible that some of those stick-on sensors (or however they fasten) might be misplaced on yours in a way that causes them to come on too often.

As always, both I myself and my employer disclaim any and all responsibility for anything I have suggested in this post.

 

[tokyofan]

Re:

Thanks for the post! I think the fans are operating normally but do get noisy at times, especially in the summer here (Tokyo). I have a closet booth and the doors are not very thick or padded very well so there is a little noise but not so noticeable unless I crank up the volume of the headphones. Wonder if it's nothing to worry about. Maybe I should invest in a Mac Book Pro or Mac Mini for quieter recording.

 

[XLR]

I agree that if you can hear it, it's too much noise.

To keep the noise out, seal the door with weather stripping so it's practically air tight... including the bottom of the door just like you'd do with an exterior house door. Then if anything's still coming through, hang a thick blanket or pad on the outside of the door. Replace the fluorescent fixture with a silent one. Make sure the computer isn't amplifying its fan noise by sitting on something resonant.

Tim

 

[dgatwood]

I agree that if you can hear it, it's too much noise.

To keep the noise out, seal the door with weather stripping so it's practically air tight... including the bottom of the door just like you'd do with an exterior house door. Then if anything's still coming through, hang a thick blanket or pad on the outside of the door. Replace the fluorescent fixture with a silent one. Make sure the computer isn't amplifying its fan noise by sitting on something resonant.

Agreed. I'd add to that:

Don't put the computer in a tiny closet. It will probably be less audible on the opposite side of your recording room than in the closet, since in the closet, the fans will frequently spin all the way up to keep it cool.

Alternately, have a small electric fan handy and when you aren't recording, open the closet door and blow outside air into the closet.

Another thought is building or buying a soundproof box. I don't know how much they cost, but I have a feeling you could build a better one for a lot less money.

The way I'd design one is to put the computer in a closed box (up on rubber to minimize direct sound transmission), build two large tubes (say 8" x 10") out about a foot or two (the longer, the better), then bend each tube back and run it back towards the box again, then back out. Do this two or three times. Both tube should look like a giant maze when you're done. (Note that most pre-built enclosures aren't quite this elaborate.)

Once you've build the tubes (but before you put the top on it), add cloth baffles in the air path to minimize sound transmission. Get two fans that are as large and as quiet as you can find. A 6" case fan would be about the smallest you should consider, but ideally bigger. Put them both where the tubes enter the box, with one pulling air into the box and the other one pushing air out the other side.

Put the computer in the box and close the box. Turn on the air flow fans. Turn on the computer.

 

[XLR]

Don't put the computer in a tiny closet...

He said that he's recording in the closet and the computer is out in the next room.

Tim

 

[uobio_sound]

http://www.bandland.co.uk/catalog/images/amplifiers/Leem/LEM-1210-MP-combo-s.jpg
this is the multiamp that my brother use for his bass.it has a few entries(for keyboard, mic, jack mic, another estereo) and it has three outs(line out stereo, monitor out and phones).so i came up with an ideea.what if i use it as a recording rack?so i did it.i conected the line out output to my sound blaster card.downloaded the audacity and start to record througt this amp.
but a problem ocurred:the amp generates a "sssssssssssssss" noise.if i use any level of volume of the amp or of the pc the noise does not disapear.i can only lower it but not eliminate it.what can i conect to the amp or to the pc to eliminate that noise? a di will do?if not it is probably because this type of amp is not suitable for pc rec?what other amp or rec rack can i use?
thank you very much

 

[Dani Pace]

If the noise is comming from somewhere outside your pc, find it and turn it off while recording. Often appliences in another part of your house cause noise, refrigerators are a common source of noise. Florescent light will cause hum, neon is even worse. If you are in an appartment building the noise can even be comming from one of your neighbors. Being to cloce to your pc while recording also causes unwanted noise. You may hear noise more through your headphones because of their frequency response (possibly higher than your monitors) but as already stated, any noise is too much. Hope you find the cause, try turning things off, one at a time and see if the niose is comming from something other than your pc.

 

[uobio_sound]

If the noise is comming from somewhere outside your pc, find it and turn it off while recording. Often appliences in another part of your house cause noise, refrigerators are a common source of noise. Florescent light will cause hum, neon is even worse. If you are in an appartment building the noise can even be comming from one of your neighbors. Being to cloce to your pc while recording also causes unwanted noise. You may hear noise more through your headphones because of their frequency response (possibly higher than your monitors) but as already stated, any noise is too much. Hope you find the cause, try turning things off, one at a time and see if the niose is comming from something other than your pc.

thanks i will do so but i think i have ALL those problems you said but that helped anyway.