Ask HN: Noise from new furnace; How to effectively record?

[pasbesoin]

I know from reading comments that some here have more than a passing acquaintance with audio recording. My new furnace is making noise intermittently; unfortunately for diagnosis/service, largely in the later afternoon and night. Next Tuesday will mark 11 weeks I've been living with this, including disrupted sleep and worry.

I'm becoming desperate to get this fixed -- effectively. In order to demonstrate to the contractor -- and now wholesaler and manufacturer what is happening, I need to be able to present good recorded examples. I don't have a lot of money to keep trying different equipment; I'm hoping some advice from HN can steer me in the right direction. What recording device and microphone might serve well, having flat response across the audible spectrum and not missing nor aggressively filtering out what it decides is undesired noise -- even and as that may be the sound I am after?

[tjr]

Something like this would be a good, inexpensive option for a microphone:

http://www.amazon.com/MXL-770-Cardioid-Condenser-Microphone/...

For a recording device, most people use their computer. You'd need to add an audio interface into which you can plug both the microphone (XLR) and the computer (Firewire/USB, generally). Lots of options. The cheapest one would probably be fine for this purpose. Then use, say, Audacity software on the computer to record.

[tjr → tjr]

I've never used this one, but this may also be a fine option, and would eliminate the need for a separate audio interface:

www.amazon.com/CAD-U37-Condenser-Recording-Microphone/dp/B001AIQGUO/

[pasbesoin → tjr]

Thank you very much for both responses. I looked at the first item and will look at this next.

If it's not inconvenient, could you expand briefly on what kind of audio interface you are speaking of? This is all quite new to me, and I'm as yet unclear on what I should be looking for. (I don't know -- yet -- how such a set up hangs together.)

Audacity I'm passingly familiar with and think I can further figure out.

P.S. I'm also looking and can probably figure out on my own. So no worries if it's not convenient -- this already gives me a/the direction to look in.

P.P.S. Browsing Amazon now with the browser that does not have NoScript, I see links to interface products appearing on those pages. Operating on 5 hours of sort of sleep, here...

[tjr → pasbesoin]

Sure. Something like this would probably work just fine for your needs:

http://www.sweetwater.com/store/detail/AudioBoxUSB/

There's all sorts of more expensive interfaces (and microphones) that you can buy, but for what you're describing, they likely wouldn't help much. I don't think you're needing to do professional foley recording of your furnace for a major motion picture. :-)

So in sum, if you went the separate interface/microphone route, you'd have something like:

- microphone sitting on microphone stand, say, eighteen inches away from the furnace. If you don't know exactly where the sound is coming from, set the stand so the mic is about half-way up the height of the furnace.

- XLR cable running from microphone to audio interface

- audio interface connected to your computer via USB or FireWire or whatever cable (based on your selection of interface)

- For that particular microphone, it needs to be powered by the interface, so press the 48v button on the interface to activate the power to the mic.

You'll need to adjust the input knobs and such on the interface ensure getting adequate audio signal. I can't tell you exactly what to set it to without being familiar with the particulars, but it shouldn't be hard to figure out. (You can record digital audio at a very low level and it still turns out usable, but if you record too high, it clips, and is pretty much ruined. So favor too quiet rather than too loud, if you're not sure, and boost the level in Audacity, if needed.)

[pasbesoin → tjr]

I ordered the USB microphone with next day shipping (a bit excessive, but that will ensure it's here in time for our next major transition to colder weather).

If that doesn't do well enough, I'll follow up with the microphone that requires a separate interface. This gives me a little more time to investigate those details and to talk myself into the $200 or so.

Thanks again, so much. I knew there must be good choices out there, but wading in with zero knowledge felt kind of overwhelming, especially on top of the stress of the circumstances.

Years ago, people would tell me I should do voice acting (voice-overs -- whatever the right term is). (I never really heard that, in my own voice.) Who knows, maybe I'm inadvertently on the cusp of my new career.

[pasbesoin]

I realize this may be a bit OT for HN. My karma here's generally decent, and on a personal level I could really use the help.

Also, this and some other experiences with noise have me thinking again about learning to design products and services that help people document unreasonable noise and get it addressed. Whether a malfunctioning appliance or piece of equipment, or the neighbour kids with the booming subwoofer. Timing, localization, and calibrated measurement of intensity.

--

It's actually been a series of noises that have changed after each of the two attempts at repair. I have an older analog tape cassette recorder whose built-in microphone captured the first sound fairly well.

The built-in microphone of an old iAudio MP3 player with a record function didn't capture that sound well, but it did capture the lower sound made after the first repair.

Between the two devices, I assumed one would capture the "in between" sound that followed the second repair. However, both built-in microphones seem to be "dead" in that frequency range.

I borrowed a Sony "stick" digital voice recorder when the first repair produced the second noise profile, but it did not seem to register this at all. I don't have the manual for it, but I've played with / guessed at its settings, and it is now picking up the third noise following the second repair to some extent, but not too well. It does have a microphone in mini-jack.

P.S. While I've learned that more minor noise with this unit hints at the real trouble to come, I'm not what is just a minor background noise. I'm speaking of "wake you in the middle of the night", give you headaches at your home office work desk types of noise. Unfortunately, since particularly the more recent noises are intermittent, I can't count on them manifesting for the very limited time a service technician may be on-site.