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AudioAcoustics

Serving the Acoustics Community Since 1994

Cross-Spectrum Acoustics Inc. offers Sound & Vibration Consulting Services

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Mar 19, 2003

I bought a used G4 AGP PowerMac off of eBay a few months back for use as a test server and to run a few (relatively) processor-intensive programs. The machine I bought was well stocked, with a SCSI card, 512 MB of RAM and an ATI AGP DVI card. When I first turned the machine one, I heard the hum of the hard drive and various fans. I thought it was kind of loud, but in the end didn’t think much of it.

A couple of weeks ago, I started to hear a high-pitched whine come from the machine. I figured the hard drive was dying, so I started pricing replacement drives. However, when I opened the machine up while it was running, I noticed that the whine didn’t come from the hard drive - it was coming from one of the expansion cards. Since the ATI card was the only card with a fan, I removed it and restarted the machine. Without the ATI card, the machine was probably 15-20 dB quieter. Yep, the friggin 1-inch fan on the video card was causing all the raquet. Using the stock PCI video card, the G4 quietly hums in the corner.

I got to see David Griesinger talk today at the March GBC-ASA meeting. Dave is a great speaker. He holds some very strong opinions regarding architectual acoustics and the sound quality of opera halls (who else would have the guts to tell Leo Beranek that he’s wrong?!), but he can back it up.

We talked a bit about the need to challenge some of the assumptions that are common in the acoustics community (for example, that a 1.5 second reverberation time is ideal for opera halls). You do see this a lot in acoustics, be it noise control, architectural acoustics, vibration, etc: there are certain long-standing assumptions that we acousticians just treat as gospel in our assessments. Every once in a while, someone needs to stand up and say “hold on, wait a minute.”

I have a new toy to play with: a TerraSonde Audio Toolbox Plus courtesy of Odyssey Pro Sound. So far, I’m very impressed by it’s capabilities (RTA, FFT, signal generator, RT60, PC and Macintosh download software and more). I am also very impressed by their tech support - I sent an email at 11:30pm last night, and got a response at midnight. There are several high-end SLM manufacturers that could learn a thing or two from TerraSonde.

Finally, I have an RSS feed up and running for those who monitor such things.


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