PC Spectrum Analyser?

The street price for the Terrasonde Audio Toolbox is $750; it's not cheap, but still a very good value. It has a high quality built in microphone, test signal generator, and the RTA is selectable for 1, 1/3, 1/6 and 1/12 octave accuracy. Plus the Toolbox performs a number of other functions. Visit their website and see if it makes sense for you.

Sean, that's good to know about the mic. You are also correct about the sound card. However, the programs I pointed out (at least 2 of them) have sound card calibration, where you plug the input directly to the output and it tests and stores a correction file for the sound card. This is very useful, because I want to use this with my portable computer, where I really can't put in a full size soundcard. But you are right--there must be some correction if you aren't using a high quality sound card.

Where or how can one contact Old Colony Sound Labs, for this microphone?

Another option to consider is renting a professional rig. Though I have not done it yet, I have found a sources. AudioClassics.com. I f you look under "Test Equipment", you'll see they will rent an Audio Control SA3050-A with all the trimmmings for $ 90/week. Since this is not something I would use every day (in fact, only when making a MAJOR change to louspeakers type/position, room, room treatments and/or listener position), this may be worthwhile. On another website, someone also suggested hiring an acoustic engineer for a day to come in and do the measurements, etc. I'd love to this, but there don't seem to be any AE's for hire in Cincinnati (the one I found in the yellow pages was very polite, but said he only did large venuses - as in stadiums and churches!)

Well, I hate to admit it but I gave up on the idea of the PC Spectrum Analyser using my soundcard for now. Running a 1kHz test signal from CD through an osciloscope gave a nearly perfect sine wave. Running it through the spectrum analysis software on the PC showed TONS of harmonics at as little as 10dB below signal level... If those were really there, I should have seen them on the o'scope as well. Besides, signals above about 10kHz just did not get digitized very well at all. So my conclusion was: Forget about the sound card.

So I looked at a few solutions that have external attachments, like digital osciloscopes. Some looked like they might do the job, but still not really what I needed. Still, there was the issue of the linear mic and calibration.

So the next best thing I coudl find was the Audio Toolbox mentioned above. It is independant, but it is connectable to a PC for reading out results. We will see how well it works...

Niels.