Posted by Charlie Biern [ 68.100.104.204 ] on November 02, 2005 at 18:22:24:
I'm an novice at speaker building but I have completed a pair of Bill Fitzmaurice's Omni 12 tops and Tuba 24 subs and I'd like to see a frequency response plot to make sure I've done things correctly.
Wayne recommended Audio Workshop but I find it lacks a good deal of information about basic setup and usage or assumes that I should already know those basics.
I've got a Behringer ECM 8000 mic into a Eurotrack 802 mixer to get phantom power, all the contols set midrange. Out of the soundcard into the left channel of a QSC RMX850 to the cabinet.
I originally set the speaker on a stand outdoors with the middle of the cabinet 5' above the ground.
The mic is set up 1m away also 5' up, dead center. (Wayne later told me that I should put both the speaker and the mic on the ground and measure in 1/2 space)
I used a 1k sine for level setting and the peaks hit a little over 30k. No visible distortion (30k what? Samples? )
I assume I am to use a sweep 20-20k. Log or linear? (I used linear) - Number of steps 10 (arbitrary setting since no explanation is given as to the effect of more or less steps)
When I hit Record the Volume is at 50. - Left Chan. Only - Calibration is Left. - Data is Left. Type is Frequency
Play and record times 5 sec (again arbitrarily)
Several charts are produced.
How are the chart properties to be set to see what needs to be seen? Should they be set to (whatever) before the recording ?
What is the dataset and why does it default to stop at 5.4k?
What does the FFT chart show?
Should I make other tests using pink noise or bursts etc. there are a bunch of waveform types that must be used for something.
I'm posting what I got from one go 'round.
It's a lot of questions I know but the program seems to demand them if you've never done this before. I'll happily follow instructions if they exist!
Thanks,
Charlie
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