| Measurement distance was about 6 feet back from the mouths of upper-bass horns and centered between the L and R stacks of horns (this is a plot of both upper-mid horns playing together... You will probably tell me that I should have tested a single horn, which is what I usually do). The mic is supposed to be calibrated, its not very old, and it has not been abused. The HF rolling off could be due to the fact that I was not on axis, or that both horns were playing; I also suspect the tone generator... I've been using a little computer program which seems to do ok until it hits the HF range, at which point I can hear it going a bit nuts. The computer sends the signal to the DAC, the same as if it were a music file. I also have a Tektronix tone generator, but have not dared connect it to either the preamp or directly to the power amps. I guess its just a question of measuring the strength of the output signal from the tone generator to make sure I don't fry something in the audio gear (any advice here would be very appreciated). |
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