
kgirl72
New member
darrin_h2000 said:Most surround sound recievers have Pink noise output for testing the levels of the speakers. If you can put that on a cd.
So that is what that is for!
-Kirstin
darrin_h2000 said:Most surround sound recievers have Pink noise output for testing the levels of the speakers. If you can put that on a cd.
Marik-Marik said:BTW, I am driving to Tempe in a couple weeks to perform at Katzin at ASU and to make some recordings. How about some beer and shooting some pool?
I guess that it is quite important for comparative testing that the measuring criteria and situation is consistent, so it might be good to use a recording of noise each time, rather than use the raw output of a generator?
Also obviously the relative positioning of the source, the microphone that is subject to the testing, the stand etc all be the same each time?
Another thing to consider of course would be other environmental influences such as boundaries etc that can cause reflections?
I've just tested the HF response of my mic AT4022. I don't have a spectrum analyser so I used a signal generator and oscilliscope, and wound the frequency slowly up noting the peaks and troughs, which are often very close together. These peaks and troughs are wildly different in level, sometimes 20 times = 26dB. What causes these peaks and troughs? The mic was sufficiently close to the tweeter of the speaker that it couldn't be room echoes, and slightly varying the distance completely changes them so where there was a peak there is now a trough. The figures obtained are so far apart that a graph is meaningless, so I added each adjacent peak and trough and divided by 2 to give a usable figure, and I did three sets of measurements at 6" 12" and 18" and summed the results. The final graph produced looks very similar to the response curve that came with the mic except the peak has moved from 8.7kHz to 8kHz. My question is what causes these peaks and troughs? It cant be the mic or the tweeter because they change as you alter the distance between the mic and tweeter. Also it cant be interference between the tweeter and the midrange speaker because it is the same using a tweeter on its own.
That's a bit challenging to answer exactly; variations are normal as a result of tweeter and room response, but the magnitude is larger than I have typically seen for high frequencies (it's not unusual for bass frequencies though). The usual method is subtraction, where you compare to a mic of known response, usually a flat-response small-diaphragm omni. That will mostly eliminate variation in high frequency response *if* you are careful to colocate the capsules.