posted
i was playing around with my termlab standalone rta and noticed that the frequency read was about 20 hz more than that was being played. i played a 79hz tone and it read it as around 100hz. i had it run straight through my sound card so there was no mic involved. whats up with it?
Posts: 12 | From: columbia, tn | Registered: Mar 2005
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posted
You need to increase the resolution of your measurements. Increase the FFT length to 2048. This will provide more resolution (more bars). In addition, you should lower the bandwidth if you want precision measurements at low frequencies. You do this by lowering the sampling frequency. A lower sampling frequency will provide more resolution at lower frequencies. When set properly, the Broadband RTA can resolve frequencies 4 Hz (approx) apart. This is about an order of magnitude better than a traditional 1/3 Octave RTA.
The Term-LAB SPL meter (sold seperately) provides 1 Hz resolution! I am not aware of any other product that provides low-frequency resolution of this nature.
Have fun!
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