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outsider
New member
hi i want to use my notebook as a rt analyzer, what do i have to do to get the objective reading of value? do I need a stand alone analyzer and to di a paragon?
thanks
thanks
Massive Master
www.massivemastering.com
RTA's are as accurate as the source they're fed. It's that simple.
O
outsider
New member
i am confused about this principle, if on my software on pc,assumed that i use a professional mic i get for example 74 db spl, how i set the audio card inputs to get the real objective reading of that value,di i have to get a parameter of paragon?
sorry for my writing
sorry for my writing
Massive Master
www.massivemastering.com
A "professional" mic means little -- You need a very specific mic with a specifically known frequency response feeding a preamp with a specifically known frequency response at a specifically known level.
You don't need to spend a bundle on it - Behringer's measurement mic is a decent mic with easily attainable calibration curves for most popular measurement software. The preamp might be another story. In any case, few typical mics are acceptable for the task - Razor flat, omnidirectional condensers don't need to be expensive, but they aren't used often.
Doing the math, you could figure out the SPL in the room (I'm assuming you're shooting a room here) or you could use a SPL meter (much easier for the purpose).
You don't need to spend a bundle on it - Behringer's measurement mic is a decent mic with easily attainable calibration curves for most popular measurement software. The preamp might be another story. In any case, few typical mics are acceptable for the task - Razor flat, omnidirectional condensers don't need to be expensive, but they aren't used often.
Doing the math, you could figure out the SPL in the room (I'm assuming you're shooting a room here) or you could use a SPL meter (much easier for the purpose).
O
outsider
New member
my question is related at preamp level, i have an m audio 1814, how i knwo whiwch is the right sensitivity and gain that i have to set to get an objective measurment?
mshilarious
Banned
What exactly are you trying to measure? Do you need to know SPL? In that case, buy an SPL meter, they will be accurate +/-2dB.
If you need to measure the frequency response of a room, then you need a measurement mic and a signal source. Your monitors should work fine as a signal source. Pipe pink noise through your monitors and record the result. The preamp is relatively unimportant, because nearly all preamps will be flat enough from 20Hz to 20kHz to be within your margin of error. The setting on the preamp is not important since you don't care about absolute level, just relative frequency response. Just set it with a normal amount of headroom.
The resulting .wav will not look very flat on FFT. That is mostly because of your room and partially because of your monitors. It is partially because of your microphone. To eliminate the monitors as a source of error, record their response at a few inches away from the woofer/tweeter (you have to do them separately). That will eliminate nearly all of the room response from consideration. If you have a calibration file for the mic, you can adjust for that as well.
Now you take the measured room response, adjust for the variance in your monitors and microphone from flat response, and you have your actual room response at the position that you measured.
If you for some reason need to calibrate absolute SPL with your mic and preamp, you will need to know your mic's sensitivity (in dBV/Pa). For many measurement mics, that figure is +/-2dB. Then you need to calibrate the gain at your preamp and the dBV=0dBFS point of your converters. If your preamp or converters are not specified/labeled, you can use an RMS meter to measure AC voltage at the microphone output and preamp output. That will measure the gain of the preamp at a particular setting and the level that corresponds to 0dBFS. Given that you know the sensitivity of the mic, and using all that information and a little math (mostly addition and subtraction, and some logs if your RMS meter doesn't have a readout in dB), you will then be able to derive dBSPL from dBFS.
Why you'd need that I am not sure, since an SPL meter is quite a lot easier.
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outsider
New member
thats what i was meaning, thanks, any way i will purchase of course an spl meter