Problems with Audio input selection
Is there a known issue with the selection of the audio input source. It appears that the signal is always registering something from the internal microphones even when selected to input the external source. I have tried to do this both from the system sound control panel as well as the program module both simultaneously or separately.
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There is no known problem with audio input selection in SignalScope. What external source are you trying to select?
I am selecting input from internal to line in. When line in is selected it seems that there is a ghost signal from the internals bleeding through.
Another anomaly that is present is that the program seems to drop the input voltage 5 db or so on one of the inputs when using the unit in stereo for microphone pairing purposes. (the red plot is 5 db hotter than the green) but only when the input is selected as line in. Weird.
Eugene
Ben
A couple of questions, I take it the powerbook only has a mono built in mic? I ask because the scope acts like it has two discrete inputs when set to internal. Also should I make any effort to change the input under the system control panel for sound? or just through the program, like I have been doing.
What I am using the program for is to read the commonalities in the relative sensitivity of microphones to group them into stereo pairs. I set the scope to "both, FFT analyzer, 22050, 1054, Db autoscale, log, uniform,exponential, 10" Under input I have "built in audio, line in, 44100, stream one (pulldown inoperative), and 24 bit"
I hope that helps.
Eugene
Typically, the built-in mic gets routed to both channels of input. From SignalScope's perspective, then, the built-in audio device appears to have 2 discrete channels when the built-in mic is selected, but the signals are the same.
You should just make the change within SignalScope.
Is this when you have two mics connected to the line input? It's possible that one microphone is more sensitive than the other. It's also possible that this is a result of the way the mics are physically connected to the input. Another possibility, which seems very unlikely, is that there is actually a problem with the built-in audio codec in your Powerbook.
Ben
No. I am certain that the microphones are not the issue. Because I have checked these against each other numerous times in Protools and an actually checking their sensitivity using this scope program.
It sounds to me like there are two options, one, the powerbook is defective.
Two, the software has a glitch, you are unaware of.
i need to find a way of accurately measuring the inputs using another application to check out the first issue.
What type of connectors do the mics have? XLR? 1/4" phone plug? Mini plug?
Do they require preamps? Phantom Power?
Are they routed through any kind of mixer (or other hardware) before being routed into your PowerBook?
You mentioned that you have worked with Pro Tools, which suggests that you have access to a compatible audio interface. Have you tried using that to get your mic signals into SignalScope, instead of using the built-in input?
Depending on what type of mics you have, there can be various places along the signal chain for problems to arise. This is why I asked before about your exact setup.
Ben
I dont know how much testing the software gets after it is designed, and how often specific models of powerbooks have anolmalies that might could bring about such an event.
E
Neumann KM184 mics (XLR) were used and a prootools 002rack interface unbalanced out stereo mini to rca adapter
Here's another possibility: Open the Audio MIDI Setup application (found in /Applications/Utilities) and, under the Audio Devices tab, look at the properties for the Line In source of your built-in audio device. You will see a Volume slider for each input channel. Do they have the same value? If not, that is almost certainly the reason for the discrepancy in SignalScope.
Ben