Hey y'all, I'm new to these forums. I have an old-ish oscilloscope lying around (analog discovery 2 by digilent) and was considering using it to measure some audio equipment (especially interfaces and mics). It's got 30 megahertz of bandwidth (which is ridiculous by audio standards), an fft, and a signal generator. I also got a bnc adaptor for it.
One of the problems I see with existing tests is that, from what I can tell, they don't measure how the interfaces react to a condenser mic being plugged in. Generating 48 volts, using it to drive a capacitive load (like a condenser mic capsule), and sending the resulting signal to the preamp - all these things can cause challenges for analog circuitry in ways that are difficult to measure. I've always wondered if that might be the cause for certain interfaces sounding worse than others despite having mostly the same THD+N and IMD measurements.
The simplest way to measure that would be to take a mic, hook it up to the interface, play a test tone through a speaker, and record the result. Unfortunately, room noise, acoustics, speaker and mic quality would all interfere with the measurements. Using a signal generator can eliminate these issues, but it wouldn't simulate a real mic load on its own. On top of that, the 48 volts produced by phantom power would probably fry my lil usb scope. Does anyone know if there's a circuit I could build to connect my oscilloscope to phantom power safely while simultaneously simulating a condenser mic load?
I hope my question was clear.
EDIT:
Just to be clear, the idea would be to take my USB scope's waveform generator, use it to drive a circuit that imitates the electrical qualities of a real microphone (including drawing phantom power), and routing that signal into the mic input of an interface in order to measure how the preamp and DAC behave under a realistic load. Then, I could just test the outputs using the scope's FFT. That's how I'd plan to test interfaces, anyway.
As far as testing mics, that was kinda an after thought haha. I wouldn't have the best setup for that.
One of the problems I see with existing tests is that, from what I can tell, they don't measure how the interfaces react to a condenser mic being plugged in. Generating 48 volts, using it to drive a capacitive load (like a condenser mic capsule), and sending the resulting signal to the preamp - all these things can cause challenges for analog circuitry in ways that are difficult to measure. I've always wondered if that might be the cause for certain interfaces sounding worse than others despite having mostly the same THD+N and IMD measurements.
The simplest way to measure that would be to take a mic, hook it up to the interface, play a test tone through a speaker, and record the result. Unfortunately, room noise, acoustics, speaker and mic quality would all interfere with the measurements. Using a signal generator can eliminate these issues, but it wouldn't simulate a real mic load on its own. On top of that, the 48 volts produced by phantom power would probably fry my lil usb scope. Does anyone know if there's a circuit I could build to connect my oscilloscope to phantom power safely while simultaneously simulating a condenser mic load?
I hope my question was clear.
EDIT:
Just to be clear, the idea would be to take my USB scope's waveform generator, use it to drive a circuit that imitates the electrical qualities of a real microphone (including drawing phantom power), and routing that signal into the mic input of an interface in order to measure how the preamp and DAC behave under a realistic load. Then, I could just test the outputs using the scope's FFT. That's how I'd plan to test interfaces, anyway.
As far as testing mics, that was kinda an after thought haha. I wouldn't have the best setup for that.
Last edited: