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Measuring audio signals with an oscilloscope
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drummerdimitri:
I would like to test if my amplifier is clipping at certain volume levels when playing my loudspeakers however I'm having issues connecting the probes correctly. Is this because I am shorting out the signal to ground? I get nasty looking wave-forms and have already fried some resistors on my amp doing so.

What am I doing wrong and how to measure this correctly?
capt bullshot:
First, check if your amplifiers output is bridged (BTL, bridge tied load) or single ended ("-" connected to circuit GND).
In the latter case, be sure to connect your scope's GND wire to the correct (GND) output pin and watch out for ground loops.
In the first case, either connect your scope's GND wire to circuit ground and watch only one output pin, or use two probes and scope channels (each probe tip connected to one output pin) and set the scope to subtract these channels, or use a proper differential probe (which would be the easiest to use but most expensive option).
drummerdimitri:

--- Quote from: capt bullshot on December 17, 2018, 09:16:23 am ---First, check if your amplifiers output is bridged (BTL, bridge tied load) or single ended ("-" connected to circuit GND).
In the latter case, be sure to connect your scope's GND wire to the correct (GND) output pin and watch out for ground loops.
In the first case, either connect your scope's GND wire to circuit ground and watch only one output pin, or use two probes and scope channels (each probe tip connected to one output pin) and set the scope to subtract these channels, or use a proper differential probe (which would be the easiest to use but most expensive option).

--- End quote ---

Thanks for the reply.

I've switched over to optical input to isolate the USB from ground loops with my scope and now I'm seeing the pure waves I was looking for.

Cheers!
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