That would be one of the ones I was looking at. Is Hantek made by SainSmart?
No, Hantek is not made by Sainsmart.
What is the Gain Range? I thought I knew what that meant (The 1600W amplifiers put out 40ACV at 1ohm so I would need an oscilloscope with the 5V/50V range?) but the Hantek spec just says 10mV - 5V, 9 steps....so now I'm thinking I -don't- know what the gain range means.
It's pretty simple really. It's just adjustable sensitivity. For some things, you need to see small signals, so you'd go to a lower setting. For your needs, you're looking at relatively high voltages, so you'd select the higher setting (less sensitive), and use a 10x setting on the probes provided. That should give you enough headroom for what you're doing.
And I have no clue what you mean by the FFT display lol. I'm an amateur/noob when it comes to oscilloscopes.
Sorry, that was inappropriate of me. FFT is just a fancy name for looking at all the individual frequencies that make up a signal, stretched out over a spectrum chart. I suspect you've seen frequency-response charts, that show how flat or variable the response of an audio component is. This is similar, because it shows all the frequencies that are present. If your test tone is a pure sine wave, then the frequency chart (FFT) would be a flat horizontal line at 0 level, with just one vertical spike, at the test frequency. But as you turn up the volume, distortion will rise. Distortion is any frequency in the output that wasn't in the input. So you will see small blips start to appear on the frequency chart, at multiples of your input sine wave frequency. (And those multiples are 'harmonics'.) Those will be noticeable much sooner than the top of the sine wave will start to look clipped.
I like to offer my customers the best service possible which means properly tuning their amps, not just doing it by ear. I know there are two things to look for while tuning. One would be the clipping at the peak of the wave and the other would be the distortion in the rise and fall of the wave. Is that what you mean by the spurious harmonics from overdrive?
Well, clipping is a really 'hard' distortion, where the maximum drive is reached, and exceeded. The amp just can't put out any more voltage, so the top of the sines go flat. Certainly there will be plenty of 'spurious harmonics' (other frequencies you don't want) at that point, but there will be some even before you reach that point.
The technical term for the distortion of the rise/fall of the wave is slew-rate. Slew rate limiting usually becomes an issue at higher frequencies. I.e., you may be able to put out a certain voltage at a lower frequency, but as you go higher, the voltage can't change fast enough, and the shape of the sine curve won't be maintained. And eventually you can no longer reach the desired peak value at all. Slew-rate limiting will be even harder to see initially, just by looking at a sine wave shape, though since it's related to the bandwidth of the amplifier, you'll eventually notice it as reduced amplitude (height) of the sine wave. I.e., it will shrink.
The question there is determining at what point do you back off and say, "
that's too much limiting?". High frequencies are not emitted at as high a level as low ones... if they were, tweeters would be blown out all the time. You sure don't want to run that test at full-rated power levels.
The good news is that all of these can be easily seen on the FFT graph I mentioned.