testing amps with square waves

[Henry8]

I've done some tests at 1KHz into 10R plus 1uF.
Less bandwidth gives less overshoot, but how much overshoot is acceptable?

[Tekko]

I'd say none. Any overshhot is a potential output transistor killer.

[Conrad Hoffman]

Square wave testing with amplifiers is tricky business. The rise time of the generator is important, especially since you'll never have a real world signal that's even close. Do some sims on output networks and you'll see that they can get involved in the ringing. There have been some much more detailed threads on this topic here in the past. IMHO, without a lot of qualifiers this test doesn't tell you much, and there aren't any standards to follow so that everybody gets results that can be compared.

[ingenieus]

Apparently, testing an amp with a resistor and cap in parallel isn't a very realistic test and designing for optimum results with such a load has no real benefits. I think it is in Randy Slone's book that I read it. I will look it up and elaborate.

[VladimirK]

I guess the Square Wave tests are very good checking tools for possible device ringing, at increased powers and frequencies. This test can reveal errors as in the schematics layout, and in PCB and wiring as well. No ringing even at rather tuff front edges signify about no parasitic electromagnetic links and is good for reproduction of sound microdetails.