On 11/28/23 08:47, Steve Wahl via Jukebox-list wrote:
Ah, I think I get it.
The square wave has all the odd harmonics, so your 300Hz square is like simultaneously putting sine waves at 300, 900, 1500, 2100, 2700, 3300, ... (at decreasing amplitudes) through the amp.
Correct. Don't expect the output to be perfect, especially if your amplifier has a magnetic RIAA equalized input. Tone controls will also affect it. Rounded corners show poor high-frequency response. Peaked leading edges show poor low-frequency response.
So you're testing the amp over a wide range of frequencies at once, but also seeing if there's interferences / interactions between those frequencies within the amp.
Is that right?
Yes, also any instabilities. In the case shown in the video there is leading edge ringing which shows a tendency to oscillate or unwanted resonance.