Null test with music.Gold wrote: ↑Wed Dec 30, 2020 3:39 pmA null test won’t tell you anything about the dynamic behavior of the transformer. Without quantifying the dynamic behavior you get an incomplete picture of what the preamp is doing in the wild.
I would null test with music after removing Raytheon RC5534 op amps from SSLs and replacing them with Signetics NE5534s.
A pair of RC5532-equipped channels wouldn't null well with each other and the residual was pretty gritty.
A pair of Signetics 5532 channels would null well and the residual sounded like the attenuated source.
It was pretty convincing for the client to hear the difference.
I couldn't have done this running tone.
I replaced thousands of RC5532s at no charge to the client.