Izjjzi,
Interesting information on the different taps. Looking at the impedance graph of the Sopra 2 it looks like the 4ohm tap would be the right one. You want to match the lowest point of the impedance to the tap and the Sopra dips to 3.7-ish around 100hz.
Going to the 2ohm tap will probably not change the tonal balance (because it is lower than the speakers so it will not add gain to higher impedance sections of the speaker) but it will reduce your power. I would guess by about 1/3rd. This is because you already have enough current and the 2ohm tap will reduce the voltage.
But really the amp is powerful and runs cool so using the”wrong” tap will not hurt anything if it sounds good to you.
If you look at stereophile’s measurements of the MC462 (link below) you can get some in-site as to why you want to match the lowest impedance. It will reduce the distortion and still maintain the full 300 watt output. For most speakers the 4ohm tap is the right one.
“Figs. 6–9 indicate that distortion is extremely low, lying below the noise floor at powers below 30W or so. I therefore plotted how the THD+N changed with frequency from the 8 ohm output at a level of 28.3V, equivalent to 100W into 8 ohms and 200W into 4 ohms, where I could be sure I was looking at distortion rather than noise. The result (fig.10) reveals that the THD into 8 ohms (blue and red traces) and 4 ohms (cyan, magenta) rises above 1kHz, but still remains below 0.007%. I haven't shown the THD+N trace into 2 ohms from this output, because it was >2% in the midrange and treble and >3% in the bass at 28.3V, which is equivalent to 400W into 2 ohms. The moral: Match the MC462's nominal output to the lowest impedance magnitude of the loudspeaker used.”
https://www.stereophile.com/content/mcintosh-laboratory-mc462-power-amplifier-measurements
As for the the popping sound it could have been a driver bottoming out if it was super loud with deep bass. It probably will not break a well designed driver but it will be uneasy for sure.
If it was power related the Mac’s power guard lights would have come on (lights up orange like startup) and cuts the power.
Interesting information on the different taps. Looking at the impedance graph of the Sopra 2 it looks like the 4ohm tap would be the right one. You want to match the lowest point of the impedance to the tap and the Sopra dips to 3.7-ish around 100hz.
Going to the 2ohm tap will probably not change the tonal balance (because it is lower than the speakers so it will not add gain to higher impedance sections of the speaker) but it will reduce your power. I would guess by about 1/3rd. This is because you already have enough current and the 2ohm tap will reduce the voltage.
But really the amp is powerful and runs cool so using the”wrong” tap will not hurt anything if it sounds good to you.
If you look at stereophile’s measurements of the MC462 (link below) you can get some in-site as to why you want to match the lowest impedance. It will reduce the distortion and still maintain the full 300 watt output. For most speakers the 4ohm tap is the right one.
“Figs. 6–9 indicate that distortion is extremely low, lying below the noise floor at powers below 30W or so. I therefore plotted how the THD+N changed with frequency from the 8 ohm output at a level of 28.3V, equivalent to 100W into 8 ohms and 200W into 4 ohms, where I could be sure I was looking at distortion rather than noise. The result (fig.10) reveals that the THD into 8 ohms (blue and red traces) and 4 ohms (cyan, magenta) rises above 1kHz, but still remains below 0.007%. I haven't shown the THD+N trace into 2 ohms from this output, because it was >2% in the midrange and treble and >3% in the bass at 28.3V, which is equivalent to 400W into 2 ohms. The moral: Match the MC462's nominal output to the lowest impedance magnitude of the loudspeaker used.”
https://www.stereophile.com/content/mcintosh-laboratory-mc462-power-amplifier-measurements
As for the the popping sound it could have been a driver bottoming out if it was super loud with deep bass. It probably will not break a well designed driver but it will be uneasy for sure.
If it was power related the Mac’s power guard lights would have come on (lights up orange like startup) and cuts the power.