Alcorn McBride Knowledge Base

The AM4 Amplifier option is rated to drive speaker loads of 4 to 8 ohms. However, some speakers can actually have a much lower impedance at certain frequencies. The lower impedance often occurs at low frequencies, and if the impedance becomes too low the AM4 output(s) will shut down. If your speaker has an impedance characteristic that goes much below 4 ohms (i.e. 3.5 ohms) at low frequencies, you should be sure that these frequencies are not present in your source material, or add some series resistance to the speaker line(s) to ensure that the impedance never drops too low.