Musical Fidelity M250 monoblock power amplifier Measurements
The review sample of the Musical Fidelity M250 that we received for measurement—one of the five MF used for his review—was inoperative on arrival. Inspection revealed that the transformer had come loose and pulled out some of its connections in shipment, but a few minor repairs put it back in working order. Normally, in a case such as this, we would request a second sample, but our test-bench results indicated that the repaired unit was functioning normally. All measurements were made from the M250's single-ended (unbalanced) input and at a line voltage of 120V; all power results are to the nearest watt.
The M250's frequency response measured -0.2dB at 10Hz, -0.07dB at 20Hz, -0.11dB at 20kHz, and -0.56dB at 50kHz. The gain was 30dB, and the signal/noise ratio was -97.2dB (A-weighted) at 1W into 8ohms. The THD+noise measured 0.014% from 20Hz to 20kHz at 1W into 8ohms or 2W into 4ohms. The M250 clipped (1% THD+noise) at 274W at 1kHz (260W at 20Hz) into 8ohms, and at 466W at 1kHz (362W at 20Hz) into 4ohms. —Thomas J. Norton