Vintage

The largest of Goodmans' ‘M’ series is still fairly compact and, at just 6.5kg, has a fairly lightweight cabinet design lacking the bracing or damping that would likely be employed today. Cabinet modes are quite pronounced [see CSD waterfall, Graph 2], reflecting quarterwave and other resonances at 760Hz, 1.7kHz and 2.5kHz, the former exiting the rear-facing port at just –8dB below the level of its (broad) 28Hz tuning. Combined with the 200mm polypropylene bass/mid unit, which rolls off below 100Hz, the Magnum achieves a 52Hz bass extension (–6dB re. 200Hz), although Goodmans suggests a close 10-20cm rear wall position to further boost this figure.

The Magnum’s rated 89dB sensitivity is more than met in practice at 90.5dB/1kHz and 89.5dB, averaged across 500Hz-8kHz, while the response is slightly tilted from 300Hz-10kHz before showing a +3dB ‘sting’ in the high treble [Graph 1]. The 19mm alloy dome tweeter has a primary breakup mode at 30kHz [pink shaded area, Graph 1] while the ‘better’ sample of our pair [black trace] enjoys tight response errors of just ±1.9dB. The other sample [red trace], with a dip at 5-7kHz, drags the pair matching out to a poorer 3.9dB. Otherwise, the Magnum shows excellent off-axis uniformity [blue trace] while the grille, aside from a dip at 7kHz, is also fairly benign [grey trace].

Despite its high sensitivity the Magnum remains a fairly easy drive. The impedance modulus rarely dips below 5ohm and hits a minimum of 4.3ohm/31ohm where modest swings in impedance phase of ±35o contribute to a manageable 2.3ohm EPDR at 42Hz. The trade-off comes in bass extension. PM