Perfomance 6 Measurements and Analysis
Though the Mordaunt-Short's are a relatively efficient loudspeaker (89dB 1/watt/meter). They appear to be tuned at around 35Hz as specified in their literature. Their impedance profile is reactive in midrange and the overall impedance leans more towards 4 ohms rather than 8 ohms. Thus we recommend partnering these speakers with a solid amplifier that can put out an honest 150wpc or more into 4 ohms with a reasonably low output impedance of under 150mohns for the entire audible bandwidth.
Red trace -
on axis
Blue Trace -
15 degrees off axis
Green trace -
30 degrees off axis
Purple trace -
45 degrees off axis
The tweeter level appears to be set a bit too high as indicated by the +3dB bump at 15kHz (on axis measurement). Though in our extensive listening tests, we never found this to be fatiguing or overly colored sounding. The Performance 6 speakers measured best at 15 degrees off axis, maintaining a ±2dB window from 100Hz to 20kHz. This partly explains why Clint found they sounded best with only a modest toe in. The downward trend in the 2-5kHz region, coupled with the slightly hot top end may also explain why Clint found the upper midrange to be a bit recessed sounding compared to his RBH Sound reference speakers. In any event, the family of on/off axis curves indicate excellent polar response and a very wide listening window which is what Clint experienced when putting these high performance speakers though their paces.
