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Article Index
Graham Audio BBC LS5/9
page 2 Sound Quality
page 3 Conclusion
page 4 Measured Performance
All Pages


MEASURED PERFORMANCE


Our frequency response analysis shows a smooth response over most of the audio band. There was no dip between midrange and treble units to soften the sound, although a phase dip did appear as the microphone was moved up to the tweeter axis and above. Because the drivers are physically far apart this is inevitable.
    Upper treble rolls away above 10kHz even on the tweeter axis, likely due to the protective grill. There is also some lift in upper bass, just enough to ensure the Graham has body to its sound.
    Lower bass peaks quite substantially around 70Hz our analysis shows, and this correlates with box overhangs visible in a 200mS decay analysis, so bass will be prominent and possibly a tad boxy or fulsome. The port, tuned to 45Hz extends bass down well, so in all the Graham will have strong bass, if not deep subsonics.
    The bass unit has a high DCR of 7 Ohms – most are 4 Ohms these days – and this results in a high overall measured impedance value of 12 Ohms. This high value lowers voltage sensitivity, the Graham managing a reasonable 87dB from one nominal Watt of input (2.8V). It needs amplifiers of 60 Watts or more to go loud.
    Although a 200mS decay analysis revealed bass overhang at low frequencies, across the midband the bass/midrange unit was clean in its output, suggesting low coloration.
    The Graham Audio LS 5/9 measures well, with distinctive characteristics. It will have an ‘easy’ sounding balance, with fulsome lower frequencies and strong bass. It needs power to go loud. NK.



FREQUENCY RESPONSE (what it means)



Green - drive unit; Red - port


IMPEDANCE (what it means)




DECAY SPECTRUM 200mS (what it means)




DECAY MAP 200mS (what it means)




 

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