The other day I was reviewing some very high quality bookshelf-sized loudspeakers, and decided I’d check their bass extension. What I measured was quite at odds with both my listening impressions and the manufacturer’s specifications. The makers say 50 hertz more or less flat, 42 hertz at -6dB. That was also my sense. Very solid with what it did, but lacking a firm underpinning of deep bass.<\/p>\n
But my measurements said flat to about 36 hertz , -6dB at 32 hertz. Which is such an impressive result I immediately doubted my measurements. I’ve recently acquired a new high-end microphone pre-amplifier\/ADC (Focusrite Forte<\/a>) and was quick to blame that.<\/p>\n To check, I tested the bass end of some mid-priced floorstanding loudspeakers and the result was remarkably similar. Could the Forte be doing something weird?<\/p>\n I still had my old FastTrack Pro interface around — Windows 8.1 broke its drivers so it now only works at 44.1kHz sampling, whereas the Forte goes up to 192kHz. It gave the same results. I filled most of the morning using different test tracks, different amplifiers, different digital decoders, different recording and analysis software, and even a different microphone (not a measurement one, but one with reliable bass so I could see if anything was grossly wrong).<\/p>\n Eventually the issue was more or less resolved. Instead of measuring on tweeter axis at one metre , I measured from my listening position which is sort of on-axis, but about 2.7 metres away. The bottom end now went down to 44 hertz and fell away quite quickly. Do’h! That’s what I was hearing!<\/p>\n Regardless, it does seem that the loudspeaker maker is being modest in its bass claims.<\/p>\n Despite all this, my morning’s efforts had left my confidence in my measurement rig a little shaken. This morning, however, I was measuring a different speaker (with a claimed low end extension of 25 hertz!) which gave a weaker than promised result. Indeed, a weaker response than the bookshelf. So I left the microphone in place and changed back to the bookshelf speaker for final confirmation. Yes <\/p>\n , the rig is capable of measuring substantially different bass ends, from which I can conclude that it’s probably accurate!<\/p>\n","protected":false},"excerpt":{"rendered":" The other day I was reviewing some very high quality bookshelf-sized loudspeakers, and decided I’d check their bass extension. What I measured was quite at odds with both my listening impressions and the manufacturer’s specifications. The makers say 50 hertz … Continue reading