Measurements and Analysis

All measurements were conducted in room, on axis at the acoustical center of each speaker 1 meter away. The results were 1/3rd octave smoothed for easier readability.

Onix x-ls, Polk M30 & HSU HB-1 Frequency Response
Onix – blue trace; Polk – red trace; HSU – purple trace

The Onix x-ls measured the most linear of the group with usable bass extension down in the 45Hz range. The Polk’s had +5dB bump above 5kHz topping off at +7dB above 10kHz. These speakers were very bright making me wonder if they skewed our bias towards them in the instantaneous comparisons of the more tonally neutral x-ls and HB-1 speakers. The HSU HB-1’s surprisingly measured a few dB hot above 5kHz. I wish I would have pulled some off axis measurements to understand why they sounded more recessed off axis.

RBH TK-5CT & Usher S-520 Frequency Response
RBH – green trace ; Usher – red trace

Both speakers measured quite well, though the Ushers were a bit more linear in the upper midrange. The bump in the 1-2kHz range of the RBH’s may be attributed to the slight midrange coloration we heard due to cabinet resonance. The Usher’s appeared to have lower bass extension with a -3dB point around 45 Hz compared to the RBH’s 50Hz but it was a moot point since the Usher’s couldn’t play these frequencies at adequate SPL levels without bottoming out.

RBH Sound MC-6C; Dali Mentor 1, Ascend Acoustics Sierra 1 Frequency Response
RBH – blue trace; Dali –yellow trace; Ascends – purple trace

The RBH MC-6C measured the most linear of all the speakers in this review. it had a slightly elevated midrange response which most manufacturers tend to recess to hide speaker imperfections. They also had the steepest low frequency rolloff of the group and were the only sealed speakers in this comparison.

As you can see in this measurement, the Dali’s had a +7dB bump above 10kHz. I found it highly unusual that a speaker company would incorporate such a deliberate boost of the ultra high frequencies, but there is no denying our listeners preferences (at least short term). For such a small speaker, they had impressively low end bass extension (mid 40hz range) but were prone to bottoming out.

The Ascend Acoustics Sierra 1’s had the most pronounced bass extension of all the speakers in this review. They almost seemed like floorstanding speakers with usable bass extension in the sub 40Hz region. They had a slightly elevated response in the 5-10kHz region gradually tapering off above 15kHz.