[dick thoreau]

PMC seem to claim that their speakers have the same frequency balance (bass levels to higher frequencies) at all listening levels.  I haven't heard any PMC speakers but I am interested in the OB1, IB1 and IB2 models.  I was wondering if this claim is true?   I have the Mirage M3si speakers and the bass on them is excellent at higher volume levels but at lower listening levels the bass is noticeably attenuated.  My listening room is quite small ,about 16ft x 14ft,  and in order to really get the Mirages to come to life the sound level in my room has to be so loud that it is uncomfortable on the ears.  Any thoughts on whether the PMC models I mention above would work in my smallish room and would the PMC transmission line bass sound natural and balanced at low to moderate listening levels.  Thanks in advance for any opinions.

[brucek]

PMC seem to claim that their speakers have the same frequency balance (bass levels to higher frequencies) at all listening levels................I was wondering if this claim is true?
I have the Mirage M3si speakers and the bass on them is excellent at higher volume levels but at lower listening levels the bass is noticeably attenuated

No doubt PMC's claim is true, but since human hearing suffers from a loss of frequency response at lower volumes, you will still have the same problem (as everyone else has) as you now have with your present speakers. Unless PMC has incorporated a loudness contour into their crossovers   , the problem of low and high frequency loss at low volumes will have to be taken care of by your equipment.

brucek

[Dokter_doug]

I have owned both FB1's and (now) IB1's. Prior to both purchases I auditioned both sets of speakers (in my own listening room). Both models sounded great at low volumes. Both sets of speakers were mated to 7B ST monoblocks. IMO it is the transmission line design of PMC's (among other factors) that allows for terrific bass response when music is played quietly. Others more in-the-know will no doubt tell you other things about PMC's design and contruction that account for the excellent sound reproduction at all volume levels. I love the sound of PMC speakers and recommend them highly.

Doug

[thomaspf]

I am afraid that even a transmission line bass design will not have the power to change an inherent characterisitic of human hearing. What you describe is an effect of the non linear behavior of the human ear.

http://www.sengpielaudio.com/Fletcher-MunsonIsNotRobinson-Dadson.pdf

gives the curves of equal loudness across the frequency range for head phones and free standing speakers standardized by Robinson/Dadson.

In order to make any music sound right you first need to now the level at which the performance or mastering took place. Then you can either crank up your system to the original level or use a technique called loudness restoration to get the correct balance of frequencies at a different playback level.

Some modern surround sound processors with enough DSP power and microphone calibration provide a loudness corrected volume control. Given that DVDs have a prescribed mastering level wich is a health hazard these unit allow you to enjoy a fully balanced surround sound at safe levels.

Cheers

    Thomas