I suspect that you have a room resonance problem. To find the approximate frequency at which a room will resonate divide 565 by the room dimension or in your case 565/18 = 31.5Hz and 565/12 = 47Hz. By taking multiples of these fundamentals you get overlapping modes at about 94Hz and again at about 190Hz with several other close modes between these frequencies. This could account for what you are hearing in the mid bass. You can determine if this is the problem by placing a 1/3 octave band equalizer between the preamp and poweramp and notching out frequencies at the overlapping resonances. If you like the results you then know what frequencies you are trying to treat or you could leave the equalizer in place. Just remember that the least equalization is generally the best.
Please help me tame the bass beast
I own the Joseph Audio RM50si's which go all the way down to 20Hz. My preamp is the Classe SSP-75 and the amp is the Classe CAV-150. CD is Sony SCD 777. The 75 does not have controls to turn down the bass level. What can I do accoustically to eliminate such an annoying rumble in the mid bass. I moved them around the room but nothing seemed to really make a difference. Is the problem the amp or the speakers or the room. I have read reviews on this site and people seem to think Classe amps deliver a lot of muddy bass. The low bass frequencies seem to be okay, it is really the mid bass that is the problem. If I sit really close it is better but not great. What can I do?? My room is rectangular 18x12. Please offer me some suggestions. They are great speakers except for this problem.