Bass distortion-Playing LP's only,,,,please help


VPI Prime----Ortofon Black Quintet (low output moving coil cart)-----Plinius Koru Phono Pre( loading at 20 ohms/gain at 66 db)-----Parasound Halo Integrated -----Martin Logan Montis speakers which have powered bass cabinets.

Using any other source component I have absolutely no issues. When I play an LP and increase the volume past 10 O'clock which is a little loud....but not ridiculously loud-I at times get this huge wave of bass distortion. I do have bass controls on the Montis's...and I have turned them down into the negative, but I still get what I previously described occasionally. 

Any and all help would be appreciated. This doesn't always happen, but its frequent enough to drive me crazy.

Thanks in advance.

krelldog

Showing 3 responses by stereo5

I am willing to bet you are getting some feedback. Can you remove the grill and observe if the woofer is oscillating abnormally? If it is, its a feedback problem. I had this problem with my Scout and now my Prime. My turntable is on top of a rack on a solid 3 inch thick maple air dried platform which is sitting on a sandwich material I bought from Mapleshade. I still got it. I bought a KAB Rumble filter for 180.00 and put it through the tape loop. Now the problem is solved and I haven’t lost any bass quality. You should hear how subteranian it goes during some songs on Amused To Death.  I could rattle the fillings out of someone's teeth!
The KAB rumble filter uses audiophile grade parts and I can't hear any difference with it in or out other than the bass not distorting and the woofers not going into oscillation..  The quantity and quality of bass remains the same.  You can order one from KAB and have it within a week.  I run mine through the processor loop on my preamp, but a tape loop will do the same thing.  Also I moved my Scout and Prime all over the living room, trying different platforms, even one bolted to the wall but in the end, the rumble filter was the only thing to eliminate.  I have an old house with squeaky floors so perhaps that had something to do with it.

+1 yogiboy

Looks like it will do essentially the same thing for a lot less money.  You have nothing to lose by trying these.