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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
cerrot's avatar
cerrot
1,700 posts
 
I would look at my tonearm alignment.  If the VTA is off, you'll get overwhelming bass.  Assuming you have a VPI unipoint arm, they are very good, but very difficult to set up.  Look at the arm as you track a record and see how it looks.  Make sure the azimuth is set correctly, the stylus is 90 degrees in the groove (cartridge isn't 'listing' to one side).  Look at the base of the tonearm and make sure that is balanced perfectly and not listing as well.   It should appear as its floating, not dragging.
pmiller115's avatar
pmiller115
97 posts
 
It has been a while since I had to deal with issues like you describe but, as one other poster suggests, this sounds like it could be a feed back issue of some sort since you may be unknowingly producing frequencies with this recording that are somewhat distinct from other recordings. I would also try changing slightly the direction of one or more or your speakers as a way of seeking to diagnose and fix the problem.
moonglum
619 posts
 
My apologies Krelldog. I didn't realise that you'd already tried negative values. Doh!

Memo to self: please read the entire post before commenting ;^)
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knownothing
1,584 posts
 
How compatible is that Ortifon cartridge with the VPI arm?  Is it possible that this is just an arm mass - cartridge compliance mismatch that accentuates rumble on certain albums, and that it becomes more evident at higher volumes?  Have you tried a cartridge with a lower compliance on your arm?
krelldog OP
323 posts
 
The KAB rumble filter did not solve the issue. In fact my system did not like the addition. I am solving the issue by adjusting the bass controls on the Martin Logan Montis's,,,,,and moving the Montis's farther out into the room away from the turntable. I did try these adjustments before I bought the rumble filter.....but for some reason I'm having better results now. I'm still considering a isolation platform for my VPI Prime also.....thanks for all the suggestions.
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