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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
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moonglum
619 posts
 
Dear Krelldog,
Glad to hear things are working out.
I've had to correct my posts because I got the multiplier wrong :)

Use the x10 Rule to decide the cartridge loading rather than sticking with Ortofon's minimum figure of 20 ohms.
Since the manufacturers internal impedance is 5 ohms this would make your "realistic" minimum 50 ohms. I personally prefer x20  which gives 100 ohms, but many would suggest even higher values. It's a subjective decision based on your own taste and your phono stage. 
The important thing is to try it if you haven't tried it already.
Cheers,
Bill

perazzi28's avatar
perazzi28
234 posts
 
I would advise against the use of filters.  Yes cartridge loading can be a real issue and 20 ohm loading should be increased to 100 ohms and see (or rather hear) any difference.
Secondly, most good preamps will pass DC which will of course create havoc with your woofers.  Some woofer motion with normal vinyl playback will be present on a fair amount of material. 
So as presented earlier, TT isolation is paramount + proper cartridge loading.
Best of luck,
krelldog OP
323 posts
 
I get the cartridge loading, I have a lot of choices with my Plinius Koru.

Without sounding stupid...and I've never proclaimed myself an audio expert....

What exactly is Turntable isolation???  The first thing that comes to mind is a 2-3 inch platform underneath the turntable. I'm all in on this. I've certainly made the investment in LP playback. What else am I missing in terms of isolating my turntable???

As always I truly appreciate the help and guidance of other audiophiles that know a helluva lot more about this stuff than I do.
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