Scratchy sound on certain notes right side only?


What could cause a "scratchy" sound on certain notes at certain volume, be it voice, piano, but especially with saxophone, right side only? I have switched cables, no luck. Checked all connections. I know its not the speakers because if I switch l/r cables from the phone preamp out the noise comes from the left speaker. Equipment is jr michell orbe with sme iv.iv arm & clearaudio virtuoso cartridge. Tracking force etc seems to be right on. Any help would be appreciated.
Thanks
yohjo
Definitely it is a bad tube or tubes! either pre-amp or phono stage. Best to test all tubes in the path.
Sorry guys, I should have added what the phono pre is, the EAR is gone, I am using a ps audio gcph. It's definitely the gcph. Not the 99 as no problems on any other source. Gain on the 99 is in same position as it always has been.