What was found
A VIBRATION OF UNDETERMINED LOCATION. COULD BE FELT THROUGH OUT THE ENTIRE AIRCRAFT. SEEMS TO LESSEN WITH SPEED BUT NEVER GOES AWAY. VIBRATION OCCURRED CLIMBING OUT OF 3000 WITH THE FLAPS & GEAR UP. REMAINED THROUGHOUT THE ENTIRE FLIGHT UNTIL LANDING. BUT IT DID GET LESS WITH SPEED. CHECKED ALL DOORS & FOUND ALL SECURE, LANDING GEAR DOOR FOUND SECURE. ALL PANELS SECURE. RAN ENGS & NOTICED A DIFFERENT SOUND WHEN THE RT PRESSURE SOURCES SELECTED & WENT AWAY WHEN ON LT SELECTED. ASKED TO RUN AT HIGH POWER & TO TURN ON WING ANTI ICE . AFTER RUNNING SECOND TIME, ALL NOISES WENT AWAY WHEN SELECTED RT OR LT SOURCE & ENG BLEEDS, ASKED TO DOWNLOAD ARES. READ ARES DOWNLOAD & SAW NO DISCREPANCY. RAN A/C AGAIN WITH MANY DIFFERNT BLEEDS ON & OFF & POWER SETTLNGS, ONLY HEARD A LOW RUMBLE FIRST TIME & NEVER HEARD IT AGAIN. LOOKED AT ALL DUCTS IN AFT BAY ALL LOOKED SECURE.