Originally Posted by
Doug_MPS6
Are you parked outside a brothel?
Forgive me - I couldn't resist that!
How many kms on the car? I don't follow your "as I speed up it becomes constant" as this suggest it is in fact variable.
Is it affected by variable road surface. Suspension noises will be worse over more variable surfaces and may subside on smooth surfaces.
Is it a knock or a click? CV joints should not be discounted, esp if you or a previous owner has launched hard.
The previous suggestion is also valid - check wheel nuts.
Good luck!