Changed to flats - getting fret buzz

[project_c]

I put some TI Flats on my PJ (which was levelled and setup to perfection by a pro only a couple of weeks ago), and now I'm getting some fret buzz on the E string (8th fret). On closer inspection, I can see that the cause of the buzz is that the string is hitting the 6th fret. Am I correct in assuming that the neck will need a little more relief to fix this?

Also, does anyone know why changing to a different brand / type of string would cause buzzing on an otherwise perfectly set up bass? (the previous strings were Roto's, not sure if that has any relevance).

[CapnSev]

TI's are really, really low tension, and tension varies from string to string depending on brand and gauge.

Some setting up is usually required every time you change type/brand/gauge of string.

Back off the truss rod slightly, or raise the E string saddle a little bit, no big deal.

[Lo-E]

Yup. Changing strings to a different type (or even just a different brand) can change the string tension, requiring a neck adjustment.

You could take it back for a new setup, or just loosen your trussrod 1/10 of a turn at a time until it feels just right.

[project_c]

Will do - many thanks for the advice.

[elgecko]

You might get away with just raising the string.

Different strings have different tensions/diameters and will affect the neck different. Setups are only valid for one type/diameter/tension string.