Buzzing Strings help please

Hi Guys, looking for a bit of help please.

I have just picked up another Cutlass Classic (slight Frankenstein - pics to follow) which was sett up really well with 10's, lovely low action, no issues, just not my preferred string gauge.

I have just changed them over to a set of 9-42's and after tuning to pitch I am getting buzzing across all strings up to the 9th fret and then everything is fine from there.The action is still very usable but would prefer no buzzing obviously. I have looked through my Dan Erlewine Guitar player repair guide so far to no avail.

If someone could explain what is happening and how I can adjust it that would be most appreciated rather than me just jumping in and potentially creating more issues. Please excuse my knowledge base at this stage.

Much appreciated, Si

Truss rod needs adjusting.  The 10's had greater tension, pulling the neck straight or with very slight relief.  The 9's don't have as much pull, allowing the neck to back bow more, causing the buzzing on the lower frets.  Loosen the truss rod a quarter turn or so which will add more relief.  This should do it.    Let me know!

Thank you Chad, that did the trick, certainly won't forget that now, very much appreciated as always and now I can gig her this coming Saturday.

Super cool, those are sweet guitars that we don't see on this side of the pond! 

And that thing must have had a super straight neck to cause buzzing with 9's... sounds like a great guitar you have there.

I love learning new things particularly to do with guitars at the moment Chad and strangely enough I had just read the opening chapters of the Erlewine book (Xmas gift) which goes into necks and adjustments but I guess it's a confidence thing (felt a bit of a numbty raising the question) but put as plainly as you did it makes sense in a practical way.

The new Cutlass is a classic with the addition of a middle single coil like the Corsair Classic only this has the advantage of still being the Alder wood body which I prefer. The neck is a hybrid which has both the usual side markers but also main board inlays. Really enjoying having those extra positions. When I get a moment I will put up some pics.

Thanks again

Pics for sure, looking forward to them!  Rock that thing this weekend...

Congrats Si. Yes, pix please when you can. We could use a few to go with the blurb on the web site.

Job done, had the new album launch last night, the new cutlass played out just fine...

https://s1016.photobucket.com/user/Meadows61/library/Rise%20Up%20Album%20Launch?sort=3&page=1

Very cool, thanks for sharing!