I had to adjust the truss rod quite a lot as it arrived with a neck shaped like an English longbow.
How much did you have to adjust it? Half a turn would be "a lot" on a normal, fully functioning instrument, unless the truss rod wasn't tightened AT ALL at the factory. That would actually be cause for concern in itself, as the bass should never have left the factory like that.
Any in any case, if the neck had shifted THAT much after it left the factory... That's not a good sign.
If you had to tighten the truss rod close to a full turn or more when it arrived I would start to get worried. That shouldn't be necessary on a fully functioning neck/truss rod, and would be a sign of an unstable neck or a faulty truss rod. I mean, we're not talking about an entry level Ibanez SR with an ultra-slim neck here. Slim necks on cheap basses can bend like bananas and may need the truss rod to be tightened quite a bit with high tension string. But on a Vintera P-bass? Those wider, chunker "vintage style" P-bass necks should be able to handle high tension strings without going nuts with the truss rod.
Even with the truss rod loosened all the way (which shouldn't have been the case on a brand new bass) the neck shouldn't be "shaped like an English longbow" with these wide/chunky Vintera necks. At least not with the factory installed 45-105 roundwounds.
Having to tighten the truss rod a bit when going from the stock roundwounds to Fender 9050ml flats is perfectly normal, but it shouldn't need much more than around a quarter turn (provided that the neck relief had already been adjusted correctly with the stock roundwounds of course). If we're talking about more than half a turn when going from the stock rounds to the Fender flats I would start to get worried.
The wide/chunky necks on these basses SHOULD be able to handle high tension flats just fine (in theory...). In fact, if any currently made Fender bass should be able to handle high tension flats it's the Vintera P-basses (and the AVRI IIs, which also have the wider vintage-style P-bass necks). But a bad neck is a bad neck, no matter how chunky/wide it is. All pieces of wood are different.
its shifted very slightly since,but I'm assuming that's because it's new and needs to settle and changes in temperature.
How much is "very slightly"? With changes in temperature/humidity throughout the year it would be normal to have to adjust the truss rod maybe once or twice every year for a perfect setup. Cheap necks made from poor quality wood typically need more/bigger adjustments than high quality necks. It shouldn't need more than a quarter turn though. Anything more than that for a seasonal adjustment would be the sign of an unstable neck.
The fact that the bass is new shouldn't matter. Any smaller adjustments to to the truss rod should stabilize within couple of minutes. Sometimes, if you need to adjust the truss rod a lot (half a turn or more) the neck might need a couple of hours to settle. But not three months.
I'd really like to install the la bella 760m as I love the duck dunn jamerson sound,but I'm worried about my neck warping.i don't know how well made the vintera necks are and whether they'd hold up to the extra tension.
The wider, chunkier necks on Vintera P-basses SHOULD be able to handle these strings. But all pieces of wood are different. If your neck has stability issues, it might not be a good idea. But if the neck is really that bad it should be returned. Whether this is actually the case is impossible for me to say without inspecting the bass myself.
Does anyone know how much more tension they have compared to my fenders?I don't mind the stiffer feel,and I like the idea of being able to get the action nice and low.i know the next gauge down are la bella 760fs,but again,how do these compare to the fenders?am I worrying unduly about the neck?I'm not sure how much play there is in the truss rod if the neck were to bow markedly.
sorry for waffling,but any thoughts would be appreciated
The 760M will obviously have more tension than the Fenders, but how much is pure guesswork.
You could try the following:
Loosen the string tension, and loosen the neck to get proper access to the truss rod.
At this stage (without the tension of the Fender flats) the neck will probably have a bit of backbow.
Try tightening the truss rod a bit further (which will bring the neck into a further backbow, but as long as you don't let the neck sit this way for long time it won't cause any damage). If you can still tighten the truss rod AT LEAST a quarter turn you will PROBABLY be fine with the 760m. If you can tighten it even further, you will almost certainly be fine (but don't go much further than a quarter turn when doing this test, and stop IMMEDIATELY if the truss rod gets much harder to tighten).
If you can't tighten the truss rod AT LEAST a quarter turn further (from the point where you have correct neck relief with the Fender flats) I would say the neck is probably faulty, and you should return it. Whether Fender will agree with this assessment is a different matter of course... And I have to stress that I can't say anything for certain without actually inspecting the bass myself.
Make sure to loosen the truss rod back to where you started before you re-install the neck and the Fender flats.
Of course, even if you CAN tighten the truss rod further, there's no way of knowing how this neck will actually behave with the LaBella 760m, or how this specific neck will handle the tension over time. Those are rather extreme strings. Are you sure you will even like them? I'm guessing most bass players probably won't, and a more "normal" set of LaBella flats (like the 760FL) will get you pretty close. At least tonally (and they will also intonate better). The "feel" will of course be a bit different.
We can discuss tension charts all day long, but the only thing that matters is how the neck/truss rod actually works in real life. Based on your description I have to admit I get a slightly bad feeling about that neck. But like I said before, it's impossible to know anything for certain without actually inspecting the bass.
In that case I wouldn't worry too much about testing the LaBella 760m. The Vintera P-bass necks are more robust than most, and should be able to handle the tension. Of course, there's no way of predicting how the neck will behave after several years with those utterly insane strings, but that's a risk you have to take if you want to try them. For the short term it will probably be fine.
