JTV 69 goes out of tune with 9 gauge strings

[grandinq]

I got my JTV 69 about a month ago, and switched it to 9 gauge strings, which I use on my other guitar.  I had it professionally set up, but I find it goes out of tune a lot.

 

Would going back to 10s with another setup help, or is there some other issue?  I thought it might be humidity, but I keep 3 other guitars stored in the same areas as the JTV and they all stay in tune.

 

Thanks!

[snhirsch]

Achieving stable tuning on any floating tremolo system can be a bit of a black art.  A couple of things to look at:

 

- Is the bridge plate absolutely level when you look in from the lower strap button end?  I've seen a lot of cases where folks try to adjust treble and bass string height by cranking the pivot posts to different heights.  That's a non-starter on this type of bridge.  It needs to be absolutely level with the height adjustment made only at the bridge pieces (or in extreme cases by shimming the neck).

 

- Try removing the middle spring and retensioning the remaining two.  Sometimes you get more linear behavior that way.  While you have the spring cover off, check very closely for anything that might be binding or rubbing against the guitar body.  On older 69s the cable dressing was a particular problem.

 

- Dan Erlewine and others recommend that you bend the hook at the bridge end of the tension spring to match the angle of the hole it seats in (when tuned to pitch).  You don't want the spring being torqued laterally as the bridge moves back and forth.  This can be a bit tedious to do, since you need to relieve tension in order to get the hook out each time.  I think it does make a difference.

 

- When you look at the bridge from the side, the rear should be about 3/16" higher off the body than the front.  I find this gives the best stability - YMMV.

 

- More expensive and invasive options:  Replace the plastic nut with a lubricated Graphtec.  Install a MagLok.  The MagLok is not a magic bullet for tremolo stability problems, but if you have all the other issues addressed it can help get you that last little bit of accuracy when setup correctly.

[Charlie_Watt]

Just because you had a "professional" set it up doesn't mean it was done right.  The trem spring tension will have to be readjusted when changing string gauge.  Lighter gauge strings require less spring tension.  The nut is also wrong when you change string gauge.  Strings may hang up in the slots which will be too deep. 

[jandrio]

my 69s maple fingerboard plays with 9's absolutely in tune.

u need a "proper" setup...

[grandinq]

Thanks for all the advice! I will look into these options.

[pinoy1]

Just because you had a "professional" set it up doesn't mean it was done right.  The trem spring tension will have to be readjusted when changing string gauge.  Lighter gauge strings require less spring tension.  The nut is also wrong when you change string gauge.  Strings may hang up in the slots which will be too deep. 

Charile_watt, how do you "loosen" the trem spring tension on a 69JVT?  I'm sorry, I'm just a novice when it comes to guitar hardware adjustment.  I'm asking the questions because I just recently changed the string gauge of my 69s JVT to 9's.  

Thanks.

[edstar1960]

Charile_watt, how do you "loosen" the trem spring tension on a 69JVT?  I'm sorry, I'm just a novice when it comes to guitar hardware adjustment.  I'm asking the questions because I just recently changed the string gauge of my 69s JVT to 9's.  

Thanks.

 

The springs are stretched between the trem block and a claw that is screwed into the body - the tension is controlled by the distance between the trem block and the claw fix points.  The screws that hold the claw into the body can be loosened which moves the claw fix points nearer the trem and will lower the tension produced by the springs as they are not stretched as far- conversely if you tighten the screws and move the claw fix points further away from the trem then the springs are stretched further and more tension is produced.  You adjust the amount of tension to suit what you feel comfortable with.

[Charlie_Watt]

You want to adjust the spring tension until the trem plate is level with the guitar body when the strings are in tune.  There is a balance between spring tension and string tension with this style of trem.  Lighter gauge strings require less tension so you will have to loosen the screws that hold the springs to reduce the spring tension.  It's an easy adjustment to make.  You have to take the plate off the back to access the springs.

[pinoy1]

The springs are stretched between the trem block and a claw that is screwed into the body - the tension is controlled by the distance between the trem block and the claw fix points.  The screws that hold the claw into the body can be loosened which moves the claw fix points nearer the trem and will lower the tension produced by the springs as they are not stretched as far- conversely if you tighten the screws and move the claw fix points further away from the trem then the springs are stretched further and more tension is produced.  You adjust the amount of tension to suit what you feel comfortable with.

Thank you edstar for the clear instructions on how to loosen the trem spring tension.

[jandrio]