More set up issues - intonation's off when I detune

[Jono Bolton]

I'm having trouble intonating my Peavey Foundation when it's detuned to C# (all 4 strings down 3 semitones). The main issue is the 4th string (low E/C#). Even though the string is in tune, and it's intonated correctly at the 12th fret, it's quite out of tune between the 2nd - 8th frets. The 5th, which should be tuned the same as an open 3rd string, is about a quarter tone sharp. It's very noticeable. I don't have this problem when tuned to E standard.

When I had the Peavey tuned to C#, I was using Newtone High Tension strings and when I tuned it to standard I had a set of D'Addarios on that came off my P Bass. The Newtones went on to the P Bass and had no problems with it. I don't know is that means it's down to the strings or not. The only other thing I think it could be is that the neck pocket it slightly too large for the heel of the neck. When I'm tuned to E the neck seems stable enough, but when I'm at C# there's certainly a bit of give and I can wiggle it ever so slightly side-to-side. Is that because of the reduced tension when the strings are tuned down? Any ideas what could be causing the intonation problems?

[Thunderbird]

Have you tried a shim at the side to see if it helps I would think if the neck moves it can't do the intonation any good

[Jono Bolton]

[quote name='Thunderbird' timestamp='1424006186' post='2691407']
Have you tried a shim at the side to see if it helps I would think if the neck moves it can't do the intonation any good
[/quote]

Not yet, but that was my next course of action unless someone else came up with a reason I may not have thought of.

My thinking is that the tension of the D'Addarios when tuned to E is higher than that of the Newtones in C# (even though they're meant to be high tension strings). When the D'Addarios are at E the tension is helping to hold the neck firmly in place, this stopping any intonation issues. When the bass is tuned down to C# the lower tension allows the neck to move in the pocket this causing the intonation to be out, although I can't work out why it would just be on one string.

A shim on either side of the neck will hopefully sort it out as the Peavey sounds great and suits my band's style better than the P Bass.

[88reaper88]

Necks shouldn't move even with the strings off. Shim it!

[iiipopes]

Nut slot and nut compensation. First, check the nut slot to see if it is as low as it will go without buzzing with your normal playing style, and has a good leading edge witness point and a smooth slope back to the tuner. It will pull sharp otherwise. If it doesn't do it at standard tuning, I would bet if you put it on a tuner, it does pull sharp in standard tuning, just not enough to be noticeable.

Second, your nut may need compensation like mine did:
[url="http://basschat.co.uk/topic/174777-and-now-for-something-completely-different-in-a-pj/page__p__1633365__hl__different__fromsearch__1#entry1633365"]http://basschat.co.uk/topic/174777-and-now-for-something-completely-different-in-a-pj/page__p__1633365__hl__different__fromsearch__1#entry1633365[/url]

It is more thoroughly explained here:
[url="http://www.mimf.com/nutcomp/"]http://www.mimf.com/nutcomp/[/url]

[Bloodaxe]

Check your relief. You've downtuned three semitones so there is a lot less force being exerted on the neck. As a result it'll have relaxed & may even have a slight back bow.

Tension is not the same thing as 'stiffness'. It takes a set amount of tension to take a string up to pitch for a given scale length - this is universal. If it takes 100Lb/Ft to get a 34" G string up to pitch on a 1951 Precision, then it'll take exactly the same pull to hit pitch on a 2015 Jazz. This is caused by Physics.

Odds are the Newtones are engineered to have a greater resistance to bending so they [u]feel[/u] as though they have more 'tension', the 'High Tension' bit ought to be re-named 'Low Compliance' or 'Extra Stiff'.

More on that here:— http://liutaiomottola.com/myth/perception.htm

Big +1 on sorting out that neck pocket though, it shouldn't move around at all. See if the screws will take a turn with the strings off or slack - it [i]might[/i] be that at standard pitch the strings are gradually stripping the threads in the heel.

Pete.