Strange intonation problem

[Funky Doctor]

I have a Geddy Lee bass with an allparts neck on it. After putting it all together, and setting the intonation all good, I noticed a strange thing. When tuning by ear, and using 5th and 7th fret harmonics, it's all good, it's in tune with itself as far as that goes. But when I play the bass it is out of tune quite bad. Upon checking the tuning with the 5th fret/next open string, for example, the A on the 5th fret of the E string and the open A string, the open A string was very noticeably flat. This is happening with all the strings on this bass. What could be the problem? Could the nut be too far from the first fret? I have no idea. I need some help bad!

[pkr2]

Whenever a neck is changed, the replacement must be exactly the same scale length as the original neck or you will have problems such as you describe.

Make sure the distance from nut to 12th fret is the same as the distance from 12th fret to bridge saddles. If the two measurements are not the same, the bridge will have to be repositioned.

[Hookus]

I would imagine that the scale lengths are the same, any variation should be able to be adjusted by moving the bridge saddles.

[Funky Doctor]

Originally Posted by Hookus

I would imagige that the scale lengths are the same, any variation should be able to be adjusted by moving the bridge saddles.

Yeah, what you said. Being a direct replacement neck, it has the same scale length. Also, the bridge is a badass 2, so it can move a long way in either direction from the middle. Thanks all the same though. Anyone else?

By the way, I checked the fret spacing and it was all good. I still have no idea what is going on.

[Hookus]

Also, the bridge is a badass 2, so it can move a long way in either direction from the middle. Thanks all the same though. Anyone else?[/quote]

That may be the ticket, I don't remember if BA2 bridges place saddles in the same place as a stock bridge. Run the G saddle all the way out, then back in 1/8" or so, and check that measurement to the 12th fret. That saddle should be your reference point for installing a new bridge, and should be pretty much right at 34". The rest of the saddles usually are set back by about the width of the string, with the exception of the B. I am beginning to think your bridge placement is off.

[Sonorous]

Originally Posted by James Hayes

I have a Geddy Lee bass with an allparts neck on it. After putting it all together, and setting the intonation all good, I noticed a strange thing. When tuning by ear, and using 5th and 7th fret harmonics, it's all good, it's in tune with itself as far as that goes. But when I play the bass it is out of tune quite bad. Upon checking the tuning with the 5th fret/next open string, for example, the A on the 5th fret of the E string and the open A string, the open A string was very noticeably flat. This is happening with all the strings on this bass. What could be the problem? Could the nut be too far from the first fret? I have no idea. I need some help bad!

It kind of sounds like the intonation just isn't set right, and thats all the problem there is. Even with really bad intonation, you can still make the 5th and 7th fret harmonics come to the same note. The whole point of proper intonation is getting that to happen while everything else is good too.

[rkmullen]

the saddles on the bridge mostly effect the intonation from the 12th fret up, if its off from the 5th-7th fret back to the nut, I would first adj. the neck, an over-bowed neck causes intonation problems past the nut, and if the neck IS adj. properly, check the string height off the nut, press the string down on the 3rd fret and look at the first fret, the string should be barely missing the first fret, you can use a business card as a gauge, if its a space bigger than that the nut slot needs to be filed lower, and dont forget to make sure you file the slot at the proper angle, or it will buzz when you play open strings.

[Funky Doctor]

I think I may have figured it. The neck was rather bowed, and the intonation was not what I said it was, in that it wsn't set properly. The intonation is getting better the more I play with it. The bridge is in the correct position and it's all good. Thanks everyone.