Wazkelly Build diary for DIY closing down sale Ash J Bass

[wazkelly]

Hi Simon, things measured up perfectly with lighter gauge strings where high G was 0.45 but had to shorten things up a fair bit moving up to a slightly thicker gauge. Always use an electronic tuner to tune and check intonation and have found myself too far forward on the treble side. Stock bridge measures 80mm wide by 45mm deep and that identifies lack of depth as the issue. Could always revert back to lighter gauge strings but now looking at bridges with about 50mm to 60mm depth to give me the string gauge flexibility. I will use some masking tape as marker reference points once I get around to doing the re-fit to save time and also help with positioning.

[Simon Barden]

That should do it.

You can pay an awful lot for a bass bridge. I once bought a collection of bass parts from eBay to put together a P-bass. It was from someone who played in a Shadows tribute band (so you can guess the body colour), who had bought the bits but never got round to putting them together and had since bought a fiesta red P-bass. I wasn't taken by the bent tin bridge that came with it, so I looked on eBay and managed to pick up a used ABM lock-down bridge for £40/A$64 when they were just under £200/A$320 in the shops. Made a big difference to the sound and really evened out the string-to-string response. Not sure I'd be tempted to pay quite that much for a new one when there are very similar models for a lot less money, but it shows that spending a bit more can make a big difference.

[wazkelly]

Sounds like you scored a bargain there Simon.

Have been playing both the J Bass & the Tele a bit tonight and took these shots of the measurements to high G bridge saddle and also to the 12th fret with the long ruler placed against that string and butted up against the inside edge of the nut.....


As you can see in the first shot scale length for these is supposed to be 34" yet the high G saddle is about 1/8th of an inch short of that and still a little bit flat thus requiring a small amount less string length. 2nd shot is taken above the 12th fret which should be 17" and if taken along edge of fret board that would have very, very close.

Fairly satisfied that original position of bridge was OK for the lighter gauge and have today ordered a Gotoh style bridge that has 8mm more forward travel and that should be sufficient for this set of strings. Funny how camera angles can distort things?

[Simon Barden]

It's weird that G saddle is forward of the 34" position. It may be a peculiarity of that particular string. Unfortunately, bass strings aren't cheap, so it's not as practical as on a guitar to simply try another set of strings on.

[wazkelly]

Had me scratching my head too as with the lighter gauge it was spot on???

I did read somewhere that string thicknesses do affect the intonation and thus requiring string length to be adjusted which makes sense. It just requires a bit of experimentation in either direction to figure out which way is correcting the problem. Usually Flat means string needs shortening which is what I did on this baby, and yes remainder 3 other strings also required some fine adjustment too.

Edit: D'addarios are not cheap but these ones feel as smooth as for a set of round wounds so no chance of changing these in a hurry.

[DrNomis_44]

I have a set of Bass strings on my Squire P-Bass where the thickest low E-String is a 105 gauge, as far as I can tell, the intonation is pretty well spot on, I'll post a pic so you can see where I have all the saddles positioned.


Incidentally, I have a set of Elixir Strings in 42 to 09 gauge on my Hot Rod Strat, and I have the low E-String saddle set so that it is as far back from the neck that it can go, but it still reads as being slightly sharp, my conclusion is that they positioned the bridge-routing a bit too far towards the neck than it should have been.

I'll also post a pic of where I have the string saddles positioned for the Hot Rod Strat.


Here's a pic of the bridge on my Squire P-Bass guitar, the little black mark near the number 17 indicates where the scale length measurement is for the distance between the nut and 12th fret ( I used my longest metal ruler which is 600mm in length and has scale markings in both mm and inches, I used the inches scale for the measurements in this case), the bridge is made by Gotoh:




Here's a pic of where I have the string saddles positioned on the HotRod Strat's bridge, as you can see, the saddle for the low E-String is set pretty much close to it's limit for lengthening the string, and it still reads a bit sharp:

[Simon Barden]

Well, the frequency of a given length of a string is all related to the square root of the string tension divided by the mass per unit length. So for a thicker string, the mass per unit length is increased, so the tension also has to increase in proportion to give the same frequency. On wound strings, the core wire really provides most of the tension element, whilst the wrap provides most of the mass. Different manufacturers will use different combinations of core wire diameter and wrap thickness to give different tensions for the same overall string diameter.

The actual string length is always slightly hard to define exactly because (and especially with thicker strings), there is a small part of the string at the two fulcrum points that isn't really vibrating, so the overall string length becomes slightly shorter. This is one reason why the bridge saddles are normally further back than you'd expect from measuring the nut to the 12th fret distance and doubling it. As the non-vibrating length of string is always the same length for a given string, then the proportion of the string not vibrating is higher with the string fretted at the 12th fret, than with an open string - or conversely, the length of the vibrating string is proportionally shorter when fretted at the 12th fret, so the bridge saddle needs to be moved backwards to compensate.

It's an iterative process, because as you move the saddle back, the overall string length increases so you then need to increase the string tension, measure again, then adjust position, increase string tension, measure again etc. Almost impossible to get it perfectly in tune.

So maybe Waz, there's some slight variation in string thickness on your G string that means the bridge end of the string has a slightly higher mass per unit length than the nut end of the string. But without cutting it up into little equally sized pieces (a feat in itself) and weighing them on a very accurate scale, you'll never know for sure.

[Simon Barden]

The Doc's photos illustrate my point above well. The thicker strings gave a longer 'non-vibrating' length, so the saddles step back nicely according to string type and size.

(Obviously the 'non vibrating' string section isn't all non-vibrating and increase from zero at the fulcrum to a value at some point along the string where it can said to be fully vibrating, but it's easier to imagine if you just say 'non-vibrating').

[DrNomis_44]

That distortion in the camera-angle could be something like parallax distortion, I could be wrong though.

[Simon Barden]

There's a very small amount of curvature in the picture, probably due to the wide-angle lens of the camera, but as the 12th fret is fairly close to the centre, any distortion should be the same on both sides of the picture. Also, as we now know that there is a slightly shorter distance from the 12th fret to the G saddle that from the 12th fret to the nut, it's probably not distortion at all.