I have to address it. It’s such a big part of a lot of young bass players world that I have to. I may not like it, but as a responsible mentor and guide, I must.
Downtuning. Tuning the strings on your bass lower than the standard (B)EADG(C). I think players are doing this to emulate certain grindy metal sounds they hear on their favorite albums. Back in my day it was a trip that Black Sabbath tuned to C# (C-standard) on some of their albums. And apparently even lower on later stuff that I didn’t listen to.
Ok. So you’re doing it. And I think I know why. So what are the pitfalls, challenges, problems and obstacles? And how can you deal with them? Here’s what I know. Although I don’t even pretend that it is a complete picture of the downturning world, I hope it helps some readers.
First, a review. Putting strings on a bass guitar and tuning them to pitch, puts a certain amount of tension on the neck: as much as 150 pounds or more, pulling the headstock towards your audience when you’re in playing position.
But the way we combat this kind of bend is with the truss rod. Its main function is to fight the strings. It typically pulls the neck backward, moving the headstock toward you and away from your audience. You might think that the ultimate aim is to make the neck perfectly straight. In most cases, no. That is wrong. A perfect balance between strings and truss rod, making a 100% straight neck is almost certainly not what you want.
The neck of your bass guitar cannot be too bent, nor can it be too straight. It has to have just the right amount of bend, or “relief,” in order to play right. Typically a good go-to neck relief on an average bass is 12 thousandths of an inch, or about 3 millimeters. You can measure this in the following way:
Put all the strings on your bass and tune it to standard pitch. EADG, for most of them.
Next, put a capo just behind the wire of the first fret. Like you’re playing all strings on the first fret. (This takes the nut out of the equation.)
Then hold down the E string on the fret where the neck meets the body. (The truss rod doesn’t do anything beyond that point.)
Now you can measure the straightness, or relief, of your neck How? Well, you’ve just made your E string into a straight edge. We just have to see how far the neck curves away from the string in the middle of these two points. Around the 7th fret, typically. The place where the gap is the largest. You measure the gap the same way your great grandfather measured the gaps on spark plugs: with a feeler gauge. The details can be found here.
If the relief is more than 12 thousandths of an inch, the strings are winning the tug-o-war. Tighten the truss rod to show them what for. Tighten it until the 12-thou gauge just fits between the string and the fret wire of the 7th fret but does not raise the string when inserted.
If the relief is more than 12, the truss rod is winning and it needs to back off, or loosen a little, until the relief reaches 12-thou.
Ok, great. People familiar with this website will understand this quite well. But supposing you have adjusted your. truss rod to just the right relief, and then you decide to tune all of the strings down three semi-tones. That is to say, tuning the E string to C#, the A string to F#, The D string to B, and the G string to E. Every string now rings out three frets below standard pitch. This will of course lower the tension of each string.
What happens to your neck relief? (Insert jeopardy theme here)
It will increase. The strings are not pulling as hard as they used to. The truss rod was dialed in to balance against full tension and now it is making the neck too straight. This may cause fret buzz. The strings will now rattle against the frets when played because they don’t have enough room to vibrate freely.
So what do you do? Well, you can loosen the truss rod until the relief is what you want.
This is all made more complicated by the fact that many downtuners are also moving to heavier gauge strings. The fatter the strings, the more tension they will have.
But if you put the strings on it that you intend to use, and tune them the way you intend to use them, then you should be able to set your neck relief accordingly. Then and only then.