Bit Of Truss Rod Science Please!

theevilplankton

theevilplankton

Jul 9, 2009
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#1
I’m the lucky owner of an American Vintage 2 P-bass. And I’ve got a dilemma…..to be posted elsewhere…..

Anyhow, my question here….the AV2 has the truss rod at the heel of the neck……for me, bit of a pain.

My bass is tuned to standard pitch for one band, but my main band plays in Eb.

I think my action is about ‘standard’, so a slight down tune, it should still be playable, if a bit more floppy.

Question is, when I do that, maybe leave the bass for a few days, and then afterward return to standard pitch, would the truss rod move?

Appreciate it may sound like a daft question, but I’m happy with how it plays now, and don’t won’t to compromise anything by detaining…..and then the faff of adjustment. And if I keep it as my sole P bass - an option - it may be a procedure I have to repeat given the two bands different tunings.

Any thoughts? 👍
 
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#2
theevilplankton said:
I’m the lucky owner of an American Vintage 2 P-bass. And I’ve got a dilemma…..to be posted elsewhere…..

Anyhow, my question here….the AV2 has the truss rod at the heel of the neck……for me, bit of a pain.

My bass is tuned to standard pitch for one band, but my main band plays in Eb.

I think my action is about ‘standard’, so a slight down tune, it should still be playable, if a bit more floppy.

Question is, when I do that, maybe leave the bass for a few days, and then afterward return to standard pitch, would the truss rod move?

Appreciate it may sound like a daft question, but I’m happy with how it plays now, and don’t won’t to compromise anything by detaining…..and then the faff of adjustment. And if I keep it as my sole P bass - an option - it may be a procedure I have to repeat given the two bands different tunings.

Any thoughts? 👍
Click to expand...

As a veteran Truss Rod Scientist, I can answer that! Basically No; the truss rod won't move if you de-tune the bass. Not unless you turned the adjusting nut.

The question really is: Will the neck move? Will it flatten out slightly when you lower the tension on the strings? Which could cause buzzing, and would require loosening the truss rod a little bit. The answer is: Probably not. Unless it's a really thin springy neck. Detuning a half step isn't much, and a Vintage P-Bass neck should easily handle that without moving. If you were detuning down to D or C, then you might see some movement of the neck.

But even if the neck does move detuned to Eb, it's not a big deal. Loosen the truss rod a little bit, and work with it to get the relief right when playing in Eb. Then when you re-tune back up to E, you may have slightly more relief than you had before. But it should play just fine. And you should be able to flip back and forth between Eb and E without having to adjust the truss rod again.

What I'm saying is: If you do see the neck moving when you detune, then optimize the setup for the lower tuning. It will still be fine when you take the tuning back up.
 
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#4
Bruce Johnson said:
As a veteran Truss Rod Scientist, I can answer that! Basically No; the truss rod won't move if you de-tune the bass. Not unless you turned the adjusting nut.

The question really is: Will the neck move? Will it flatten out slightly when you lower the tension on the strings? Which could cause buzzing, and would require loosening the truss rod a little bit. The answer is: Probably not. Unless it's a really thin springy neck. Detuning a half step isn't much, and a Vintage P-Bass neck should easily handle that without moving. If you were detuning down to D or C, then you might see some movement of the neck.

But even if the neck does move detuned to Eb, it's not a big deal. Loosen the truss rod a little bit, and work with it to get the relief right when playing in Eb. Then when you re-tune back up to E, you may have slightly more relief than you had before. But it should play just fine. And you should be able to flip back and forth between Eb and E without having to adjust the truss rod again.

What I'm saying is: If you do see the neck moving when you detune, then optimize the setup for the lower tuning. It will still be fine when you take the tuning back up.
Click to expand...
Absolutely awesome response, thank you so much! 👍👍👍
 
#6
Tuning down a half step will indeed reduce the relief of the neck, IME. The question is whether or not it will reduce it enough to negatively affect the way the bass plays. That's partially subjective, and partially based on what your relief is in E standard tuning. If you play with a fair amount of relief in E, you'll certainly be fine in Eb. The bigger problem will be that your intonation will get a bit screwy. OTOH, if you play with very little relief in E standard, then detuning all four strings can lead to a poor playing bass (in addition to the intonation problems).

If you will be going back and forth between the two tunings, the best path to take is to use a healthy amount of relief in E standard. You'll likely find that it plays "better" than factory specs this way anyhow.

I never go back and forth between tunings on the same bass. Too many compromises with proper setup. Better to use two basses, even if one of them is just a cheap-O. That lets you set each one up to perform its best – including with different string sets (heavier strings on the Eb bass).

As an example of what tension differences you get from different tunings, let's take a set of GHS Boomers Mediums (M3045).

E tuning on the left, and Eb tuning on the right:

.105: 42.2 – 37.6
.085: 49.4 – 44.0
.065: 50.2 – 44.7
.045: 44.8 – 39.9
Total: 186.6 – 166.2
Percent tension reduction by downtuning the bass a half step: 11 percent

Compare that to going to a set that's .005" lighter across the board:

.100: 37.8
.080: 45.0
.060: 42.2
.040: 33.6
Total: 158.6
Percent tension reduction from M3045 set: 15 percent

So, by these tension figures, you can see that the effect of downtuning half a step will have a little more than 2/3 the effect on the neck as will using the next step lighter string gauges. 10–15 percent tension difference is significant enough to require a truss rod adjustment (as well as an intonation adjustment, and ideally, string height too).
 
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#7
tpaul said:
If detuning one half step caused the truss rod to move, we'd all be adjusting our truss rods after every string change.
Click to expand...

But that is actually something most of us WOULD do (or at least SHOULD do) if we're changing to different tension strings. The difference in tension when detuning from E to Eb is comparable to the difference you get when changing from 45-105 to 40-100 strings. With most basses this means the truss rod will need to be adjusted for a good setup. Not because the truss rod itself has moved of course, but because the neck has moved and the truss rod needs to be adjusted to compensate for this.

Having said that, those chunky American Vintage P-bass necks are sturdier than most. I'm sure it will be ok with those.. It should be possible to adjust the truss rod for an amount of relief that will work fine with both tunings, although possibly with a small compromise, maybe a tiny bit too much relief with E-tuning. The important thing here is that the truss rod should be adjusted in Eb-tuning, to make sure there won't be any fret buzz in lower frets when downtuning, due to insufficient relief. Slightly too much relief in E-tuning will be MUCH preferrable to insufficient relief i Eb-tuning.

If this bass had been something like an Ibanez SR with a much slimmer/softer neck, the truss rod would probably have to be adjusted between the different tuning for a good setup. But those chunky vintage-style P-bass necks are pretty much in a category of their own. They're usually very sturdy (depending on the quality of the wood of course).
 
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#8
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#9
Killing Floor said:
Not a teussrodolologist but I think the most appropriate solution is everyone with a bass or guitar that adjusts at the heel should take at least one right hook at everyone who does that to their customer. Just me?
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It's better in the long run for the neck, and it adjusts more of the area your playing over. As long as there is a slot for the Allen key Id prefer heel adjust. I had an MTD 6 string that had heel adjust and it was almost a 2k$ instrument.
 
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#13
Generally, a 1/2 step detune in the real world should result in little or no movement in the relief. As others have pointed out, different strings in even slightly different gages could generate more of tension change. If you were going down to C or B or tuning up several steps, but a half-step? Not much if anything IF IT HAS a properly adjusted truss rod at standard pitch.

You could check relief at standard pitch, then check it again down a half-step to see if it actually moved. If it did, it would / should be just a very tiny fraction of an inch, if at all.
 
#14
theevilplankton said:
I’m the lucky owner of an American Vintage 2 P-bass. And I’ve got a dilemma…..to be posted elsewhere…..

Anyhow, my question here….the AV2 has the truss rod at the heel of the neck……for me, bit of a pain.

My bass is tuned to standard pitch for one band, but my main band plays in Eb.

I think my action is about ‘standard’, so a slight down tune, it should still be playable, if a bit more floppy.

Question is, when I do that, maybe leave the bass for a few days, and then afterward return to standard pitch, would the truss rod move?

Appreciate it may sound like a daft question, but I’m happy with how it plays now, and don’t won’t to compromise anything by detaining…..and then the faff of adjustment. And if I keep it as my sole P bass - an option - it may be a procedure I have to repeat given the two bands different tunings.

Any thoughts? 👍
Click to expand...
I have a $550 solution that has nothing to do with the setup of the bass.

If everyone else is happy with tuning down and changing setups and strings to accommodate, that's fine, carry on.

I play in one band where the artist requests we tune down. Consequently, the cover version of that band does the same.

I futzed with all of the tuning-down tricks for a year. NEVER got the feel right. Not the action nor the setup, but the feel, the playability of whatever bass I was attempting to set up for 1/2-step tuning. I hated it. With me so far?

I noticed the guitar players using a Digitech Drop. I tried one, not happening. It was fine on guitars, but didn't do well with the lower range of the bass.

I exchanged the Drop for a Helix Stomp. The Stomp has solved any and all issues I had with playing down 1/2-step. My basses feel and play like they always did. It's set up like I prefer, and it's 99% effective for the entire range of the bass. And I can use whatever bass I feel like playing on a particular given night. I carry two basses, one primarily as a spare. Sometimes, I'll pick up the spare somewhere in the show or the gig.

It has been a great solution to the tuning-down scene. For me, anyway.
 
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