Are Low Action and String Tension Related?

[Dennis D]

I saw a mention in another thread of how scale length can impact low action and string tension. Is this true? If so, how ? I guess I can't seem to get the concept of why I can't have low low action with the same string tension as though the action were set much higher. And what would the scale length have to do with how the bridge and neck are set ?
The luthier I use, and I know he's good - -seems to have a benchmark he uses, and it seems to take me several times whenever I change string gauges to get the string height close to where I like it.
I know there are truss rod adjustments luthiers do, and then bridge adjustments, etc etc..I just think luthiers can do anything, so ok, can I have low action but with string tension like a cheapie guitar ?? Or if not why not? Do I sound baffled,'cause I am.
Thanks - Dennis

[jzucker]

you don't need to make any adjustments to the truss rod when you lower the action. It probably does change the tension in some miniscule when you adjust the string height but unless you are making a huge change in string height (something on the order of 3/16) it would not enough to require any other adjustment.

[NiAg]

Hi Dennis:

>>> scale length can impact low action and string tension. Is this true?

No, scale length does not directly affect action.

Yes, scale length directly affects string tension.

String tension is affected mostly by: the string size, the scale length, and the pitch to which the string is tuned.

Now the pressure needed to deflect a string down toward the fret is mostly affected by string tension, but is also affected (more subtle, but it's there) by the string length beyond the nut and bridge. No, really. It's a long explanation, but it is also simple fact.

>>> I guess I can't seem to get the concept of why I can't have low low action with the same string tension as though the action were set much higher.

Action height has no affect on string tension. There is no concept to get.

>>>And what would the scale length have to do with how the bridge and neck are set ?

Scale length has no specific direct affect on how a bridge and neck are set. You gotta stop reading the National Enquirer luthio-section?

[Zuck] >>> you don't need to make any adjustments to the truss rod when you lower the action.

This is not necessarily true at all. Yes, changing the action has almost no bearing at all on the relief in the neck. But for many players, the preferred relief changes significantly as the action is lowered.

[Zuck] >>> It probably does change the tension in some miniscule when you adjust the string height

It does not. There is a set of long-standing myths regarding string tension, so some confusion is understandable.

[Dennis] >>> seems to take me several times whenever I change string gauges to get the string height close to where I like it.

That is a MUCH different issue. When you change gauges, you change the tension, by quite a bit. The pressure required to fret a note may not seem to change much, but the total tension of the six strings can change by about as much as hanging a canned ham off the neck.

>>> can I have low action but with string tension like a cheapie guitar ??

Lets make sure that by "string tension" we refer to the tension, in pounds or Kg, of the string at rest, unfretted.

I can not relate 'cheapie guitar' to a given string tension. Again, action height is not a factor in string tension. BUT,...

Action is a factor in how far you need to move the string to fret a note. And the farther you deflect the string off its preferred path, the more pressure you will need to apply.

Sorry if any of this confuses.

[jzucker]

[Zuck] >>> It probably does change the tension in some miniscule when you adjust the string height

It does not. There is a set of long-standing myths regarding string tension, so some confusion is understandable.

You're wrong about that. Think about the geometry involved. As you raise the bridge you are increasing the length of the string. Think of the nut, the tailpiece and the bridge as the 3 angles of a triangle. As you extend the bridge you are actually lengthening the perimeter of the triangle ever so slightly. Not enough to require a truss rod change IMO.

Also, most modern guitar setups do not add additional relief when the action is lowered. I think you just confused the OP !

[NiAg]

>>> You're wrong about that.

I disagree with your opinion. I also try to keep out of the picayune and stick with what has some practical application.

>>> Think about the geometry involved.

I'll try. Please try to be patient with me.

If one really wants to pick nits, then consider that string height, when changed by a bridge height adjustment, would be accompanied by a corresponding change in bridge compensation. This change in compensation would affect the scale length and thus string tension far more than the micro and hypothetical effect that you imagine.

In practice, and for the purposes of reasonably helpful discussion about guitars (what a concept), no - action height does not affect string tension in the way the original poster asks.

If we pick nits (and promote myths while at it) this will get extremely complicated.

Please try to understand that, in my opinion and experience, keeping absurd mythology out of what affects playability it a bit of a balancing act. It helps to keep some focus on practical effects. It also helps, in my opinion, to have some genuine understanding and experience combined with limited need to bicker.

>>> Also, most modern guitar setups do not add additional relief when the action is lowered.

It is my experience that many players do best with less relief as action is lowered.

In my opinion, you assumed something exactly backwards here, then disputed it.

If you want to have a Harmony Central style battle of half-info, let me know so I can step away.

[jzucker]

Nobody in the real world changes the intonation when they adjust the action. This is beginning to be one of those creepy "i have to be right" threads.

[NiAg]

Yep. Too dopey. Over and out.

[Dennis D]

..Thanks for the replies...maybe I ought to have phrased my question in a different way: " Is there some thing or things that limit a luthier's ability to significantly lower a guitar's action or playability? "..and / or " What should a perfectly set fingerboard look like - absolutely straight, or with somewhat of a bow ? "
...still curious, but thanks again ....

[NiAg]

Hi Dennis,

Saw that you posted on this thread. Sorry for the earlier drift off topic and the web-stupid vibe.

Regarding your questions:

>>> Is there some thing or things that limit a luthier's ability to significantly lower a guitar's action or playability?

Yes. Many things can cause trouble.

1. Uneven frets: A luthier can fix this under most circumstances.

2. A compound bow in the neck, or a bow that can not be brought under control with the fairly basic action of most truss rods: This is fixable, but can require some surgery. Heat can be helpful, but in practice it is difficult to get a neck/FB hot enough to affect a permanent fix. More typically, frets are removed and the FB is re-shaped.

3. Mechanical limits to the bridge: Usually a reasonably easy fix.

4. A gradual change in the neck/body angle. Sometimes this is due to a failure of the neck joint, but far more often (particularly on flat top acoustics) the body itself deforms over time (and tension, and humidity cycles) requiring a "neck reset". This involves removing the neck and reshaping the neck to body joint. This is a more common problem with flat tops than it is with archtops.

5. Playing style. Some players have technique that involves both more string vibration amplitude, AND more amplitude perpendicular to the FB surface during the attack. Players can be prickly when you suggest this, but a simple rotation of the right wrist can do wonders to reduce the vertical amplitude of the strings.

6. Poor, or ill-advised setup. Most nuts are cut too high. Many necks have excessive relief. Both of these will result in higher action (as measured at the 12th fret) at the onset of practical fret buzz.

7. Unrealistic expectations. a 1/32" action at the 12th fret is unlikely unless the player has a very controlled technique.

There are more, but these are some highlights.

>>> What should a perfectly set fingerboard look like - absolutely straight, or with somewhat of a bow

Depends.

Most setups for most players work best with some relief (a concave bow) to the neck. This is for two primary reasons.

a. The string vibrates in something of an arc (ignoring transient attack overtones here). If the FB follows this arc somewhat, then most players will experience less fret buzz at a given action height.

b. Relief results in a non-linear progression of fret clearance as you play up the FB. This non-linearity tracks well with both the playing style of many players, and it tracks well with the duration and amplitude of the transient overtones (not necessarily actual "harmonics) as you play farther up the FB.

Some players with a very restrained low-position chord technique and overall very low action, do best with almost no relief at all. Others do best with relief approaching .025" or even more in some cases.

I am a low-relief guy myself, but there is nothing wrong at all with a setup than has more relief if it helps keep a clean sound to low-position ker-chunk comping.

All in my opinion. I guess I have done some thousands of setups, but a new idea from a relatively inexperienced person may be very useful here.

[RonD]

NiAg,
"2. A compound bow in the neck, or a bow that can not be brought under control with the fairly basic action of most truss rods: This is fixable, but can require some surgery. Heat can be helpful, but in practice it is difficult to get a neck/FB hot enough to affect a permanent fix. More typically, frets are removed and the FB is re-shaped."

Have you found this to be a lasting solution?
I tried this solution a couple of times, at least, my luthiers did, and the problem re-occurred later. Now I don't bother.

What's your experience?

Cheers, Ron

[NiAg]

>>> Have you found this to be a lasting solution?

You may have lost me in pronouns.

If you mean does heating and re-shaping a neck work, then in my opinion it is often not a lasting solution.

It is really difficult (and pretty risky) to get the neck hot enough to really make a permanent fix.

Often, the glue between the FB and the neck softens FAR before the resins in the wood do. So the FB-to-neck glue joint shifts, which makes things look pretty good. Then over time (typically a month of two), things gradually go back nearly to the original condition. The tension in the neck and FB forces the glue between the FB and neck to creep back to near where it was originally.

I have had a few roaster jobs work - meaning the fix lasted. This required getting things VERY hot. But more often it is better to consider reshaping the surface of the FB to get things under control.

There are exceptions, but this is a generalized description of my experience and observation of others' work as well.

[RonD]

NiAg,

Thanks for the response.
Sorry if my question was a little confusing!
I simply meant, does heating and reshaping work?
Once, I had the fingerboard reshaped, on a late 60's Les Paul.
This worked well, for about a year... then the "twist" came back, with a vengeance! An expensive lesson, to say the least.
My current luthier describes Canada as "the place good guitars come to die!"

Cheers, Ron

[NiAg]

>>> I simply meant, does heating and reshaping work?

Often it works for a relatively short time for the reasons mentioned - the real change is only in the glue joint between the FB and the neck.

But if a given luthier claims to be able to fix a given neck primarily with heat, then I would not want my comments to seem to dispute that specific claim. Maybe he has a specific plan and a good reason to think it will work.

>>> My current luthier describes Canada as "the place good guitars come to die!"

Seasonal temperature and (often more important) humidity cycles can be tough on a guitar. So often guitars that will be fine in a stable maritime (or otherwise relatively stable) climate, will have trouble in a more cyclical continental climate. In my opinion and observation.

[RonD]

Thanks.

[Dennis D]

Thanks. I always knew there were limiting factors in a guitar's setup, but I never knew how the pieces interacted. Bottom line, my two archtops are right on, and my two electrics aren't - yet. But now maybe I know what to ask for.
Thanks again.
Dennis

[oldane]

There is one and only one string tension which will produce a given note with a given string at a given string length. The higher the tension, the higher the note and vice versa.

So....string tension is not dependent on action and relief.

String tension is dependent on scale length, since a given string will have to be tightened more with a longer scale to produce a given note as compared to a shorter scale - because the vibrating string is longer. That's why people often percieves more or less the same fretting resistance of a 13-56 string set on say a Johnny Smith guitar (short scale) as they do with 12-52 string set on a L5 (long scale) - of course provided other factors are equal (i.e. same action, relief etc.).

A higher action is harder to fret. Not because the string has a higher tension, but because the string has to be streched more to reach the fret. With very high action - such as used on archtops set up for full volume acoustic rhythm playing - it may be necessary to move the bridge back a tiny bit to compensate for the stretching of the string (one actually does the same as when one bends a note). It may also be wise to tune by fretting notes around the middle of the fretboard instead of with open strings. Ideally the nut should be perfectly compensated for the given set up (the Buzz Feiten system is an attempt to do that), but nuts rarely are that - and it doesn't need to be that big a problem if one doesn't use open strings.

I agree with other posters about the relationship between action and relief. The higher the action, the greater the desired relief. But there is a big element of personal preference here. There are players who play with high action and an almost straight neck, and there are others who has a low action with relief. None of them are wrong. Personally, I adjust the relief to provide the same "buzz threshold" all over the neck. That is also a relief that gives about the same percieved fretting resistance all over the neck which I find comfortable. I do this by feel and not by using feeler gauges.

Specifically with reference to archtops, through the years, there has been a persisting opinion that a more acute string break angle at the bridge would give a higher string tension. That's reportedly one of the reasons for the existence af adjustable tailpieces (on say some L5 guitars). I don't believe in this. Again, to produce a given note, a given string at a given lengh can have one and only one tension. What a more acute break angle does is to increase the downward pressure on the guitar top, which often changes the tone a bit. Not much, but percievable. It can be noted if one raises the bridge significantly. The Epiphone "Frequensator" tailpiece with different lenghts of string between bridge and tailpiece for the the first and last three strings was supposed to "equalize" and optimize the string tension. Epiphone soon realized that it didn't work that way, but they kept the tailpiece anyway, because it had by then become a brand identifier for their guitars which made them instantly recognizable. Actually the Frequensator tailpiece is not optimal, as it has a tendency to break. Many old Epiphones have had repairs due to that.

[NiAg]

Hi Oldane,

Agreed that there are no rules and many very good setups have some unusual properties.

On the other hand, there are typical setups that end up pleasing a large majority of players once they have the chance to try a well executed version of a classic setup.

One classic: Moderately low action of 1/16" at the 12th for the high E and slightly higher at the 12th for the low E. Relief between the 1st fret and the 14th fret (measured at the 7th) of around .010 to .015". I like a little less than .010" relief myself, but some like relief that ends up (only coincidentally) corresponding to the diameter of their B string - this makes for a quick and easy visual check on relief as the humidity and seasons change.

The above is a classic for a reason - decent fast playability all around. But there are many variations that many players love.

Again (and again), most nuts are too high. This affects playability to a surprising extent, and badly affects low position intonation.

A compensated nut can really help some situations (it's a long story). Unfortunately, it can also be poorly applied as a way to compensate for excessive nut height.

The absolute first thing in a setup is to get the nut slots down at fret height. Remarkably, this is still not really done in many cases.

***************************
Oh man, the string break angle over the bridge,... Agreed, it affects tension exactly as much as the color of your socks.

[M-ster]

... it affects tension exactly as much as the color of your socks.

I knew it! I've always suspected the color of my socks!

[NiAg]

The T-I gauge mix of 12 to 50 (vs. 12 to 52) goes SOOOOOoooo much better with argyle.

[pingu]

The absolute first thing in a setup is to get the nut slots down at fret height. Remarkably, this is still not really done in many cases.

Hi Nick,

The nut on my Ibz Archtop feels high to me
empirically by playing a F bar chord at Ist fret .......ouch !
But sighting it using that Stew mac method it would seem to be about right

Do you think there would be any value in me having a go at it with
zee Nut files ?
I'm scared of going too far and then being into a new nut
which would be beyond me and I don't want the Guit out of action
in the shop for ages

Maybe I can build up the nut slots again if you I too far ?
Some kind of plastic ? its a plastic nut
I realise experience is needed here with the files etc
(And I don't have any ........)

Im a vaguely tech kind of guy (sound eng)

ta

[pingu]

The T-I gauge mix of 12 to 50 (vs. 12 to 52) goes SOOOOOoooo much better with argyle.

If you can find somewhere that's stocking them

[Archie]

If you cut a nut slot too deep, a drop of super glue will build it back up again.

[NiAg]

Ping,

I understand Dan Erlewine to be beatified, and Stewmac to be a very successful company. Nonetheless, the advice from them on nut slot height is subject to remarkable error based on factors that really need to be set up AFTER the nut slots. It is a fundamentally unsound procedure. It is, however, simple and seemingly objective, which holds a marketable appeal. But, using the Stewmac method, you are carefully (and with a Stewmac tool!) measuring something that is subject to considerable variation that is NOT based on the height of the nut slot.

I strongly suggest that you use a procedure that isolates the nut slot height from factors that are best done later. Here is a fine write-up:

Nut Action

EDIT: On my own guitars I get the nut so low that there is no visible clearance over the first fret when using the frets.com test. I can hear the clearance by tapping on the short length of string between the second fret and the nut. The string slightly clicks against the first fret when there is a tiny but of clearance. It works. It makes low-position playing great. It improves low position intonation considerably. It is maybe not for the faint of heart.

As for doing it yourself:

>>> I'm scared of going too far and then being into a new nut
which would be beyond me and I don't want the Guit out of action
in the shop for ages

It is possible that you will go too far. It happens. Especially with brand new strings that have not settled into the break over the front of the nut.

>>>Maybe I can build up the nut slots again if you I too far ?

A deep dark luthio-secret is that nut slots are built up quite often (and very successfully) by many luthiers. It is common to have only one or two slots too low - so a fix is chosen over a brand new nut.

On a bone nut, a mix of CA and bone dust works very well. (You need to say fee-fi-fo-fum, while grinding up the bone dust, which smells awful.)

Note that CA is not really instant glue. The CA and bone dust matrix will continue to harden for many hours. So it is best to fill, then wait a while.

>>> its a plastic nut

Styrene nuts cut very quickly, so go very slowly. You can also fill a styrene nut slot with CA if the slot is not polished. Draw some 400 grit paper through the slot then fill with CA. It works.

NOW,... Really I am not suggesting that all nut slots should be filled-in rework. A nice new bone nut cut well (and per a sound method for determining height) is a better solution than a filled in slot. Nonetheless, filling is done and it works quite well if done well and with good materials.


>>>I realise experience is needed here with the files etc
(And I don't have any ........)

Yes. A crappy guitar and a few nut blanks are a better way to get the idea.

[fumblefingers]

Ping,

I understand Dan Erlewine to be beatified, and Stewmac to be a very successful company. Nonetheless, the advice from them on nut slot height is subject to remarkable error based on factors that really need to be set up AFTER the nut slots. It is a fundamentally unsound procedure. It is, however, simple and seemingly objective, which holds a marketable appeal. But, using the Stewmac method, you are carefully (and with a Stewmac tool!) measuring something that is subject to considerable variation that is NOT based on the height of the nut slot.

I strongly suggest that you use a procedure that isolates the nut slot height from factors that are best done later. Here is a fine write-up:

Nut Action



EDIT: On my own guitars I get the nut so low that there is no visible clearance over the first fret when using the frets.com test. I can hear the clearance by tapping on the short length of string between the second fret and the nut. The string slightly clicks against the first fret when there is a tiny but of clearance. It works. It makes low-position playing great. It improves low position intonation considerably. It is maybe not for the faint of heart.

As for doing it yourself:

>>> I'm scared of going too far and then being into a new nut
which would be beyond me and I don't want the Guit out of action
in the shop for ages

It is possible that you will go too far. It happens. Especially with brand new strings that have not settled into the break over the front of the nut.

>>>Maybe I can build up the nut slots again if you I too far ?

A deep dark luthio-secret is that nut slots are built up quite often (and very successfully) by many luthiers. It is common to have only one or two slots too low - so a fix is chosen over a brand new nut.

On a bone nut, a mix of CA and bone dust works very well. (You need to say fee-fi-fo-fum, while grinding up the bone dust, which smells awful.)

Note that CA is not really instant glue. The CA and bone dust matrix will continue to harden for many hours. So it is best to fill, then wait a while.

>>> its a plastic nut

Styrene nuts cut very quickly, so go very slowly. You can also fill a styrene nut slot with CA if the slot is not polished. Draw some 400 grit paper through the slot then fill with CA. It works.

NOW,... Really I am not suggesting that all nut slots should be filled-in rework. A nice new bone nut cut well (and per a sound method for determining height) is a better solution than a filled in slot. Nonetheless, filling is done and it works quite well if done well and with good materials.


>>>I realise experience is needed here with the files etc
(And I don't have any ........)

Yes. A crappy guitar and a few nut blanks are a better way to get the idea.

what about headstock length? did the Johnny Smith use the super 400 headstock as opposed to the L5 headstock to gain back some tension after relinquishing it to the shorter scale?

or is that bunk?

i have noticed that the Gibson Legrand (not having the large headstock of the old Johnny Smith) has lower tension (with the same strings and action etc) as another 25.5" guitar with a longer headstock.

[NiAg]

Fingers,

This is a non-simple part of the picture.

Yes, the length of the string that is past either the nut or the bridge has an effect.

But first let's get grounded. As Oldane said earlier:

>>> There is one and only one string tension which will produce a given note with a given string at a given string length.

I would note that he refers to the string length that is free to vibrate.

So if we have an .012" string on a 25" scale it will need roughly 23 pounds of tension to make our beloved high E.

You can have a two foot long headstock and the tension will still need to be ~23 pounds to make a high E note.

BUT,...

Once you start to fret other notes something besides this 23 pounds of tension comes into play.

Lets go back to a normal (non-two-foot) headstock and play a C note.

We press down on the string and it travels a bit off its preferred straight path from nut to bridge; it also gets pressed slightly past the 8th fret down toward the FB. All of this increases the path length from tuner post to tailpiece.

This increased path length results in higher string tension. When we let go of the string, the tension goes back (more or less) to where it was.

NOW,...

If you have 25 inches of vibrating string length (and a given action height), the absolute path length increases by some small amount as you fret your C note. Lets VERY roughly approximate this path length increase as 4/10,000 of the 25" the scale length. This number is likely wrong since I did not do any geometry to make this guess, but the idea is that it is a very small fraction of the total path length. It is also a very small absolute number.

BUT,

Since strings can move a bit over the nut and bridge, when you fret the C note, the actual path length increase, and corresponding tension increase, can draw some string from both behind the nut, and past the bridge into the 25" scale area.

So, you have to see the path increase as part of the TOTAL STRING LENGTH, not just the scale length.

So when we fret a C note, we increase the path of the string by (roughly) 4/10,000 of the 25" scale, but ONLY 3/10,000 of the total 34" of string (I decided to add a total of 9 inches of string for the trip to the tailpiece and tuner post)..

Soooooooo,...

The string length past the nut and bridge does NOT affect the tension of the tuned string, BUT it does affect the INCREASE in tension that we feel as we fret the string.

Now if we went to a 2 foot long headstock (with the tuners placed way up at the top for some reason), our path increase would be more like 2/10,000 of the total string lenght. The strings would feel like they had less tension.

All of this assumes (incorrectly) that there is no friction over the nut and bridge. But let's go one step at a time here. This is a tricky subject and covered in enduring mythology. So for simplicity I am ignoring the friction over the nut and bridge for now. I am also ignoring the friction within the turns of string around the tuner post, which can be a surprisingly large problem under some circumstances.

AGAIN: My numbers are very approximate (4/10,000 and such). They are designed to keep it a little simpler but still make the point.

>>> i have noticed that the Gibson Legrand (not having the large headstock of the old Johnny Smith) has lower tension (with the same strings and action etc) as another 25.5" guitar with a longer headstock.

Unfortunately, this observation you have made is contrary to the basic physics involved. Sorry. Presumably there were other factors involved in your observation. All things being equal, a longer headstock would result in the same actual string tension, but a reduced increase in tension as you fretted a note.

PLEASE, do not try to apply this to bending notes. There is more to it once you try to bend a note to a given pitch.