Neck Action and Setup Experiments!

[Ninja00151]

I leveled the frets on one of my guitars yesterday, and decided to do a little tone and playability shootout experiment.

Once fret leveled, the guitar was stringed up and neck was set dead flat. Saddles were raised so that string action is 5/64"th or 2mm at the 12th fret, without a capo (medium-low action).

I proceeded to play every note, fret by fret along the fretboard. I noticed an interesting observation. A plucked note will be initially clean on the first 1-5ish frets, but the sustained note will then "crash" into the frets somewhere, resulting in a slight buzzing. I then played a few chords to try and listen for the fret crash. Not really noticable.

Neck relief was increased incrementally, with the same test conducted. As neck relief increased, fret crash decreased.  Now there is a little problem- as neck relief increases for a given saddle height, the action increases. 

So I worked my way incrementally up to the standard .01" neck relief, and then lowered the saddles so that action was again 5/64th. I was shocked at how much less fret crash there was compared to a dead flat neck with the same relief.  I honestly thought it was placebo effect the first time, so went through the huge ordeal of trying it a few times. Even though you couldn't really hear the fret crash with chords on a dead-flat neck, the neck relief setup sounded a TON better. 

I came to the conclusion that Chords acoustically ring out substantially better with .01" neck relief vs a dead flat neck at the same 12th fret action. String crash on sustained notes was eliminated on every string but the low E, with only a little remaining on the low E. Raising the low E to 6/64th did not eliminate fret crash.

Conclusion: Sustained notes or chords experience "fret crash" on the first few frets when the neck is set too flat. Increasing relief eliminates or substantially reduces this fret crash, and is acoustically audible as an improvement in tone with chords in the same fret area. The industry standard .010" neck relief is recommended over flatter settings, even with perfectly leveled frets.

So my question goes out to you guys, what's your preferred string action? Do you measure it, or eyeball it? Personally, I use a FretGuru2... probably the best guitar tool I've ever bought.  No affiliation  :icon_thumright:

 

[Toulouse_Tuhles]

About .010ish at fret 8 when the string is depressed at fret 1 and the fret that joins the body, and about 4.5/64 on low E and 4/64 on high E @ fret 12

All of that is on a compound, or flatter (10 or 12 inch) radius fret board.  For a 7.5 inch radius.. takes some trial and error there to dial things in.
Folks can gather up the feeler gauges and such, but the high E string diameter is the reference in this case... I do measure the fret 12 string elevation with an old Starrett machinist rule
One thing I see, is the changes in season, opposite many "up north".  Here in southern swampland, AC is run in the summer, so we have dry interiors, but windows open in winter with much more humidity.  All it takes is a minor change in the truss rod tension to keep fret 12 elevation as you expect it to be.  That's because, as you noted, as relief increases, it "raises" the elevation at fret 12

 

[BigSteve22]

My set up goal is between .040" and .050" at the 12th fret, with a relief of about .008" at the 7th. (Fender's recommendation is .062" at the 12th, but I never saw any mention of a relief factor, so that may be at dead flat.) Another important, and often overlooked, consideration, is the depth of the nut slots. If the distance between the bottom of the string and the first fret is anything over .012"-.013", geometry starts working against you, requiring a higher action to avoid string buzz against the upper end of the board. These settings work for me. I don't generally play very aggressively, not a lot of power chords. If I played differently, I would probably need to set things a smidge higher.

As for tools, I use feeler gauges to set the relief, and a "Baroque String Action Ruler", ($8 on Amazon), for the action measurement. Anything unexpected comes up, I keep a Starrett machinist rule, and a digital caliper, on standby.

 

[Toulouse_Tuhles]

http://www.frets.com --- Frank Ford has a great way to adjust nut slots
Yah, the overall "feel" of the action is dependent on both ends of the string.  And... you're playing style.  And... the type of strings.
One can predict, mathematically the envelope of the string's vibration given many factors.  What is harder to predict, is the direction of the envelope.  In other words, if you could magically "look down the string", the vibration is not in one stationary direction, but it tends to vary.  You'd see  | / -- \ -- as all various directions of the vibration envelope.  String core, winding, etc effects not the total envelope, but the dynamics of the envelope's direction.
One of the hardest things for me to do, is switch between acoustic and electric instruments, if I've been playing one or the other exclusively for a long while.  Especially that acoustic to electric switchover.... I go way way to heavy handed on the strings, have a very hard time controlling dynamics.... so playing style matters a lot.

 

[BigSteve22]

One of the hardest things for me to do, is switch between acoustic and electric instruments...

Here's my solution to that dilemma:

An Epiphone, Chet Atkins SST Custom, solid body acoustic, strung with RotoSound, JK9, "Jumbo King", 9-48, phosphor bronze, acoustic strings. Certainly not a perfect solution by any means. I mean, it can't compare to a "true" acoustic Martin or Gibson, but the piezo is pretty good, and it does an admirable job through any decent amp. And, after years of playing solid body electrics exclusively, it's the only acoustic that feels comfortable to me.

 

[Ninja00151]

My set up goal is between .040" and .050" at the 12th fret, with a relief of about .008" at the 7th. (Fender's recommendation is .062" at the 12th, but I never saw any mention of a relief factor, so that may be at dead flat.) Another important, and often overlooked, consideration, is the depth of the nut slots. If the distance between the bottom of the string and the first fret is anything over .012"-.013", geometry starts working against you, requiring a higher action to avoid string buzz against the upper end of the board. These settings work for me. I don't generally play very aggressively, not a lot of power chords. If I played differently, I would probably need to set things a smidge higher.

As for tools, I use feeler gauges to set the relief, and a "Baroque String Action Ruler", ($8 on Amazon), for the action measurement. Anything unexpected comes up, I keep a Starrett machinist rule, and a digital caliper, on standby.

Dang Steve, you must seriously play lightly! That's pretty dang flat and low. ~3/64 action would be uncomfortably low for me, but that's the beauty in being knowledgeable with setups, isn't it? Set it up exactly to YOUR own preference .

Fenders recommended neck relief is here. 

https://www.sweetwater.com/insync/fender-recommended-neck-relief/

Thanks for the protip on nut slot depth! The fretguru actually has a thinly machined end of the fretrocker portion that you can put into the first few nut slots, and measure the height off the fret with a feeler gauge. I always knew about it, but I didn't know what was a "good" measurement.  I'll check it out when I get home .

 

[BigSteve22]

Fenders recommended neck relief is here. 

https://www.sweetwater.com/insync/fender-recommended-neck-relief/

Thanks for posting that! Seems I'm right in line with Fender's relief spec for a 16" radius neck at .008".

 

[musicispeace]

I think mine is 4/64 with a little more on the bass. I want to be able to get under a string for bending but prefer not to be either too low or too high off the frets. I'm working on lightening my touch and tend to pick notes over doing hammerons, unless I am adding to create a sus 4 chord quickly. Using 6105 and 6150 frets. Trying 6100 on my next guitar. Living in the Pacific Northwest my guitar necks stay pretty stable across the year.