Acoustic Action - Update

Grampa · June 2022

I like a low action on my electric, suits the way I play. Desperate to make a concerted effort on acoustic I splashed out on a PRS P20 Parlour from the Peach sale section.... Sounds great when I get it right but am I supposed to be able to drive a bus under the strings at the bridge end of things? Checked online and found that 2.8mm on the Bass side and 2.0mm on the Treble side at the 12th fret was acceptable but seems bloody high to me.

BigPaulie · June 2022

That does seem a bit high.

My Martin D-16GT action is comfortably under 2mm on the bass side and it doesn't seem unusually low. The Yamaha LL16 looks about the same. Maybe a smidgen higher.

Gandalph · June 2022

I'd agree that seems too high.

I try to aim for around 2mm low E and 1.75 high E.

Mellish · June 2022

I usually like to be around 2.48mm low E at the 12th.

You need to be careful, though, especially with Martins. In your quest for lower action you can take away the guitar's fire

Tannin · June 2022

It all depends on the guitar, and it's not just the action.

But 12th fret action first: 2.8mm and 2.0mm is a little high but not outlandish; @Gandalph's 2.0 and 1.75mm is a bit low but not out of the question.

Correct cutting of the nut slots makes a huge difference. You won't see any difference at all if you measure the 12th fret action, but all the difference in the world if your nut is too high, especially on acoustic where you are more likely to spend more time at the shiny end.

But before either of these, the neck relief curve needs to be right. (Remember, truss rods don't adjust action, they adjust neck relief - not the same thing.)

Finally, acoustic guitars (unlike electrics) have flexible tops. You can't see it with the naked eye, but the top flexes a tiny bit when you fret a chord. On a very stiff-top guitar (e.g., a 1980s Eko 12-string) that flex is insignificant. On a very soft-top instrument (such as ultra-responsive fingerstyle guitars) you can really feel it.

I don't understand the physics of this properly, but I have observed that my two American-style guitars (lightly built and responsive) work best with actions closer to the high end of the normal range while my more robust Australian-style instruments can safely go a little lower. Other factors play a part too: my WA May Maton is a big, bold guitar, well-suited to harder playing and it works best a little higher so that I can hit big notes without buzzing. Good classical guitars have an ultra-light top just barely strong enough to resist the (very low) tension of the nylon strings, and they are normally set up with very high actions. In short, there is no "right", it's all horses for courses.

@Grampa, your best bet is to spend a few pounds (and I do mean just a few). Go to your local luthier or guitar tech and have your guitar set up. In most cases he or she can do everything necessary in about 15 minutes. It might cost £20 or £40 and it can absolutely transform your playing experience.

BillDL · June 2022

The problem with the action on an acoustic guitar has always been, and probably always will be, that you can only lower the saddle to a point where you still have a sufficient breakover angle from the bridge pins over the apex of the saddle to stop the string from rattling on the saddle and having insufficient downward pressure to get good string definition. You can mitigate this by cutting slots from the bridge pin holes towards the saddle and have them slope downwards into the hole whereby the takeoff point of the string is lower than the surface of the bridge, but again there is a limit to how deep you can go.

When I said that there "probably always will be" an issue, there are some manufacturers that have a carved out "plateau" area for the bridge pins that is lower than the surface of the bridge, and this allows for a better angle up to the saddle even if the saddle sits quite low in the slot. I have a small bodied electro-acoustic that I could not lower the saddle any more while keeping a decent breakover angle, so I carved this "plateau" on the bridge and fixed the issue. I don't know why more manufacturers don't do this to their bridges. Here is an example. Slightly blurry, but you should be able to see what I am talking about.

ICBM · June 2022

For me 2mm on the top E is a *little* high, but not much - 1.75mm is about right. I prefer more on the low E, usually around 2.5-2.75mm as it allows me to thrash the low strings a bit more (I do tend to).

But it does depend on the relief and in some cases how 'loose' the body resonance is, sometimes you just can't get them that low without at least some buzz and rattle.

Gandalph · June 2022

Tannin said:
But 12th fret action first: 2.8mm and 2.0mm is a little high but not outlandish; @Gandalph's 2.0 and 1.75mm is a bit low but not out of the question.

@Tannin, 2.8/2mm is a little high but it would still work for some depending on their playing style.

I might be at at the lower point on the bass E but I don't think so much on the treble.

Interestingly Collings suggests:

Bass-side string height at 12th fret: 3/32" (.09375") (2.38 m/m)
Treble-side string height at 12th fret: 2/32" (.0625") (1.58 m/m)

I'd have thought 1.58 a bit low on the treble but there you go.

Horses for courses.

bertie · June 2022

Grampa said:

I like a low action on my electric, suits the way I play. Desperate to make a concerted effort on acoustic I splashed out on a PRS P20 Parlour from the Peach sale section.... Sounds great when I get it right but am I supposed to be able to drive a bus under the strings at the bridge end of things?

well if you like a low action on leccy, then anything on acoustic is going to appear "high" - also it depends what you're trying to play really, and where (on the fretboard) - keep things down at the "normal" end and you can get used to it better.............try and do stuff further up the neck might take some time getting used to the extra "strength" required to fret the strings............

Grampa said:

Checked online and found that 2.8mm on the Bass side and 2.0mm on the Treble side at the 12th fret was acceptable but seems bloody high to me.

throw it back at you for a second, what then, based on these "findings" , would you consider to be "ok" ? it might just be you're expecting too much ?

Sometime "numbers" can be a distraction and take your focus away from the real job of getting used to playing in a different style on a different beast. Bit like people being obsessed with pick up height - a measurement is only someone elses opinion, adjust and do what's best for your ears. Same with action. (tho admittedly there's less room for scope)

FWIW Ive never measured an action height in my life, just try it, feel it, hear it - adjust it if necessary and get on with it

maltingsaudio · June 2022

You lot would hate the action on my Fylde! However do bare in mind an acoustic guitar is all about moving air as opposed to an electric where the movement is picked up, therefor the more room you can give to the strings to vibrate naturally the more tone you will get.

There is also a real benefit in playing lots of acoustic guitar when you go back to electric your fingers become stronger and more precise

more · June 2022

Action is more about feel and tone than mm . High action = more volume , improves tone good for rhythm playing , But ,harder to fret and play fast runs . Low Action = easy to fret good for fast lead , But .the risk of fret buzz, less volume and the tone might not be as good
So as rough starting point. Tune to concert pitch . The first fret should be just a bit higher than the second ,when you are fretting the first fret . Set the body fret height to Bass 3.18 treble 2.38 . Adjust as required.

Winny_Pooh · June 2022

Adjust the relief first. Try for just a teeny bit of relief and you may feel the action as lower under the fingers

Grampa · June 2022

Thanks for all the responses, appreciated, though I did have to read a couple of them more than once. I think a trip to my friendly neighbourhood luthier would be the safest bet as there appear to be far too many variables involved for me to start attacking it with a BFH and quite possibly ruining a perfectly good guitar.

Grampa · June 2022

Quick update....Luthier on holiday and being the "it can't be that difficult" type I decided to have a play. Having spent most of my life as an engineer in predominantly aerospace, pharmaceuticals, and submarine fibre optics I can pretty much turn my hand to anything. Simply slackened off the strings, removed the saddle, measured both ends, removed 1.2mm from the bottom, reinstalled, tuned and tested. Plays so much easier, no discernible change in tone, no fret buzz, intonates perfectly, job done.

TheMadMick · June 2022

^^^^^^ And it didn't even hurt!

guitarjack66 · June 2022

Grampa said:

Quick update....Luthier on holiday and being the "it can't be that difficult" type I decided to have a play. Having spent most of my life as an engineer in predominantly aerospace, pharmaceuticals, and submarine fibre optics I can pretty much turn my hand to anything. Simply slackened off the strings, removed the saddle, measured both ends, removed 1.2mm from the bottom, reinstalled, tuned and tested. Plays so much easier, no discernible change in tone, no fret buzz, intonates perfectly, job done.

Do you have files to widen or deepen the nut slot? I presume you do have these tools close by?

Grampa · June 2022

@guitarjack66 Nope, only attacked the saddle and that seems to have done the trick.

Mellish · June 2022

@Grampa ; - well done mate - gives you bragging rights

Grampa · June 2022

Mellish said:

@Grampa ; - well done mate - gives you bragging rights

Cheers mate, a small amount of skill and a huge amount of luck to be honest

Skipped · June 2022

Very good result.

A couple of years ago, I made what was (for me) an amazing discovery relating to my 30 year old Canadian Dreadnought.

The early guitars made in the Godin factory had a bolt on neck!

The nut is visible through the sound hole. A neck reset on the guitar took maybe 30 minutes and the only tools required were: A socket set. Piece of course sandpaper. Piece of fine sandpaper. A very small amount removed from the back of the heel lowered the action by maybe 3mm, and was a perfect result.

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Acoustic Action - Update

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