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Old 05-14-2022, 12:40 PM
Deliberate1 Deliberate1 is offline
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Default New Buzz (and truss rod advice)

Friends, I just got a 2018 Merrill OM-18. A lovely guitar. It came with new D'Addario XT strings. No buzzing issues on arrival. But about a few days later, I noticed some buzzing in the low E and, to a lesser extent, on the A. Now, this is only when the string is plucked open, and mostly when the pluck is robust, and it seems, more so with nail than pick. Now, it did not make the same sound when I got it a bit over a week ago, and I am playing it at the same level of force as I did then.
The guitar arrived here in Maine from NC. So I am wondering if a change in climate/humidity might have something to do with it. I know little about such things, but did remove and reseat the strings, to no avail. My next step would be a truss rod adjustment, but I do not have a tool to do that, and am a bit squeamish about it, though I am game.
So, first off, does this sound like a neck geometery thing. If so, is an adjustment of the truss rod a place to start. And if so, which one should I buy? And how should I approach the task once I have it.
Any other observations most welcome,
Thanks.
David
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Old 05-14-2022, 02:43 PM
Mirosh Mirosh is offline
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The first fret may be a bit high at that side of the fretboard.
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Old 05-14-2022, 02:47 PM
schoolie schoolie is offline
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I would say it's probably the nut slots, if it buzzes when plucked open. One of those things not noticed immediately.
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Old 05-14-2022, 05:37 PM
Deliberate1 Deliberate1 is offline
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Thanks for the replies. Is there any way to test for the nut slot, and is that something that just happens? Again, I did not notice this issue until a few days after I took delivery. Though I confess, I may just not have "heard" it. And is there a way to test for a high first fret. I have done it further up the neck with a credit card, to see if there is a pivot point.
Thanks again.
David
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Old 05-14-2022, 07:14 PM
Rudy4 Rudy4 is offline
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Quote:
Originally Posted by Deliberate1 View Post
Thanks for the replies. Is there any way to test for the nut slot, and is that something that just happens? Again, I did not notice this issue until a few days after I took delivery. Though I confess, I may just not have "heard" it. And is there a way to test for a high first fret. I have done it further up the neck with a credit card, to see if there is a pivot point.
Thanks again.
David
It's about a 99% probability that it's just acclimating to your humidity conditions. Checking the nut slot depth is a good thing, but work with the actual symptom that you are experiencing.

If you have a buzz from a change in the amount of relief then attend to that, THEN check the nut slot depth.

The quick n' dirty way to check relief is to slap a capo on the first fret, hold a string down at the neck / body juncture, and visually look for the amount of clearance between the string bottom and the top of the 7th fret. You should normally see about .014" gap. You can use a short piece of a first or second string as a gauge in a pinch.

The nut slot depth is checked like this:


Last edited by Rudy4; 05-14-2022 at 07:22 PM.
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Old 05-14-2022, 07:31 PM
Deliberate1 Deliberate1 is offline
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Quote:
Originally Posted by Rudy4 View Post
It's about a 99% probability that it's just acclimating to your humidity conditions. [/IMG]
Rudy, thanks for the straight forward explanation. I suspected humidity issues given the journey from NC to Maine. Again, it took a few days for the buzz to surface, perhaps as the guitar acclimated. Truss rod time.
Got any suggestions for a tross rod wrench?
Thanks again for your effrots.
David
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Old 05-14-2022, 09:09 PM
Rudy4 Rudy4 is offline
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Quote:
Originally Posted by Deliberate1 View Post
Rudy, thanks for the straight forward explanation. I suspected humidity issues given the journey from NC to Maine. Again, it took a few days for the buzz to surface, perhaps as the guitar acclimated. Truss rod time.
Got any suggestions for a tross rod wrench?
Thanks again for your effrots.
David
I did a quick Google and found that it can be "problematic" to figure out what kind and size of wrench is needed for a Merrill. It seems that Merrill built with rods that have several different sizes. Hopefully the original case still has an Allen wrench in the neck compartment, although it may not have had one included since the type that is shaped to go around the top brace is often used for initial adjustment.

The offset adjustment tool costs a lot more than a simple Allen wrench, so that might be why a proper wrench was not included when the guitar was originally sold.

I have also heard that some manufacturers aren't including wrenches because they feel it's much less of a chance of having a truss rod broken if the owner takes it to a shop to have it tweaked.

Once you figure out the size then you can get one of the offset wrenches from Stu-Mac if you want to have the proper tool on hand.
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Old 05-14-2022, 10:00 PM
Mirosh Mirosh is offline
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Anyone else think .014" relief is way on the high side?

Many here know more than I do... just asking.
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Old 05-15-2022, 01:38 AM
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JayBee1404 JayBee1404 is offline
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Quote:
Originally Posted by Mirosh View Post
Anyone else think .014" relief is way on the high side?
Yes, I do.

0.014” of relief would be very uncomfortable for me, more than double my ideal relief - I shoot for 0.005” - 0.007” on my guitars, and it works very well. 0.014” would be virtually unplayable for me mid-neck.

As always, the standard disclaimer applies - IMHO. However, I realise that YMMV, and I’m cool with that.
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Brook ‘Lamorna’ OM (European Spruce/EIR) (2019)
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Old 05-15-2022, 06:58 AM
Rudy4 Rudy4 is offline
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The .014" relief recommendation is based on a maximum amount for players who focus a lot of physical energy into their playing style.

When you're looking to eliminate relief when chasing down mystery buzz then a larger amount of relief is an excellent diagnostic tool.

Relief can go much lower based on your playing style and string choice, obviously. I've known players who prefer a straight board, but the majority of players would probably shoot for something in the .007" to .010" range.

When you look at the entire range of playing styles you have to consider players who use a very physical style and don't leave the cowboy chord area as well as the melodic up the board player. The need to compromise is the nature of the beast, but sometimes extremes are necessary for certain playing styles.

Note: Anyone interested in setting up their acoustic guitar should download and study Charles Tauber's excellent "Basic Guitar Setup" pdf guide. The relief listed as "typical" is .010" in the guide.

Last edited by Rudy4; 05-15-2022 at 07:10 AM.
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Old 05-15-2022, 08:16 AM
Mirosh Mirosh is offline
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Thank you for that explanation! You have broadened my understanding of relief.
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Old 05-15-2022, 09:15 AM
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JayBee1404 JayBee1404 is offline
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Quote:
Originally Posted by Rudy4 View Post
Anyone interested in setting up their acoustic guitar should download and study Charles Tauber's excellent "Basic Guitar Setup" pdf guide. The relief listed as "typical" is .010" in the guide.
I’ve had Charles’ treatise on my iPad for a couple of years now. It’s a Tour de Force on the subject of guitar set-up, and I second your recommendation.

https://www.charlestauber.com/luthie...May%202015.pdf

I would also recommend Bryan Kimsey’s Luthierie website, which also contains a detailed discussion on the effects of neck-relief.

http://www.bryankimsey.com/music/lutherie.htm
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Brook ‘Lamorna’ OM (European Spruce/EIR) (2019)
Lowden F-23 (Red Cedar/Claro Walnut) (2017)
Martin D-18 (2012)
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Old 05-15-2022, 11:07 AM
coder coder is offline
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Default Checking the nut

If it is indeed and open string buzz, it is likely that the buzz was there to begin with, you just did not notice it. This is because there is no way for the nut slot to change its dept on its own. It is not dependent on air humidity.
It is worth verifying which fret is buzzing. For a nut slot problem, it will usually be the first fret. It is remotely possible that you have a high fret somehere, but I am saying that that fret would likely buzz even if you fingered some note before it.
To verify which is the case, play all the fingered notes on the problem string, and verify none of them buzzes.

Assuming this is strictly an open string buzz, it is caused by incorrect nut slot depth. (If no buzz with any of the fretted notes on the buzzing string(s) . If there was a neck geometry issue it would likely produce some buzz with some of the fretted notes IMO. So: focusing on strintly the nut slot depth:

To check if the nut slot is cut too deep:
I usually use an automotive thickness gauge for this. Firtst find the fret hgt.:
Find one, or a couple of thickness gauges that match the heigth. When you put the thickness gauge betweem any 2 frets, try a set of neighboring gauges, or individual ones while you rest a straight edge on the 2 frets, find a good match where no daylight shows between the straight edge and the thickness gauge, but where the straigth edge does not rock on it. Once this is done, you can put the selected thickness gauge blade(s) next to the nut and see if it "lifts up" any of the strings there.

If you find that some of the nut slots are too low, the best option is to cut a new nut, and dial in the slots correctly. A hackish solution of masking out the surrounding area with masking tape, and building up the problem slot with layers of superglue and fine bone dust, and then re-cutting the slot a bit higher (using the thicjness gauge as the guide, to prevent cutting it too deep again). This is may be a bit hairy for an inexperienced person, perhaps I would hire this work out.

If you made sure it is not the slot depth, there is a set of possible operations, first setting the correct / desired neck relief and then the action.

It is my belief that neck relief is just a way to mask a poor fret leveling job. My preference is to set my guitar necks straight, and level my frets perfetly, lowering any individual frets that buzz. (I learned this from Dan Erlewine)

The truss rod nut is usually just a hex (allen) head nut, you need a set of Allen hex keys, and find one that fits. When you bought the guitar, it should have had a truss rod adjusting key come with it in the case , double check if you got one. If you did not get one, get in touch with the seller and ask for one. Selling a guitar wihout one is just un-cool! On Merrils, the truss rod can be accessed from inside the body, I think the allen key is 4 mm or a hair smaller, 9/64 SAE. If the 4mm fits without slop, use that. I think these guitars have a 2-way trussrod, which actually allows you to force a bow into the neck.
As you turn the truss rod nut counter-clockwise, at first it will feel looser, then after a while will feel tighter again, as you start forcing the neck to bend more.

Counter-clockwise turn loosens the nut, adding neck relief, clocwise tightens it taking relief out (that is, straightens the neck) . No more than quaeter inch turn at a time, maybe even less. Then re-test. There may be a bit of time before the neck settles, esp if you are loosening the nut. I would give it an hour tuned up to full pitch before testing. (The truss rod can be safely losened without detuning the strings, if you want to tighten, tune the strings down a note or 2 before the adjustment to be safe). To get in with a regular allen wrench, you probably need to losen the strings so you can reach in through the sound hole. This guitar may have come with a Larrivee style offset wrench, which would make it possible to get in without losening the strings.

Last edited by coder; 05-15-2022 at 02:31 PM.
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Old 05-15-2022, 11:15 AM
Mirosh Mirosh is offline
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Charles Tauber's guide has been my go-to these last 2-3 years when I started working on my (increasing number of) guitars. It has been a godsend. I have read it many times and made notes and underlines as I have done more and learned more.

I especially appreciate Rudy4's explanation of setting a high relief to aid in tracking down a mystery buzz. I used a piece of .010" string in my early work on relief, but now go with .04-.08" mostly. Might experiment with a higher relief now, after considering Rudy4's thoughts.
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Old 05-15-2022, 11:47 AM
Robin, Wales Robin, Wales is offline
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I have to say that this YouTube video of SCGC using their PLEK machine was a bit of an eye opener regarding relief, fret buzz and set-ups in general. What struck me most was the slow motion vibration pattern of a string. The way the energy pulse travels up the string to the nut or fret and back down really made me think about set-ups. You can see the pulse within the first couple of minutes of the video. Basically, a string does not vibrate in a uniform ellipse, with the widest vibration in the middle of the string - it is a totally different pattern.

I have noticed a few strange things myself. Such as, if I use a 1mm Dunlop nylon pick I get fret buzz - every time. If I use a 1mm Wegen or even a standard celluloid pick then I don't. So the pattern of the energy pulse from some picks is different to others.

Incidentally, unlike Martin who fret the board and then mount it to the neck and then mount the neck to the guitar, and then PLEK the frets. SCGC mount the fretboard and neck to the guitar BEFORE installing the frets. The fretboard itself is then profiled by the PLEK machine, then the frets installed, then the frets profiled by the PLEK (plus nut and bridge profiling).

Anyway, with the talk here about how much relief you need, I though that this video would help to show that it is perhaps not how much relief is needed in the middle of the fretboard that is important but how much relief is needed in the first few frets beyond where you happen to be fretting. And some necks will bend slightly differently to others at various points, so you cannot dial in a uniform amount of relief and get the same results from every neck.
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