Neck Relief

[MikeB]

I have a mandolin from a respected builder, on trial for a week or so. It's a beautiful mandolin, very responsive, etc.

But, as I sight down the neck from the nut, I can see a noticeable bow in it. It is concave looking down on the frets. This makes the action seem rather high, IMO. It looks to me that if I lower the bridge, I'm going to get buzzing, i.e., I'm thinking it's a truss rod issue. Trouble is, no adjustable truss rod.

So, my question is, should there be neck relief on mandolins? (My Collings and Gibson A are nearly perfectly flat.) If so, how much? Finally, when there is no truss rod adjustment, what do you do? This is a new mando, btw.

I think I know the answers to these questions, but I bow to the experienced luthiers here...please comment.

[MikeB]

Hmmm. No replies. #Well, here's more info, anyway.

I lowered the saddle. #Got just what I expected. #Plays nice in first position, but buzzes when you go up the neck. #In fact, now I can see that the stings are actually higher (off the frets) at around the 5th fret than they are at the 12th. #This can't be right.

No truss rod adjustment. #Nice, new mandolin. #What gives here? #(I don't want to mention the builder here, but I had higher expectations from this one....)

[mrbook]

I like as little relief as possible in all my instruments - guitar, mandolin, etc. There are a couple schools of thought, but I find the instruments easier to play. The mandolin I've played for the last few years came my way (purchased by mail) with more relief than I liked; after trying to get used to it for a couple months, I finally straightened the neck and have loved playing it ever since. I repairman once refretted my guitar (my only one at that time) to give the relief he liked rather than what I asked for, and I wasn't happy. In both cases I could adjust the truss rod; I don't know what you do if there isn't one. If it is a new instrument I would ask the builder about it. When trying an instrument in a shop, I have asked for adjustments - only if I am sure I will buy it if it is set up to my liking. I wouldn't ask a dealer or maker to change something I wasn't planning to buy.

[Dave Wendler]

The lighter your touch, the less "relief" you will need. If your main impetus is a heavy bluegrass chop...you'll need a bit....

First thing to check is the height of the unfretted strings above the first fret. You can check this against fretting a course at both the first and fourth frets, and checking the gap between string and the second fret...this will give you an indication of how high the strings need to be above the first fret when the string is fretted at the third....

Once you've done this(AND made the necessary corrections), THEN you can set the string height at the bridge....and make a judgement about the amount of "relief" you need or want to have. If it's still not right...send it back or have your local luthier do a plane and refret...this should be a warranty issue though.

And on behalf of the maker....wood moves when it has lots of tension on it...this should have been accounted for, but sometimes it gets missed, and if you're in a drier climate than where the instrument was made, this could be the underlying cause for too much underbow.

[MikeB]

Thanks, Guys. This is an odd situation. This instrument was offered to me, as a trial, just to try out. Then give back my reactions. Kind of a fun deal, I thought. You don't get these every day. I like the guy who sent it to me a lot, have wanted to try these mandolins. I can't very well judge much about this one with what is, to me, an obvious neck problem.

I have adjusted truss rods before with good success. As I see it, this one has a neck problem. I hate to tell my friend he sent me a defective instrument. This IS a drier climate (except for the past few days), so maybe that's it. I think this is actually the guy's personal mandolin (and he is a VERY good player), so it stumps me that he would send it to me like this....and I'm not sure what to say to him about it. I mentioned it once and he said something about some people liking more relief than others. Maybe so, but when the action is higher in the middle than at the 12th fret, something ain't quite right... http://www.mandolincafe.net/iB_html/non-cgi/emoticons/sad.gif

[mrbook]

Some people do like more relief than others. I have a fairly light touch, and really like a straight neck. We had a recent gig as an opening act, and I thought I would play guitar on an encore song (if we got one). Not wanting to bring my guitar for one song, I thought I would borrow our guitar player's spare (he breaks strings a lot). I tried his guitar while we were setting up, and found I could play it, but not do the hot flatpicking that I was sure would thrill the crowd (if I didn't screw up). We did get the encore, but picked andother song, and I played another instrument. The relief was just like he liked it - and he's a fine rhythm player - but not for me. It may be the same for your friend. If you are just trying it, you can just mention it's not set up quite the way you like it, just to get his reaction. It still surprised me how an instrument with such a short scale can be so hard to play if it's not set up right.

[Bandersnatch Reverb]

I've got lots more experience with guitars than with mandolins, but here goes.

Think of a string as a jump-rope. The vibration is in the middle - where the string moves a lot, but at the ends, the string barely moves. To accound for the greater "envelope" of vibration at the middle of the string, some relief is usually needed, because otherwise the bridge would have to be elevated much further to make the strings not buzz.

On a guitar, I like the barest possible relief... only a few thousandths of an inch - like half the diameter of a .010 string. To see it, I can capo on fret 1 and hold down the string at the fret that is closest to the body joint. In the middle of the the string (about fret 7 or so) there ought to be the barest clearance under it. That clearance is adjustable with the truss rod (if you have one).

On my mandolin (Tacoma) it had much relief when I first got it, and I adjusted it out after I let it sit for about a week to acclimate to its new surroundings. Now its set to my liking.

What will make relief change? Temperture, humidity, STRING GAUGE, and the wood "settling in".

Keep in mind that heavier strings NEED more relief since their envelope of vibration is greater. So... heavier strings need more relief, and they will tug on the neck more to create more bow, so in some ways, they "self adjust" to a point. You'll still find that heavier strings will move the neck more than just the tiny amount needed to keep them from buzzing.

I find that in the winter here in Florida, my guitars go nuts - since we have no-A/C days where its more humid than in A/C environs, but... we mix that with the occasional A/C day... so the necks get a real workout. In the spring summer and fall, we pretty much run A/C all the time, and the necks are very stable that way.

[Chris Baird]

Bandersnatch is right. Neck relief is only used to compensate for the slight parabolic space that a string needs to vibrate in. In other words the string needs slightly more room in the middle than at the ends. Almost all guitars require some relief but the same is not true for mandolins. For any action above what would be considered medium/low a mandolin doesn't need any relief. Relief for a mandolin only comes into service on the very lowest of actions. And then a relief of .010" at the 12th fret is usually more than enough (different strings and breakover angles create a variance; generally the less tension the greater the space the string needs). If a builder chooses to not use an adjustable truss rod then he/she should use carbon fiber rods. I have used carbon fiber with success(so far).

[Flowerpot]

The other thing that a little relief helps with is sympathetic vibrations between the fretted note and the nut. If you run very low action, little relief, and a low nut height, you can run into weird ghost notes ringing, coming from the length of string between your fretting finger and the nut. A little more nut height or a slight bit of relief makes things sound cleaner, if that is a problem.

[MikeB]

Thanks again, to everyone for your help. #Besides getting a thorough education on neck relief, in general, I am convinced beyond any doubt that this mandolin is bowed. #This is much more than "relief." #

My benefactor has asked me to send it on to someone else--another trial, I presume. #I am going to have to advise him not to do that, but to have this neck repaired first. #No one would want a prospective buyer to see it like this. #It's almost unplayable above the fifth fret.

The rest of the mandolin is very nice. #VERY nice. #Great sound, nice design. #I just don't #want to endorse this one with this problem. #Thanks again, guys.

[Mark in Nevada City]

Just out of curiousity can you measure the relief before sending it back? You can approximate by fretting at the 1st and 14th and looking at the gap between the top of the 7th fret and the bottom of the G string. Does the gap equal the thkness of a plain E string (.011) or 2x or more? Or use a pick thkness (usally in mm) to estimate. BTW the way you can (usually) deal with teh neck bow is by compression fretting, that is re-fretting using a tang wider than the slot to force toward a backbow.

TIA, mmm

[Michael Lewis]

In regard to Mark's comment about "compression fretting", I wouldn't try to straighten a mandolin neck that way unless it just needed a little bit of help. That is a method used by the Martin guitar Co. for lots of years before they started using adjustable truss rods. It is a somewhat effective and touchy method of controlling the relief in the fingerboard. The mandolin in question here sounds like it should have the neck reinforced, and that is a pretty involved job at this point.