Fretting intonation issues with Trinity College OM

Hey folks -- new member and my first post. But I finally hit an issue that I have no idea how to address.

Just got a new TC Octave. Here's my difficulty -- I get a strange intonation when I chord. If I push the string down in the fret, it actually raises the note by up to 1/2 step. So, I have to gauge the pressure across the fret board by ear to make sure the chord is in tune. That's a problem when I'm playing in my worship band since I really don't have time to make adjustments in any given song. Especially since the pressure is not consistent from fret-to-fret, or string-to-string. I have tried different thumb positions to alter my finger positions. But, to no avail.

I went back to the store -- a very reputable dealer with great luthiers that I will choose not to name -- but the tech told me he didn't see anything wrong. He adjusted the neck truss and bridge placement. He suggested I may need to let the strings settle in a bit longer. It does not sound bad with picking, but then again I am only on one or two strings at a time and it's easier to quickly hit a move. But chording is the real issue.

I have two regular mando's and a tenor banjo. So I am not a stranger to fretted instruments. But I am wondering if I have met my match with the OM. It's almost as if the fret bars are too high and create too much distance from string to fret board. But, I have no idea. I have never had this problem with my other instruments.

Is this a standard TC anomally, just a badly build instrument, or does my technique need some work? Looking for help. Thanks.

Welcome to the Cafe!

My first thought is -- have you put new strings on it, or are you using the strings it shipped with? Start any investigation of intonation with fresh strings.

If the strings are new, then my second thought is that the store tech just hasn't placed the bridge properly. This is easy to do yourself. Start with reasonably fresh strings, and compare the 12th fret harmonic with the note you get when pressing the string down at the 12th fret and plucking it. Move the bridge back or forward to correct the pitch, and tilt the bridge as needed to get all four string courses in decent intonation.

For what it's worth, I've read a lot of posts over the years about Trinity College OM's, and I don't recall that intonation was a major problem on these instruments. They do need a good setup by someone who knows what they're doing, and appropriate string gauges. After that, you should have a playable instrument.

Foldedpath -- Thanks for the response. I haven't put new strings on it yet. Just picked some up today and will install them tomorrow. I will recheck the bridge after I put new strings on. thanks again.

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Originally Posted by scott miles

It's almost as if the fret bars are too high and create too much distance from string to fret board. But, I have no idea. I have never had this problem with my other instruments.

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Unless you have superhuman power in your fretting hand, that shouldn't be an issue. The string should make firm contact with the fret, but there is no need to press it all the way to the wood -- indeed, I don't think I physically could press the strings so hard that they (or my finger) make contact with the wood, especially on the double strings of the OM rather than single guitar/banjo strings.

I note you're saying "up to 1/2 step". If the note is raised by exactly a half step, the problem may be a high fret so that the string doesn't make contact with the intended fret but the next one up the board. If the note goes progressively more out of tune the harder you press, you may have to look at your fretting force to press only just hard enough to make firm contact without buzzing. Also, make sure you're pressing the string vertically down, not pull it sideways.

Martin

Hmm, I've developed this weird obsession with the depth of the slots in the nut. If they are too shallow, the strings will be too high off the frets, and notes go sharp when you fret them, particularly close to the nut. A good luthier should recognize this issue.

I'm not sure exactly how far the strings should be off the frets near the nut, I think the rule of thumb is roughly the string diameter. I tend to slowly deep the slots with nut files and check as I go. Hopefully somebody here can quote the measurement for this distance, you can check it with a feeler gauge, or just be comparison with an instrument that doesn't have this problem.

Thanks!! I think you all have given me somewhere to begin. I don't have a superhuman fretting hand, but I do tend to over-press. I didn't ever think it would challenge me on a bigger instrument than I already play. The funny thing is that I actually played the Eastman for a week before I exchanged it for the TC -- and I did not have this problem. Different instruments play differently I guess.

I will focus more on technique, as well as check the technical measurements as suggested. Thanks again. This has been invaluable to me.

Scott

A light touch is what you need to apply.... Just enough to fret the string. Of course, too much pressure will sharpen the string. This is no mystery. Technique is your problem.

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Originally Posted by sheets

... obsession with the depth of the slots in the nut. If they are too shallow, the strings will be too high off the frets ...

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Yeah, sort of, but... It's not the "slot depth" itself that matters, but how high the slots hold each string above the first fret (and, obviously, all following frets). Any nut material between and above the strings (that determines "slot depth") is largely meaningless once it's above the widest point of the string (meaning, more than half the string's diameter), and would properly be filed down to that point at the end of adjusting the nut slots.

Quote:

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Originally Posted by sheets

... not sure exactly how far the strings should be off the frets near the nut ...

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THAT is a point of continual debate! IMHO, the nut would ideally act as if it were just another fret, and hold the string the same height above the first fret as fretting it causes the string to ride above the 2nd fret. (Some instruments, mostly European, use a "0-fret" next to the nut to ensure that consistency). In reality, most good setups put the string just a bit higher over the first fret, allowing for some wear over the long term (years, decades, maybe centuries?), as the strings eventually file themselves down into the nut material.

I just noticed this thread. Sorry I didn’t see it sooner. At least part of your problem, maybe most of it, is that the bridge compensation on a TC is incorrect. They put regular mandolin saddles on those, with the intonation set, low to high, like this: down, up, down, up, if that makes any sense. This works if your second course is solid, but will not work if the second course is wound. Compensation should be down, up, up, same. A new saddle is the cure, or some fix it by gluing a small piece of rosewood carved just right onto the second course of the saddle and re-cutting the slots. This is a real weak spot on an otherwise nice instrument and I don’t understand why they don’t correct it.

Thanks Don -- that's something I will look into. It is a nice instrument and I am enjoying it immensely.

And thanks all. I put heavier strings on it, and adjusted my touch. I was indeed pushing too hard especially with the light factory strings. Going much easier now and I think I am getting used to the feel of something bigger than my regular mando. Thanks again.