Setting intonation on octave mandolin

Hi, not sure if this a question best asked in one of the other sections but I just bought a Trinity College octave mandolin locally. It has a floating bridge and I think the intonation is a little flat. I come from playing double bass and have never set the intonation on a floating bridge. I know which way the bridge needs to go, but I am a little nervous about messing with it without some encouragement or advice. Also, I feel the G strings are a bit looser than the other strings, if that makes sense. Like I am able to more easily bend it out of tune accidentally if I don't get my fingers on it squarely. I'm new to an octave mandolin so not sure if that's typical. I do like the feel and sound of the instrument, and I am very excited to progress on it. Long ago I used to play a mandolin in high school for a while and got good enough to jam with my teacher and her circles, but alas the double bass pulled me into a different life of jazz. It's been a lot of fun picking up the mandolin family again though. Basically, I guess I'm wondering if this is something I should play with myself or is it best left to a luthier? Thank you!

What I do to set a bridge is loosen the strings enough so the bridge can be relocated easily. Then I bring one g-string and one e-string up to proper pitch, check the results at the 12th fret with and electronic tuner to make sure it is a pure octave, and then bring the other strings up to pitch. Note: Generally, I only do this when installing a new set of strings. This gets one very, very close.

Go for it - you can’t go that far wrong if you know which way it needs to go and you don’t want to have to go running to a luthier every time you need a slight adjustment. Just make sure you sufficiently loosen the strings to allow the bridge to move without putting sufficient pressure on the top to mark it. You might also like to mark the existing position so you can get back to where you started should you need to.

If it’s only the G strings which feel loose, that suggests to me that you need a heavier gauge.

I hate to be the bearer of bad news, but the bridge intonation on Trinity College octaves is always off. It is a weak spot on an otherwise pretty decent instrument. If you look closely at the bridge they use, you will see the baked in intonation is the same as a regular mandolin. I would describe it, starting on the bass side, as “ low high low high”. That is for an instrument with two wound courses and two solid courses. Most octaves have three wound and only one solid course. The intonation on the A course is therefore set too low. The bridge on mine is straight with no compensation, the compensation being set with the tilt. A compensated bridge for that should be more like “low medium high high”. That would result in less of a tilt. With the bridge you have now, you can move the bridge position all you want, and it might even get better, but it will never be right. Unfortunately the best cure is to have a new bridge made, compensated correctly. I have heard of some folks glueing extra material on the A course to shorten the compensation there, and that would help. As for the strings, the reason your G string feels loose is because it is too thin for the scale length. When most people get hold of a TC octave, the very first thing they do is switch out the strings. They have just over 20” scale length, and most octave mandolin strings are designed for 22”-23” scale. The short scale requires heavier strings all around. In my experience the D’Addario EJ72 set (light mandola) works well, and really make the tone wake up! Better feel too. You might have to widen the nut and/or bridge slots a bit for heavier strings though. Sounds like a lot of trouble, but totally worth it!

Thank you all for the responses. This is great information. My first thought was that I would probably have to get another Bridge for it. Your post definitely confirms that for me. I thought I had read in the past that their Bridges had a design flaw. How much do you think it would cost for me to get a bridge made for this? I'm in the DC Metro area and I hear good things about Appalachian Bluegrass Shoppe in Catonsville. I'll probably contact them about getting it set up with a new bridge but would love your input on that

A luthier would charge 50-75 dollars to fit a new bridge not including the cost of the bridge. It’s not easy to find a pre-made bridge for an octave so how much they would charge to make one from scratch is the great unknown. Seems like another 100-150 would get you a nice adjustable bridge. You can buy pre made ones from Bruce Weber’s Montana Luthierie but those are for arch tops. He might make you a flat top version if you asked. If it were my instrument I might be tempted to go cheap and get the “mandola bouzouki” bridge from Hobgoblin Music and fit it myself with some sandpaper. They cost around 30 dollars. Non adjustable of course. They have a straight bone saddle which is installed at a slant, so the bridge itself can stay more or less straight and the saddle’s slant takes care of the intonation.

This gives me a good idea of what to expect. I contacted the Appalachian Bluegrass Shoppe and they said they could do this work and determine whether they could use a premade bridge or would have to make one. I'm probably going to hold off though because I'm pretty sure I'm gonna sign up for Matt Flinner's Octave Mandoline webinar which starts the end of March and the shop said it's a 4 week turnover. Thank you for the information!

Oh, I did want to clarify one thing. I would tune the mandola strings on it as you normally would tune the OM?

That's right, tuning is the same with the heavier strings.

(Another Baltimore area local and fan of ABG here...)

I just wanted to clarify a bit on the string question. Why would one use mandola strings on an octave mandolin? The answer to the question lies in the scale length. There is no standard octave mandolin scale length. I’ve seen or heard of instruments called “octave mandolins” with scale lengths anywhere from 18” to 23 1/2” . These scale lengths require vastly different gauges. On any fretted string instrument we are shooting for somewhere in the neighborhood of 20 pounds of tension per string for the best tone and playability. It’s seldom possible to be perfect but a couple of pounds north or south of that is generally ok. There is a complex formula to figure out string tension for a given string relative to scale length, string composition, and gauge, but fortunately there are on line string calculators to do all the hard work for you.

The most obvious example of the problem of the discrepancy between short scale and long scale octave mandolins can be found with Weber instruments. They have made OM’s with both 20 inch and 22 inch scales. They knew that the same string set would not work on both. And that no string manufacturer was making a special short scale set. So they commissioned John Pearse to make a custom set for their short scale instruments. They also sell them to the public. The set is call the John Pearse Custom Octave Mandola Set. They work well on any instrument with a 20 inch scale length. I have found, however, that the EJ72 Light Mandola set by D’Addario is very, very close to the same tensions, and a bit easier to find. I was worried at first they would be too short to reach the tuners, but D’Addario packages them with very long lengths. They fit easily. Anyone who uses them on a Mandola surely has to throw away a lot! And yes, you tune them to the octave mandolin notes. You are using the Mandola strings simply as an easy way to get your hands on more correct gauges. If you want to go even further, you could always use a string calculator to come up with your own customized set, with exactly the tensions, materials, and gauges you want, then purchase single loop end strings to achieve it.

As I said previously, the nut and bridge grooves might need to be widened. Or not. A job best left to a luthier. Too narrow and the string will get pinched. Too wide and it will buzz. While you get the new bridge made and the instrument is being set up, tell your luthier what string set you want to use and he can customize the slots for that.

I’ve always thought it a shame that the Trinity College instruments have this flaw. The “entry level” price that attracts customers is negated when money has to be put into it to make it right.

Would you recommend the Eastman Octave Mandolin?

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Originally Posted by Mandular

Would you recommend the Eastman Octave Mandolin?

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I have had one for several months now, and I am very happy with it. Here is a good demo: https://www.youtube.com/watch?v=JiM8zoq9f20

The strings which comes stock on the Eastman are on the light side. Using standard D'addario MANDOLA strings works if you want to get a bit fuller sound from the Eastman. I have tried those, but actually prefer the slightly more "twangy" sound of the standard D'addario OM strings which come stock.

Being a carved-top, it is going to sound quite a bit different than the TC, so it all depends on the sound you want.

The Eastman has a more or less correctly compensated bridge. Much better design than the TC.

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Originally Posted by multidon

The Eastman has a more or less correctly compensated bridge. Much better design than the TC.

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I have a question that I don't think is far off topic; it's compensation on a flattop OM. Mine is a 20.5" flattop with a simple bridge and a 1/8" saddle. There's not much allowance for compensation on the saddle. But in checking the string harmonics, I'm not hearing much need for adjustments. So, are flat tops a bit less prone to compensation needs?

I think a shorter scale magnifies intonation problems. Do you play much above the 7th fret? Problems get more noticeable the higher you go. Is the saddle inset with a tilt, or straight? And is your simple bridge installed with a slant? A straight saddle can work for an OM but either the saddle hast to tilt, the entire saddle has to tilt, or a combination of both.

Don't play much above the 7th-but some. The saddle is set straight in the bridge but the bridge is slightly slanted. I've only been playing OM for a few years and I play mostly melodies saturated with chords so I may be missing some intonations.

+1 on the EJ 72s for the 20 inch scale. I use them on my Weber Bitterroot OM and they dramatically improve the G string floppiness and tendency to bend out of tune that you mentioned.

Agree, too bad about the bridge issue. Eastman is making some excellent instruments if you want the arched top, f-hole focus. Check out some demos/sound clips. If you really prefer the flat top, oval tone, the TC is worth getting set up well...

You will have to find what works best for you regarding string gauge. GHS used to offer custom sets. I have been using D'Addario as the G is heavier. Also keep in mind that when you bring all of the strings up to pitch the bridge will rock forward.

This is a very interesting discussion, thank you! I have recently acquired a Weber Bitterroot F octave with a 20" scale length. The G string using D'Addario EJ-80 OM strings simply do not sound good. Loose, twangy and buzzy is how I would describe the playing experience. I'm going to to try a set of the John Pearse Octave Mandola strings suggested by multidon. I'm seeing John Pearse Octave Mandola set # 2265 "Custom Gauge" at Juststrings.com.

I do like the sound of the Eastman for sure. I like the tone of both really and appreciate their differences, having only heard the Eastman in demo videos. I grabbed this because locally I wouldn't be able to get the Eastman for a while it seems according to Eastman and the shops. I'd be tempted to grab the Eastman if I see it locally and have money for sure. I'm on the list to get the TC straightened out at the Appalachian Bluegrass Shoppe but I also signed up for Mark Flinner's octave mandolin course so I'm not sure I'll be able to get it fixed before the course starts.

John Pearse must be using the Brit terminology. The 2265 set must be intended for GDAE. To me an octave mandola would be a mandocello with a .070 or larger C. I visided severeal shops in Scottland, They all refer to the octave mandolin as a mandola. If I remember correctly the gauges of the 2265 set are the same as the GHS custom sets we used to get. I use a 21.5 scale length.

Chris, that John Pearse set was specifically designed for your instrument! You will like it a lot! And yes, the terminology is confusing. I don’t know why they choose to call it octave Mandola but that set is designed for GDAE, short 20” scale.