Tune o Matic angle

[Dansk_84]

I have noticed that all tune o matic bridges are installed at an angle on all guitars that have them. Does anybody know what the angle is? Any help would be great

[BackwardsBoB]

Pretty much all bridges are installed at an angle. You would think that since a string that's half as long at the same tension sounds one octave higher, the distance from the nut to the bridge should be twice the distance from the nut to the 12th fret, but it isn't. If you built a guitar this way, as you move up the neck, the guitar would play out of tune. When you fret a string, you bend it a little, raising the pitch. This effect is dependant on the height of the strings above the fingerboard, and the diameter, materials, and construction of the string. You want to position the bridge so that a fretted note at the 12th fret is the same pitch as the harmonic played at the 12th fret, for all strings. This is what you tune with a tune-o-matic bridge. All you need is a good tuner and patience, since you'll want to loosen the string a bit when you adjust the bridge, and you have to get the pitch of the string back to "in-tune" to make the comparison properly.

Adjusting intonation properly makes a big difference in the "sweetness" of a guitar. Most guitars come from the factory with the intonation only approximately correct, and if you change the string type or adjust the bridge height, it should be done again anyway. You'll find that intonation is less critical on an acoustic guitar with its complex harmonics and string interaction, and most critial on a solid-body with lots of bite.

So what's the magic angle? Hard to say. That's why the bridge has adjustable saddles. Generally, the strings get longer as you move from higher to lower un-wound strings, then jump shorter at the highest pitch wound string, and get longer again from there. You'll find many acoustic guitars that use two straight bridge sections arranged this way, one for the two unwound strings, and one for the four wound strings. Tune-O-Matic bridges have the ramps on the saddles cut so that the adjustment range of the high-E end is naturally shorter than the low-E end to reduce the angle that the whole bridge is tilted by.

If you've got an archtop with a floating bridge that you have to position, you'll need to experiment with it a bit to find the best position. Set the adjustment for the low-E to be a bit long, maybe 3/4 of the way to the rear (away from the nut) of its adjustment range, and the high-E so that it is 3/4 of the way to the front. Adjust the intonation by moving each end of the bridge to get the "E"s in tune, then adjust the other strings so that their intonation is correct. If you do lots of iterations, you'll note that the bridge will start to lean toward the nut, and you may have to adjust that too. Adjust intonation if you switch from a wound to unwound G string. It makes a big difference.

If you're drilling holes for mounting studs in a Les Paul body or something, you'd do well to measure on a similar guitar.

All this gets notes played at the twelfth fret in tune with open strings, and there's lots of cool multi-octave chords, drones, and bass lines available when you're playing around the twelfth fret. It makes a pretty good compromise. Unfortunately, you're not all the way to perfection yet, because you'll find that when you play notes at the first fret, they'll tend to pull sharp or maybe flat. Buzz Feiten and others actually sell technology to stagger the nut to compensate for this as well. But you still won't quite reach perfection, because the third fret will pull a little differently, and the nut adjustment needs to be a compromise...

If you want perfection, buy a synthesizer. Lots of popular tunes were recorded on guitars with lousy intonation, but I can hear it. I have trouble identifying the minor intonation problems on a properly set up acoustic guitar even if the bridge is at the proper angle but perfectly straight. I've found that on an electric, if the nut is in the right position and cut right, adjusting intonation at the bridge gets things sounding sweet, except for a little error on first-position chords. Once you're to that point, the error is less than what you get moving between fretting lightly and squeezing the string hard against the fingerboard.

Bottom line is that adjusting intonation yields big benefits, but if you get fanatical about it, it could lead to insanity.

I didn't really answer your question, but I did have fun listening to myself. Thanks.

[jrfrond]

I've never measured the angle of the Tune-O-Matic, but as a general rule, the nut-to-saddle (at center saddle travel) should be scale + 1/8" for the treble side and scale + 1/4" for the bass side. This has never failed me, and allows for proper intonation and the widest latitude of adjustment.

[Dansk_84]

Thanks for the helpful advice. I tried to take it all in BAckwards bob but its too early on monday morning for that amount of information, ill read it laters when my brain has turned on lol .

[jack briggs]

I've never measured the angle of the Tune-O-Matic, but as a general rule, the nut-to-saddle (at center saddle travel) should be scale + 1/8" for the treble side and scale + 1/4" for the bass side. This has never failed me, and allows for proper intonation and the widest latitude of adjustment.

This is pretty accurate. I measure the scale length, add 2mm to the treble side post and 5 mm to the bass side post. Works well for 10-46 and 11-48 string sets. If you're using higher guage strings you might want to add 1mm to each measurement.

The other thing to keep in mind is which TOM you're using. An ABR1 has much less travel than a Nashville TOM and so is dependent upon the stagger to afford proper intonation. The saddles usually need to be bevel facing the nut on the 3rd, 5th and 6th strings; facing the tailpiece on the others.

A Nashville TOM could be mounted straight and still be able to intonate, if the proper overall scale were observed.


Cheers,

[Dansk_84]

I have a Nashville TOM that i am installing, i should be fixing it on next week so ill post a photo when its all done. Its the first guitar im building and its all goin good up 2 now, i just dont wanna mess up the TOM!

[jrfrond]

For all of it's class looks, I still think the ABR-1 and the Nashville bridge to some extent, are quite the pain in the ass, as they generally do not have enough travel for correct intonation and can, in many cases, even on Gibson's, be place another 2mm back for proper intonation to happen. Of course, Gibson knows this too, which is why they switched to the wide Schaller bridge in the 70's in SG's, with it's it's generous almost-half inch worth of saddle travel. Even turning around the saddle on the ABR-1 doesn't ALWAYS help, and low-E's are usually a bit sharp.

[David Schwab]

Here's a little known but helpful tool. Head on over to stewmac.com, and go to the free information link. Then to calculators, and the fret calculator:

http://www.stewmac.com/FretCalculator/

Enter your scale (and the number of frets, but that doesn't matter for this use) and it will tell you exactly where to place your bridge, based on a number of available bridge types.

For Tune-o-matic style bridges they list:

'ABR-1' Tune-o-matic Bridges
Nashville Tune-o-matic Bridge
Gotoh Tune-o-matic Bridge with Standard Posts
Gotoh Tune-o-matic Bridge with Studs/Bushings
Schaller Roller Bridge
L.R. Baggs T-Bridge
Locking Roller Bridge
Gotoh 510 Bridge & Tailpiece

For an example, I typed in 24.75" for the scale, and scale, and it calculated:

24.811" (?0.030") from nut to center of treble-side post. Mount bass-side post 1/16"-1/8" further from the nut.

[rhomco]

You could always

Dial in the exact location for a particular guitar by using a cheap temporary floating bridge. After getting it adjusted you will have the exact placement you can mark with tape.
Rob

[Chadheckler1]

Dial in the exact location for a particular guitar by using a cheap temporary floating bridge. After getting it adjusted you will have the exact placement you can mark with tape.

This is a very effective method for locating accurate saddle slots on acoustic guitars when you only get < 1/8" adjustment...and sometimes only 3/32"!

C

[gellfex]

I tripped over this informative thread researching the angle thing for a travel guitar project for my son. What's confusing me is the guitar I'm referencing the most, the Traveler Escape Series has a dramatically tilted bridge, whether it's TOM or an acoustic fixed style. I used the calculators and they say to mount bass-side post 1/16"-1/8" further from the nut, but I calculate these guitars are more like 1/4 further. Why should the fact that they're pretty radical otherwise affect anything about the scale length if it's a 24.75? Should I just trust that they've experimented enough and copy them?

[the Old Man]

The guitar you are looking at has a zero fret. This means that stretch while playing at the first few frets (1 through 5, typically) is minimalized. As a result, the amount of compensation required the bridge for each string is now different. My own experience in building a similar type of guitar resulted in the base post being about 1/4" back from the treble post on a nominal 24 5/8" scale.

[gellfex]

The guitar you are looking at has a zero fret. This means that stretch while playing at the first few frets (1 through 5, typically) is minimalized. As a result, the amount of compensation required the bridge for each string is now different. My own experience in building a similar type of guitar resulted in the base post being about 1/4" back from the treble post on a nominal 24 5/8" scale.

Thanks TOM, but I think you're deceived by the photo. It has a typical nut. Here's a close up (bless some Guitar Center web geek for providing much better photos than the maker):

[the Old Man]

Looks like you are right. If the string slots are set to the same height as the the frets, it will still act as a "zero fret", and the bridge angle will be close to 1/4". The depth to which the slots are cut suggests that may be the case, although that could be an illusion caused by the camera angle.
Another factor that would impact the compensation angle on the bridge of the Traveller guitar is the tremendous amount of string behind the saddles, all of which is set up on rollers, etc., to move more easily when you adjust the tuning. This reduces the amount of change in tension caused by deflection of the string when it is fretted, and thus changes the compensation required. I guess the real question is, what kind of nut are you putting on the guitar you are building, and how much "dead" string length will be available for added stretch on the outside of the nut and saddle? If you are going to use a conventional nut with a "Typical" amount of string height, and you do not have an excessive amount of dead string length, you are probably better off with the bridge angles recommended by StewMac. If you are doing something a little more unconventional, you will need to adjust accordingly.

[gellfex]

Ah, interesting. So you think the unusual length of string from bridge around the back to the tuners is the reason for the increased angle. Doesn't that design then make it harder to stretch strings? Interestingly, the Steinbergers DO have a zero fret "for improved intonation".

Although simply copying the design of the Traveler is the path of least resistance, I'm contemplating making a custom machined bridge tuner more like a variant of the Steinberger, but more compact and hidden. In the latter case the traditional angle should hold fine.