Archtop setup question 2 - for you experts out there

[fumblefingers]

The bridge/saddle.

Let's say that you have a 25" scale length. Given that bridges are not straight across (whether they be ebony, compensated ebony or tun-o-matic),
which string slot in the bridge should be 25" away from the nut, or the closest to 25"?

Is it the D string?

Thanks in advance!

[PTChristopher]

While waiting for an expert to reply, here is my opinion:

No string will be at 25"; they will all require some compensation.

Assuming a non-wacky gauge mix, then relative compensation will be based on the CORE diameter.

So on a wound G set, the High E will usually require the least compensation, followed by the G.

Look at the Sadowsky CNC cut bridges for a very good approximation of the relative compensation used for both a wound and a plain G set.

True-Tone Bridge :: True-Tone Bridge | SET - Sadowsky Guitars - Online Store

Chris

[Patrick2]

The bridge/saddle.

Let's say that you have a 25" scale length. Given that bridges are not straight across (whether they be ebony, compensated ebony or tun-o-matic),
which string slot in the bridge should be 25" away from the nut, or the closest to 25"?

Is it the D string?

Thanks in advance!

The bridge base posts . . . if it's a compensated saddle or a TOM. If it's a none compensated ebony saddle ... throw it away and get a Gagnon!!!

[DaveS]

Further to Chris' response, IMO you'll get very close using 25 1/8" on centerline to the saddle center. (A lot depends on the flatness & thickness of the saddles top surface, and also that all other aspects of setup have been dealt with). Tweek 'till you have a good 12th fret/harmonic match on the "E"s, then proceed with intonation.

[Klatu]

Assuming your guitar is an archtop with "f" holes, your bridge will most likely line up with the notches in the "f" holes. This will give you an approximation as to where the bridge should go initially. Once there, you will have to adjust the bridge and saddle using a tuner to reach optimal intonation.

[Archtop Guy]

Klatu, What is that pretty little orange guitar? Thank you

[Klatu]

Klatu, What is that pretty little orange guitar? Thank you

I have no idea. I just went on Google images to find a clear example of the bridge lining up with the F hole notch.

[mr. beaumont]

Perhaps none. Scale length isn't really the measurement from the nut to the saddle...it's the nut to the twelfth fret, doubled.

[fumblefingers]

Perhaps none. Scale length isn't really the measurement from the nut to the saddle...it's the nut to the twelfth fret, doubled.

well my question was 25 or close to 25 as a way of accounting for that.

it may interest you to know that several of my archtops have the 6th string (not 4th like i guessed) sitting at the scale length almost exactly - and intonation is well set up.

[fumblefingers]

Further to Chris' response, IMO you'll get very close using 25 1/8" on centerline to the saddle center. (A lot depends on the flatness & thickness of the saddles top surface, and also that all other aspects of setup have been dealt with). Tweek 'till you have a good 12th fret/harmonic match on the "E"s, then proceed with intonation.

yes, this is precisely out of Bob B's book. a follow-up point and question:

an ebony bridge like that used on a Benedetto guitar is curved and has the 5th and 6th strings set back from the middle of the bridge, and the 1rst and 2nd strings are set forward of the middle of the bridge.

if the scale length is 25.5 (like a Gibson L5 as opposed to a Johnny Smith inspired Benedetto or other) would you still add precisely 1/8 inch per the example, or would the extra length be less than or greater than 1/8"?


Thanks again, especially PTChristopher, Patrick, techs, and luthiers.

[Patrick2]

Perhaps none. Scale length isn't really the measurement from the nut to the saddle...it's the nut to the twelfth fret, doubled.

I think it's pretty much the same thing. If the nut to the 12th fret measures 12.75" . . . the post in the bridge base (dead nuts center of the base) will be 25.5" from the nut. Scale length 25.5" . . . thus, nut to 12th fret doubled. The variance will be at the saddle due to intonation.

[Patrick2]

These are pretty cool too.

[Hammertone]

Assuming your guitar is an archtop with "f" holes, your bridge will most likely line up with the notches in the "f" holes. This will give you an approximation as to where the bridge should go initially. Once there, you will have to adjust the bridge and saddle using a tuner to reach optimal intonation.

While this is good practice, many luthiers/companies have forgotten it or chosen to ignore it. Gibson was/is too cheap to do custom jigs for some guitars, so the bridge placement relative to the f-holes on the Byrdland and the Lee Ritenour mini-L5 do not follow this wise rule.

And of course the wacky soundholes found on some German archtops don't provide this reference.

Sadly, many other examples abound of egregious soundhole misplacement.
Although sometimes the results are OK:

[kris]

:-)

[mr. beaumont]

I think it's pretty much the same thing. If the nut to the 12th fret measures 12.75" . . . the post in the bridge base (dead nuts center of the base) will be 25.5" from the nut. Scale length 25.5" . . . thus, nut to 12th fret doubled. The variance will be at the saddle due to intonation.

Right...so the posts might line up, but not any one string in particular...

[Hammertone]

While this is good practice, many luthiers/companies have forgotten it or chosen to ignore it. Gibson was/is too cheap to do custom jigs for some guitars, so the bridge placement relative to the f-holes on the Byrdland and the Lee Ritenour mini-L5 do not follow this wise rule.

And of course the wacky soundholes found on some German archtops don't provide this reference.

[DaveS]

if the scale length is 25.5 (like a Gibson L5 as opposed to a Johnny Smith inspired Benedetto or other) would you still add precisely 1/8 inch per the example, or would the extra length be less than or greater than 1/8"?

Well, if you want to play with some numbers, there are calculators out there to help.
Try Fret position calculator at Stewart-MacDonald (look at "mandolin" to see the effect on archtop type bridge placement, but the wide variety of electric bridge styles are also a hoot to compare)

[Patrick2]

Right...so the posts might line up, but not any one string in particular...

eggs-ackly!! I went back and re read the OP's original question. My answer was not specific to his question (I seem to do that a lot). The question was more specific to the saddle/saddles than it was to the bridge base. My answer was specific to the base.

Regarding Hammertone's comments on Gibson not wanting to invest in an appropriate tool to accomplish this . . . just as a little piece of trivia, there is a great photo on the wall of Aaron Cowles shop in Kalamazoo, of Aaron receiving an award from Julius Bellson for designing and hand crafting an adjustable tool designed to ensure proper placement of a floating bridge instantly. Aaron still has that very first tool in his shop today. The award was for the savings in time and assurance of accuracy the tool provided. Of course, Gibson, being Gibson . . . gave Aaron nothing for his efforts except that award and the photo of it. ( I love telling stories)

There are now several tools similar . . but, there's only one of the first one ever!!

[Hammertone]

....Aaron Cowles ...designing and hand crafting an adjustable tool designed to ensure proper placement of a floating bridge instantly....

Yeah, the issue isn't bridge placement on those guitars, it's f-hole placement:

Byrdland - bridge placement above the points on the f-holes - cheap-ass design, not the end of the world, who really cared at the time? They threw a shorter neck onto an L-5 top, made the rims shallower, made a new tailpiece and Presto! - a new model!
Rit - bridge placement well below the points on the f-holes - really lazy design, utterly lame disregard for integrated design and they knew it

[fumblefingers]

Ok ya'll,

but what about the extra 1/8" mentioned above (and in Benedetto's book?)

should the added length be longer, shorter, or the same if the scale length
is 25.5"?

[PTChristopher]

Bridge compensation will always be longer than the scale length.

Any 1/8" guideline is only a consequence of a particular bridge layout. Many carved bridges position the high E forward of the posts and the low E rear of the posts. The net effect is that the posts end up positioned so that the high E saddle is slightly rearward of the scale length.

Chris

[fumblefingers]

then that would put the low E well back of the scale length, would it not?

[oldane]

if the scale length is 25.5 (like a Gibson L5 as opposed to a Johnny Smith inspired Benedetto or other) would you still add precisely 1/8 inch per the example, or would the extra length be less than or greater than 1/8"?

You can't put that squarely. It also depends on the string action. As the action gets progressively higher, the string wil stretch more (same way as when you bend a not). With a high action, the bridge wil have to be set a little closer to the taipiece than with a low action. So this practice of positioning the bridge by means of measuring with a ruler can only bring you approximately into the ballpark.

For my part, I have never positioned archtop bridges by measuring. I have always done it by ear or with a tuner. I avoid setting the intonation using the open strings. If the nut is a little higher than the first frets (which is common, just ask Chris) the string will stretch a little to bring it down to the frets which will raise the pitch a tiny bit. I use to compare the intonation on say the 3rd and the 15th fret ot the 5th or the 17th fret. Ideally they should be an octave apart. That way, I don't use a reference - the open string - I never use. I do it under real life conditions - taking into account that I never play with open strings and taking into account which part of the fretboard I use most when playing.

In real life, it's almost never possible to get totally perfect intonation. The intonation seems to change during the life of the strings set and somtimes also from week to week. Don't ask me why. But I think that we will have to be satisfied if we can bring the incosistancies below the size of the small imperfections which is built into the tempered scale (no interval is perfectly pure except octaves and 5ths).

[PTChristopher]

[FF] >>> then that would put the low E well back of the scale length, would it not?

Yes. Although it can vary widely, a decent first guess would be to run the high E about 1/16" (1,5mm) back from the measured scale length, and the low E about 3/16" (4,5mm).

Then start adjusting from there.

For a wooden bridge, you will often do far better by optimizing for the A and B strings. The overall best-fit can be better than by using the E strings.

[OD]>>> In real life, it's almost never possible to get totally perfect intonation.

In my opinion (and the tuner seems to think so as well), it is never possible to get perfect intonation. We aim for a best fit on the tempered scale and accept the errors inherent in the design of the stringed, fretted instrument.

Chris

[Patrick2]

If we're going to be talking about tolerances down to 1/16" . . and I guess for accuracy of spot on intonation we need to, then, let's not forget . . . when adjusting the intonation on some of the older arch tops . . . that sometimes you will find a bridge base and it's posts leaning ever so slightly towards to tail of the guitar . . . and even worse, towards the finger board. That will definitely affect the actual length from the nut to the saddle .. which will obviously tilt along with the posts. Everyone of my arch tops has either been aquired with, or corrected to have a bridge base with its posts PERFECTLY straight up and perpendicular to the top.