Official Luthiers Forum!

Hi,

I am currently building a flattop version of a Gibson style O guitar (which was originally a carved archtop guitar). I am doing my own interpretation of it, but am currently in doubt about what bridge type would be better....

Soundwise, what benefits are there using a regular pin bridgeor a tailpiece bridge? I would love to do a tailpiece since I have never done that before, but somehow I feel that a tailpiece bridge would decrease volume....not sure though.

I can't find any info on the difference in sound between a floating tailpiece bridge and a glued on pin bridge on a flat top.

So if anyone has any info on that I would be really grateful.

Thanks,

Ivo

If it were I, use the tailpiece first with just a single screw holding it where the endpin goes, try it for a few weeks, and if you like it keep it. Not only will it help determine the questions but it will also assist in getting the guitar set up as you can mark it for the bridge with great accuracy.
If its not loud enough then go with the pins.
IMO A lot will depend on the thickness of the top and of course the bracing.
A tail style most likely would not require as much as there is less torque on the top, but the tail block should still be substantial and the sides and lining still good and strong.
A short study of the Gibsons as they developed might provide some insight on reasons for you deciding which direction to go.

_________________
You just pick up a chord, go twang, and you're got music. -Sid Vicious

Others I am sure will offer up some science -- using a tail piece and a pedestal bridge which is pushing down on a flat top guitar likely will have disappointing results. The normal bracing on a flat top is designed to be pulled into a dome which leads to efficient energy transfer.

http://www.guitarhq.com/gibson2.html#styleo

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

This came up on this board a few moths (years?) ago and was address by Al Carruth. I suspect he build a dozen guitars with all kinds of bracing and pin/floating bridges combinations and then probably shot lasers at them [FACE WITH STUCK-OUT TONGUE AND WINKING EYE].

Ok, maybe not that, but I think the takeaway was that the forces on the top were so different that you would need radically different bracing to put a floating bridge on a flat top and have it sound like a guitar. More informed luthiers can chime in, but my distinct impression was that for a floating bridge it would be best to have a carved arch or a pliage induced arch. For a flat top, you can't get a conventionally "good" tone using the floating bridge.

Search for floating bridge and you can probably find the thread.


Sent from my iPad using Tapatalk

I've experimented a bit with bridge types and flat tops.

Don't assume that because you use a tailpiece you can't glue down the bridge. Orville Gibson (AFAIK) used tailpieces and glued down bridges. IME there is more difference from making the bridge floating than whether you use a pin bridge or a tailpiece.

If you glue the bridge, the sound isn't that different between a tailpiece and a pin bridge. The latter is a bit more complex sounding, though the difference is less than you might expect. I'd lean toward a pin bridge for fingerstyle/folk type playing. Tailpiece guitars can be strummed hard with less string breakage, and so are more suited towards this type of playing. (No one ever talks about this)

Exactly -- just because you can does not mean you should. Batson makes guitars that have a tail piece, the strategy is use a fixed bridge with an over and under string path through the bridge. To me their guitars lack volume and still sound a lot like an arched top jazz style instrument.

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

I agree totally with Ken you are going to loose a lot of transfer of energy

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I had similar questions when I built a 12 string based on the old Stella (which had glued on bridges but tailpieces). First, some simple theory - with a pinned bridge the ends of the strings are anchored to the top just behind the saddle and apply rotational torque to the top - both statically and when plucked. The top rotates around the axis of the bridge (probably in some very complex fashion). The bridge must withstand almost the full 170 pounds or so of tension and the top must resist the rotational forces (one of the reasons the X brace is such engineering genious).

Guitars with tailpieces have little or no rotational torque, but there must be a vertical component of the string tension and vibration into the top. Much of the tension is applied to the tailpiece (and tail block of the guitar). The top must move in entirely different fashion (more up and down). Because there is little or no rotation around the bridge ladder bracing (both old guitars like Stellas and SelMac's), simple X or tone bars (archtops, mandolins) all works pretty well.

Do they sound different? When I was building mine I contacted Todd Cambio who builds ladder braced guitar with pinned bridges and with tailpieces. He says that if anything, the tailpiece guitars are not as complex sounding - they do have more of the "old timey" sound. I figured that when I built mine I would put a fixed bridge on it with a big enough bridge plate that if I ever wanted to drill pin holes I could. I started with the tailpiece - it certainly has the "stella sound" that I was looking for so I've left it this way. (btw - its plenty loud!)

Well, FWIW, about 10 years ago a friend of mine built a guitar with a glued on bridge and an integral tailpiece (the strings were anchored to the butt end of the guitar after passing through basically horizontal holes in the rather smallish bridge). He eliminated most of the conventional structural bracing and just put in one cross brace at the bridge and, as I recall, some fan-like braces. He did put in a couple of full length "struts" between the neck and tail blocks.

That guitar comes to my place every Summer, and everybody wants to play it. The tone and volume are amazing.

Grant

Yifo:
It's a bit unclear whether you're making a flat top version of the original archtop, or using some form of arching.

The main issue with using a tail piece is getting enough break angle over the saddle to keep the strings in solid contact. It doesn't take much; six degrees is just enough, and ten might be better, but more than that is unnecessary. The problem with doing that on a flat top is that the down load causes the top to sink over time. One alternative is to notch the saddle to pinch the strings, as they do on banjos and resos.

The string produces two main signals as it vibrates; a 'transverse' and 'tension change'. If the string is vibrating up and down relative to the soundboard it' pushing the soundboard up and down, so that it moves like loudspeaker cone. This is a fairly easy way to move the top on a flat top, and effective at making sound. The tension signal acts by pulling the top of the saddle toward the nut twice for every full cycle of transverse vibration. It's much weaker than the transverse signal, averaging about 1/7 of the amplitude. It's also hard to move the bridge that way, since we build guitars to resist bridge torque. Finally, as it tugs on the bridge top it's pulling the back end of the soundboard up and pushing the upper part down, so the motion partly cancels out, producing less sound that it could.

If you can get the string going so that it's only moving across the top the only signal making sound should be the tension change. If the string is moving vertically with respect to the soundboard, both the transverse and tension signals are driving the top. There are a couple of ways to get the string going in only one direction, at least initially, and I've tried them both, measuring the output of the guitar with a dB meter. In both cases the 'vertical' string motion produced about 20 dB more sound than the 'horizontal'. That is, the transverse signal produces something like a hundred times as much sound power as the tension change when it's working to it's best advantage. You have to go pretty far of 'vertical' string motion for the tension change to make more sound than the transverse.

The tension signal doesn't act directly on the bridge on an instrument with a tailpiece. There's an interesting way to look at this. When you pluck a string exactly in the center the transverse signal only has odd-numbered partials. That is, the A string tuned to 110 Hz would only have energy at 110, 330, 550, and so on. That's because the even numbered partials have a 'node' (a stationary point) in the middle of the string, and you just insisted that the string move there. When you get the octave harmonic you're doing the opposite thing; imposing a node in the center and killing all of the odd partials. Anyway; the tension signal has energy at double the frequency of the transverse, so when you pluck the string in the center the tension signal only has energy at 220, 440, 660, and so on. If you pluck the string in the middle on a flat top guitar that does not have a tailpiece, you'll get output at all of the partials, with the even ones being weak because they're not driving the soundboard very effectively. On an archtop there's no energy in the even partials when you do that; the strings are not rocking the bridge.

The tension signal doesn't add a lot of power, as we've seen, but it does change the timbre of the instrument. That's one of the main reasons why using a taller saddle alters the tone. Raising the strings off the top gives more leverage for the 'tension' signal to move the top. Again, in an experiment with this I could measure the increase, in the second partial in particular, and listening tests confirmed that people could hear the change.

The bottom line is that, while there are some differences in sound between tailpiece and tied/pinned bridges they are not huge. Most of the differences you hear between arch tops and flat tops have more to do with the arching and sound holes than the bridge setup. Orville Gibson himself used pinned bridges and round or elliptical holes on his early archtops.

Hope this helps.

I'll add one more anecdote. A friend asked me to build him "an acoustic guitar that looks like an ES-175" (one of Gibson's iconic laminated archtop electrics). I told him I could but didn't have a clue what it would sound like. I used a spruce top, gave it as much dome as I could (16 inch radius) simple X brace and a bridge plate (which may have not been necessary)



Floating bridge, trapeze tailpiece, standard f-holes, elevated neck



Guess what it sounds like? Yup, an archtop.....

Told you Al C. had probably built a dozen and shot lasers or something at them!


Sent from my iPhone using Tapatalk

Well, I just finished it. It's a great resonant sound, I decided to go for a four x-bracing pattern, the bridge rests on the double X. I've added a" Virzi-tone producer like" plate under the top which really makes the guitar sound like it has some kind of built-in amp with a nice reverb. I'll post a video of it as soon as I find someone who can actually make her sing (I really stink at playing guitar ).

Here's the specs: Gibson style O Artist. Black Walnut back and sides, spruce top, maple neck and ebony fingerboard 12-fret