What years for the mother of pearl inserts?

[Chicago Jay]

On the bridge of the Pete Townshend SJ-200, there are mother of pearl inserts in all four open areas of the bridge. I noticed that the '68 SJ-200 had the same thing. What years did the SJ-200 have mother of pearl inserts in all 4 areas of the bridge? Thanks, Jay

[Buc McMaster]

Can't say for sure, but it seems to me the 4-ribbon J-200 bridges appear more often on "special" editions, like the Townshend model. The Western Classic I used to own had 4-ribbons, and I do see it on limiteds and custom shop one-offs. Personally, I think the 4-ribbon bridge is inferior to the the 2-ribbon due to the distance between saddle and pins. This distance is too much in the 4-ribbon design, making for poor angle of break over the saddle, and requiring a bit of an over-set neck and a tall saddle for a great setup. Whether or not you like the extra bling is subjective, of course, but the 4-ribbon design can and often does make for setup trouble.

[zombywoof]

The closed bridge with four inlays first appeared in 1961. Prior to that the SJ/J-200 came with an open moustache bridge with the two inlays.

[Chicago Jay]

Thanks for the begin date (1961). Would you happen to know when they stopped making the 4 inlay bridge in the non-custom versions of the SJ-200?

[zombywoof]

Thanks for the begin date (1961). Would you happen to know when they stopped making the 4 inlay bridge in the non-custom versions of the SJ-200?

 

Not sure what you mean by "Custom." Beginning in 1960 every J-200 was made in the Custom Division (which was created that year). Sometime prior to 1980 Gibson went to a totally different bridge on the J-200. The ealiest Bozeman-made J-200 I have seen was made in 1989. As far as I know it is a standard production guitar and has the old style open (2 "ribbon" inlay)bridge.

[Chicago Jay]

Not sure what you mean by "Custom." Beginning in 1960 every J-200 was made in the Custom Division (which was created that year). Sometime prior to 1980 Gibson went to a totally different bridge on the J-200. The ealiest Bozeman-made J-200 I have seen was made in 1989. As far as I know it is a standard production guitar and has the old style open (2 "ribbon" inlay)bridge.

 

Thanks again. I enclosed a copy of the PT-200 in the attachments. Did Gibson ever make a bridge for an SJ-200 like this, with the "outer section" of the bridge filled with mother of pearl inlays?

[devellis]

I think what this is, is a "closed mustache" bridge rather than the "open mustache" where you can see the top inside the loops of bridge wood. On the closed variety, Gibson sometimes put in pearl that sort of mimicked the shape of the openings in the "open mustache" bridges.

 

Concerning the positioning of bridge pins relative to the saddle, I'm not sure why that would be a set-up problem unless the saddle was way too low. A number of reputable luthiers (Al Carruth among them) have stated that break angle only needs to be steep enough to hold the string against the saddle firmly. The tone is influenced by the height of the saddle but not the break angle. The height determines the torque applied to the bridge. I used to think a steeper break angle improved tone, but people who know a lot more about guitar construction than I do have convinced me otherwise. But, of course, with a low saddle, a poor break angle might not give firm enough string-to-saddle contact. But when that's the case, i wonder if there's a neck angle issue that's really at the heart of the problem.

[BigKahune]

... break angle only needs to be steep enough to hold the string against the saddle firmly. The tone is influenced by the height of the saddle but not the break angle. ...

 

Come on . . . the higher the saddle, the sharper the brake angle. It's the break angle. People staving off neck resets have slotted their bridge pin holes to get a steeper break angle since time immemorial.

 

 

As for the number of ribbons - it's been bouncing back and forth between two and four since the 60s. In 2003 the standard issue had 4 ribbons. The 2007 TVs had 4 ribbons. My 2008 has 2 ribbons. I don't like the extra distance from the pins to the saddle with the 4 ribbon variety - the break angle is too low for my liking.

 

[Buc McMaster]

.....i wonder if there's a neck angle issue that's really at the heart of the problem.

 

Indeed! As I mentioned above, a 4-ribbon bridge requires an over-set neck to have a tall saddle because of the increased distance between the pins and the saddle. With a lesser set neck a 2-ribbon bridge can tolerate a lower saddle and still maintain good break.....much short distance between pins and saddle.

 

I'm pondering your other comments on top torque. The pin holes will be the point of highest force, where the string bends to the saddle, string tension applying torque to the bridge through the lever of the pin. Break over the saddle forces are acting directly upon the saddle, not the bridge, and most of that is directed downward.....not near the torsional force of the angle applied at the pin. In an unramped bridge, there is a relatively large area of contact between string and pin. Ramped pin holes would reduce this area of contact, making it smaller and applied closer to the bottom end of the pin.....more leverage/torque on the top? How much of this increased leverage is mitigated by the lessened angle the string takes out of the hole? The angle of break over the saddle, while I think more is better, surely has an optimal point beyond which there is no better volume/tone to be had, and this point is most likely different from one guitar to the next. Then again......maybe.......i dunno....... Who knows guitar bridge physics?

[devellis]

Guys, first the argument isn't mine. It's luthier Al Carruth's -- and he's convinced most of his critics. For those who don't know him, Carruth is a bulder whose flat-tops start at $4500 for the most basic model and whose archtops start at $9000 for the most basic model. He also teaches lutherie. He has also published articles and given Guild of American Luthiers seminars on instrument construction and acoustics. So he's a pretty knowledgable guy.

 

He suggests that slotting works only when the angle is so shallow that the string, as it vibrates, doesn't make consistently solid contact with the saddle. Imagine a taller bridge and shorter saddle so that the height of the saddle top is the same as a lower bridge with a taller saddle. If the break angle is sufficient to hold the string position, Carruth argues, then the physics of the two arrangements are identical. The torque generated is determined by the height of the top edge of the saddle, not the break angle. The strings, of course, actually attach at the bridge plate, under the top, not at the top of the bridge. So the torque has to do with the distance from bridge plate to saddle top. Now some instruments have saddles so low that there's almost no break angle. If you force a string laterally near the saddle it moves more easily than it should. But sound isn't produced by down-force on the saddle and bridge on a pin-style bridge (it is on a floating bridge, as on an archtop guitar or mandolin). The top doesn't primarily pump in and out on a pin-bridge guitar -- it forms a wave pattern, dipping in front of the bridge while raising behind the bridge, then rebounding.

 

Again, I was skeptical of all this until I read a lengthy description, complete with criticisms and rebuttals. The evidence seems to support Carruth's argument. But of course, you can reach your own conclusions.

[Buc McMaster]

The torque generated is determined by the height of the top edge of the saddle, not the break angle.

 

I disagree. Imagine yourself inside the guitar body, looking up at the bridge pins. If you could grab the end of the pins and push them toward the endpin of the guitar you would be generating torque on the bridge/top assembly. This the the force that string tension applies to the pins - a rotational force toward the endpin at the bottom of the pin, and toward the headstock at the top of the pin (force applied to one end of a lever, the pin, moves the other end in the opposite direction). Even if the saddle was not there at all there would still be torque on the top. Certainly the saddle, a taller one moreso, sees force, but top torque comes from the string/pin interface, not string/saddle contact. Given an adequate angle of break, the saddle serves to transmit vibration to the bridge/top with mostly down pressure, not torque. Torque is a measurement of rotational force and we don't want torque at the saddle, trying to rotate it out of the bridge slot, we want down force for optimal transfer of vibration. If we pin a string into place on the bridge and pull upward on it, perpendicular to the top, there is no torque. As soon as you lay it down the length of the neck and tension it up you create torque on the top - the pin becomes a lever and the saddle is not required for torque to be applied to the bridge/top.

 

I'm not a guitar builder, nor am I a college-trained engineer, but my day job is application of the mechanical transmission of force, and with over 35 years in the job, I have acquired a solid understanding of torque, levers, angles and other such applications of physics. And I'm not meaning to be fussy about this.........really.......but I do not agree that the height of the saddle has anything to do with top torque. Torque is generated by the string/pin connection and does not need the saddle to produce this torque.

[devellis]

But strings don't pull on the ends of the bridge pins. They pull on the underside of the bridge plate. Actually, it seems to me that the farther the bridge pins are from the saddle, the longer the lever. If the axis of torque is the lateral midline of the bridge, then I would think that a bridge (and bridge plate)that was wider fore to aft and had the pins farther back would load a longer lever. If you wanted to pry a bridge off a top, would you want a shorter or a longer handle on your prying tool to get the bridge off (ignoring damage issues)? But these thought experiments can be misleading.

[Buc McMaster]

But strings don't pull on the ends of the bridge pins. They pull on the underside of the bridge plate. Actually, it seems to me that the farther the bridge pins are from the saddle, the longer the lever. If the axis of torque is the lateral midline of the bridge, then I would think that a bridge (and bridge plate)that was wider fore to aft and had the pins farther back would load a longer lever. If you wanted to pry a bridge off a top, would you want a shorter or a longer handle on your prying tool to get the bridge off (ignoring damage issues)? But these thought experiments can be misleading.

 

 

Right, the don't pull on the pins, they push with a rotational force......torque. And yes, they are pulled tight against the bridgeplate, but it is the angle the string follows out of the bridge pin hole that turns the pin into a lever, generating torque. I suppose the axis of torque is actually the string itself.......that is where the force is. String tension is trying to straighten the string out, trying to overcome the angle it is bent into coming out of the pin hole. The ball end presses against the pin. Have you ever seen plastic pins from and old, old guitar? They get bent slightly from the pressure of the string trying to straighten itself. Again, the saddle does not even have to be there at all for there to be torque. The torque comes from string tension turned at 90 degrees (unramped pin hole) applying pressure to the pin; trying to rotate the pin. Torque. No saddle required for torque.

 

I love a lively conversation!

[devellis]

It was my understanding that the only role of the pin was to keep the string ball in contact with the bridge plate, which was the actual load bearing surface. That would explain why bridge plates are made of durable stuff like maple or rosewood and pins can be made of relatively soft plastic. In fact, one rationale for slotting (as opposed to ramping) the bridge pin holes is to put the force more squarely on the bridge plate. With a slotted bridge, you can tune to pitch with no bridge pins in place at all. The string may be the vector of force but the axis around which torque (rotational force) occurs has to run perpendicular to the strings, doesn't it? I may have this wrong, I'm just trying to make sense out of the physics of the guitar top as I understand it (which is a long way from "completely"). I'm certainly not claiming that I've got this 100% correct, just trying to convey the logic of a particular point of view on the matter.

[Buc McMaster]

Yes, a slotted bridge doesn't necessarily require a pin to keep a string in place. Which is what I was thinking when I spoke of the string being the axis of torque......so perhaps in the case of a slotted bridgeplate the pin does not become a lever. But the application of the torque is the same in either case. The string is still bent, under tension, through an angle and generates torque on the bridge and thereby the top. Still the saddle is not necessary for this torque to be present, and in the case of a slotted bridgeplate, apparently not even the pin need be there. I'm convinced the saddle is not part of the torque equation. But I could, of course, be wrong, and I, like you, am trying to reason this out.......

 

Good talking with you, sir!