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How does one get about designing which style/type of bridge you are going to do on your archtop?

Full solid base or with feet , all wood, wood and bone ala classic guitar or tom maybe?

What motivates one preference over another?

Can you just use a Stewmac's B.Benedetto ebony model for ex?

or is it s result of calculations if the guitar has a sound post or none....?

Thx

Sol

The great thing about archtops is that changing bridges takes just minutes. So if you don’t already have a preference, start with something readily available and experiment.

Target type of string, type of music played and whether pickups are involved all factor in. You playing acoustic big band jazz on this archtop, or throwing p90s on it to do the Eddie Cochran thing?

I find ingl-footed bridges give better sound than two-footed ones for me. Don't go too light, especially on the top part of an adjustable height bridge.

The only use I've ever found for a sound post in an archtop guitar is to kill the sound and help control feedback when playing amplified.

Thank you both for your replies,
As luck would have it I was just reading Alan C.'s posts on the subject on MIMF....more to read I guess....
It's a jazz box 14 in lower bout 1.75" body depth and always used with p-up . I'm not looking for a more acoustic sound, in fact less would be best.....It has a wooden 2 feet on it now non adjustable with a bone saddle....It's feet seem to be resting on the bracing but am not 100% certain, it does look that way...I'm testing different bridge types but so far nothing better than the original..

I've tried a graph tech resomax , but did not enjoy this....It was adjustable though and very very light...

I am tempted to try a tune o matic (2 feet) or a stewmac benedetto full lenght next....

My question was more about which criterias are used when deciding to build an archtop bridge? does one aim for a certain lenght? height etc...

I've seen Ken Parker's super light hollow bridges fairly hi also but he's going for a very lively acoustic sound....

thx

Sol

I had an adjustable bridge on my archtop at first. The belly rose, (curly redwood, and carved light) and it became too tall. The feet would disappear! I made another solid bridge of cherry wood. It wasn't bad. Then I made a Parkeresque bridge of Tulipwood. It seems to work well. It is a strictly acoustic archtop, but it doesn't have the Parker sound. It sounds like an archtop.

I have a bridge made for the 13" archtop. Solid, not hollow, Tulipwood base, with a tune a matic attached above it. The base will not be very tall. It is probably 3 times (4.5 times, or 72 grams!) the weight of the 15 gram on my bigger archtop. It too will be strictly acoustic. I'm sure they will do different things. The 13" is to be like a Les Paul, so it has to be. The sound will be the result.

I would think that the bridge acts like a cross brace. Mine are parallel braced, so vibrations as sent straight up and down. With an x brace it would be different. How? I don't know. Just different.

It will be interesting to see how the heavy bridge works on a tiny body.

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Why be normal?

I've been making bridges based on a D'Aquisto design. The solid bridge base is fitted to the top. It's about 5/8" wide. Rout a 1/4" slot in it almost to the bottom, making sure the bottom of the slot is clean. Make an ebony wedge that's a good fit in the slot, and an ebony or bone saddle piece to sit on top of it. Trim off the top of the saddle to the correct curve and file of the front and back edges to get the correct intonation. Sliding the wedge in and out adjusts the string height.

this one ?

Sol

https://www.guitarrasjaen.com/vimeo-video/double-wedge-bridge/


I also found this prototype modification of the d'aquisto on Jaen guitars,

S

SolR:
That's the one. I was going to see if I could dig out a picture of one of mine.

Can that D'aquisto variation be done with a bone saddle as opposed to a wooden/ebony?

Strangely enough Ken Parker has mentioned before he invented this bridge,(around 13 min of this video )https://www.youtube.com/watch?v=GeSTwjA3GSA and uses a plastic type saddle on a non adjustable bridge, he does use an adjustable neck...

S

is it possible to increase the tension (down load or down force) the bridge exerts on the top without raising the bridge or lowering the tailpiece? Increase string gauge?

As a test I applied some pressure (by hand) on the treble side and the tone improved.....I presently only have "2 footed" bridges, I wonder if a single would work better for this.....or wider than the bracing?

Sol

String gauge is the easiest way. String break angle is pretty well fixed by the design, unless you have an adjustable neck. Increasing the break angle increases downforce. I would venture to guess that most archtops could stand more downforce.
Maybe not Parker's.
I have been corrected on my view of smaller footprint before, but it doesn't stop me.

If you have 25 pounds of downward string pressure, and it is spread out over a single foot bridge, you may have the vibrations spread out over more of the top. But if you had 2 smaller, maybe 1/4 of the surface area of the other you would have the same 25 pounds; but the PSI on that area would be 4 times the other bridge. But the surface that is subject to direct vibrations would be maybe 1/2.

25 pounds of force on a 2" diameter table leg will make a deeper impression in a carpet than 25 pounds on a 4" diameter table leg.

A Parker type hollow bridge SHOULD spread the vibrations out over more surface, AND double the PSI while doing it. At least that's the way my brain works.

_________________
Why be normal?

At one point I did some experiments with that. I made a tailpiece that was 'L' shaped, with the foot of the L hooked over the edge. Under tension the strings would follow a line from the top of the bridge to the contact point of the L, so they could actually make an angle that would have routed them through the top. I varied the contact point on a guitar to see how the break angle affected the sound. Basically, at a more or less 'normal' break angle the sound was good, but if I increased it beyond a certain point it just died. There are a couple of mechanisms that might account for that. For one thing, increasing the down bearing force on the top pushes the pitch of the 'main top' resonance downward; it's roughly the opposite of increasing the tension on a drum head.

A subsequent experiment on a normal Classical guitar showed that changing the break angle within 'normal' limits did not change the output of the guitar in any measurable or audible way.

The bottom line for me is that it makes sense to use a minimal break angle on arch top guitars: just enough to keep the strings from hopping off the top of the saddle or rolling or sliding sideways. Since archtop saddles are usually notched anyway, that means using a break angle of 10-12 degrees.

I just strumbled on a design that Alan C made with what looks like a bone saddle ?

No reason not to use bone for the saddle IMO. You just need to cut your own or find large enough blanks. I've made a few of the D'Aquisto sliding wedge style bridges and really like them. Never made one with a bone saddle though.

As a matter of fact , I watched a Ken Parker YT and he actually uses some kind of plastic akin to Ivory .....https://www.masecraftsupply.com/Alternative-Ivory-Bar-1-14-x-1-58-x-5_p_2081.html

Another point of interest is that contrary to most other bridges I see he uses a rather wide saddle with long notches, most others have a point shaped notch .....??



S

I've been using bone saddles with these for some time: I just haven't gotten around to digging out the pictures yet. I'll see if I can come up with something clearer.

Bone is more dense and hard than wood, of course, both of which could theoretically alter the sound.