Double Bass better tone tranferring bridge wood

[Paul Warburton]

Again, do some research. The great Itailian luthiers, at least most of them, didn't like to make double basses for obvious and specific reasons. Too much wood, too much time to make and took up too much room in their shops.
They could make some big bucks making great violins, violas and celli for big name virtuosi on those paticular instruments.
Flat back DB's came into the scene for one specific reason. The backs didn't have to be carved. More money, less work.

 

[Matthew Tucker]

Again, do some research.

Longfinger probably thought that asking a question on Talkbass was research.

Anyway, Paul didn't answer why roundbacks continue to be made today. If it was simply "flatbacks are easier and cheaper" with the net result the same, then no-one would make them, surely?

There are as many theories of what should vibrate as there are luthiers. But I agree with a premise that Arnold came up with some time ago, that you need to make basses as light as you can without them imploding under the string pressure. This means that the whole thing will vibrate to an extent; its a matter of balancing the stiffness of the body/neck assembly with the flexibility of the belly arching to achieve an instrument that achieves the volume you are after and the colour of tone you are after.

Sonically superior is subjective. You could probably make a very loud bass with a flat belly arch and a heavy rigid carcase, but the tone that instrument produces might not be as complex as you might want, as well as the bass being a dog to carry around.

And an instrument designed to be bowed has different properties and requirements to one designed only to be plucked.

Bear in mind, some of the nicest sounding basses are not the loudest basses. and vice versa. And a bass that sounds gorgeous bowed, might sound like an old hot-water-bottle when played pizz.

But sometimes, if you are a good maker - or you get lucky - you achieve both

 

[Paul Warburton]

Longfinger probably thought that asking a question on Talkbass was research.

Anyway, Paul didn't answer why roundbacks continue to be made today. If it was simply "flatbacks are easier and cheaper" with the net result the same, then no-ne would make them, surely?

Matthew, I didn't answer why "round backs", as you seem fond of calling them, for one specific reason. Nobody asked me. And try as you may, your posts confuse me. I'm sure, as before in another thread here, you'll say "TYPO" when I ask you what "no-ne" means. It really is impossible for me to communicate in a verbal sense with you.

 

[gbaker]

There are a lot of things about a bass I am not sure of, I am not going to list them unless provoked. I am fairly sure of these things:

1. Less parts is better. Why round backs when flat backs are cheaper? Because round backs have less parts, and less parts means less parts to go wrong. Less potential for failure, un-glues, rattles, buzzes, etc.

2. The ribs and back do not contribute significantly to the propagation of sound (directly). There are measured (and charted) studies to support this. They provide structural strength to other components and an acoustical enclosure.

3. The sound post provides a stationary rest for the G foot to pivot on. And provides some timbre adjustment.

4. String motion drives the bridge mostly laterally. Through the G foot pivot the force translates (rotates) to vertical movement of the E foot bearing on the top plate and the bass bar which helps transmit the energy along it's length to the top.

5. The mechanism is rather simple (good) and fairly inefficient (bad) with more energy being expended on compression and friction losses than to producing sound.

Why has it not been improved much in centuries? See point 1.

 

[Matthew Tucker]

I'm sorry, i have corrected my mis-typing so i don't confuse people.

And it's not just me that is fond of calling roundback basses that way! http://www.google.com.au/search?hl=en&q=roundback+basses&btnG=Search&meta=

 

[William Hoffman]

Thanks Matthew for replying…we appreciate the exchange of information TB allows from experienced luthiers and feel we have more to learn as self taught hobbyist. If I re-trace how Lonnie’s cuts a bridge he does leave the legs of the bridge as long as possible. The feet are shaped to the top plate of the bass then he shapes the top (cap) of the bridge to echo the shape of the fingerboard. He sets the string spacing grooves with rat tail files and then details the bridge by shaping and sanding. The legs are left as long as possible by sanding down the feet of the bridge. The photo on the left was the 1953 Kay but we do have some Epiphone basses that have a really low overstand which does not for much wood to remain above the heart. Thanks for the explanation.

http://www.talkbass.com/forum/attachment.php?attachmentid=139850&stc=1&thumb=1&d=1252894111

M

OK, looking at the left hand picture, if he took another 2-3 mm from the bottom of the feet before shaping them to fit the top, he wouldn't have to reshape the ankles anywhere near as much. That Despiau bridge shape is a more squat shape than some other bridge shapes; if you like taller legs there are blanks you can buy that start out that way...

interesting digression from OP, but i just have to ask because i'm interested: What is gained (in terms of sound, vibration transfer, or other qualities) by sanding down the "ankles" and "toes" of the bridge leg? Molly Kay's picture shows Lonnie doing that, and Matthew originally thought that excess wood ought to have been but from the bottom of the foot but later seemed to drop that issue. The luthier who made my bridge did this as well (it seems like it was sanded down off the ankles and toes) and while it looks more elegant than the stubby toes of a simple fit bridge, is there any advantage sound-wise? Matthew, can you please come back to this point?

 

[Matthew Tucker]

Well ........ *I* think that the bridge feet need to be solid, elegant, and flexible.

If the feet are too small you are putting a lot of pressure on a small area and this may accelerate damage to the finish (almost ALL old basses have damaged finish under the bridge, but I think its a pity to be the one responsible). So that's why the feet splay out at the bottom of the legs, i think. A well-fit bridge will not usually damage the finish unless it is knocked around or allowed to tilt, or the finish is unreasonably soft.

The G foot particularly, *I* think, needs to be able to flex as the bridge pivots around the soundpost. If the ankles are too thick, it makes the feet rigid and they can't flex unless the edges of the feet lift. That's exaggerating of course, we're talking tiny tiny movements. But tiny movements are what makes sound.

Thirdly, I think a bridge needs to look elegant, and I prefer a slender "ankle" curve, to a stubby one with varicose veins. This is why I and most luthiers prefer to spend a while "dressing" the bridge, if you like, with neat chamfers and smooth edges and neat corners. But actually, yeah sure the bridge will work fine without the dressing. That part is cosmetic. But you will spend a fair while looking at it, and so why not make it look good? And if you like to give your luthier some free advertising, he/she can put their own brand on the bridge. I don't do this, because i don't want to be "in your face", but I will sometimes sign my name under the bridge foot if I'm particularly pleased with my bridge work.

Lastly I come back to the idea of efficiency; If I buy a "blank" bridge, I want to make sure its already close to how I like it, and I want to make my job quicker and therefore cheaper for the user. Maple is a wonderful wood to carve, and looks nice, so its an obvious favourite for luthiers, and the blank makers make them of maple because they sell. I could carve a bridge from ebony or blackwood, but it would cost more, and take me many more hours to do nicely. The blank is designed to be customised, the makers do most of the tricky work and leave enough wood to allow the luthier to do the fitting. That is, fit the feet quickly and well, shape the crown, space and file the string grooves, thin the breast of the bridge. And that's basically it, unless the luthier wants to remove more wood from the wings or the legs for tonal reasons, or needs to add adjusters. But 90% of the time, if you choose the right blank to start with, the edge profile doesn't change much.

There are a number of basic styles of blanks, and makers, and you choose the blank you like and that you think will suit the bass and what the owner wants. There's all sorts to choose from; treated, untreated, tall legs, short legs, A-frame Belgian styles, with different size wings, hearts, kidneys ... and probably lungs, spleens, gall bladders and prostates too if you search hard enough ....

 

[William Hoffman]

Matthew

thanks a bunch for this detailed, well-written and thoughtful response, delivered with great wit and good information.

i was curious about the thinness of the feet, not about their smallness or the area of the top they cover, so your second point nails my question.

flexibility. you write the feet can't be too thick or they won't flex. can you give any measurement there?

in other words, can one say, apart from the cosmetic aspects (which are all important in their way), "if the toes are much less than 3 or much more than 5 mm thick, then you are either too thin or too thick"? what about, for example, the feet thickness in the attached photo?

regards and thanks

William

 

[Matthew Tucker]

Luthiery is not a science, so its hard to say "you must adhere to this measurement"

For me, 2-4mm works and looks OK. Yours look OK to me, if a bit chunky. Bt that's just my taste. In any case, the fact you've got adjusters in there means they'll flex anyway so its not really an issue. On thing I could say, that if your bridge feet are *too* thin, you've got more of a chance of snapping off a corner if you drop it.

See how the side of the bridge is rough off the saw? I wouldn't leave it like that, i think it looks cheap. But it will not matter one iota acoustically! And the bridge hasn't been "dressed", but is probably perfectly functional, if a bit plain. To my taste, anyway!

 

[Matthew Tucker]

One small thing - I feel I should point out that I am by no means an expert luthier. I have never been to luthier school. I have made two basses from scratch and have been working on basses for only four years or so. Compared to Arnold or any of the professionals here, I am but a pimply novice and, despite what some may think, am very open to learning from those more experienced than I. But I have found there is rarely only one correct answer, and quite often its a matter thinking things through and following a hunch. I am happy to share my own experiences and observations and thought processes, and if it makes sense, and is useful to you, great ... but if anyone thinks what I write is crap, you can either correct it, or ignore it, or take a cheap shot at me. Up to you!

 

[William Hoffman]

Matthew

thanks for your comments. the 2 - 4 mm rule of thumb sounds about right.

am attaching a picture of mine, the bridge was done by an expert luthier and the feet look up close like they are about 2.5 mm thick. it has all the trimmings and looks elegant like a good bridge should...

and your disclaimer is for me implied here on TB.

William