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Double Bass Redwood topwood?

#21
If I make the string longer, should the body be proportionately longer also?

Yes. 1200 mm for a full size bass versus 1100 for a 3/4

If the string is longer (42-43ish), should the fingerboard be wider to keep the strings from hitting each other? Or will the increased tension on a slightly longer string (of the same gauge and material and tuned frequency) adequately diminish the lateral vibration?

Yes make the spacing wider, string 1-4 spacing at nut should be 33mm and at bridge 92 versus 30/84 for 3/4. I don't know about a five stringer. Ask Paul what his measures.

I have observed significant variability of width of the lower bout and less variability in the upper one. Is there a formula for these proportions, some mathematical model to follow? I see significant variability in the arch height too. For instance proportionally, a 1.25" arch and a 1.75" arch are really different, but I've seen both.

No formula, you will just want to be able to reach around the thing. A proper amount of air volume will help low end support. To get the ideal support from the air (helmholtz) mode on a DB it would need to be huge, so it is a compromise. The ratio of upper bout width to lower is not important really, just the overal internal volume. Make it a big sucker if you can handle it. See Arnald Schnitzer's ergonomic bass for for more hidden info.

If I change the angle of finger board to top, this seems to have more radical implications because it will alter the ratio of the component force vectors produced by string tension. As the angle over the bridge becomes more acute the component squeezing the top between the saddle and the neck end block becomes less and the opposing component (approx 90 degrees apart) vector that puts downward pressure on the bridge and top becomes greater. Is there an optimal equilibrium angle across the bridge? Does it depend on the stiffness of the top, etc.? How do we determine, other than a tried and true plan what that angle should be? Most importantly, Is it different for 5 strings than 4? Or since the component vectors essentially oppose each other, one squeezing the top and tending to swell it at the bridge and the other pushing it down, does the tension of the additional string cancel out and just affect the rigidity of the ribs, back, and neck? Does making the bridge taller give the strings more leverage on the top?

Start with what's important i.e. the bridge height. (fb height extended to bridge is 169mm for a full sizer). That is going to effect tone, playability and volume, the three musketeers of good bass design. You can alter the string angle a little then by changing the saddle height. Sounds like you really do understand this concept from you questions. :cool:
 
#22
That sounds like the straight dope on it for sure, Arnold. Always the concise approach, and much appreciated by a fellow like me who asks way to many questions!!!

Without getting into that whole (hole?) controversy of what constitutes the mythical 4/4 behemoth, can we somewhat safely plan for a body length of 45.25", a string length of 42.5", an upper bout of 22", lower bout of say no more than 30", C bout kept at 14" (to make sure the bow has ample access), with the structural adjustments that you have recommended? More or less?

I'm guessing since you haven't said otherwise that we leave the fingerboard angle the same as for a 3/4 4-stringer???

Should the rib depth be more than 8" or leave that alone also???
 
#23
Ken - I know George Boran used to have full size plans avalible for a 4/4 bass. I don't remember if it was a 5er or not. When you talked to George, did he mention if he had any plans left? I know George's health is failing and he is no longer making instruments, but that plan might be the answer for Silversorcerer if George has any left. As I recall, several of his 4/4 basses were being played in California orchestras.
 
#24
Great day here!!! I can proceed with some confidence. Ken, Arnold, Bob, and Paul, I will find an appropriate way to thank you. I got that last reply up before Ken came in, so I guess that 45" body should go to 47ish (thanks, Ken for the non-controversial answer!). The boards are 48 so that will be close. I'll make it so the end at the saddle is a little safer from the edge, than the neck end, which will get a cut out for the neck join. Jean says saws tend to tear up the wood and recommends coming in a bit from the edge with the carving to avoid invisible edge cracks.

I have just checked out Strobel. Interesting fellow. Surprisingly similar to Wake, but a more readable writer. He and I shared some of the same childhood hobbies. Photography became my first livlihood. I ordered one of his books already and will order some of the others as I finish them. Also, I got your paper, Bob. All I can say so far is that if this isn't rocket science, I've never heard a sonic boom. I'll always be glad to get more on theory. Some of the best references I have on silver photography are out of print also. Perhaps one day I will post them on the web.

Ken, I am greatly encouraged by your vote of confidence in my questions, but mostly what I understand is that a great deal of experience that I don't have is the only way to these answers. I promise I will persevere and make very careful drawings before starting and document this project in detail. I have access to a good recording studio up the street, and will try to get a reasonably neutral and dry recording of her with a good microphone when she's done. Again, thank you all for sharing and special thanks to Paul for the forum. :)
 
#26
Bob Branstetter said:
Ken - I know George Boran used to have full size plans avalible for a 4/4 bass. I don't remember if it was a 5er or not. When you talked to George, did he mention if he had any plans left? I know George's health is failing and he is no longer making instruments, but that plan might be the answer for Silversorcerer if George has any left. As I recall, several of his 4/4 basses were being played in California orchestras.
Click to expand...

Yes Bob I did talk to George Borun. He is at the autumn of his life. He told me he has donated all of his plans to a museum and sold all of the wood and stuff. I got the last copy of his book! But luckily it does include a 1/4 scale copy of the 4/4 bass that he designed. I got my fused amber from him and it makes great varnish. I may build that bass next year, we'll see!

Paul, you crack me up!!!!!!!

I have more to say about side depth, stay tuned.
 
#27
Silversorcerer said:
I'm not an expert, and redwood use seems pretty rare anyway, but 8 annual rings seems too low and the wood might be overly soft. Look for the close grained stuff.
Click to expand...
An 8 ring count is the minimum number of rings to be classified as an old growth tree. That is the way they are classified here. Of course the higher the ring count the better.

I'm not a luthier and I don't play one on TV, but I have worked with redwood. IMHO redwood is not strong enough for a bass top. It splits very easily when it is dry and being so straight grained, it will split the entire length of the top. As thin as it needs to be for the top, unless you plan on bracing it, you could probably split it with finger pressure.

Spruce, on the other hand is very strong and lightweight. They used to build airplanes with it. That's probably why it's the preferred wood for bass tops.
 
#28
Bwulf,

I think there must be a great deal of variability in redwood. I have a redwood flute that is quite different from a redwood picnic table that my folks had when I was a child. The picnic table, although it was very thick (3/4") redwood was very porous and open grained. One could easily scar it with a fingernail. Of course it sat out in the weather for ages, never rotted and my folks eventually sold it.

The flute, which has a ring count of 25-30 rings per inch is quite hard on the other hand. Not like oak, but more like poplar, or close grained cedar. It is much harder than white pine. It has a course grainy look to it that I find rusticly attractive. The way the Cherokee make their traditional flutes is similar to a bass top in that two pieces of hollowed out wood are joined longitudinally. Then they are shaped on the outside, mine with a lathe. As you play one of these flutes, moisture condenses inside it, causing the wood to swell and these flutes are known to split along the seams at times, or in other places if the glue is stronger than the wood.

I have two other flutes like this, all from the same maker, one of eastern red cedar (the traditionally preferred wood) and another of tulip tree (poplar). The redwood flute is just as stable if not more so than the others. The cedar one is the only one that ever split and it split along the seam and was easily repaired.

The wood (18"x2") I ordered (while I have not seen it yet, reportedly has 40+ ring count) was advertised as tonewood. Most of the stock went to a guitar builder, who examined it in person, then bought all the boards that could make one piece guitar tops. If you do the arithmetic, this wood is from a tree that must have been more than 700 years old when it was cut. The lumber was 6 ft and longer, but not too much longer than 8 ft, so it came from a salvaged short piece of an old log.

A guitar top is much thinner than a bass top and unless it's an archtop with a tailpiece, the top sparingly braced, bears all the string tension. Unless some of these other folks posting, some of them with direct redwood experience (if you've read their posts) are playing me for a fool, then it might not be a bad choice. 40+ rings per inch is extremely close grain for this species. No one has guaranteed me that this will work, and I could get to the end of the project and the whole thing split to smithereens. In which case we can cry, laugh, etc. and you can say, I told you so, fool.

And then I'll get some spruce and start over and we'll all know more about redwood. Unfortunately most learning is trial and error, usually almost as many errors as trials, and then there is that one time when success happens, and then we all try to find out what was different that time and repeat it. I'm really not afraid to fail, or to learn the hard way. In life we all ultimately reach the same destination, it's the journey that counts.
 
#29
If possible Ken, even in 1/4 scale, I'd love to check out George Boran's 4/4 plans if we can make copies of them. Do we need to ask him? He's a Master and I'm totally novice. It would seem appropriate.

It's daunting how quickly these things become generally unavailable. I was unable to find anything out about his book beyond a small mention on this forum by Bob B. Thanks for remembering George, Bob. It makes me realize how few people at any one time are hand carving DB's. A virtual small world indeed. There is a fellow in Savannah, George Hofer, who repaired DB's and also plays or did play in the Savannah Symphony. I may call him tomorrow and see if he can offer some 4/4 plans or if he might have Boran's book. I think he may be in retirement or nearly so. A couple of years ago he was diagnosed with a degenerative disease the name of which escapes me now and I don't know what the implications were. I think Edgar Meyer bought a bass from George that he still plays.

So by the way, If it's not too personal, Paul, what does your 5-string measure? :)
 
#31
Silversorcerer,

George is no longer playing. I used to play down there a lot. SSO folded about a year and a half ago, but George hadn't played in quite a while when I started playing with them in ' 99. He sold off his Gagliano bass to Charles Barr.

I doubt if he is still doing anything with basses, but you never know. Age just kind of caught up with him. It's a shame...

FWIW
Brian
 
#34
Good news about George Hofer, but no 4/4 5-string plans. George Hofer's most recent bass restoration is for sale at Roland Huthmaker's violin shop in Duluth, GA and George is currently restoring 2 more basses. He only has Wake's book and feels like it is lacking in details (a concensus has solidified). He was not familier with Strobel or Boran, and does not have any 4/4 bass plans.

He did offer some suggestions: He believes that a string length of 42.5 should be the maximum. In his opinion longer BB strings simply will not have enough room to vibrate fully or the spacing required to allow such would result in a very difficult to play bass. He recommended a violin making workshop (class) to me. When I asked what made a great double bass he said no one really knows, but they are easy to recognize.(!?) He favors old instruments of Italian origin and design.

I've made plans to visit his shop and those of two more Savannah luthiers, one who specializes in mandolins, and another that makes lutes. The mandolin maker is using a type of pine topwood from Europe that is now being grown in south Georgia (USA).

Ken, so about the Boran 4/4 plans: Do I get a peek or do I get to wait until you build one? ;)
 
#36
Silversorcerer said:
Bwulf,

I think there must be a great deal of variability in redwood. I have a redwood flute that is quite different from a redwood picnic table that my folks had when I was a child. The picnic table, although it was very thick (3/4") redwood was very porous and open grained. One could easily scar it with a fingernail. Of course it sat out in the weather for ages, never rotted and my folks eventually sold it.
Click to expand...

There are many varieties of redwood. Years ago, the logs were dumped into a pond and pushed around by boats. Some of the logs were so dense that they would sink. The soft part you describe is the sap wood, the part between the growth rings. When there are many growth rings close together, there is little room for the sap wood, therefore you have a denser, harder wood. There is also curly redwood, which is like flame maple with wider flames and burl, which is actually a growth on the tree.
Like I said, I'm not a luthier. It may work. Give it a try. I would be interested in your results.
It is beautiful wood. There is a lot of it around here.
 
#37
Bwulf,
I e-mailed a supplier about some salvaged sunken redwood. Definitely some dense stuff there. Apparently he wasn't interested in selling any for tonewood, or felt he didn't have the right stuff. But it was extrordinary looking from the photos. It becomes mineralized and takes on all kinds of colors in the red-purple-orange spectrum. I don't think it hurts a Redwood log to be totally submerged. You just might want to go fishing for some. Not necessarily for instruments, but it is the log version of sunken treasure. I think the guy who had that mineralized stuff was getting pretty good $ for it.

The whole Redwood family (about 4 species worldwide) is unique in many ways. In Georgia we have Bald Cypress and Pond Cypress. It is very rot resistent and slow growing and pretty soft stuff ususally. The roots of these two varieties when submerged in a swamp produce cypress "knees" that look like stalagmites sticking up out of the ponds. Very primordial looking places. The lower trunks swell in the ponds so the trees have a huge tapering base. These varieties don't get much taller than 75 feet or so. Like all redwoods they are extremely hardy, and the soft wood lasts against the weather for ages. Bugs don't eat it either. In fact it pretty much has no natural enemies othe than the logging industry, and even then the stump sends up shoots in circles around the wide base, which is left in the pond with the roots and knees.

I've seen some solid body guitars with redwood burl veneers. It is the preferred sound board material for hammer dulcimers, dulcimers, psalteries, and some harps, so I suppose my "big" experiment is not so unusual really. What do you think I ought to use for the ribs and back? :)
 
#39
Hi Bwulf,

The original idea was to make a bent flatback, not laminated. I was thinking some hardwood for the back. Perhaps spalted maple, which I think is just a way to describe a pattern in the wood that is some kind of pattern of striping in the grain;- it's not a species. Cherry was suggested by Jean, my luthier teacher and has a nice color harmony with redwood.

Perhaps using something inexpensive hardwood for structure and laminating a redwood burl veneer onto it for beauty is not a bad suggestion, though. I might not simply because then I have to get into how laminating works, and that compounds the learning curve on this project a bit. I have heard a number of luthiers who favor using laminated sides and backs because of better resistance to warp and splitting. Jean, my local teacher here is one who favors it for guitar construction (not for the top of course). Then there is also that fellow who makes the ribs out of two pieces with cloth sandwiched between them for structural purposes. I think the inner and outer wood is the same, though.

The biggest potential disaster I see with laminating soft to hard (wood) is not matching the drying characteristics of the inner wood with the outer wood (well, I thought that wood get me out of the double entendre, but instead it just compounded it). What I really mean:
Sudden humidity/temp changes can send woods with different properties in different directions and with wood this large that might result in the construction of a giant imploding/exploding musical barometer/thermocouple.

Here's the way it works: Heat tends to expand wood, but hot air tends to dry wood out. Drying wood tends to shrink. No matter how well seasoned the wood is, it's moisture content will stabilize to the relative humidity of its environment (assuming the environment is stable, which it is not, despite the best efforts of Carrier or Rudd). So even a fairly thin wood rib varnished on one side and not on the other has the same problem if it gives up or absorbs moisture easily, because it shrinks or expands more rapidly on one surface than the other. There was a musical professor who bought Hauser guitars on custom order who always wanted them raw, unfininshed. This may have been why. It is probably why violin makers have generally used very slow drying flexible varnishes, but that is just me speculating. I haven't studied any of this enough yet.

A general idea is beginning to develop that could be summed up roughly as "balancing the linear expansion of the ribs to the perimeter area expansion of the top/back." Constant expansion/contraction coefficients for wood are impossible to establish because of the opposing moisture/temperature thingy as well as the inconstant weather.

The solid body electric guitars don't have near the same problem because they are sealed on the outside and moisture doesn't get in or out easily or quickly.
 
#40
Silversorcerer,

They use different woods to make laminated gun stocks for rifles. They are very stable but I don't know if the woods have similar properties ie; shrink rates, hardness, etc. I believe they are laminated at 90 degree angles to each other so that any movement of individual slices of wood is bound between two layers of wood with the grain at right angles. Before the advent of polymer and carbon fiber stocks, this was one of the most stable gunstocks made, although usually very heavy. The individual layers of wood are pretty thick also. Here is a link to some, if that is any help.
[Invalid or Expired Link Removed]
 

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