Carbon Fiber reinforcement question

[jim1457]

I'm trying to learn more about carbon fiber rods. Mostly I'm concerned about the tonal difference. I've heard they add sustain and brightness, but would that be at the expense of deep, clean low end? I'm more concerned with the tone issues than with stability.

I originally posted a similar question in the basses forum,
Should I add carbon fiber rods?
then found out about this place. Thanks ddnidd1.

[ehque]

my zon has deep clean low end. and you could think of the whole thing as one big graphite rod. haha. its stable, almost freakishly so. but it does move a little. and yes, its quite bright. of course, if you dont EQ your bass at all, anything increasing in volume will reduce the volume of the others - cos you'll turn down your amp to be at the same volume. im still getting used to the sound, so im actually EQing a lot of the treble down.

dont worry about the tonal differences. its a lot more about the pickups and the strings than about the neck.

My next bass, the one im building, will have 6 carbon fiber stringers. Im hoping it wont need a trussrod ths way.

[Suburban]

The idea with graphite rods is to add stiffness. If the neck is of the right stiffness (infinite...) it will not vibrate and hence not kill any frequences of the string.

IME, the more stiffness, the more bottom fundamental. My BassLab STD has a big low end, but the L-bow, with the extra stiffness of the bow (esp. torsional) helps to get even more! And it is the bow, I have compared with a C-bow too, which is the same bass but with the bow "cut away".

[erikbojerik]

Don't even think of going without a truss rod. Even with carbon fibers, if you leave the bass strung up you'll get some neck movement over time. A few years from now, you'll wish it was there.

[ehque]

aw come on, double basses have gone without truss rods AND carbon fiber for years!

seriously tho, do you think it'll NEVER work?

[Rodent]

yes, DB's have gone without truss rod + carbon reinforced necks for years - but they also have a significantly thicker neckprofile than most every electric bass on the market. That extra thickness allows them to be reinforcement free, something that can't be said of anything short of a Wish bass

all the best,

R

[Frank Martin]

Originally Posted by ehque

aw come on, double basses have gone without truss rods AND carbon fiber for years!

seriously tho, do you think it'll NEVER work?

Also, DBs have had sky-highs action for years, is that what you are looking for?

Originally Posted by Suburban

The idea with graphite rods is to add stiffness. If the neck is of the right stiffness (infinite...) it will not vibrate and hence not kill any frequences of the string.

I have to disagree, Sub.
The rods are there to add stiffness and stability. To make the neck move less during tension and humidity changes, as wood would do.
Stiff things do resonate and vibrate. Brass or steel resonate nicely - cloth doesnt...

[ehque]

i dont see how sky-high action puts less tension on the neck. in fact, it looks like the forces resolved would put MORE tension - a higher component of the force being horizontal and pulling the neck forward.

its a bit like asking if i would like a 42" scale. sorry, but i dont think it affects anything we're talking about.

how thick are wish bass necks? ill build one of the same thickness with carbon fiber, but slightly thinner.

i think the idea about the carbon fiber is to add stability, as well as stiffness in the right amounts, such that the neck resonates at a note the strings cannot produce, and thus no dead spots.

[Rodent]

Originally Posted by ehque

how thick are wish bass necks? ill build one of the same thickness with carbon fiber, but slightly thinner.

some have about a 3:2 ratio of width to thickness. that's like playing a tree trunk

i think the idea about the carbon fiber is to add stability, as well as stiffness in the right amounts, such that the neck resonates at a note the strings cannot produce, and thus no dead spots.

the idea with carbon fiber is to add stiffness at a reduced weight compared to using steel or aluminum bars. carbon fiber also has increased stability over steel/aluminum, especially when confronted with severe climatic changes.

it's important to understand the properties of the carbon rod/bar you're using, as not all rods/bars of a given dimension have equal properties. this is due to the materials that the bar/rod is made from, and the specific orientation(s) of those materials when bonded together with a specific resin and cure cycle.

For bass/guitar building, the best product to look for is a pulltruded bar of the required dimensions. pulltrusion has all of the fibers aligned along the x-axis, and contains more carbon fiber per weight unit than a laminated fabric weave or tape product. suffice it to say that people building carbon fiber composite stiffeners at home will end up with a product that is less stiff and heavier than any pulltrusion product they would purchase from a supplier.

all the best,

R

[Frank Martin]

Originally Posted by ehque

i dont see how sky-high action puts less tension on the neck.

No, you are looking at the wrong aspects.
When you make a neck, it is straight.
Now put on the strings, and it starts bending.
If the relief is not good, and you don't have a trussrod to adjust it with, you'll have to set the action high to avoid severe buzzing. Or sand the fb.
If the weather - temperature, humidity - changes, the neck wood and fb will react to it. Again, without the trussrod, you can't reset the neck to the proper relief.

Want to build according to Wishnevsky's specifications? Sure, go ahead, but don't say we didn't warn you.

[jim1457]

Thanks guys, I think I’m beginning to understand. The bassLab site was very interesting, especially the part with the comparison between their composite and wood.

So I guess I will use it. So far I’ve only found one supplier that’s oriented towards musical instruments. It’s about $20 for a four foot rod, .200” x .250”. The glue is another $34. Seems worth it.

Frank, I think you misunderstood Suburban when he said “infinite” stiffness (…there’s a joke there, but I’ll stay on topic), I think he meant that a string connected to a boulder will ring better than a string connected to a shirt.

ehque, I agree with you about most of the tone being in the pickup and strings, but I disagree with leaving out the truss rod on your next project. I’m sure you’ll regret it eventually. It’s not just about resisting the strings. Wood moves and continues to move with the weather, even after it‘s seasoned. I’ve seen warped baseball bats. In fact, everything moves to some extent. Even BassLab started adding truss rods, and they’re pure composite. On the double bass, the neck is only about one third of the length of the scale. Plus it’s fat. I think that’s why it might not need one. On an electric it’s a lot longer by comparison. Plus it’s thinner. Not to mention lower action=less tolerance.

So thanks again for posting. I’ll put up pics when it’s done, but that might be a while.

Jim

PS: Nice job on your bass Frank!

[Suburban]

Frank, I think you misunderstood Suburban when he said “infinite” stiffness (…there’s a joke there, but I’ll stay on topic), I think he meant that a string connected to a boulder will ring better than a string connected to a shirt.

Exactly my point!
And that increased stiffness moves the resonance freq up, and a stiff neck will thus not inflict 1st to 5th harmonics, which in turn means avoiding dead spots.

BassLab added truss rods because many customers wanted to vary their relief.
Mine has been thru a lot, and the action is the same, and I retune only to accomodate to the piano I play with for the moment. At times, I play with the same piano with a month in between, then I don't need to retune....
And, I have found no dead spots, yet (after 3 years).

[Frank Martin]

Originally Posted by Suburban

Exactly my point!

Didn't sound so on first reading

Originally Posted by jim1457

So far I’ve only found one supplier that’s oriented towards musical instruments. It’s about $20 for a four foot rod, .200” x .250”. The glue is another $34. Seems worth it.

PS: Nice job on your bass Frank!

You can use epoxy to glue in the rod - many use that method.

Thanks! The top is eye-candy, but I still have to get it working right, though.

[GregHolmes]

The BassLab composite withstands string tension easily by itself, and of course is not affected by weather, so the truss rods are there only to assist with action adjustments.

It may have been at my urging that Heiko started installing truss rods, because I often explore crazy tunings and string guages, and I need the flexiblity of adjustment. But for instruments in a normal tuning the truss isn't needed. For example, I have in my showroom a Soul-IV with a woody paint job that plays beautifully and is very light, partly because it has no truss rod and partly because the body shell was made deliberately lighter overall for tonal effect. The action is great. On the other hand, there's a green Soul-IV with a truss rod, and the instrument is denser feeling with a crisper and sleeker quality to the body (achieved with a number of subtle variations from the normal design).

Heiko and I talked about a number of alternatives to truss rods, even some methods that could perhaps be added to existing instruments. Currently, he embeds truss rods completely in the composite material just under the fretboard (the neck is still hollow). The truss becomes part of the resonating mass, rather than fighting against it.