Jacobson Carbon Fiber Mandolin Prototype

[Marty Jacobson]

Hello everyone. Here's a prototype carbon fiber mandolin I just finished. I think it came out great, considering I have no idea what I am doing when it comes to composites. There are some obvious flaws in this instrument, but I have learned the value of not worrying about aesthetics on a prototype.

I was concerned that it would feel cheap and plasticky, but once I got some varnish on it, it just felt like a mandolin. It sounds better than I had any right to expect it to sound.

The top is simple, with the reinforcement layers arranged so there is no need for bracing. The resulting top plate tapped and sounded a lot like a wood plate.
It is loud and responsive in tone. I think it is one of the best mandolins I've made to date.

The manufacturing process is surprisingly simple. There's a top and there's a back. You put 'em together. You get a mandolin. More luthiers should work with carbon fiber. It is a very inspiring material.

Will try to record a sound sample once the boys are in bed.

[Steve Sorensen]

Wow! Really attractive design.
Steve

[Nathan Kellstadt]

Very cool. It will be interesting to see where you, in particular, take this.

Are zero-frets standard on your instruments, Marty?

[Marty Jacobson]

Very cool. It will be interesting to see where you, in particular, take this.

Are zero-frets standard on your instruments, Marty?

Thanks! Yes, zero frets are standard for me. If you think about it, a hand-cut nut slot is always going to be ever so slightly too high. The likelihood that you can actually cut a nut slot to within 25-30 microns to get optimal action is unlikely, you'll probably stop slightly high or, in the quest to get it optimal, cut it too low. With the zero fret, it's just there. Of course you lose the ability to experiment with magical nut materials which will make your mandolin sound better (sarcasm), but I think it's worth it to have guaranteed optimal action at the nut.

[Graham McDonald]

Very tasty!. You coming to the GAL next month, and bringing that with you?

[dan in va]

i'm seriously wondering how an oval hole designed top would sound in CF. Maybe it would bring some warmer overtones. Good mandolins have come and gone and i've decided to keep only one, a Stanley A5s (not counting the O18T set up as a 4 string octave mandolin). But there are 2 more i would like to have if they sounded good: a tater bug and carbon fiber oval hole. Since there isn't much action on these last 2, the A5 may always be lonesome.

Marty, i hope you keep building with CF and refine an oval hole design. Thanks for the post and pics. Looking forward to the sound clip.

Nice tuning machines, too.

[Skip Kelley]

Marty, that is so cool!

[Marty Jacobson]

Graham, I will be in the Seattle/Tacoma area visiting Bill Hay during some of the conference. I hope we can get together at some point. I will have this with me.

Dan, I will build more and I'm partial to oval-hole mandolins, so there will probably be some of those at some point.

Here are some sound samples. It has a lot of volume and doesn't break up when I was hitting it as hard as I could, it just keeps giving. Plenty of depth and sustain for more mellow pieces, too.





A couple more are on my SoundCloud if you click through.

[Tom Haywood]

Wow! Outstanding sound, Marty.

[Don Grieser]

Very cool in every way. I want one! Outstanding work, Marty!

[Ron McMillan]

Superb work, Marty. I am certain that there is a market for quality CF mandolins. Best of luck with this new line.

[multidon]

Very interesting. What kind of fretboard? Ebony? I always wondered why makers who do carbon fiber don't do Richlite or some such. Looks like there's still wood in the headstock. Any way to eliminate that? Also, it would appear you subscribe to the theory that a carbon fiber neck doesn't need an adjustable truss rod. I'm not convinced.

[Ted Eschliman]

Fantastic!

[Marty Jacobson]

Very interesting. What kind of fretboard? Ebony? I always wondered why makers who do carbon fiber don't do Richlite or some such. Looks like there's still wood in the headstock. Any way to eliminate that? Also, it would appear you subscribe to the theory that a carbon fiber neck doesn't need an adjustable truss rod. I'm not convinced.

Hi Don, the fretboard and tailpiece frame are industrial waterproof micarta, kind of like Richlite on steroids. It's commonly used as a knife handle material for extreme environments. The only problem I had working with it is that it is so tough, I should have cut wider fret slots, and ended up with a pretty extreme compression situation in the fretboard. So I'll cut .028" fret slots next time instead of the usual .023" I do for wood.
There is wood in the headstock, I really like the way it looks and I will probably keep it as standard. I don't think it's a problem, since it's encapsulated in epoxy, kind of like a canoe paddle. But the wood could be acrylic stabilized in the future, or other materials like garolite or aluminum could be used if the customer desires.

The bridge is one of my normal wood bridges, which I used because I had some made up. I will probably engineer a super low mass aluminum and carbon fiber bridge for these in the future.
I'm also thinking of making an integral, epoxied-on bridge base which will really help to make this instrument low maintenance and tough.

[Tom Haywood]

I'll jump in briefly to say I looked it over pretty thoroughly before the fret board was fretted and installed. I was immediately curious about the neck strength with no truss rod design. What was most impressive was that Marty experimented with different layering orientations of the material and came up with something that is extremely strong yet has some flexibility similar to wood. For the neck, the combination of this material pattern and the micarta fret board appeared to be far stronger than any solid neck I've seen. With very little weight. So, I'm curious now whether any relief resulted or how to build that in to it if any relief is necessary.

[Steve Sorensen]

Marty,

Thank you for posing such a range of tunes for the recordings. Very impressive results right out of the gate!

Again, impressive! Congratulations!

Steve

[Jake Wildwood]

Folks, we have a winner!!! It's hard to make CF shine.

I roll my eyes at CF instruments until I hear ones I like well enough. This thing sounds awesome and looks killer, too! I love new materials when they're used correctly. I hate to say it, but my standard guitar that's hauled to gigs is a lam-top Gibson from the '80s... for the reason that it sounds just fine and is stable as heck.

[Marty Jacobson]

Thank you for posing such a range of tunes for the recordings. Very impressive results right out of the gate!

Yes, I definitely got lucky. I hoped to get a good starting point, but I didn't expect to get to this point without several more iterations. I will be posting the "recipe" for anyone who wants to do something similar, so they have a starting point as well.

[Marty Jacobson]

I'll jump in briefly to say I looked it over pretty thoroughly before the fret board was fretted and installed. I was immediately curious about the neck strength with no truss rod design. What was most impressive was that Marty experimented with different layering orientations of the material and came up with something that is extremely strong yet has some flexibility similar to wood. For the neck, the combination of this material pattern and the micarta fret board appeared to be far stronger than any solid neck I've seen. With very little weight. So, I'm curious now whether any relief resulted or how to build that in to it if any relief is necessary.

Well Tom and Don, as to relief, I got 1mm action at the 12th fret on the E and 1.5mm action on the G without buzzing. I haven't measured the relief because I only care about relief if it's keeping me from getting the action I want. 99% of the time, I adjust truss rods because some instrument owner cluelessly mis-adjusted it thinking they would make things better.
This is without a doubt the stiffest neck I've ever made, and I think that is a good thing, especially in combination with its extremely low mass. Also, there's essentially no way you could break the headstock off of this.

Mmm... think of the possibilities for incorporating an ultra-low-mass "Tone Gard"...

[dang]

So cool!
And it still looks like a Jacobson, I like you could adapt the material to your style.
Where's the plug in for the pickup?

[soliver]

Marty, this is SUPER cool!... it look beautiful and sounds awesome!

Hope I can see it in person sometime!

[Astro]

Beyond cool.

[rdfmando14]

I agree. It's beautiful and sounds awesome! Good job! I'm so glad you showed it to Tom, Mark and me last weekend. Nice to meet you too. I'll be watching for more from you.

Robin

[Dale Ludewig]

I love it!

[billhay4]

Ah, Marty, you strike again. Can't wait to see this one.
Bill