Mandolins in progress

[kyken]

El Toro in progress

[hank]

Can you elaborate on the leading particulars of your creation Ken? I zoomed in on the tailpiece to see if you had engraved a bulls flared nostrils. For some reason I'm hearing old Herb Albert & the Tijuana Brass songs in my head.

[Skip Kelley]

Ken, I love the burst on that El Toro! It looks perfect!

[Marty Jacobson]

Making some progress...

[fscotte]

Gotta ask Marty, are you just "winging" it on the stiffness/mass? What criteria are you using for the carbon fiber top and back?

[Marty Jacobson]

I made a few test lay-ups to check stiffness and frequency response. This is my first attempt at working with composites, so I had to prototype the process anyway. Still lots more refinement to go. There are a lot of parameters to control, like thickness of weave, weave pattern, pliability of the different weaves, and biasing layers at different angles to get the stiffness correct in each axis.
But I think I got a plate that responds well enough to go forward with a build.

It sounds not entirely unlike a mandolin top should sound. I had one at 33 grams which was almost there, but the top end response just wasn't there. This one is 85g, which is perfect for a mandolin top. It might be a little too stiff, but I hear a lot of harmonic complexity so I think it'll be fine if I go light on the bracing. I've had some redwood tops that sounded almost exactly like this, which is encouraging since I really like how those sounded.
Tap tones: https://www.dropbox.com/s/o3h2wbi5il...raced.mp3?dl=0

There is no information anywhere online about how people have constructed their tops on previous builds. When I get this one done, I'll publish the particulars so other people have at least a starting point.

The cool thing about this process is that if I tell you how I make a CF mandolin, you can make one that sounds EXACTLY the same just by following the process and geometry specs. Something you can't do when you're starting off with wood instruments, since every piece of wood is different and the necessary adjustments are essentially impossible to make until you've built quite a few.

[hank]

That's an amazing looking top plate Marty. Your approach and professionalism are trademark. The shape looks like it might be made with an adjustable inflatable bladder protruding through the shaping tabletop for the lower mold. Are you using a vacuum bag over the layup and infra red cured epoxies? The light curing gives more control over the setup time. We used to use old refrigerator compressors to pull our vacuum on composite rotor and airframe repairs many years ago before vacuum sets were available.

[Marty Jacobson]

Hi Hank, I do need to experiment with resins. For now I'm using West System 105/206, and I like the long working time as well as the acoustic properties. I bag it up on an HDPE mold.

[Don Grieser]

Looking forward to see and hear how this develops, Marty!

[Matt Harris]

Marty, thanks for posting the tap tone sound file. Very enlightening! I would love to hear some other files from various woods if you have them (redwood in particular, as I'm in the midst of carving a top right now). It would be a great way for some of us amateurs to wrap our ear around things a bit. It seems the only way to get this knowledge is extensive trial and error, and having some sort of reference that allows you to compare and say, "Hey, maybe I am heading in the right direction here" would be invaluable.

[Marty Jacobson]

I sent Matt an email with a DropBox link to a bunch of plate tap tone samples including top unbraced, top braced, and backs. Most of the instruments are complete and can be correlated with sound samples of those instruments available on YouTube. If anyone else is interested, send me a PM or email.

[amowry]

Very cool, Marty, looks like a big undertaking! Is this a one-off, or a new product line for you?

I'm finishing up some inlays this week...

[Marty Jacobson]

Very cool, Marty, looks like a big undertaking! Is this a one-off, or a new product line for you?

I'm finishing up some inlays this week...

Very pretty, Andrew.

I plan to make more carbon fiber instruments. It's an interesting technique, and as a skill set, has much more commercial potential than musical instruments. A good year for me is doing slightly better than breaking even. If I'd spent as much time and effort developing medical devices or, as Charles Fox says, owning a liquor store, I'd have made much more money. Of course, money isn't everything. But I have three boys, and I am supposed to save over a quarter million dollars for college in the next ten years. Not happening at the current rate.

[amowry]

I hear ya, Marty! I have precisely the same conundrum.

[Skip Kelley]

Looking good, Marty!

I love that peghead, Andrew!

[GarY Nava]

Hi Guys,
Here are my next 3-
Brazilian mahogany and sitka (with a touch of herringbone) Standard mandolin
Cocobolo and Adirondack twin-point
Ash and maple e-mando.
Cheers Gary

[kyken]

here's a finished El Toro

[Steve Sorensen]

Ready to give these necks to their bodies. Love it when a plan starts to come together --



Steve

[Ron McMillan]

Ready to give these necks to their bodies. Love it when a plan starts to come together --

Great to see such strict adherence to The Sorensen Formula* in evidence here.

*There is no formula

[Steve Sorensen]

Less of a "formula" and more of a philosophy. However, if you look closely, the philosophy is fairly formulaic.

My goal with each build is to answer these questions --

1. What do I have to add to the conversation? (Historical excellence is the starting place, not the destination.)
2. Can I create interesting variety without unnecessary complexity. (Cohesive design, refined.)
3. Will the design, form, and voice of the instrument delight, engage, and excite the projected player for an extended period of time? (It must.)

Steve

[Ron McMillan]

Less of a "formula" and more of a philosophy. However, if you look closely, the philosophy is fairly formulaic.

My goal with each build is to answer these questions --

1. What do I have to add to the conversation? (Historical excellence is the starting place, not the destination.)
2. Can I create interesting variety without unnecessary complexity. (Cohesive design, refined.)
3. Will the design, form, and voice of the instrument delight, engage, and excite the projected player for an extended period of time? (It must.)

Steve

Admirable aims, beautifully achieved. Just for the record, in my own ham-fisted way, I was celebrating how you do not stick to rigid formulae observed by the vast majority of makers. The Loar-era F5 is a wonderful thing, but I love to see interpretations such as yours. That they push the design while delivering fantastic sound is a credit to your creativity and craftsmanship.

[Steve Sorensen]

Ron,
Thank you so much for your kind words and consistent support. I absolutely understood what you were saying and wanted to highlight the approach I am taking for creating "riffs on the theme" of the modern arch-top mandolin.

This past couple of weeks, I got to spend time with each of the original four Pacifica mandolins from my first attempt at re-thinking the basic form of the Gibson F.



It has been so cool to see these instruments after they have been out in the world for years. Really keeps me motivated and excited to make more!

Steve

[Steve Sorensen]

Before she headed back home, this was my parting shot after getting to spend a little time refreshing ol' Sorensen Pacifica #003. So glad she is busy and getting played every day!



Steve

[Steve Sorensen]

Front and back of a Big Dog octave headstock in the home stretch --



And the first pass of French Polishing on the Curly Claro Walnut back --



Steve

[kyken]

I thought this looked nice out in the natural light.