Choob sighting

Dear MMM folks,

Carl Lumma kindly pointed me to this recent choob sighting. I have responded with some video and photos of Whitney, the 22-EDO carbon-fibre choob I built for Carl last year.

http://www.handmademusicclubhouse.com/forum/topics/pic-of-homemade-abs-bass-in

For those of you unfamiliar with the origins of the choob see this MMM post from April 2007.

/makemicromusic/topicId_16313.html#16661

Regards,
-- Dave Keenan

Hey Dave! I can't believe no-one has responded to this yet. Thanks so much for the video and photos, the glowing frets are visually stunning.

Mat Cooper.

That looks very cool. It would work great for a bass as well, I think.
And it seems very natural for bowing (whether guitar or bass) due to
the curvature. Would a fretless version be feasible?

- Dave

On 10/30/2010 2:24 PM, ixlramp wrote:
>
>
> Hey Dave! I can't believe no-one has responded to this yet. Thanks so
> much for the video and photos, the glowing frets are visually stunning.

Hi Dave S.

Yes, it would be very feasible to do a fretless version.

-Carl

At 08:35 AM 10/31/2010, you wrote:
>That looks very cool. It would work great for a bass as well, I think.
> And it seems very natural for bowing (whether guitar or bass) due to
>the curvature. Would a fretless version be feasible?
>
>- Dave

Reminds me of the 'Solene':
http://home.flash.net/~solene/home.html

These tubular instruments always suggest to me that there should be strings completely encircling the tube. Perhaps 2 or 3 sets of strings in different tunings? ... or just rotate the instrument to fret particular strings.

Mat Cooper

Thanks Mat and Dave. Yes. Would definitely make a great bass. Definitely can be bowed. And definitely can be fretless.

The biggest differences between the solene and the choob are the diameter (solene 75 mm, choob 55 mm), the tuning machines (solene conventional, choob hand-made axial), and the patent (solene yes, choob no).

Yes, the choob could have strings all the way around because of its Steinberger-like axial tuners. I built an 8 string PVC choob for Robin Perry in a clever tuning he invented.
http://dkeenan.com/Choob/Roz.JPG

I have also fretted one for 12-of-meantone using the nylon lace-up method to make fretlets.
http://dkeenan.com/Choob/Fretlets.JPG

Here's a link to a 2007 tuning list post where I mention the solene. This post also has a link to some older video. This time it's me strumming a few chords on a PVC choob.
/tuning/topicId_70434.html#70478

Regards,
-- Dave

--- In MakeMicroMusic@yahoogroups.com, "ixlramp" <ixlramp@...> wrote:
>
> Reminds me of the 'Solene':
> http://home.flash.net/~solene/home.html
>
> These tubular instruments always suggest to me that there should be strings completely encircling the tube. Perhaps 2 or 3 sets of strings in different tunings? ... or just rotate the instrument to fret particular strings.
>
> Mat Cooper
>

Wow, thanks for the link. I wasn't familiar!

I like the cutaway for the tuners. The fret pattern also
apparently exerts less force on the tube than the "D" cross-
section pattern used on choobs to date... N.B. Dave.

-Carl

At 06:11 PM 10/31/2010, you wrote:
>Reminds me of the 'Solene':
> http://home.flash.net/~solene/home.html
>
>These tubular instruments always suggest to me that there should be
>strings completely encircling the tube. Perhaps 2 or 3 sets of strings
>in different tunings? ... or just rotate the instrument to fret
>particular strings.
>
>Mat Cooper
>

> The fret pattern also
> apparently exerts less force on the tube than the "D" cross-
> section pattern used on choobs to date... N.B. Dave.

Yes good idea! Perhaps a better way to lace up the choob frets? ... which would also uses less nylon line.

Carl and Mat,

I'm not sure what you are proposing. The solene frets are almost certainly made from bent metal fretwire and glued or screwed (or both) to its aluminium tube. It's hard to make out in the low resolution photos, but being a tapping instrument, the frets would need to be hard.

To achieve a similar form with nylon monofilament under tension would seem to require pins or screws to be set into the carbon-fibre tube at suitable angles so that the tensioned fretline would not pull over them (or pull them over). Carbon-fibre epoxy and composites in general are not very strong for small hole-fixings like this, and placing such pins would be a lot more work than lacing frets through holes. Nylon line is not expensive. Also, the frets could no longer be illuminated. For light to enter the filament and be internally reflected, it must strike the surface at a shallow angle.

-- Dave

--- In MakeMicroMusic@yahoogroups.com, "ixlramp" <ixlramp@...> wrote:
>
> > The fret pattern also
> > apparently exerts less force on the tube than the "D" cross-
> > section pattern used on choobs to date... N.B. Dave.
>
> Yes good idea! Perhaps a better way to lace up the choob frets? ... which would also uses less nylon line.
>

Hi Dave,

>To achieve a similar form with nylon monofilament under tension would
>seem to require pins or screws to be set into the carbon-fibre tube at
>suitable angles so that the tensioned fretline would not pull over
>them (or pull them over). Carbon-fibre epoxy and composites in general
>are not very strong for small hole-fixings like this, and placing such
>pins would be a lot more work than lacing frets through holes. Nylon
>line is not expensive.
>Also, the frets could no longer be illuminated.
>For light to enter the filament and be internally reflected, it must
>strike the surface at a shallow angle.

Good points. -Carl

I didn't explain my idea well, sorry. What I mean is lacing up the frets like this:

Around the outside of the tube as a fret.

In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.

Out through a hole and around the outside of the tube in the opposite direction to before as a fret.

In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.

Out through a hole ... and repeat the above.

The fret filament is always in contact with the outside / inside surface of the tube. Maybe this is how you do it anyway? I had the impression from Carl's description that the filament crosses the internal empty space of the tube and therefore exerts a force that tries to squash the tube into a slight elliptical cross-section.

Mat Cooper.

<d.keenan@...> wrote:
>
> Carl and Mat,
>
> I'm not sure what you are proposing. The solene frets are almost certainly made from bent metal fretwire and glued or screwed (or both) to its aluminium tube. It's hard to make out in the low resolution photos, but being a tapping instrument, the frets would need to be hard.
>
> To achieve a similar form with nylon monofilament under tension would seem to require pins or screws to be set into the carbon-fibre tube at suitable angles so that the tensioned fretline would not pull over them (or pull them over). Carbon-fibre epoxy and composites in general are not very strong for small hole-fixings like this, and placing such pins would be a lot more work than lacing frets through holes. Nylon line is not expensive. Also, the frets could no longer be illuminated. For light to enter the filament and be internally reflected, it must strike the surface at a shallow angle.
>
> -- Dave

I am missing what is gained by this.
Wouldn't a person lose the option of retuning it?
and wouldn't an added edge cause the nylon to wear out quicker?

--- In MakeMicroMusic@yahoogroups.com, "ixlramp" <ixlramp@...> wrote:
>
> I didn't explain my idea well, sorry. What I mean is lacing up the frets like this:
>
> Around the outside of the tube as a fret.
>
> In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.
>
> Out through a hole and around the outside of the tube in the opposite direction to before as a fret.
>
> In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.
>
> Out through a hole ... and repeat the above.
>
> The fret filament is always in contact with the outside / inside surface of the tube. Maybe this is how you do it anyway? I had the impression from Carl's description that the filament crosses the internal empty space of the tube and therefore exerts a force that tries to squash the tube into a slight elliptical cross-section.
>
> Mat Cooper.
>
> <d.keenan@> wrote:
> >
> > Carl and Mat,
> >
> > I'm not sure what you are proposing. The solene frets are almost certainly made from bent metal fretwire and glued or screwed (or both) to its aluminium tube. It's hard to make out in the low resolution photos, but being a tapping instrument, the frets would need to be hard.
> >
> > To achieve a similar form with nylon monofilament under tension would seem to require pins or screws to be set into the carbon-fibre tube at suitable angles so that the tensioned fretline would not pull over them (or pull them over). Carbon-fibre epoxy and composites in general are not very strong for small hole-fixings like this, and placing such pins would be a lot more work than lacing frets through holes. Nylon line is not expensive. Also, the frets could no longer be illuminated. For light to enter the filament and be internally reflected, it must strike the surface at a shallow angle.
> >
> > -- Dave
>

This device looks to be pretty easy to implement DIY.

very cool!!

Chris

On Sun, Oct 31, 2010 at 11:35 AM, Dave Seidel <dave@...> wrote:

>
>
> That looks very cool. It would work great for a bass as well, I think.
> And it seems very natural for bowing (whether guitar or bass) due to
> the curvature. Would a fretless version be feasible?
>
> - Dave
>
> On 10/30/2010 2:24 PM, ixlramp wrote:
> >
> >
> > Hey Dave! I can't believe no-one has responded to this yet. Thanks so
> > much for the video and photos, the glowing frets are visually stunning.
>
>
>

[Non-text portions of this message have been removed]

Thanks for explaining, Mat. You are correct in assuming that the filament crosses the internal empty space of the tube and therefore exerts a force that tries to squash the tube into an elliptical cross-section

Yes, your lacing scheme would eliminate the tendency to go elliptical while retaining fret illumination (although it may be reduced). But I can't see any easy way to actually thread it up.

Threading up the frets on a choob is currently done without using any tools inside the tube. It is done by cutting a chisel tip on the end of the monofilament, taking the roll-curl out of the first 70 mm or so by counter-bending so it effectively becomes its own needle, having the holes angled toward each other, sighting down the inside of the tube, pushing the fretline in through one hole, shining a small flashlight through the hole you're aiming for and "homing in on the beam".

Threading up fretlets requires a lacing pattern to be drawn up in advance, that results in the fretine going internally between points having the maximum angle between them, and angling the holes accordingly. Any internal hop should preferably subtend 90 degrees or more (so no hole needs to be angled more than 45 degrees).

Whitney mark-I was made from PVC as were the choobs before her. But they were all 12 frets per octave (12-FPO) (although not 12-equal after the first). With 22 frets to the octave, the PVC Whitney became unplayable within only 3 months due to going elliptical near the middle. When this happened I reviewed the literature on plastic creep and learned that creep rate was typically proportional to the fourth power (or more)! of the stress.

I then compared the creep rate of the 22-FPO choob with that of a 12-FPO choob that had been fretted for about a year and found indeed a power of 4.3 relationship. So while the 22-FPO PVC tube remained playable for only 3 months, a 12-FPO PVC choob should remain playable for more than 3 years. Temperature has a significant effect too. The creep rate approximately doubles with every 10°C rise in temperature.

Carl then suggested a fret lacing scheme where the frets still wrapped around 180 degres on the outside of the choob, but with every second fret rotated 90 degrees (+-45 degrees). This would have halved the stress in any one direction, and so reduced the creep rate back to 12-FPO proportions. But there are aesthetic issues with this, and Carl also convinced me to use Carbon-fibre/epoxy tube, which we hope has eliminated the problem by having creep rates several orders of magnitude lower than PVC.

But for use with the lower-cost PVC or ABS there are a number of such lacing schemes whereby the stresses are spread more evenly, without violating the 90 degree minimum internal hop rule. Basically you want a scheme where, when you look down the inside of the tube, you see either a cross (like a plus sign) or a square, or an equilateral triangle.

-- Dave

--- In MakeMicroMusic@yahoogroups.com, "ixlramp" <ixlramp@...> wrote:
>
> I didn't explain my idea well, sorry. What I mean is lacing up the frets like this:
>
> Around the outside of the tube as a fret.
>
> In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.
>
> Out through a hole and around the outside of the tube in the opposite direction to before as a fret.
>
> In through a hole and immediately turn to run along the inside surface of the tube parallel to the axis of the tube, for the distance of a fret spacing.
>
> Out through a hole ... and repeat the above.
>
> The fret filament is always in contact with the outside / inside surface of the tube. Maybe this is how you do it anyway? I had the impression from Carl's description that the filament crosses the internal empty space of the tube and therefore exerts a force that tries to squash the tube into a slight elliptical cross-section.
>
> Mat Cooper.

Yes, definitely DIY-able. No special tools required. The 55 mm OD, 2 mm wall pre-preg CF tube is available in a 1 m length here:
http://www.en.carbon-europe.com

Specifically:
http://www.s271082832.e-shop.info/shop/article_03985/Carbon-Tube-%C3%9855mm-x-%C3%B851mm_2mm-x-1000mm.html?shop_param=cid%3D118%26aid%3D03985%26

Flat sheet for the end caps:
http://www.netcomposites.com/netcommerce_features.asp?1632

-- Dave

--- In MakeMicroMusic@yahoogroups.com, Chris Vaisvil <chrisvaisvil@...> wrote:
>
> This device looks to be pretty easy to implement DIY.
>
> very cool!!
>
> Chris

Thanks for the details Dave, interesting. I had indeed begun to think how difficult it must be to lace up the filament when you can't get your hand or tools down inside the tube! ;D

Mat Cooper.

Here are a couple more video fragments of the 22-EDO choob in action.
Heavy Metal Light Composite (15 seconds):
http://www.youtube.com/watch?v=fxJ8FzQowYE
What the hell am I doing here (59 seconds):
http://www.youtube.com/watch?v=f1yiBPHnXaU

-- Dave