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Double Bass 1/2 size body with full scale bolt on neck conversion

J

JBarz

On indefinite internet sabbatical
Supporting Member
Mar 6, 2015
1,970
3,274
#1
Friends,
I am beginning conceptualization of my next really big potential project, but I want to run it by ya'll first.

I've got a couple of vintage 1/2 size basses with totally jacked up necks that I don't know what to do with... What would be the potential pitfalls and difficulties I might have to circumvent to get everything to line up? Shooting for a 41.5"-42.5" scale length bolt on conversion for a travel bass kinda deal.

It's an ambitious project with my limited skill set, for sure, but you lot have a funny way of giving a guy an incredible amount of confidence in sharing your knowledge and experience (thank you!).
 
#3
stefaniw80401 said:
Well.... the "D-neck" or in some cases "Eb-neck" stop that you're used to is largely determined by the (fixed) distance between the notches of the ff's and the neck block. Meaning, if you do manage to put a 3/4 sized neck on a 1/2 sized body, your D-neck could be more like a "E-neck" or even an F.
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Which in my opinion would not be a bad thing, for some applications. I hope @zootsaxes follows through with this and lets us know how it turns out. For the longest time I've had an Engle EM-3 body to which I wanted to mate a half size neck, but there seem to be no half-size necks to be found.

If a 3/4 neck on a 3/4 body gives a 41" - 42" mensure, I'm guessing a 3/4 on a half would be more like 39+ to 40+?
 
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#4
GretschWretch said:
Which in my opinion would not be a bad thing, for some applications. I hope @zootsaxes follows through with this and lets us know how it turns out. For the longest time I've had an Engle EM-3 body to which I wanted to mate a half size neck, but there seem to be no half-size necks to be found.

If a 3/4 neck on a 3/4 body gives a 41" - 42" mensure, I'm guessing a 3/4 on a half would be more like 39+ to 40+?
Click to expand...
This kind of instrument sounds great to me. I'm interested to see how the idea develops.
 
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#5
Oh yeah, don’t worry— I love to post projects on this forum, especially when I’m trying to avoid stupid f’n Facebook -- I’ll try to make it fun for all of us! Still in the very early stages of just thinking about it now, though. I’ve been doing luthier stuff either in my music room or my kitchen here to fore, but neither space is ideal — I really want to set up a proper bench in my new workshop
/bass barn before I let myself dig in and lose myself in the work. I might swing by the wood store on Monday and see if I can find an appropriate piece of maple for the neck, though. I was considering Chinese made prefab necks on eBay, but don’t think I’ll have enough extra material on the heel to compensate for the smaller body. I am secretly crazy excited to design and carve a cool scroll - maybe a lion or dragon, I don’t know - something with some personality...
 
#8
Logdrum, I don't think I can take a prefab 3/4 neck and toss it on there, no --- it'll have to be a custom neck, and I'm not concerned about what pitch the heel stop comes to (although if it came up to the octave instead of the 5th, I'd be super pleased...). Also, the scale length is not for tone enhancement - It's so I won't have to adjust or compensate my technique to make this bass play in tune. I wouldn't consider this on a bass that was already working well ("...if it ain't broke..."), but these basses I have are literally falling apart, so if I mess it all up - no big deal.
 
#10
logdrum said:
I've asked the people at (world renowned ) Robertson's here in ABQ if that would work and they said no. My 1/2 already has Eb neck and it is 38 inch scale. They also said that my bass sounds huge for its size and a longer scale will not make it sound any better.
Click to expand...

Maybe it isn't so much about tone as it is moving the octave further out to give you more notes before having to go to thumb position.
 
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#12
logdrum said:
I won't argue with Christian Pedersen and his team who also make world class basses here in NM. With longer strings you will be subjecting the body to more tension if tuned at pitch.
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Well, since I don't have the advantage of speaking face to face with Christian Pederson, I won't argue with him either. But your initial post seemed to be that the focus was all about tone, while @zootsaxes and I are considering other aspects. And I still think it would be worthwhile if somebody did this experiment just to see what would be the outcomes. If you are correct the neck can always be removed.
 
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#13
I had this same argument a looooooong time ago when I worked at the mandolin factory. To prove a point, I brought in an old 3/4 bass body and we rigged it up with a new 13 7/8" scale bolt-on mandolin neck.

You could play it and make squeeky little mandolin like noises, but within 15 minutes we all agreed to take it apart. We headed to the pub and played a gig with a traditional F5 mandolin and an old 3/4 Kay, never mentioning our experiment ever again. I've also done the same thing with a guitar neck and P bass neck.

I make no reservations about my love for experimentation and modification. I also try to remind myself that the body shapes, air volumes, and proportions that we accept as traditional are actually the results from 1000s of experiments over time that failed while we are left with a conglomerate of what worked reasonably well enough to make another.
 
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#14
GretschWretch said:
Maybe it isn't so much about tone as it is moving the octave further out to give you more notes before having to go to thumb position.
Click to expand...
Thumb position is nothing to be afraid and is easier than the lower positions, anyway! Ultimately, we go into TP once it is the most comfortable in the hand, not because of the neck or heel - even though it works fine lower.

While it is also thinner and not quite half size, it is pretty much what Barry Guy's luthier, Roger Dawson ended up doing and shouldn't cause any more issues than an Eminence. There are ways of reducing the string tension.


I would guess the answer to converting a 38" scale half size bass that plays beautifully vs. a couple 1/2 size basses with trashed necks would be be different.
 
#15
You guys are the best. I can’t even begin to tell y’all how fun this is for me even to just discuss with you lot. Ya’ll make me want to get the best 1/2 size of the three of them (the hybrid) going as a 38” first as the “control” in the experiment. That’s cool too because it’s way less ambitious to start with and maybe one of my kids’ll want to play. I’m going to try to run to the old shop later today and I’ll post some photos of what we’re working with for some more specific context. Thanks again for playing with me, guys! I love this stuff.
 
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#16
damonsmith said:
Thumb position is nothing to be afraid and is easier than the lower positions, anyway! Ultimately, we go into TP once it is the most comfortable in the hand, not because of the neck or heel - even though it works fine lower.

While it is also thinner and not quite half size, it is pretty much what Barry Guy's luthier, Roger Dawson ended up doing and shouldn't cause any more issues than an Eminence. There are ways of reducing the string tension.


I would guess the answer to converting a 38" scale half size bass that plays beautifully vs. a couple 1/2 size basses with trashed necks would be be different.
Click to expand...


Actually, Damon, I agree with you more than disagree. But you are speaking from the perspective of a vertical bass while my comments were from the perspective of a horizontal one; i.e. a lap played bass. I have and for years have had a Framus 1/2 size, so that is covered. 3/4 size is covered. And so is 1/4; it's just that trying to nail the octave there is a little beyond my reach because the shoulder inhibits it. I'm looking for a horizontal bass with an E or F neck.

I've got bassoguitars which, believe it or not, can be played quite comfortably across the knee, that have the heel/body connection at the octave or thirteenth fret, depending on the instrument. And I've got a homemade
(not by me) Frankenparts mandobass whose heel is at what would be the seventeenth fret, giving me an octave and a major fourth clear of the body.
 
#17
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Here’s what we’re cooking with. The middle is the hybrid, and it’s the worst neck with a gnarly crack down the middle of the top.
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#18
So if I understand this correctly, the goal is to have a bass with a 3/4 neck and scale with a small 1/2 sized body? If that's the case, I would think there may be issues with the location of internal support structures on a 1/2 size like the bass bar and soundpost. The soundpost can be moved, the bass bar...not so much.
 
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