Double Bass Optimal neck angle and bridge height?

[Saxophone Phil]

Hi there -
Is there an ideal angle for a bass's neck? Obviously neck angle and bridge height relate to each other, so I'm also asking if there is an ideal bridge height. Usually you just adjust the height of the bridge to fit the neck (since resetting the neck is a major job), but I need to reset the neck, so I thought it worth asking (since a lot of you know a lot more than me).

If the neck angle is too shallow, then the bridge height is too low, meaning that there will be less downward force applied by the strings to the bridge. And if the reverse is true, then the break angle of the strings over the bridge will be too acute. Is there any 'official' range of bridge heights that is considered to be ideal?

I'm working on repairing an old bass that has been officially condemned by the local luthier - it's a mid-20th century German student-level bass that needs repairs that are far more expensive than the bass is worth. The neck angle is currently too shallow - the action is too high even though the bridge has been filed way down. My plan is to remove the neck and re-fit it as a removable neck, held in with bolts, and shim it to get a perfect angle. I've never done any repairs on a bass before, but I've worked on other instruments, and, as I say, this bass has been pronounced to be firewood, so I can't make things worse.

 

[james condino]

You also need another measurement to make those determinations: overstand- the distance at the end of the neck between the top plate and the bottom of the fingerboard. If you have the overstand fixed, then neck angle and bridge height vary based on your desired setup, et cetera. Arch heights will change the scenario too. Some folks also use a tall / short saddle change...

Ten different folks will give you 20 different evasive answers to your questions, but I'll try:

I never change the saddle height, arches are generally 1 3/8- 1 3/4" tall, so approx. 35mm fixed overstand, 6 - 6 1/2" bridge height.

Get a copy of Henry Strobel's "Useful Measurements for the Violin". It is a tiny little book loaded with all kinds of useful instrument numbers.

Book List

 

[Saxophone Phil]

I thought there might be no one correct way - but your answer give me somewhere to start, so that's very helpful

 

[Saxophone Phil]

I've just measured the overstayed on my bass, which is only 20mm. Looking around on these forums it seems that's a little unorthodox, but there are plenty of people with low-overstand basses who seem to be happy with them, and my main ambition is jazz pizz, so it would seem to make sense to leave it at 20mm (yes???).

I'm assuming that if a typical bridge is 6 to 6 ½ (i.e. 150 to 165mm) I'd be looking at a bridge that was 15mm lower? (135 to 150mm)?

If it's any help I've attached a pic of the neck joint.

 

[tyb507]

"I can't make things worse"...hold my beer!

It looks like you've got an old carved bass there, with a figured maple neck that hasn't had a heel break (from what I can see in the picture). I'd say there are certainly ways to make it worse! I can't speak to your plan to make the neck removable. If it was me, if the neck-set was solid and depending on the thickness of the neck I'd be thinking about a hard maple shim under a new ebony fingerboard, 5mm at the heel down to 1mm or so at the nut (it makes planing the gluing surface easier if there's a step down to the pegbox, that way you can plane off the end without hitting the pegbox). That would increase the overstand and projection. Another option to increase the overstand would be to add wood to the back of the heel and reset the neck. Either option will require sharp tools and skill using them. If you're removing the neck to make it removable, I would still think you'd want to replace that fingerboard and that's a chance to improve the projection and overstand, getting it closer to 25-30mm+ and 150mm+ bridge height.

 

[Saxophone Phil]

Too late - most of the work is already done - I'll post pics soon.
The bass isn't that classy - it's an early 20th century student level bass with a pear fingerboard and the flame on the maple neck is painted on (looks realistic except where it has rubbed off!). Laminate back and sides.
I've removed the neck and re-attcahed it with two long bolts (so it's removable). Kowhai (similar to maple) shim under the heel to adjust the angle, spruce shims on the sides of the heel for lateral stabilisation - very tight neck joint even without the bolts. I've added wood to the back of the heel, and reset the neck so the overstand is now 35mm. I've planed the fingerboard so that the bow in the neck has been reduced to a normal amount of relief/scoop. So far, so good.
Today I fit the new bridge. Might be playable by this evening!

 

[Saxophone Phil]

Thanks for all the help I received here! In the end she turned out beautifully - here's the tale in detail...