French Bass Brace advice

[Adrian Levi]

I've removed the fat brace from the back and what a nice piece of old spruce it is . It will come in super handy for the top repairs that are needed.

The back is in decent shape and Ill be inserting a centre strip throughout which means Ill need to remove a bit of back wood.
Im sticking to Kens ''do it right first time '' advice.

Now for yet another question or two ( if Im asking too much please tell me to shut up )!
How many back braces should this bass have ?And also is there an optimal positions for them ?
I've seen basses with 3 , 4 and 5 braces before ?

[Adrian Levi]

Originally Posted by Adrian Levi

I've removed the fat brace from the back and what a nice piece of old spruce it is . It will come in super handy for the top repairs that are needed.

The back is in decent shape and Ill be inserting a centre strip throughout which means Ill need to remove a bit of back wood.
Im sticking to Kens ''do it right first time '' advice.

Now for yet another question or two ( if Im asking too much please tell me to shut up )!
How many back braces should this bass have ?And also is there an optimal positions for them ?
I've seen basses with 3 , 4 and 5 braces before ?

oooook , no bites on this one

So now Ill try and be more direct .

'' Is the Venerable Arnold E. Schnitzer in the house ? "

What really interests me is the middle back brace seeing that it is directly coupled with the sound post .
Are there any thoughts on maybe using lighter wood to facilitate vibration to the back plate , or would heavier wood be better better for some reason , or is it just a simple matter of there being no definitives here ?

[Thomas Erickson]

Originally Posted by Adrian Levi

Tell me more ???

I've seen brown cardboard box type paper being used before but have never been able to find out much about it .

Well, I don't know a lot about it either, but I've been meaning to track down some samples and whatnot. If anybody has looked into it or has a suggestion of what to look at/for specifically, I'd be happy to hear it - I have two basses with super thin ribs that need something done with them, and I plan to try this on one or both.

But basically there's a whole spectrum of high quality Japanese papers out there that people use for various art/craft purposes; a lot of them are made by hand (to some degree) and should be of conservation-type quality. The fiber used is very specific, high quality, single source and minimally processed, and the papers come in every thickness, texture etc. that you can imagine. As far as I know, this is where you want to look to find the strongest/lightest very best quality paper - and if it is like Japanese tools, I don't doubt it!

So in theory you should be able to find an ideal paper for this sort of purpose - it makes sense to me, I mean, after all what is paper but an extremely uniform manufactured wood product, yes?

[Matthew Tucker]

Aah ... easy questions I see

Why do you want the back to vibrate at all? just asking.

[Thomas Erickson]

Originally Posted by Matthew Tucker

Aah ... easy questions I see

Why do you want the back to vibrate at all? just asking.

Dynamat?

[Adrian Levi]

Originally Posted by Thomas Erickson

Well, I don't know a lot about it either, but I've been meaning to track down some samples and whatnot. If anybody has looked into it or has a suggestion of what to look at/for specifically, I'd be happy to hear it - I have two basses with super thin ribs that need something done with them, and I plan to try this on one or both.

But basically there's a whole spectrum of high quality Japanese papers out there that people use for various art/craft purposes; a lot of them are made by hand (to some degree) and should be of conservation-type quality. The fiber used is very specific, high quality, single source and minimally processed, and the papers come in every thickness, texture etc. that you can imagine. As far as I know, this is where you want to look to find the strongest/lightest very best quality paper - and if it is like Japanese tools, I don't doubt it!

So in theory you should be able to find an ideal paper for this sort of purpose - it makes sense to me, I mean, after all what is paper but an extremely uniform manufactured wood product, yes?

I must say that does sound interesting , Ill check out some art supply shops to see if they have and then maybe do a test or two .

[Adrian Levi]

Originally Posted by Matthew Tucker

Aah ... easy questions I see

Why do you want the back to vibrate at all? just asking.

Well Matt this is what interests me , should the back vibrate as much as possible or not ? Or does it really matter? Will my bass perform better if I fit a
middle brace of maple (heavy) or one of spruce...or once again does it really matter?

[Matthew Tucker]

Well that is the balancing act ... and where the art comes in i suppose. Whatever vibration is happening at the back of the instrument, that is energy that is NOT moving the front. So it robs the front of energy at certain frequencies and thus colours the sound and decay characteristics of the bass. I like to imagine the extremities; if the back was made of concrete the top would receive and emit all of the string energy, with a lot of sustain,but the sound might not be pleasing (it might - who knows?). On the other hand I imagine if the back were made of rubber and could freely vibrate it would dampen the movement of the front resulting in short sustain and dunno what tone. And that's not taking into account the structural necessities. Somewhere in the middle is right. As a broad generalisation, I think for arco, sustain is not so critical but darkness is, for pizz/jazz use sustain is more useful and the decay characteristics of the bass are more important. but it depends on the player too.

But with all that above, its still hard to know for sure what the effect of one or other change will be!

I would replace the brace with spruce as it was originally, probably a 4-5" centre brace, one across each bout to give a slight and even radius to the back if possible, and one at the bend if it needs it. Depending on the position of the bend, you may choose to put one brace near or on the bend for the upper bout.

Or you could get really funky and do a cross brace!

[Adrian Levi]

Originally Posted by Matthew Tucker

Well that is the balancing act ... and where the art comes in i suppose. Whatever vibration is happening at the back of the instrument, that is energy that is NOT moving the front. So it robs the front of energy at certain frequencies and thus colours the sound and decay characteristics of the bass. I like to imagine the extremities; if the back was made of concrete the top would receive and emit all of the string energy, with a lot of sustain,but the sound might not be pleasing (it might - who knows?). On the other hand I imagine if the back were made of rubber and could freely vibrate it would dampen the movement of the front resulting in short sustain and dunno what tone. And that's not taking into account the structural necessities. Somewhere in the middle is right. As a broad generalisation, I think for arco, sustain is not so critical but darkness is, for pizz/jazz use sustain is more useful and the decay characteristics of the bass are more important. but it depends on the player too.

But with all that above, its still hard to know for sure what the effect of one or other change will be!

I would replace the brace with spruce as it was originally, probably a 4-5" centre brace, one across each bout to give a slight and even radius to the back if possible, and one at the bend if it needs it. Depending on the position of the bend, you may choose to put one brace near or on the bend for the upper bout.

Or you could get really funky and do a cross brace!

Interesting thoughts there.
What is the deal with cross bracing ? I've always wondered about those basses with a single longitudinal brace .....

[Matthew Tucker]

Ask Ken McKay he's done it. I haven't.

[Ken Smith]

What a bunch of confusing opinions I see here.

Ok, one single brace is not good.

Depending on the bass, it's size, your climate and what tone you want you can go with just about anything that works but a single wide center brace like you just took out. Also, there is little advantage if any making the smaller center brace out of the wide one you just removed. If you can, do it for the enjoyment. In that case you will need one across the lower bout and upper bout on the average. I think 3 or 4 braces with two uppers is quite normal but that depends on the back itself. I have seen as few as 2 and as many as 5 on the back braces (or 1 in the case of French basses). Again, take a chance and do what looks good for you in your mind, the bass itself and the climate it will live in. The X-system is a choice in some cases depending on all of the above as well and in that, there are a few ways to do the X. Two pieces with a lap joint, 3 pieces with no joint, one angled piece with a separate lower bar type cross angled or what ever the bass needs in your mind. Other than the center brace, the other braces should be shaped more like bassbars and not flat wide pieces, I think!


Have fun. The restorers that have repaired the most backs successfully will have the best advice in my opinion. Nothing is ever easy with a flatback. You have the birdseye view of the back in question to decide how much support it needs to work and how much to let it breathe.

I have had and played basses with just about every kind of back out there, well most of them. You don't know whats best without changing things and living with it for a decade each way. The back vibrating is not a problem. Even the scroll vibrates. My Gilkes was as loud from the back as it was in front. The Sound post will make it vibrate but the top should float more than the back. Don't get too technical here in the mind. Repair it sensibly and go play the bass, That's part of the recovery, the playing in of a restored bass.

[Matthew Tucker]

Wayne, how on earth can X braces be an easy way out?

[Matthew Tucker]

Originally Posted by wayne holmes

seriously, less cutting, less thought, less everything, less clamping, less coverage of the middle seam, lesser number of pieces, less measuring,less amount of wood crossing the middle seam, less confusion- less time, less creativity, shall I continue? less balance and support of structure- less lipstick!

Would you be happier with far simpler lattice bracing perhaps??

[Adrian Levi]

[quote=Ken Smith;21709]What a bunch of confusing opinions I see here.

[quote]Have fun. The restorers that have repaired the most backs successfully will have the best advice in my opinion. Nothing is ever easy with a flatback. You have the birdseye view of the back in question to decide how much support it needs to work and how much to let it breathe.

I like the fun part , and the excitement of the unknown / Im going with the 3 braces.

[Arnold Schnitzer]

Originally Posted by Matthew Tucker

Would you be happier with far simpler lattice bracing perhaps??

Nice! But just a bit too much glue for my taste...

Adrian, I agree with the 3 brace technique. Keep them away from the linings, and feather the ends after the glue is cured. Glue it all up when climate conditions in your shop are toward the dry side. Use a caul on the outside of the back under each brace as you glue up. Good luck!

[Ken Smith]

[QUOTE I like the fun part , and the excitement of the unknown / Im going with the 3 braces.[/quote]

My Mougenot is about as French as it gets as far as the Tradition goes. Full sized Vuillaume model (7/8th by our standards), flatback and it had a single wide center brace. Like my Hart bass, the back never cracked but opened up in the center seam, 3/4's its length, both basses. The Hart has a very stiff & strong back so it got a center and lower brace only and studs and linen I recall at the angle break ( I will have to look inside to make sure). The Mougenot is still on Jeff's bench getting the C-extension but I think we agreed on 3 or 4 braces, 1 or 2 upper (I will have to look as I forgot what we discussed). French basses usually bend gradually from the upper corner block and never a direct angle break. Both basses got an added center strip most of the way up which is a good thing because it shows that rather then the back splitting over time, the center just opened which looks much better repaired than a bunch of back splits.

So, depending on the length of the back, just the upper bout in the center would be fine unless the back is thin and needs more support. Like I said in my last post, you have the best view of this and must decide what it needs.

[Adrian Levi]

The ribs are now as clean as I'm going to get them without doing more damage to the damage.It seems as if the bass was about 50% wood and 50% epoxy.
The one lower bout is the only one left to reinforce . The other lower bout with the repairs was less than 1 mm in places and still needs the back edging to be replaced.
Now that the two pieces of back are flattened and ready to plane for an insert I'm not quite sure how to figure the exact size that the insert should be.
The back has shrunk a fair amount and to compensate the ribs were force epoxied in. The freed rib structure now spans about 20 mm more in its relaxed state.
Is it a matter now of lying the rib structure on top of the back to measure the space needed for insert ?
Or is it better to measure the back against the top for size ....?

[Ken Smith]

Looks good. I would suggest fitting the Top first since it is the least flexible part and prone to cracking. The Back can be widened as needed but dry fit and estimate it first before making the center spline/insert.

[Adrian Levi]

Originally Posted by Ken Smith

Looks good. I would suggest fitting the Top first since it is the least flexible part and prone to cracking. The Back can be widened as needed but dry fit and estimate it first before making the center spline/insert.

That makes total sense and I just sat the top on the rib assembly and it is a perfect fit .I was worried that I may have to cut the ribs down to accommodate the top.

[Thomas Erickson]

That bottom block looks like a real thing of beauty...