new back?

[Matthew Tucker]

Originally Posted by Ken Smith

Because two of the Basses we added this brace to were in my possession before the brace was in and I know the sound before and after. Also, where else is the sound being transferred in your mind from this addition, the scroll?

Try it yourself with a few old Italian Basses with Oppio backs and get back to me. Make sure you know what the bass does before hand as well so you can make a good post brace audible assessment. Playing the basses in a symphony Orchestra before and after is the best test. Ask the concert master across the stage what he hears differently.

Ken, I'm not contesting that a brace for a roundback is a good idea and can improve the sound of a bass. And I'm not contesting that you or a concert master (or a cloth-eared donkey for that matter) can hear a difference between a bass before restoration and the same bass after restoration.

I was just wondering about your specific comment that it helps to "spread the sound across the back."

My own instinct would be that the back brace stiffens the back, thus reducing the damping effect of flexible wood. Like a stiffer neck, this would result in more movement of the top for a given input energy, you could say that results in a louder or more penetrating sound.

But I don't understand the concept of sound spreading across the back and how that would translate audibly.

I find the rest of your comments a little condescending so I'll ignore them.

[Ken Smith]

Originally Posted by Matthew Tucker

Ken, I'm not contesting that a brace for a roundback is a good idea and can improve the sound of a bass. And I'm not contesting that you or a concert master (or a cloth-eared donkey for that matter) can hear a difference between a bass before restoration and the same bass after restoration.

I was just wondering about your specific comment that it helps to "spread the sound across the back."

My own instinct would be that the back brace stiffens the back, thus reducing the damping effect of flexible wood. Like a stiffer neck, this would result in more movement of the top for a given input energy, you could say that results in a louder or more penetrating sound.

But I don't understand the concept of sound spreading across the back and how that would translate audibly.

I find the rest of your comments a little condescending so I'll ignore them.

Well, was not trying to insult but you seemed to not believe me so I went in towards the deep end. Sorry if it came off that way. I do not know how much you really know about my experience with basses but it's well over 40 years now as a professional on bass in one way or another.

Now, as far as scientific spreading across the Back, I don't have that data. As far as the bass pushing out more clear tone, that I can feel and hear. Also, a Flatback has the brace and roundbacks usually do not. Adding it to the roundback can get you some of that flatback spread. The post on the back of a roundback pushes out the back over time. On one new bass of mine it was within a few years and the original post became too short. Another old bass of mine also suffered from a short post when I got if and looking down the back you can see the bulge from the post. If the back has a crack or a seam near the post area or within a few inches of it, the center brace can act as a post patch as well in the back. It doesn't have to be as big as the braces seen on commercial German basses but something shorter and not as thick will work. Also, having the back brace will help prevent the back from bulging and cracking as well in that area. I know two Luthiers personally here that build new basses with roundbacks with center braces in them.

How do I actually know it spreads the sound on the back? I don't but I do hear the difference and it is enough to make me believe that it does. My word should be good enough I think. It's not just a theoretical guess..

[Arnold Schnitzer]

Bridge pressure on a bass top would be deadly if not for the arch, which provides strength while still allowing the vibrating plate to be relatively thin. The soundpost pressing on the back does not take advantage of the back's arch because the back is convex, not concave (in other words, the pressure from the post works against the back's arch). I install a "soundpost pad" in my roundbacks, so I can carve them to a thickness that vibrates nicely without the soundpost bulging or breaking the back. I have experimented with many sizes and shapes.

[Matthew Tucker]

yes.

I have sketched out a plan for a bass with the back arching INWARDS for this very reason, to support the soundpost with a minimum back thickness. But it looked so weird, I haven't really thought about it much more. It also reduces the volume of the box a fair bit, and beefing up the ribs to compensate is impractical.