Question about braces

[Ken Smith]

Originally Posted by Matthew Tucker

That's why I love basses so much

What does what? Who knows.. It is easy sometimes to gauge too much or too little in thickness and builds but which way to go to get the right stuff done is always interesting.

My Cornerless bass was/is ultra powerful and the back is a gradual taper with some gentle bend in the upper back, not an angle break cut. When I got it I glued up all the cracks that were open mainly from the outside just to keep it going till the restoration. It would shake itself apart and you could see daylight thru the F-holes coming from the back cracks. Other than fixing all that's loose and re-doing EVERY previous repair, we are leaving the bass alone. What's done was done and with old basses, over modifying is not always a good thing.

Why did that bass sound so good and so loud? A combination of things. How much of each we don't really know but it had the right stuff! It had its own internal can of whoop-ass!

The copy bass will have a gradual taper from block to block as well BUT a shallowish round back with a center brace. Three of my roundbacks currently have center braces as well. The Panormo School which is very old if not original, my Candi which was partially put in for a repair and to strengthen the softer maple used for the back and my Martini which is the same soft wood but thicker made in 3 piece. The partial brace in that is to protect the joint on the soundpost side. The two that were just done recently slightly improved the projection of the bass as far as speed of sound or it feels like it. The other is older than time but for a huge bass, not a bad idea.

Back designs, bracing systems, sizes of basses, the species or wood used and the thickness of the woods. All of these factor in.

[Thomas Erickson]

Originally Posted by Eric Rene Roy

I've never liked the bend on flatbacks. Why build in a weak point? Why add anything that stops the back from vibrating freely??? I understand the ergonomics of it, the tradition of it, etc...but I like the idea of doing it through a greater rib taper from end block to neck block and keeping the back vibrating more.

I've always likened the crease on a flatback like the creases they add to a car's hood or fender. The crease on the hood of a car adds rigidity, keeping the panel from vibrating at higher wind speeds and making it stronger without overly bracing it on the inside. I think keeping the plate vibrating freely can only be beneficial to the tone.

I'm not sure if there has been any Chladni studies on bass plates the way they do violins...but I have to imagine the bend making a pretty big disruption to the lines of the plate.

Thoughts?

The break is going to affect the rigidity of the back across the top bout, yes, but there's no reason why that's going to make the back as a whole any less resonant. It isn't like the break in and of itself is going to change the mass of the back or introduce any stress into it.

As for the resonance of the back goes in general - I'm not sure it even matters much; certainly in the case of an orchestra player resting the back on his knee there's not much there to resonate! And even if it is left free to resonate, it certainly isn't being driven anything like the way a top plate is, so comparing the two doesn't make sense even with a carved back...

[Matthew Tucker]

Ken have you thought about adding cans of "KSB whoop-ass" to your online store?

[Ken Smith]

Originally Posted by Matthew Tucker

Ken have you thought about adding cans of "KSB whoop-ass" to your online store?

Matt, I can tell when it's there but I just can't put my hands on it physically!

Why, are you looking to order a few cases of it?

[Matthew Tucker]

Originally Posted by Ken Smith

Why, are you looking to order a few cases of it?

Depends on your warranty

[Matthew Tucker]

Originally Posted by Eric Rene Roy

I'm not sure if there has been any Chladni studies on bass plates the way they do violins...but I have to imagine the bend making a pretty big disruption to the lines of the plate.
Thoughts?

my be wrong but that thesis "round back vs flat back" floating around a few years ago probably did this.

My thoughts on this are that chladni patterns of a braced bent plate would probably be just as good/bad as an unbent braced plate, except that the the plate would be effectively shorter. But that said, you're not going to easily get the common modes 2 and 5. And it all changes when you attach the rim of the plate to the ribs, eh.

I'll try to find a picture of the chladni pattern of my ladder-braced bent back on my first bass. As I recall it was almost a perfect circle mode centered around the lower bout. Above the C's there was very little resonance at all, perhaps if there was no break there would have been a circle mode there as well at a higher freq. But what they all mean ... that's the big secret isn't it?

[Matthew Tucker]

Last page of Andrew Brown's research project on the matter. The paper was highly technical, and I think the conclusions were ... inconclusive!

[Ken McKay]

The papers I have read on vibration patterns of basses are on assembled instruments using lasers. This is a bit different from the free plate patterns which show the area of vibration of the plate only.

I think you are absolutely correct Eric, and Matthew. Bending the plate pretty much stiffens it enough to make it rigid so it only vibrates at higher frequencies in the area of the back above the break angle cross bar.

I think the major important factor of understanding this whole back stiffness concept is in the way it effects the bass response to bowing.

edit, thanks for putting that up Matthew, I am a big fan of Andrew Browns thesis work. I really think using the knowledge learned from his work has resulted in me making a better bass. In addition, I can't apologize for understanding the "technical" nature of the thesis. And it certainly doesn't imply that a maker has to understand what's in it to make a good sounding bass...obviously!

[Ken Smith]

Lasers, patterns, frequencies, research.... VOODOO

What ever happened to listening and feeling?

Unless you take the EXACT same Bass and keep remaking it with various backs and bracings you are Pissing in the wind.

You cannot compare Backs or bracings on different basses. There is that 'different bass' factor you are forgetting about.

I own many basses that were altered from one system to another, flat and round back. In this way we can tell BUT, even so, other restoration work was performed as well. Still, the other work performed had somewhat predictable results as it was not new science added into the bass so I am fairly certain I know what I am hearing when I listen to the changes.

Changing a bass from a 3, 4 or 5 piece brace system to a single 1/2 X brace with a bottom left angles bar (I have some like that) frees up the back in two ways. One, it can move easier with the weather and two, the sound spread up the back is aided by the long singe brace. The bottom angled Bar forms a an inverted 'V' pattern at the bottom with the longer brace to stabilize the wider lower bout.

On one of the basses like that it has an angle bend but is covered in sheer cut linen. It was left alone, unbraced or modified from the maker in 2007, England. The other is Italian about 30 years old, Cello-like un-tapered ribs, no angle break. Both of these basses were set up and played before the modification was done. Only set-up work was performed mainly other than the back work and some repairs that came about after the sound was evaluated.

I don't do this work myself but I do play the basses and my ear is pretty good.

I have two other basses in restoration that will be modified as well. One is an Italian round back and it will get a center brace. The back is fine but I like the idea. The other is an old Flat back pedigree (can't tell you for business reasons) and it had normal bracings before. It will get the modified X as mentioned before and what ever else it looks to need after all the back cracks are repaired and evaluated.

One other bass I have in repair is a large French bass with a single wide center brace. That will be modified to a normal center brace, one lower centered at the bottom bout and one upper brace just above the upper corner.

My Hart is a flatback with only a center brace and a lower brace. All braces other than center or X are shaped like a bassbar, never the wide flat ones you see in normal basses. The angle break has linen and vertical finger patches spaces along the bend.

Each bass got what it needed. No patterns here, just careful thought.

[Arnold Schnitzer]

There are two schools of thought about bass backs: 1) The back should be stiff and thick, so the top does the majority of the vibrating, and the bass will be more powerful; 2) The back should be treated like the top in that it vibrates and resonates freely, and the whole instrument will vibrate and the bass will be more powerful.

Several prominent bass makers carve their backs quite thick, and the tops fairly thin, adhering to school #1 above.

[Matthew Tucker]

So lets go for the more powerful one!

Interesting in Browns results is that the observation that the player is often able to mask or compensate for the difference in response between roundback and flatback so the differences are un-noticeable. I suppose if the back is contributing significantly to tone and volume you have a built in tone filter available with your left knee.

My observations of a free plate oscillating at a low resonant frequency, where the edges and centres of the plate can move by a centimeter or more, lead me to believe that a flexible rib structure helps allow the top to move, which is essential to transform string energy into movement of air, thus sound. The controlling factor is the strength of the box which must stay intact under high tension and compression. So you can see how both the schools of thought can work. But for me I think the back has a structural priority while its resonance is a by product of what's going on elsewhere.

Understanding its role in tone production I agree is not science yet!

[Pino Cazzaniga]

Put me in the second school, as I don't like heavy instruments, but top is moved mainly by bridge, back by soundpost (forgive the coarseness), and we have to consider the difference.
On flatbacks, sometimes I thought that a broken bend was due to the weather movements of the bend brace wood, locally stressing the groove.

[Brian Gencarelli]

Originally Posted by Arnold Schnitzer

There are two schools of thought about bass backs: 1) The back should be stiff and thick, so the top does the majority of the vibrating, and the bass will be more powerful; 2) The back should be treated like the top in that it vibrates and resonates freely, and the whole instrument will vibrate and the bass will be more powerful.

Several prominent bass makers carve their backs quite thick, and the tops fairly thin, adhering to school #1 above.

Maestro,

Which school do you subscribe to?

Brian

[Ken Smith]

Originally Posted by Brian Gencarelli

Maestro,

Which school do you subscribe to?

Brian

Is there a Column 'C' (school 3)?

[Arnold Schnitzer]

I personally treat the back like a secondary soundboard. I want resonance, and I also want some stiffness in the soundpost area. My back graduations (on roundbacks) would be considered thin by some.

[Ken Smith]

Originally Posted by Arnold Schnitzer

I personally treat the back like a secondary soundboard. I want resonance, and I also want some stiffness in the soundpost area. My back graduations (on roundbacks) would be considered thin by some.

Are the Backs that are thin as you decribe Braced in the center somewhat like a flatback?

[Eric Rene Roy]

Originally Posted by Thomas Erickson

...it certainly isn't being driven anything like the way a top plate is, so comparing the two doesn't make sense even with a carved back...

Again...same as Matt...I am not comparing it to a top plate at all. Is this assumption because I sited Chladni pattern studies?

I guess I am greedy and I want it all. I want a back that is as resonant as possible while providing enough strength to support and work with the top. Both plates are different and perform differently...I am not saying at all that they are the same.

It just never made sense to me to have a canted back, other than to gain playability (which I believe can be done other ways). I like to approach the bass like it's a giant cello...if I reduce my thoughts on this subject to the simplest comparison.

[Ken Smith]

Originally Posted by Eric Rene Roy

It just never made sense to me to have a canted back, other than to gain playability (which I believe can be done other ways). I like to approach the bass like it's a giant cello...if I reduce my thoughts on this subject to the simplest comparison.

In my opinion, it's the 'giant cello' syndrome of makers in the past that made necessary all of the cut down basses we have seen made all over Europe.

Eric, I do not know all of your personal experience of playing bass or of owning/playing old basses that were cut or should have been. I have owned quite a few that were cut, some that were not and some that could have been. I also have over 4 decades of playing the bass under my belt. Just ask Arnold how much that belt has had to be loosened over the years!

For me, you can take those 'giant cellos' of bass design and .. well.. you get my drift.

As far as a canted or angle bent back which is what I think you are referring to, I don't know of a single orchestra sized d'Salo, Maggini or English copy of one that has ever had to be cut down.

Currently, my Hart bass is one of the easiest to reach the upper register because of this cant/angle break despite its fairly wide upper bouts. That coupled with the rib depth that looks like a half sized bass sitting in the rack beside the 4/4 Panormo school bass I have. The Panormo having massive rib depth, massive top and back arch and wide upper bouts is still more playable with the canted round bent upper back then it would be at that size shaped like a cello.

I have played this monster in Concert and I was very comfortable on it. It was a bit of a stretch as compared to playing the Hart but still, it was playable.

The other alternative is gradually tapering the rib depth from the lower block to the upper corner and then sloping it more towards the neck with a gentle back bend getting the width as the neck block close to 6" or so. Two of my biggest basses that have/had their original shoulders (only a block cut for string length) have under 6" rib depth at the neck as does the Hart and Cornerless as well. A few others measured around 6 1/2" give or take an 1/8th".

Cello shaped shoulders and ribs combined make for a difficult time playing all the registers as needed in Orchestra bass playing and I don't mean solo playing.

[Eric Rene Roy]

Taking the cello comment very literally, huh? Had we been talking about body shapes then I could see your points as valid to my comment (I do agree with your points in general on this....they are valid Ken, just not to my comment). I think the bass I made for last years ISB competition was the smallest bass in the room, so you know I don't subscribe to the cello shape idea.

We are talking about graduations and theories about how we view the back plate to the top at this point. It is in this regard that I study cellos to make better sounding basses.

[Ken Smith]

Originally Posted by Eric Rene Roy

Taking the cello comment very literally, huh? Had we been talking about body shapes then I could see your points as valid to my comment (I do agree with your points in general on this....they are valid Ken, just not to my comment). I think the bass I made for last years ISB competition was the smallest bass in the room, so you know I don't subscribe to the cello shape idea.

We are talking about graduations and theories about how we view the back plate to the top at this point. It is in this regard that I study cellos to make better sounding basses.

Ok, but are you referring to a braced Flatback? If so, we are talking Viols and not violin family instruments. I guess I missed in the reading there about your exact point. As soon as I read 'Cello' my back started to ache as if I was bear hugging a giant bass, lol.