Arching Profile

[Craig Regan]

I have noticed different arching profiles on string bass tops. Some rise up in hight quickly then flatten out across the f holes. Others are more dome shaped, cresting at the middle of the top. How does this effect the sound?

[Ken McKay]

I have noticed different arching profiles on string bass tops. Some rise up in hight quickly then flatten out across the f holes. Others are more dome shaped, cresting at the middle of the top. How does this effect the sound?

Yes Craig it does. One of the greatest, if not THE greatest violinmaker thought so. Guarneri del Gesu altered his arching over time. Of course this is violin but it is directly related. While he kept other things surprisingly similar. He was getting more power and the later violins are more desirable by players.

The arching is the voice of the instrument. Along with other factors such as wood and how stiff it is across and along the grain, plate thickness, ff hole placement, bass bar placement, varnish etc...

You won't know how the cross arching will effect your sound until you make similar instruments and just change one thing.

Intuitively you can try for a stiffer or less stiff arching for whatever reason you have, such as if your wood seems to be floppy across the grain, it could be made stiffer in that direction by arching a more dome shape rather than a flatter slope. But it is hard to determine the cross grain stiffness in a wedge or thick plank. With thin guitar top wood this is easy just by flexing. Make a guess and hope you are right, if not you can then alter stiffness by leaving it a little thicker. Ideally, theoretically you want the top as thin and light as possible yet not too thin to promote cracking. And for similar wood (identical) a more domed shape will be stiffer at the same thickness.

All that said, it is more practical and advisable to look at the arching of good sounding basses, pick one and follow it.

I am posting this now and will add another thought later about a pinched arching.

[Ken McKay]

Here is a quote for a description of a 1802 Panormo ex Fred Zimmerman.

"The top and back are not purfled, but the top does show places where the purfling was scribed (i.e., painted) on. The varnish is a dark orange-brown color on the back, ribs and scroll, while the top has a deeper reddish brown color. The arching of the top was modeled beautifully to correspond to the back arching. Over the central bridge area the arching reaches deeply to the channel along the edges, providing a strong yet flexible platform. The back is carved flatter in the central area to provide power and projection." I believe from the Elgar book, which I don't have. I got it off the cozio site.

So that also might give you some ideas.

[Ken Smith]

Here is a quote for a description of a 1802 Panormo ex Fred Zimmerman.

"The top and back are not purfled, but the top does show places where the purfling was scribed (i.e., painted) on. The varnish is a dark orange-brown color on the back, ribs and scroll, while the top has a deeper reddish brown color. The arching of the top was modeled beautifully to correspond to the back arching. Over the central bridge area the arching reaches deeply to the channel along the edges, providing a strong yet flexible platform. The back is carved flatter in the central area to provide power and projection." I believe from the Elgar book, which I don't have. I got it off the cozio site.

So that also might give you some ideas.

A Panormo without Purfling? This from a guy whose Violins sit side by side with Strad? I have recently seen another Bass attributed to Panormo as well with similar graduations on the Top that he used (6mm, all across the Top!). This Bass however did not look to be of the same level of workmanship expected from V.Panormo.

Who can this be then that looks, talks and smells like Panormo? Did he have any assistants or apprentices other than his Sons? The answer is, Yes. His name was William Taylor and is listed as Panormo's assistant as well as having made many of his own Basses in the style of Panormo. Probably most or some have a carved Round back with angle break.

When examining the attr. Dodd I used to have just after I got it some years back, we noticed the Studs across the upper angle break of the Flat Back. This is a feature usually only seen on Panormo Basses. Panormo also worked for some time in or for the shop of John Betts. Not all that Panormo built was built as his own work or model. Not every Bass carrying his attribution is Panormo either. He was one of the most famous of that English school then so you have to assume there were others that followed suit when the occasion arose to do so.

[Ken McKay]

By the way Ken, Craig who started this thread is copying a Panormo bass from a plan by that maker in Canada who passed away a couple years ago. I don't know how I knew that, must have read it some where... Craig?

Ken, Thanks for the William Taylor link.

[Ken Smith]

By the way Ken, Craig who started this thread is copying a Panormo bass from a plan by that maker in Canada who passed away a couple years ago. I don't know how I knew that, must have read it some where... Craig?

Ken, Thanks for the William Taylor link.

I think his Amati plans are from the same Bass from the Elgar book attr. to Daniel Parker. I don't know if that bass is a Parker but it is cut down and probably British, not Italian. It does have a great sound no doubt.

Copying a great Bass in my mind is better than just copying a name. It doesn't matter if it's Panormo or not or Amati or not. Good is good and that's what matters to the player mostly. A big name with no sound is for the Museum, not the stage.

I mentioned to Arnold that he should learn what he can when he opens up my attr. Storioni cornerless Bass. That is one of the greatest sounding Basses. We need to know what makes it 'tick'! Maybe I will commission a copy if I get up the nerve.;)

[Arnold Schnitzer]

I have noticed different arching profiles on string bass tops. Some rise up in hight quickly then flatten out across the f holes. Others are more dome shaped, cresting at the middle of the top. How does this effect the sound?I am a believer in moderate arch and also in having a nice flat zone around the edges (which actually become a bit concave after carving in the recurve). Basses with tops that rise up right from the edge sound stiff to me and rarely produce the subwoofer tone people crave. Basses that have arching that is really flat in the middle lack definition to my ear. As Ken McKay stated above, a lot depends on your wood. Graduating your plate to a set of numbers fails to take into account the density and stiffness of a particular piece. But telling a person who is building his first bass to use his instinct is not helpful. So I would err on the side of slightly higher arch or slightly thick graduations. You can always open it up and remove wood later, but it is really hard to add wood. By the way, when you glue that top on, use weak glue!

[Martin Sheridan]

My observation is that Italian arching usually rises fairly quickly from the edges. On the tops it tends to level off at about where the tailpiece starts and runs fairly flat to under the fingerboard before dropping off. Many of them tend to be somewhat barrel shaped. That's a pretty overall view. Like Arnold, I like fairly moderate arching.

What a great thing it is to be able to share and hear opinions on these vital topics.

I don't use arching guides. I like to choose my height and then pretty much carve to what pleases me.