Before the "Virzi" came the "Ceccherini"

[Tavy]

Before the Virzi brothers got in on the act, Ceccherini was making bowl back mandolins with an internal resonator (often called a "double top"), having recently inspected one I thought you all might be interested to see how they were constructed:

[billhay4]

Thanks, Tavy,
I'd like to see a sketch of this as it's hard for me to visualize from the pictures. But they help a great deal. Maybe out sketch guru, Marty Jacobson, can chime in here.
Bill

[Marty Jacobson]

That is pretty interesting.. I've been thinking about Kerman instruments lately. Bill and I have discussed internal baffles/plates/whatever at great length, and I have some parts cut out for some experiments. Just haven't messed with them yet.

It looks to me like this was almost intended to work as a bellows. Whether or not that's how it actually functions, I could see an attentive craftsman thinking that would be worth a try. Is it attached with just two posts at the soundhole end, or are there other joints/supports?

[DavidKOS]

Very interesting, thank you.

My Vietnamese French copy flatback mandolin has a series of holes in the sides, and what appears to be some sort of second resonators parallel to the sides, but not touching the top or back.

I'd love to see inside it the same way as your video showed the Ceccherini.

[Tavy]

Thanks, Tavy,
I'd like to see a sketch of this as it's hard for me to visualize from the pictures. But they help a great deal. Maybe out sketch guru, Marty Jacobson, can chime in here.
Bill

Have you seen the standard of my sketches?

Oh well here we go anyway:



One thing I didn't show in that was the cloth (?) strip wrapped around the edge of resonator to protect the end grain. These days thin CA wicked into the end grain would probably work just as well.

It looks to me like this was almost intended to work as a bellows. Whether or not that's how it actually functions, I could see an attentive craftsman thinking that would be worth a try. Is it attached with just two posts at the soundhole end, or are there other joints/supports?

Yes just the two blocks (one in each corner) at the soundhole end. Two more 2/3 of the way to the tailpiece, and then a wedge at the tailpiece itself. It's thin stuff too - I estimate just 60thou thick - with 80thou stiffeners running it's length.

The bellows analogy is a good one, though I suspect the top braces would severely restrict airflow in and out of that area? Perhaps more like a smooth lower surface to the sounding board? From time to time I've fantasised about a top made more like an aircraft's wing: thin coverings above and below separated by spacers. A little like the nomex-based double top guitars but with all the braces and structural elements internal to the top. But then I do have strange fantasies

[billhay4]

Thanks, Tavy,
A very helpful diagram. I was just looking at this instrument: http://www.joytransmitters.com/instruments-de-musique/ by Hans de Gier which is loosley modeled on a Kerman. It seems to use a similar resonator.
How much space is between the resonator and the top brace?
I think Brian Dean uses a different approach on his Grand Concert model, but I may be wrong. His resonator (whatever it is called) is not partial but fully covers the cavity. If anyone knows differently, I would apprecaite being corrected.
Very interesting stuff.
Bill

[DavidKOS]

The Kerman design has inner resonators?

I am not familiar with their construction.

[pfox14]

That's really different than a Virzi TP. The VTP attached to the back with a small block. Personally, I really never understood what Loar thought was so great about them.

[billhay4]

The Kerman design has inner resonators?

I am not familiar with their construction.

I don't know anyone who is really familiar with the construction of the Kermans, but they do seem to have a second soundboard. The one by Hans is his take on them and he has seen one up close (more than I have done). Various pictures seem to show a second soundboard. Hans says, "the second soundboard is just held at three points, the neck and at about a third length either side of the string attachment. There is no connection between the two boards as this would make it to stiff, so they vibrate in unison only by air movement" about it.
Bill

[derbex]

Interesting, mine is at least slightly different in that the blocks are set further back behind the top brace, and wider apart rather than over the stringers. You can't see them easily from the sound hole at all. I don't know if the rest of it si the same as your one.

[Tavy]

That's really different than a Virzi TP. The VTP attached to the back with a small block. Personally, I really never understood what Loar thought was so great about them.

No the Virzi attaches to the top via 3 feet in the centre of the resonator. This is larger and attaches at 5 points around the edge.

How much space is between the resonator and the top brace?

Almost none!

[Tavy]

Hans says, "the second soundboard is just held at three points, the neck and at about a third length either side of the string attachment. There is no connection between the two boards as this would make it to stiff, so they vibrate in unison only by air movement" about it.

Interesting!

I've speculated that all these devices basically function as energy storage devices - they cannot in principle generate sound directly if they're completely enclosed inside the sound chamber - but what they can do is feel the instrument vibrating, steal some of that energy to vibrate themselves, and then give it back at a later time. Effectively generating a sort of hardware reverb effect. Certainly the one Virzi containing mandolin I built seems to have a certain "zing" to it, but it's a small effect. There was also someone (don't remember the details unfortunately but it was mentioned around here) who built guitars "back in the day" with metal rods set into the neck block which presumably would have the same effect?

[vic-victor]

My Embergher Liuto (Sistema Ginislao Paris) also has the double top:

[Tavy]

My Embergher Liuto (Sistema Ginislao Paris) also has the double top:

Interesting - how are thing oriented in the image - that's looking towards the tailpiece with an internal "soundhole" just before it yes?

[vic-victor]

The other way around. Here is the better view of a second top:

[Jim Garber]

1879 patent for double-top violin by E.R. Mollenhauer of New York. I actually found one at a flea market. Never sounded like much and it needed two soundposts, one on either side of the internal soundboard.

John, do you know the patent date for Ceccherini?

[MikeEdgerton]

That's really different than a Virzi TP. The VTP attached to the back with a small block. Personally, I really never understood what Loar thought was so great about them.

Actually no, they were attached to the top by feet.

http://www.mandolincafe.com/glossary/glossary_14.shtml

[Tavy]

The other way around. Here is the better view of a second top:

Hmmm, I'm still not clear on that - is that the tailpiece on the right? Or are you saying that's the neck on the right?

Also that looks like slab sawn maple to me? Cecherini used very thin/flexible spruce with the grain running across the width of the instrument.

[vic-victor]

Tailpiece on the right. You were right. I mixed it all up, sorry.

I think the second top is spruce and it is not that thick either.

[tom.gibson]

C. Giacomel's unusual bowlback with a carved top also has an internal plate. You can glimpse it quite clearly on the Youtube videos of it being played by Carlo Aonzo. Don't know how it's attached.