String slots in nut

[adriaan]

Whilst drooling over the March FC (the mighty Roman Conqueror!) I noticed the picture of the nut exposing the string slots. Sometime ago Mica mentioned that the shape of the slots was changed. She was actually talking about the bridge saddles but I'm guessing it also applies to the nut. The older ones have V shaped slots, on the newer ones it's more like a U shape.
 
I wonder why the change was made - you would think the V shape can handle a wider range of string gauges without the need to replace any hardware, right?

[bob]

Adriaan,
 
I can't speak to the history, but I asked about nut and saddle slot shapes in the process of ordering my custom, and the current approach is definitely to fit them to the strings.
 
Sure, if you want to experiment with a variety of string gauges, then a V shape will be more flexible. But if you want the best possible sound, then a carefully fitted semi-circle (or deeper U, if needed) is the only way to go.
 
You want to stop the vibrations as thoroughly as possible at one point, and the best way to do this is to maximize contact between the string and saddle or nut. A U does this much better than a V, and it's too bad there isn't a really practical way to go full circle.
 
After switching to different strings, I spent a good 3-4 hours painstakingly reshaping mine, and (to me) it was worth it. I could feel much less vibration on the portion of the string between the bridge and tailpiece on some of the strings, the harmonics were more pure, and overall the sound was noticeably better (especially on the fatter strings).
-Bob

[adriaan]

Bob,
 
Thanks for clarifying, especially as you speak from personal experience. I knew the Santa Rosa experts must have thought this through through and through - just a little surprised that this insight didn't come earlier than after 1994, the date of my most recent Alembic (the youngest in years, but has been in my possession the longest).
 
By the way, you could go full circle with a locking nut like on a Floyd Rose whammy. At least I seem to remember there were those, as well as systems with a clamp behind the nut. Personally I don't care for too much hardware making contact with the string - too many things that can start to rattle.
 
But I'm not sure about the principle of stopping the vibrations as throroughly as possible at the nut and the bridge either: I seem to remember there are basses that come with an individual bridge-and-tailpiece-in-one per string, which seems the ultimate answer to that. If that is so, then why haven't Alembic embraced the concept? Better still, why have they come up with the individual tailpiece per string, but still with a shared bridge, like on the Spyder?
 
Ah, questions, questions! Thanks for sharing.

[bob]

You only want the string to vibrate between the nut and saddle. Anything beyond this results in loss of sustain, confused harmonics, more difficult intonation, and so forth..
 
Sharing a bridge does run the risk of transferring vibrations from one string to another, but that's a somewhat different problem (pause for a moment, as we contemplate the design of a piano...).
 
I'm also intrigued by the massive individual tailpieces on the Spyder (which I suspect arose more from visual than vibrational design), but I still think it's more important to clearly define an 'end' to the string, at the saddle.
 
As it happens, I'm experimenting with a small brace beneath my bridge, such that the height adjusting screws will actually be pulling the bridge down against the brace, and the bridge will be prevented from rocking along the length of the strings (and generally vibrating less).
 
My first attempt last week was negative - for whatever reason, I preferred the sound without the brace. But it was also too high, so I was hearing some other effects (e.g. as if I had lowered my pickups). I shaved it down this afternoon and may get around to trying again later tonight.
 
As you say, questions, questions!

[adriaan]

On most upright pianos you'll see felt squeezed in under the strings between the 'bridge' and the tuning pegs, but I seem to remember concert grands don't have that. I have a book on the history of Steinway, and it does mention something like perhaps they worked on the distance from the 'bridge' to the peg to get the harmonics right. (By the way, if you've ever wondered why Steinways are so bright and loud, it's because the basic design was improved upon by 19th century beer-drinking gun club members effectively working in a steel mill, so they'd have a lot of trouble hearing any highs.)
 
About that brace - I think part of the philosophy behind the Alembic bridge is to minimize the contact area: it's just the string touching the saddle, and beyond that you have a frame that is as rigid as it can be, resting on just two bolts. Remember that the classic Fender-type bridge is basically a metal plate resting on top of the body, giving a big contact area.
 
If you add a brace to the Alembic bridge, you're probably doubling the contact area, if not more. I don't think there can be much rocking movement as it is, as there's already a few pounds of downward pressure holding the bridge still - right?
 
With a piano the strings must be coupled to the soundboard, whereas we're trying to minimize the coupling with the Alembic bridge - so perhaps there's an analogy with the damping factor between amp and speaker. It sounds as if your bridge experiments are about trying to get the damping factor intentionally wrong. Make any sense?