Six strings is pretty much the maximum in regular violin tuning - that is, if you extend the normal tuning by fifths. Even on an acoustic five-stringer, it's a challenge to get a balanced sound with that wide a range - the soundbox and scale length will either be too small for the low string (tubby, muffled sound) or too big for the high string (shrill ugly sound, breaking strings).
The maximum range between the highest and lowest string with a single scale length seems to be two octaves and a bit.
Five strings tuned in fifths span two octaves and a major third; seven strings in fourths with one third (standard guitar tuning) span two octaves and a fourth. The extra strings on an 8-string lap steel are, after all, added in the middle of the range compared to a standard guitar.
A friend of mine is an instrument maker, and he's made a lot of five-string cellos and violins, mostly with an extra low string. He made one six-string fiddle, tuned in fifths Fcgd'a'e", but it only worked because it was an electric fiddle - if it had been an acoustic that low string would not have balanced well with the others. He's made an acoustic/electric six-string cello, but it was tuned in fourths.
As far as historical acoustic instruments, the five-string cello with a high e string above the normal four was not unheard of - Bach wrote at least one piece for it - but they are smaller than the regular cello and the low string isn't as strong as on the standard instrument.
In other tunings, there's the viola d'amore with seven strings usually in open chordal tunings like Adf#ad'f#'a' (The 8-stringer Smiley Roberts mentions sounds like a reinvention of the same idea - great for chordal playing.)
Then there's the viola da gamba family in several sizes - tuned almost like a standard guitar. The gamba is my main instrument, and I've owned two. One was a small six stringer tuned gc'e'a'd"g" - with the low string the same as a violin. This was a great little fiddle and I played jigs and reels on it,
as well as jazz, blues and the Baroque repertoire it's intended for. It was stolen in Montreal. The axe I still have is a seven string bass gamba tuned ADGcead' - like a baritone guitar with an added string
on top. (The six string version doesn't have the low A.) I have a pickup on it, and I play it in as many different styles as I can. It's a fact, though, that seven-string gambas are hard to set up and often aren't well balanced - the low end is weak or the high end is shrill. (Mine's pretty good, but it's not as
loud overall as some of the bass-heavy models.) There's a similar problem with five-string cellos, and even most of the five string fiddles you hear get a little help in balancing the strings from a tweaked pickup
or pre-amp.
<FONT SIZE=1 COLOR="#8e236b"><p align=CENTER>[This message was edited by John Kavanagh on 27 December 2002 at 05:48 AM.]</p></FONT>
