I built a 5 string fiddle a few years ago. It was interesting to play. They are typically tuned with a low C maintain the 5th intervals and essentially making the lower strings a Viola. There's no rule you couldn't tune the C up to D if that suited you. You might get a better string response since one of the main issues with a 5 string is getting a decent C string sound. There are options of body size and particularly string scale length to consider. I made mine with a standard fiddle scale length and body, so essentially a five string fiddle. A longer scale length and you might start to call it a 5 string viola. But then you have the same problem trying to make an E string work as the longer length will require a thinner or higher tensioned string.

As far as playing an octave lower that standard fiddle I think I've heard there are ways to string a fiddle so it's truly an octave below standard tuning. A quick search on the net also informed me that Thomastik makes a set of strings called Octavgeige that are designed for that purpose.

If you go for a five-string, you have to choose where you want to make a compromise to get the range you want. You can choose a violin body with an extra string so that you have the size that feels normal. The C string will give added range but the instrument won’t have the sound of a viola. To get the depth and character you need a larger air volume and no amount of trying to move things around and tweak measurements can get around that. If you’re playing an electric, it’s an entirely different matter, since the sound is dictated by the electronic elements rather than the body cavity. There you can get more out of the C and make adjustments to bring out the frequencies you want.

You can also choose a viola body with an added E string. This will give you the depth and resonance of a viola body with the extra range. However, it will not sound like a violin. You’ll have to buy a long scale E to fit the longer body. It will also have a longer scale length. If you’re used to playing the viola, it won’t be that much of an issue, but otherwise it may throw you off. You’ll also need a viola bow, as the strings will require a stick with more heft to get them to speak well, and a viola case to hold both instrument and bow.

I would consider first what registers you’re likely to reach the most in your playing. If you’re really playing in the low end more and want to get the best sound possible, it’ll be better to just choose a viola. If you’re playing in the low end but briefly hit notes in the E range, a five-string viola will offer a decent compromise. If you’re playing in the upper range but want to drop down sparingly for a low note, a five-string violin will be a decent compromise.

It’s not done much in Celtic or Old Time fiddling, but you also have the option of shifting up an octave on the violin. That will free up the lowest string for an underlying drone. The violin covers a pretty wide range already, so it’s good to keep in mind that there’s a lot of unused real estate on the fingerboard. Playing in an octave that shifts the hand above first position is an unusual solution, but it’s not really any less radical than using a five-string.

NC, my thoughts: I know over 4 people with 5 string fiddles here on L.I.. None of them really use notes on the low C string that much, so I get the feeling that unless the tune actually calls for that register or you are hot dogging it on a tune to include it, that C string often goes unplayed. I've played a few of them, most the fingerboard felt a bit cramped because a std fingerboard width was used to cram an extra string on it. Most noticeable by the nut and 1st position. One had a wider fingerboard and was not cramped feeling, but required a reach now to get to the C string notes.

And - if 5 strings were the way to go, Strad woulda made 5 strings!

Its your dosh, spend it how you like.

Me, I wanted that warm chocolate sound of a viola, so I bought a used one on Craigslist for peanuts.  

The very first fiddle I owned was a five string. I was playing it down an octave as much as possible. I really liked it at the start but I later found that I was dissatisfied with the sound of the low string and I was still occasionally running out of notes. That’s how I ended up on the tenor. In my opinion the viola sized instrument would be more successful sound quality wise. But I wouldn’t swap my tenor for the world. If the stretch is an issue a 15” Viola may be a good compromise.

My advice?
Take another fiddle and tune it FCGD. F being the lowest pitch.
Or tune the 2nd fiddle to CGDA.
Mitch Reed showed me FCGD. Because of Cajun accordions.
Way cheaper to experiment with something you may already have.
Just see how much you use it.
When push came to shove, I found I didn't really need the 5th string, myself.

I had a young girl approach me as I was packing up my tenor after a session a couple of weeks ago. She is in her mid teens and plays a 7/8 fiddle (really well). She asked me what size Viola would suit her. Obviously my response was pretty vague. I gave her a try on my 16.25” tenor and she seemed to handle it ok but that was for less than two minutes and then she disappeared. I have no idea what her thoughts and plans are, whether she wants to play standard alto viola or tenor. I’ve been putting a lot of thought into the various options particularly for the tenor, so I’m keen to discuss it further with her. I assume that she’s heard me play my instrument. So if that’s the way she wants to go I’m thinking of suggesting a 15” Viola new from China, fit it with Wittner geared tuners, a violin tailpiece without the fine tuners, install a viola D string in the 1st tuned E (octave below), viola G tuned to A, C to D and put a high tension C cello string in the 4th tuned to G. That should give her a workable tenor Viola. Of course I recommend that the bridge be placed behind the sound post. All this with shoulder rest and black haired cello bow will cost a little over $1000.

LOL Marty, you sound like a gear head, hoping up fiddles an all. Like me with my MGA, put a 3.9 diff and bore out the cans .020" with a T9 tranny will get me 10 BHP more!

yes Marty has a creative solution! :-D
Actually all of you do!

I still want to be basically a normal fiddler, just be able to double an octave down on some tunes, sometimes. Some tunes I can already do it, fudging a note here and there, but it would be great to have a fuller range.

I’d probably prefer the sound of a viola with an E! But not sure about the scale/reach and how that affects speed, and if thicker strings make it harder to do rolls…maybe I will go try some small violas for fun, and go from there…hmmm.

The other thought is that for playing an octave down, maybe don’t need to be too literal…maybe can just sub other pleasing notes for any notes that drop out of range…Hmm, shocking!

I think that there’s two factors to consider. 1 arm reach..2 finger spacing. Arm reach is very important as we know. It is the whole reason we have fractional instruments for children to be able to play properly. In Ireland i see lots of young children playing full size 19 fret banjos almost effortlessly. That’s because they don’t have to reach their arm to hold the banjo. A 19 fret banjo is exactly the same 23”s as a half size cello. So the finger spacing isn’t the problem for children on violin so much as the reach. To get a viola that is going to have reasonable sound down an octave is a big ask. Some say it needs to have a 20” body. 20”s is virtually unplayable though so anything smaller is going to be a compromise. String length and gauge is another important factor the longer and the skinnier the string generally produces the best tone. I had an 18” viola. Low tension (skinny) cello strings work well on it. The problem for me was that the reach was causing me strain injuries so what I did was reduced to a 16.25” viola and increased the string length to match the 18” by shifting the bridge position. Now i have the best compromise in sound and no more strain. Would I do this to a $40k soloist grade 100 year old instrument: NO! Would I do this to a $1k brand new viola from China absolutely! To go smaller again is going to be a slightly further compromise so you probably won’t have an instrument that will bring the house down in Carnegie Hall or be good enough to record your next grammy. One thing for sure it will be fun to play around with and especially at a session when someone sings. It occupies a space where few other voices sit. I’m absolutely loving it.

I make and play a five string....so far some of the comments are very good, but it really is a complex question as to what makes a good five string. The C string is an issue, not so much for playing but for getting a quality sound out of it...it requires more volume to resonate well. I build the five string based on a four string length so you do not have to re-learn finger spacing. I added both width and depth to the body. In doing so I have and instrument that is easy to play and is balanced across all five strings....

Before buying a five string, I would suggest that you try as many as possible.. they all play differently based upon how the dimensions worked out for the builder. I will say that putting a five string neck on a four string body is not the way to go...

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