I get a fair amount of demand for five-string fiddles (Click the link for the website); in my case, that means a five-string instrument with the same footprint and scale-length as a violin, but with the added C-string, so that it carries the full range of both a violin and a viola. I have mastered this genre to the point that the low end of my five-string fiddles sound like a good, small viola, and the the high end sounds like a good violin…and the neck width is just barely wider than that of a violin (25 mm), so that it plays like a violin.
Teachers like them, because they can teach the viola part or the violin part, without having to change instruments.
One of the beauties of a five-string fiddle, is that, because it is non-traditional, I am not under the burden of using traditional woods, so I am free to experiment, and, as it turns out, there are other woods that work quite well: I have made them of domestic woods; Big Leaf Maple/Sitka Spruce, Koa/Sitka Spruce, Myrtle/Port Orford Cedar, and all combinations worked quite well. I will soon try a five-string fiddle of Bubinga and Sitka Spruce, and am open to other experiments.
I will continue to build and sell five-string fiddles either on speculation, or on commission, as the demand increases.
I am beginning to hear a call for Five-String Violas as well. This would have the same range of pitch as a five-string fiddle, but the physical instrument will be the size viola preferred by the customer. Until I get an increased demand, these will likely remain as custom commissions, not just built on speculation, as I do the five-string fiddles.
The difference, then between a five-string fiddle and a five-string viola, would be that the (larger) five-string viola will usually have deeper, richer, louder tone, just because it has a larger resonating body, both of air and wood. But not everyone can play a larger instrument, so this is a matter of personal choice. I have one begun…
Five-string cellos are not a new thing. The cello-piccolo and the cello da spalla have been extant for centuries, and music has been especially written for both. I hope to see a rising demand for these instruments, but, for the moment, they are a rarity. I can build both, and hope to soon have some to display here, but, for the moment, I do not. I have had customers ask about them, but usually, it was just an idea they had, and they were not prepared to place an order.
Here is a sample: https://fivestringfiddles.com/2019/09/25/violoncello-piccolo-project/
Five-String Double Basses
Five-string double basses are increasingly common, as people want the freedom to reach for lower bass notes, and not have to have a “B-Extension” added to their bass (which can also be done, of course, but it does add length to the bass scroll, and an additional source of fragility.)
I build an occasional double bass, but they are a lot of work, and they completely monopolize my small workspace when they are a work in progress; so I am more likely to default to smaller instruments. There is a special thrill, however, in building a huge instrument, seeing the beauty of the beast, and feeling the floor shake when I draw out long bass notes with the bow. I can certainly understand why players fall in love with the double bass, and especially the five-string double bass, with the lowest-of-the-low B-string at their beck and call.