RinconMtnErnie - Posted - 11/06/2022:  18:24:16

I have a 16" viola. I'm perfectly happy playing this solo at home. But for playing with others in jam sessions at speed I would be very limited. 

One of the reasons for buying it was to try stringing it as an octave violin. There is a recent thread on this on maestronet: maestronet.com/forum/index.php...-strings/

It used to be that you could use an octave viola G string, and then get DAE from standard CGD viola strings tuned up a step. But no one sells octave viola strings anymore. 

So now it looks like the best option is to use a 1/8 cello G string.

I think I will try this with helicores, but I did want to say something about string tension, as that is not discussed in the maestronet discussion. 

The 1/8 cello G string is designed for a 18 7/8" vibrating string length, call that 19". It has a tension of 20.9 lbs at that length!

I am not home, so I cannot measure the vibrating string length of my 16" viola, but 14.5" seems like a typical length. I'll measure it in a few days when I return. 

D'Addario's formula for tension T in pounds is T = UW × (2 × L × F)^2 / 386.4. So if one reduces length by (14.5/19), then the tension should reduce by (14.5 / 19)^2 = .58, call that 0.6. So the G string tension would be 0.6 × 20.9 lbs = 12.5 lbs, which would be quite in line with the other string tensions. That's about the tension of a standard viola A string (15.5 lbs for medium tension helicore).

Tuning up the other strings a whole step would also increase overall tension, but not terribly.

I may or may not put this into a spreadsheet when I get home.

If it doesn't work out I'll simply revert to standard tuning.

Hector - Posted - 11/07/2022:  02:34:14

You can use the same D'Addario formula to work out the tension of the strings that you want to tune up but, from memory, the extra tension of tuning up a whole tone is not insignificant. Take care!

TommyMax - Posted - 11/08/2022:  01:44:33

I am interested in what you end up doing. I have a five string 16 inch viola that I want to turn into an octave viola five string if I can figure out what strings to use.

RinconMtnErnie - Posted - 11/08/2022:  06:48:05

Thank you, Hector and Tommy for the responses. I am still traveling but will post a more detailed string tension when I return. 

Regarding strings for a 5-string, 16" viola tuned CGDAE, D'Addario sells E strings for short, medium and long scale lengths (maybe even extra long).

Having the 16" viola made me realize that I can play longer scale lengths without too much trouble. So that got me thinking about a 15.5" or 16" five-string. Someone at a jam last night said his wife has one.

How would you do the neck conversion? I'm not seeing white 5-string viola necks for sale. Though you would think they would be out there as there are plenty of 5- string violas.

At the jam, a mandolin player said he would be interested in pairing his mandola with a viola. But this is in another city.

Edited by - RinconMtnErnie on 11/08/2022 06:48:42

TommyMax - Posted - 11/08/2022:  12:41:17

I’m not doing a conversion, It is already a 5 string. Right now it’s strung with Helicore heavy strings and tuned to standard tuning. I want to put octave strings on it.

RinconMtnErnie - Posted - 11/08/2022:  18:45:50

So, I put this all into Excel. I looked at using various combinations and tunings of six different strings. The first five are D'Addario Helicore Long Medium (LM) viola strings at C3, G3, D4, A4 and E5 pitches. The nominal Vibrating String Length (VSL) of those is 15 inches. The sixth string is the D'Addario Helicore 1/8 scale Medium (1/8M) cello string at G2 pitch, which has a nominal VSl of 18.875 inches. The nominal tensions in pounds for those six strings is:

My 16" viola has a measured 14.5" VSL. I am adjusting tension using the formula T = T_nominal * (freq/freq_nom)^2 * (VSL/VSL_nom)^2. So if you increase frequency or increase length, the tension increases.

For standard CGDA tuning with a 14.5" VSL, the tension is

Another potentially interesting tuning would be DDAD, using a viola E string for the high D. That results in the following tensions

And here are the octave violin tensions, using the 1/8" cello G string for the low G

All of these look reasonable from a tension perspective, regardless of what they sound like.

Here is a summary of the total tensions for the three tunings assuming a 14.5" VSL.

I have some more thoughts, but want to post this to not lose the tables.

RinconMtnErnie - Posted - 11/09/2022:  18:53:39

I did go ahead and order the 1/8M cello G string from Johnson String Instrument. Not many places sell the individual strings. It will be at least a week and half before I receive the string and am able to try the setup in a group.

I also generated the tension table for two other D'Addario strings: Zyex synthetic core and the inexpensive Prelude steel core. The overall tensions are pretty similar regardless of the choice.

My viola has the original Preludes it came with, so I will re-use the CGD strings for this octave violin tuning experiment.

Regarding tuning choice, I mentioned three: standard CGDA, DDAD and octave violin GDAE

In the long run I will almost certainly use the standard CGDA tuning. I like to play old tunes (French fiddle tunes, English country dance tunes, baroque dance tunes). It's extremely unlikely I will ever play those with others, so I just play them down a 5th on the viola and it sounds good.

I may try DDAD someday because I think it would sound awesome on a longer scale instrument. That tuning I could actually play alone or with others, but repertoire would be limited.

I don't think the octave violin tuning is going to be great alone. I mainly want it to get a lower register to play with others. Edit: Well, I think the low G string will be weak, but I think the DAE strings will be strong, certainly better than a normal violin with octave violin strings.

Edited by - RinconMtnErnie on 11/09/2022 18:57:12

TommyMax - Posted - 11/10/2022:  04:38:12

I am very interested in how it turns out. Would you be willing to calculate what string would work for the C string. Again, I have a 5 string, 16” Viola tuned CGDAE. I want to make it an octave lower. Do you think a 1/8 celllo C string will work? Any help you can give me would be greatly appreciated.

Thanks,

Tom Sanderson

Edited by - TommyMax on 11/10/2022 04:42:20

RinconMtnErnie - Posted - 11/10/2022:  18:51:13

I updated the spreadsheet to add a 1/8 cello C string (Again D'Addario Helicore 1/8 scale Medium (1/8M) cello string at C2 pitch). I realized that I had entered the wrong tension for the G2 string (entered the C2 tension of 19.6 lbs instead of the G2 tension of 20.9 lbs). For that reason, I'm posting all of the tables from before plus adding two more tables for the 5-strings (5-string viola and 5-string octave viola).

I looked at using various combinations and tunings of seven different strings. The first five are D'Addario Helicore Long Medium (LM) viola strings at C3, G3, D4, A4 and E5 pitches. The nominal Vibrating String Length (VSL) of those is 15 inches. The sixth string is the D'Addario Helicore 1/8 scale Medium (1/8M) cello string at G2 pitch, which has a nominal VSL of 18.875 inches. The seventh string is the 1/8M cello string at C2 pitch. The nominal tensions in pounds for those seven strings is:

My 16" viola has a measured 14.5" VSL. I am adjusting tension using the formula T = T_nominal * (freq/freq_nom)^2 * (VSL/VSL_nom)^2. So if you increase frequency or increase length, the tension increases.

For standard CGDA tuning with a 14.5" VSL, the tension is unchanged from before:

For DDAD, using a viola E string for the high D, the tension is unchanged from before:

Here are the octave violin tensions, using the 1/8" cello G string for the low G (0.7 lb increase from initial estimate)

Here is the standard CGDAE 5-string viola tuning:

Here is the CGDAE 5-string octave viola tuning:

Just to be clear, the E4, A3 and D3 strings are standard D4, G3 and C3 viola LM strings tuned up one whole step. The G2 and C2 strings are the 1/8M cello strings.

I don't think it should be a problem tuning up the Long Medium strings, because those are meant for use on violas with 16--17" bodies, and you need more tension on the 17" body. I estimate the tensions of the tuned-up strings to be about 1.2 lbs heavier than they would be at nominal pitch on a 17" body (assume 15.5" vibrating string length).

As before, all of the tensions in the table look reasonable to me, regardless of what they sound like.

Here is a summary of the total tensions for the five tunings assuming a 14.5" VSL.

Hopefully I didn't make any new mistakes!

Edited by - RinconMtnErnie on 11/10/2022 18:58:01

RinconMtnErnie - Posted - 11/10/2022:  22:23:02

Here's a good video illustrating the kind of stuff I'm hoping to do: Uncle Joe (Tenor Viola and Fiddle)

TommyMax - Posted - 11/11/2022:  01:38:25

Thank you very much. I ordered the 1/8 cello strings (C&G). I’ll report back as soon as I get it strung up.
Tom Sanderson

RinconMtnErnie - Posted - 11/12/2022:  20:56:04

First the "interesting" part. The 1/8 cello G string arrived quickly. The good news is the size is pretty reasonable. it's big, but not as big as a hawser on an ocean liner. But between the ball and the winding, it's not going to fit on my synthetic tailpiece with built-in fine tuners. So I need another tailpiece, which is not a surprise. I would like to make this work with four fine tuners, so I'm going to see if a cello fine tuner will fit on a viola tailpiece.

I ordered the following from Shar Music (because they had all the pieces):

• Hill ebony viola tailpiece


• Two-prong viola string adjuster (ordered four, but plan to use three)


• Wittner two-prong cello string adjuster


• viola string adjuster (tailgut)

For experimental purposes, I'm pretty sure my bridge will work as-is. I'm not so sure about the nut. I have some spare viola tuning pegs, so I should be able to drill one of those out to make room for the G string. While I'd have no hesitation to modify the bridge (because that can easily be replaced), I'm not going to touch the nut.

My only goal is to get this together enough to see if it makes sense to take it to my luthier to set it up for real.

I'm embarrassed to say that the tensions in my earlier tables for Long Medium (LM) strings were in fact for Long Light (LL) strings. You would think I could copy the right numbers from the right column, but you would be wrong. So here are some updated tables.

The update is pretty boring, but has my updated estimate for LM strings.

**********************************

(Narrative same as before but with updated tension values in tables)

I looked at using various combinations and tunings of seven different strings. The first five are D'Addario Helicore Long Medium (LM) viola strings at C3, G3, D4, A4 and E5 pitches. The nominal Vibrating String Length (VSL) of those is 15 inches. The sixth string is the D'Addario Helicore 1/8 scale Medium (1/8M) cello string at G2 pitch, which has a nominal VSL of 18.875 inches. The seventh string is the 1/8M cello string at C2 pitch. The nominal tensions in pounds for those seven strings is:

My 16" viola has a measured 14.5" VSL. I am adjusting tension using the formula T = T_nominal * (freq/freq_nom)^2 * (VSL/VSL_nom)^2. So if you increase frequency or increase length, the tension increases.

For standard CGDA tuning with a 14.5" VSL, here are the updated tensions.

For DDAD, using a viola E string for the high D, here are the updated tensions.

Here are the octave violin tensions, using the 1/8" cello G string for the low G.

I'm most interested in this octatve violin / tenor viola tuning, and it is still reasonably balanced.

Here is the standard CGDAE 5-string viola tuning:

Here is the CGDAE 5-string octave viola tuning:

Here is a summary of the total tensions for the five tunings assuming a 14.5" VSL.

RinconMtnErnie - Posted - 11/12/2022:  21:04:53

I have two other comments, but didn't want them to get lost in the tension update.

First, I looked at using the extra-long, medium tension (LXM) strings instead of the long, medium tension (LM) strings. This doesn't change the tensions of the 14.5 VSL at all, which makes me think the LXM strings are the same as the LM strings in every way except length.

Second, I looked at tensions for a 15.5" body assuming 14" vibrating string length. I'm not going to include the whole table, but using the 1/8M Helicore cello string at this length results in a tension of 11.5 lbs for the G2 string, as compared with 12.3 lbs for the 14.5" VSL. So I think that string is potentially viable for the 15.5" body.

RinconMtnErnie - Posted - 11/16/2022:  20:59:13

I hadn't planned to post anything else until I got this strung up, but for Tom's benefit I wanted to comment on the string adjusters (fine tuners) that I ordered. I only ordered those as an experiment. Doing this for real you would probably want geared tuning pegs. It's been a long time since I used that kind of string adjuster. I forgot how clunky they are.

The cello string adjuster is massive. Although I could drill out the hole in the tailpiece to get it to fit, I don't think it's worth ruining the tailpiece for an experiment. So I don't recommend anyone try this. I'm not even sure I'm going to use the viola string adjusters.

I discussed this topic in general with my luthier. He's supportive, but he's leary of overstretching CGD strings to get DAE. He's a good fiddler, but he says he does not even like cross tuning AEAE because of increased tension. I must admit that the only repair I have ever needed was to the endpin area of my cross-tuned fiddle, as it was coming loose. Partly for that reason but also because for higher pitches you want lighter strings, I'm thinking the Long scale length, Light tension (LL) strings are a better choice to get the DEA pitches.

He said he has had good experience with octave strings on violins, especially "large pattern" instruments. He encouraged me to put an octave violin string set on one of my fiddles. So I did this. The action and general playability are good. The tone is okay. Projection is meh. I was surprised that the G string seemed to be louder than the D string. I'm thinking that is something like the soundpost needing to be moved for this setup.

The results are acceptable, but not really what I'm hoping for. I played D tunes (1) down an octave on the octave-strung fiddle and (2) down a fifth on the viola. The tone and playability of the viola are better by a large margin. If you told me I could only play one of those two instruments, it would definitely be the viola.

Probably the most interesting thing was that the idea of an octave violin has resonated with my wife. She played viola in school orchestra, but really hasn't played at all since then (about 40 years). I was playing Neil Gow's Lament for His Second Wife on the octave fiddle, and she offered to play with me on regular fiddle even though she never plays. She had pretty good intonation and was surprisingly good playing by ear, though it was an abbreviated version with maybe 2/3 of the measures. I told her I wasn't thrilled with the octave fiddle sound, but she was more positive about it. The bottom line is she is way more enthusiastic about octave fiddle than viola. When I brought the viola home, she said it had better be for me and not her. She associates the instrument with playing really boring parts in school orchestra. Her first instrument was violin, but she traded it for the viola of a friend who was too small for the viola. She has regretted that decision ever since.

My wife's enthusiasm means I will have an octave fiddle one way or another, but I think it will more likely be with a viola body than a violin body. I like my current viola with normal tuning, so I am leaning towards buying a viola already set up as a tenor (octave violin tuning). But I'm not buying anything unless I understand how it is strung.

I have everything I need to string up the viola, but I have to drill out the hole on a spare peg and fit it to the hole. I won't be able to get to that until Friday or Saturday. I plan to get a micrometer so I can measure the 1/8 cello G string diameter. Visually, it's only a little bigger than the octave violin G string. So I'm more optimistic that the strings will work with the unmodified nut, especially for a short experiment.

Regarding string tensions, here's a quick analysis using the Helicore Long Light (LL) strings. The tensions are similar to those in my original post, but now correctly identified as LL strings. I'm also going to add a tension table using the same strings on a 15.5" body viola assuming a 14" vibrating string length.

I looked at using various combinations and tunings of six different strings. The first five are D'Addario Helicore Long scale, Light tension (LL) viola strings at C3, G3, D4, A4 and E5 pitches. The nominal Vibrating String Length (VSL) of those is 15 inches. The sixth string is the D'Addario Helicore 1/8 scale Medium (1/8M) cello string at G2 pitch, which has a nominal VSl of 18.875 inches. The nominal tensions in pounds for those six strings is:

Here are the octave violin tensions for a 16" body.

And here are the tensions for those exact same strings on a short 15.5" body.

Hopefully I didn't make any mistakes. I keep copying manufacturer data incorrectly into Excel.

RinconMtnErnie - Posted - 11/18/2022:  15:46:23

I got it strung up! I'm pleased with the result.

Once or twice a year I think it would be useful to have a micrometer. I'll have to order one. In the meantime, with a caliper I measured my current viola C string (Prelude), the Octave Violin G string and the 1/8 cello G string. To the accuracy I can measure them, the dimensions are

I suspect that the Helicore 1/8 cello G and Octave violin G strings may be the same, just different lengths. In any case, they are very similar.

I had an old viola peg lying around that fit the existing hole well enough. I don't have a great assortment of small drills, but I used a 5/64" drill for the hole. The bridge and nut were both fine, no modification would be necessary.

There are no fine tuners, so tuning is unstable for now. If I decide to keep this instrument in this tuning, I will (1) get my luthier to install some geared tuners, and (2) swap the upper three strings for long scale, low tension Helicores.

My luthier thinks my viola has an "unusually pleasant tone". I'm no expert, but I like the tone. So I don't want to screw it up. I think it sounds better in viola tuning, but it sounds pretty good as an octave violin / tenor viola. It definitely sounds better than my fiddle with octave strings.

My luthier says he has a deep voiced, vintage Czech (probably) instrument that is a true Maggini pattern with a somewhat longer scale. He thinks it is a good candidate for octave strings, so he's going to try that. I'm hoping to be able to compare the three instruments next week (my fiddle with octave strings, my viola in octave violin tuning, and his fiddle with octave strings).

I'm pleased with the experiment. Now the question is do I leave this instrument as-is, or do I revert to the better sounding viola tuning and buy another 15.5" or 16" instrument. My closet and bank account think I should have one viola, not two.

I also did some research into gut and wound gut strings. That's another viable option. For pure gut strings I get that you would need a 3.2 mm diameter G string to get 12 lbs of tension on a 14.5" vibrating string length. So a wound string would be more appropriate. I'm guessing cost would be between $250 and $300 for a set of four strings.

RinconMtnErnie - Posted - 11/19/2022:  18:42:12

I don't have much else to say on this, but I had a few more observations about the 1/8 cello G string.

I did find a micrometer, and again I measure both the octave violin G string and the 1/8 cello  G string to be 1.2 mm in diameter.

Regarding the tail end of the string, the ball is big and the winding is substantial. I was just barely able to get that string into a plain Hill tailpiece. I thought I might have to enlarge the slot in the tailpiece with something like a thin diamond file, but I was able to coax it in. So no major issue at the tailpiece.

Regarding the other end of the string to attach to the peg, it is more difficult. The Helicore string is very tightly wound  along the vibrating string length. It is so tightly wound that it has a high bending stiffness, meaning it is too stiff to bend easily around a viola or violin tuning peg. So what happens beyond the vibrating string length is the outer winding becomes much looser, with fewer turns per unit length. A red-colored, strong thread is wound around that. It appears to be two layers. Something like the first winding goes between the loose wire winding. And then a second winding goes around that.

To get the string to work on the viola, I had to cut off the entire length that is meant to be wound around the tuning peg. I simply fed the tightly wound portion around the peg. But that is somewhat difficult, and it causes the string to grip the peg less tightly.

This is going to sound crazy, but it would be better to (1) unwind  the outer winding to about 1/4" beyond the nut, (2) rewind that outer winding with fewer turns per unit length (inches or mm) so that it is intact, but allows for easier bending, and (3) wind a strong thread around that (or something else like tape or heat shrink tubing). In a nutshell, I recommend rewinding the length beyond the nut to be like on the original string.

TommyMax - Posted - 11/22/2022:  13:11:33

Well, I finally got around to turning my 16”, 5 string viola into a 5 string octave viola. For the C string I used a Helicore medium 1/8 cello C string. I moved it to the top peg to avoid the sharp bend that it would have if it was on the bottom peg. I used a 1/8 cello G string for the G. I moved the original C string to the D and tuned it up I step to a D. I did the same for the A & E strings (G to A, and D to E). The original strings are Helicore long viola heavy. I bought a complete 1/8 cello set , so I might replace the D & A with the 1/8 cello D & A strings, and the E with either a Helicore medium or light long viola string. I bought a new bridge that is for a 5 string viola, it’s wider than the one that’s on it now which I think is for a 4 string. I haven’t changed the bridge yet. I’m going to play it for a while to see if I like it. If I do, I’ll fit the new bridge and replace the nut.