Question: how to inhibit nasality / brashness in the A string sound of a large viola

[Presumin Ed]

The question arises because:

 

1.       I have one viola (LOB: 435mm) with a pretty ‘forward’ kind of sound.   The lower three strings sound great but…the A is really quite brash.

2.       I have another (LOB: 444mm) whose sound is more mellow and balanced across the instrument, and  the A is quite sweet.

…which suggests to me that size alone does not necessarily dictate the character of the A string sound.
 

3.       I am making a viola at the moment (LOB: 423mm).   Sound….as yet undefined (currently working on the arching).

 

Are there any measures that people can suggest to try to ensure the A string does not shout, and instead that its sound is in balance with the other strings?
 

Thanks,

Ed.

 

[deans]

The first thing to check, and you probably already have, is the type of string. I've owned many violas in the 17-17.5 inch range and also some very large Ritter model/tenor sized instrument. I've spent lots of time and money testing every string type and even special ordering strings (the best option for really big instruments). A strings are the biggest problem.

 

Vibrating string length is the primary issue especially if you want to use wound steel, once you get above 15-15.5 inches things can get tricky. What is the string length? What is the angle over the bridge? The first thing I would try is a light Jargar, I found these usually work well on instruments with string lengths up to about 15.5 inches. My second choice would be to special order an even lighter Jargar A, hopefully they still do this, I haven't special ordered from them in about 5 years. 

 

As far as other off the shelf choices go, I haven't found many other steel As that work well on large instruments, but there are some new things out there that I haven't tried. But there are synthetic choices. Many people don't realize that Thomastic makes Dominants in larger sizes that are not only longer, but gauged for proper tension in bigger instruments. If you go to the Connolly web page you will see 41cm and 42cm sets. The 42 cm set works very well for giant instruments with 16.5-17 inch string lengths, like an 18.5 inch Ritter model. This set actually has a steel A, but I found it to be too thin, even for the largest instruments. The 41cm set has a very thin perlon A string (or at least it used to), I think this would be a good one for you to try, I have one on a 17.5 inch viola with a 16 inch string length right now and it works great, and I don't usually like perlon As. 

 

D.Addario makes most of their viola strings in a long length. However it appears to me that they are gauged the same as the other lengths. That is to say, medium gauged longs are the same thickness as medium gauge regulars. This of course means that they will have a higher tension on a longer instrument. So, it your string length is above 15 inches, go with the light gauge. The light long scale  Pro-art works well on a lot of big instruments.

 

There are other choices as well. Of course string choice may not be your problem, although I suspect it is if you are using steel. It may be some other adjustment problem, sometimes a thin bridge gives a rotten A. Or it could be just the instrument. 

[Marty Kasprzyk]

The question arises because:

 

1.       I have one viola (LOB: 435mm) with a pretty ‘forward’ kind of sound.   The lower three strings sound great but…the A is really quite brash.

2.       I have another (LOB: 444mm) whose sound is more mellow and balanced across the instrument, and  the A is quite sweet.

…which suggests to me that size alone does not necessarily dictate the character of the A string sound.

 

3.       I am making a viola at the moment (LOB: 423mm).   Sound….as yet undefined (currently working on the arching).

 

Are there any measures that people can suggest to try to ensure the A string does not shout, and instead that its sound is in balance with the other strings?

 

Thanks,

Ed.

The resonance frequency of a flat plate is proportional to its thickness divided by its length squared so, if you wanted to keep the same resonance frequency of your 440 mm old viola you liked, the thickness of your new 423mm viola plates should be  (423/440)^2  or 0.92 times your old thickness.

 

For example if your old plate was 3.0mm thick then the new one should be 3.0x 0.92 = 2.76mm thick.  Change your top and back plates by the same 0.92 amount.

 

Many small violas are made too thick.  Their resonance frequencies are high thus they sound harsh.

[Presumin Ed]

Re-reading my post, I realise I haven't made myself altogether clear: my principal focus is on what measures I could usefully take on the instrument I am actually building now.

 

@deans:  That said, I am interested to read your thoughts on string choice.   Thus far I have tended to go for pure gut, lightest gauge strings.   That's been more acceptable than the others so far attempted.   I think I'll try one or two of your recommendations and see how I get on.   I don't have the instrument in front of me now, but the string length from nut to bridge on viola no.1 is not particularly outsize:  around 375-380mm.

 

@Marty:  interested to read your observations on resonance frequency.  A couple of followup questions:

 

- how does this work where we're talking about two plates made of different materials?   I am assuming that with two flat plates, you cannot assume they both have the same resonant frequency just because they are both of the same thickness?

 

- Can you give an idea of what happens to resonant frequency as you introduce arching?

 

Thanks for any clarification you can offer - by all means point me to a book / webpage.

Ed

[DonLeister]

I have an interest in violas also and appreciate everyone's willingness to offer pointers.

 

Just thinking about an instrument with flat plates though, I think for it to be called a viola it would have to have arched plates. Flat plates are never going to do what is needed, would you agree? I don't mean to get too far off topic by asking this, but have flat plates ever worked on a violin or viola?

[Jacob]

String tension.

 

If you are using standard production strings, they are probably not optimally designed for an instrument that size. So I would select a long string brand with a lower A tension compared to the rest of the set. You will probably have to experiment, but that could become expensive and inconclusive. As a staring point I would suggest a set of relatively cheap strings like Helicore. Go with medium tension on C, G and D, and light A. Then try light D as well - that will affect how the A performs. Then you can try other combinations, but I think the bottom line is a lighter tension on A for that size instrument with standard commercial strings.

 

I'm doing a lot of work on Baroque setup of late, and having to focus mainly on gauge (and tension) rather than a myriad of brands, it has been a revelation to me how the tension spread can affect tone and response. Some of this can be applied to modern setup and modern brand strings as well.

[Christopher Jacoby]

Ed, you're hoping for direction in graduation, arching, etc. Folks have been discussing the "magic bullet" fallacy on MN lately, and this follows, some. Plates have to flex correctly, and work in concert with each other, to avoid a wild difference in one area of the sound spectrum. Evenness of sound is important, and working carefully during graduation and arching will help you get it, I think.

[Marty Kasprzyk]

Re-reading my post, I realise I haven't made myself altogether clear: my principal focus is on what measures I could usefully take on the instrument I am actually building now.

 

@deans:  That said, I am interested to read your thoughts on string choice.   Thus far I have tended to go for pure gut, lightest gauge strings.   That's been more acceptable than the others so far attempted.   I think I'll try one or two of your recommendations and see how I get on.   I don't have the instrument in front of me now, but the string length from nut to bridge on viola no.1 is not particularly outsize:  around 375-380mm.

 

@Marty:  interested to read your observations on resonance frequency.  A couple of followup questions:

 

- how does this work where we're talking about two plates made of different materials?   I am assuming that with two flat plates, you cannot assume they both have the same resonant frequency just because they are both of the same thickness?

 

- Can you give an idea of what happens to resonant frequency as you introduce arching?

 

Thanks for any clarification you can offer - by all means point me to a book / webpage.

Ed

 

I haven't seen it but I suspect that the frequency response curve of your 435 mm length viola has a high output in the range above 2000 Hz if you are describing the sound as "quite brash".  At high frequencies there are many small antinodes in the plate's resonance mode pattern.

 

The size of these antinodes is small enough that the plates's curvature height across any one of them is low.  So, as the resonance frequencies become higher, the plate behaves more and more like a flat plate and simple relationship I mentioned earlier: frequency is proportional to  thickness/length squared applies.  f~ t/l^2

 

If you also want to include the effect of different woods then the above proportion should include the speed of sound of the wood in both the longitudinal cl and cross grain cr directions. Yes, you are correct.  Plates of the same thickness and size can have different resonance frequencies their wood's are different.

 

At lower frequencies the arching becomes important and the resonance frequencies are further dependent upon the radius of curvatures in the longitudinal and cross plate directions.  The increase in resonance frequency over a flat plate is roughly  proportional to the arch height if the length and width are held constant  The mathematical expressions are too messy to type here and, if you are into self flagellation, please see the below references.

 

So in summary , if you want an especially "mellow" viola I suggest you use thin, low speed of sound wood and fairly low arches and a large size.  But if you go too far in those directions you may get a "tubby" sound.

 

 

1.  Thomas D. Rossing, Springer Handbook of Acoustics, 2007,  section 15.2 Stringed Instruments, pp582-588

 

2.  Neville H. Fletcher, Thomas D. Rossing, The Physics of Musical Instruments 2nd ed.  Springert,1998,  pp76-94

 

3.   Lothar Cremer, The Physics of the Violn, The MIT Press, 1984,  pp283-304

[go_oa]

I play a large viola.  Body length  452 mm.  String length 426.

Super Sensitive makes a nylon core string (Sensicore)

with a version calculated for big violas (18-20") and (20-22")

I use the 18-20 inch set on my instrument.

They work very well. 

The strings are very well matched.

I have used them now for about 20 years.

I like them.

[DonLeister]

Ed,

 

Do the two violas you mentioned have identical arches or how are the arches different from one another? Next I would look at how the graduations are different. Then it would be worth considering the neck sets - bridge height, projection, overstand and tailpiece & arrangement.

[DiemViolins]

I play a large viola.  Body length  452 mm.  String length 426. (.....)

 How is that possible? There is only 26 mm for a tailpiece and afterlength?

 

Frits

[deans]

Frits, I think you're thinking of stop length. What we're talking about is the length from the bridge to the nut, the vibrating string length.

[deans]

Go_oa, I used to use the Sensicores too, but switched when the 42 cm Dominants became easily available in the US, you might want to give them a try if you haven't already. I thought they worked a lot better, but it could just be my instruments.

[DiemViolins]

Frits, I think you're thinking of stop length. What we're talking about is the length from the bridge to the nut, the vibrating string length.

 

You're right. I made an error in my thinking. Sorry!