Overly powerful bass frequencies

[wjm52358]

Hello Maestronet, I have been lurking here for some time now and I have decided to finally post

 

I have a violin (with the Jacob Saunders method, probably Dutzenware fiddle from Shoenbach, late 19th century) that I have recently finished restoring in my apprenticeship that has an extremely powerful sound.  However, I find that all strings have poor sustain, the G string in particular has a very punchy and deep sound, and there is a powerful wolf on G#. These problems probably stem from the unusually soft spruce top and maybe the lack of corner blocks?

 

Does anyone have any thoughts on ways to fix this (other than adding corner blocks )? I have tried a few post adjustments and tuning afterlengths, etc. but to no avail. I understand that this problem isn't entirely fixable but I figured I shouldn't give up until I have asked here. 

 

For reference, I did a soundpost patch, replaced the integral bass bar, and regraduated the table.

 

Any help or advice is greatly appreciated! Thanks

[Jacob]

How high are the ribs? The poor sustain could a sound post issue.

[Doug Cotterill]

Way back when I was an apprentice, a violin came into the shop with too much sustain. It was like a guitar, it just kept ringing and ringing. The bass bar was very short, hardly longer than the center section of the violin. I replaced it with a normal size bar, and it had the typical sustain after that. Is there anything out of the ordinary about the length or size of your new bass bar?

[wjm52358]

Well, the ribs seem to be about 31-32 mm around.  Also, I replaced the bass bar and I believe carved it to the standards given in the Weishaar book, if this helps. Thanks,

Will

[Don Noon]

I find that all strings have poor sustain, the G string in particular has a very punchy and deep sound, and there is a powerful wolf on G#. These problems probably stem from the unusually soft spruce top and maybe the lack of corner blocks?

 

Presumably the G# wolf is in the upper position on the G string, not a semitone above the open string.  If so, then the B1- resonance is excessively strong.  From my experience, you are right in guessing that the top is lacking stiffness, particularly in the middle and lower bout areas.  I have no direct experience adding corner blocks, but I would think that should add stiffness and help the problem somewhat.  A stiffer bass bar should also help, but again I wouldn't expect a miracle cure with that, either.

[wjm52358]

Ok, thanks for the advice! I can't really do either of those things any more, but I will keep those in mind if I suspect the same problem may occur again in another instrument.

Will

[Joe Swenson]

...

 

For reference, I did a soundpost patch, replaced the integral bass bar, and regraduated the table.

 

...

 

Hi and congratulations on "coming out of the closet"! 

 

How did it sound before you regraduated the top?  It could be that thinning the top is the cause of the issue.  If makes sense for a very powerful instrument to be "wolfie" but maybe you now have too responsive a top.  

 

I have one like that myself... Although I didn't reqraduate it.  It was already pretty loud and "wolfie." I only fixed a sound post bruise and crack in the top under the chin rest which ran near the base bar.  I put a set of Eudoxa gut strings on it which are much lower tension compared to some synthetic strings and that helped quite a bit in my case.

 

Good luck...

 

Joe

[wjm52358]

Hi and congratulations on "coming out of the closet"! 

 

How did it sound before you regraduated the top?  It could be that thinning the top is the cause of the issue.  If makes sense for a very powerful instrument to be "wolfie" but maybe you now have too responsive a top.  

 

I have one like that myself... Although I didn't reqraduate it.  It was already pretty loud and "wolfie." I only fixed a sound post bruise and crack in the top under the chin rest which ran near the base bar.  I put a set of Eudoxa gut strings on it which are much lower tension compared to some synthetic strings and that helped quite a bit in my case.

 

Good luck...

 

Joe

Hmm, I should try eudoxas. I have a set of dominants on there right now, and a Pirazzi G seemed to help brighten the sound.  Before all of the repairs, the violin was basically just loud, and now it is loud and extremely bassy.  Would certain things like tuning the fingerboard, replacing the tailgut material, etc. make an improvement?

[Joe Swenson]

Hmm, I should try eudoxas. I have a set of dominants on there right now, and a Pirazzi G seemed to help brighten the sound.  Before all of the repairs, the violin was basically just loud, and now it is loud and extremely bassy.  Would certain things like tuning the fingerboard, replacing the tailgut material, etc. make an improvement?

Anything attached to the instrument has some resonant quality and could affect the wolf tones intensity and frequency. But the main players are the plates. Changing other elements will have some effect but the character of the top plate seems to be the issue.

Do you have a thickness map of the regraduated top?

You can always try a little "stiffening" although I know a lot of folkjs here will disagree. Vernice Bianca or just plain Gum Arabic solution applied to the inside of the too will add some stiffness to the plate. On my 2nd violin which was a Guarneri design. Also loud and Wolfie, I had open A resonance where I could feel the top plate vibrating excessively beloiw the treble side F-hole. I coated the inside already and after coating the outside with VB, the resonance went away. It is still Wolfie on the lower string so I'm hoping once its varnished this will tone down as well.

I've heard of someone pouring VB in through the end pin hole and coating the whole inside with F-hole taped shut, and sloshing it around for a while then pouring out wwhst is left through the uncovered F-hole. That seems a little drastic and probably messes up the label.

But it seems your plates need some stiffening. not sure the best way to achieve that.

Joe

[wjm52358]

Anything attached to the instrument has some resonant quality and could affect the wolf tones intensity and frequency. But the main players are the plates. Changing other elements will have some effect but the character of the top plate seems to be the issue.

Do you have a thickness map of the regraduated top?

You can always try a little "stiffening" although I know a lot of folkjs here will disagree. Vernice Bianca or just plain Gum Arabic solution applied to the inside of the too will add some stiffness to the plate. On my 2nd violin which was a Guarneri design. Also loud and Wolfie, I had open A resonance where I could feel the top plate vibrating excessively beloiw the treble side F-hole. I coated the inside already and after coating the outside with VB, the resonance went away. It is still Wolfie on the lower string so I'm hoping once its varnished this will tone down as well.

I've heard of someone pouring VB in through the end pin hole and coating the whole inside with F-hole taped shut, and sloshing it around for a while then pouring out wwhst is left through the uncovered F-hole. That seems a little drastic and probably messes up the label.

But it seems your plates need some stiffening. not sure the best way to achieve that.

Joe

That's an interesting idea for stiffening the plates. Unfortunately, no thickness map.  Maybe I should just replace both of the plates

Thanks,

Will

[jezzupe]

I would experiment around with some different bridges. Heavy ones, light ones, wider feet, narrow feet, more heart scoop, less heart scoop. I have a feeling that slightly narrowed feet with one on the lighter side may help reduce some "umph" which is generally a good thing , but can be a bad thing if there is too much umph'.

[Joe Swenson]

That's an interesting idea for stiffening the plates. Unfortunately, no thickness map. Maybe I should just replace both of the plates

Thanks,

Will

I'm still tempted to try it on my problem instrument. Just for reference. When my violin instructor played Iit, he mentioned it sounded more like a viola than a violin.

[wjm52358]

Sorry I hadn't responded. That's a good idea for the bridge, the one on there right now is my first, and with poor quality wood.

will

[Lars Silen]

How to fix a too boomy bass (or adding darkness when the bass is too dry)

 

If you have a very boomy bass and sound post movements and bridge changes don't fix the problem then my experience is that the problem lies in a wrong balance in the stiffness of the top. The dark boomy sound is easy to produce by making the channel between the bass bar and the neck too thin. Very small changes here produces large tonal changes. A plain guess is that the same effect can be achieved by making the bass bar to short in the same location or making it too flexible at the top end.

 

How to fix the problem of a too deep/boomy bass by a simple modification to the top without removing the top? My method is as follows:

 

You need a very simple sanding tool made from two super magnets. Use cyanoacrylate glue (Super Glue) to glue abrasive to one of the magnets. I usually use nr. 80 roughness by the company Mirka in Finland. Glue the other magnet to a thin wooden stick making sure to turn the magnet in a direction that attracts the sanding magnet's abrasive side to the magnet glued to the stick.

 

1)  Drop the sanding magnet into the violin and find it with the external tool and move it to the lower end of the top where the other end of the bass bar is located. Protect the varnish with ordinary copying paper. Sand the lower bass bar/end block channel 50 times and think a narrow triangle being sanded with the tip going through the bass bar channel and widening towards to area to the lower left hand side of the left lower bout. The sanding area goes from the edge of the tailpiece to say 20 mm from the left hand side of the lower bout of the top.

 

Test it by playing the instrument: The tone gets lighter/less dark and the tone gets increasingly smooth and silky.

 

2)  If the tone still is too dark repeat (1) with 40 - 60 sandings between listening tests until you are satisfied.

 

When after applying some elbow grease (some 5 - 10 iterations) you have eliminated the darkness in tone you need to do another fix to the tone. The tone at this stage is too smooth/silky and uninteresting.

 

3) You can add some character/roughness to the tone by sanding a similar triangle on the other side of the tailpiece (right hand side). Do 20 - 40 sandings between testing the sound. If the tone becomes too "raspy" sand slightly more on the left hand side.

 

Notice:

a) The effect of sanding is initially very strong but the change will to a large extent be undone when the sanded area cools and the surface probably hardens. A number of sanding iterations possibly spread over a number of days will probably be needed.

 

The instrument is playable all the time. There is no need to remove the chin rest if the external magnet is mounted on a thin stick. Obviously there isn't any need to remove the top. Removing the top to do the re-graduation makes it impossible to test the changes by playing.

 

c) Notice that the changes required are extremely small. We are talking about 5 - 10 micrometers. Taking the top off to do the modification is too rough and you won't have any control. The best way to do the fix is through sanding as outlined above. The sanding speed for spruce is roughly 0.1 micro meter per back/forth sanding movement.

 

 

Fig. 1

Some sanding tools for internal sanding of a violin. From the left:

1) An external tool to sand the channel between the sound post and the neck. Sanding here makes the tone darker and sanding much makes the bass boomy.

2 and 3) Small sanding magnets for general internal use for example for fixing the boomy bass in this thread. The Diameter of these magnets are ca. 10 mm.

4 and 5) Big magnets that provide a good grip on the outside. The magnets in the picture are covered by felt. Using plain paper to protect the varnish is much better though. The diameter of these magnets is ca. 20 mm and thickness 10 mm.

6) A super magnet glued to a thin stick allows sanding under the chin rest and in some cases also under the finger board.

[Lars Silen]

To give some substance to the posts above I did some recordings of an instrument I have been working on where an unfortunate internal "esthetic" fix to the top close to the neck, when removing and re-gluing it, caused a from my point of view too dark bass. The present thread unfortunately started after I had started the job. The example here is thus started in the middle of the work ... I simply don't have any recording of the starting point. All changes have been made with the sound post in a fixed location.

 

 

Fig. 1  The instrument I have been adjusting.

The example shows, I hope the readers are able to hear the difference, that changing the harmonics of a violin can change the character of the sound. A too strong bass can be fixed by attenuating the fundamental tones ... or by increasing the amplitude of the higher harmonics. The latter was attempted here.

Notice that in some ranges the amplitude has increased by 6 - 10 dB which means that the the output has increased by a factor 4x - 10x (hearing is logarithmic) compared to the starting point.  The result is a, I think, clearly audible change in timbre.

 

The starting and end point sound examples can be found on my bloghttp://larsil2009.wordpress.com/2014/08/28/hur-korrigera-en-alltfor-mork-fiolton/.

 

I beg all reader pardon for the sound examples. I am an amateur playing mostly traditional/folk music. The example is an old Swedish psalm often used today as music on funerals. My playing level isn't good enough to really bring forth the beauty of the piece. I used this melody because it is slowly moving and it is easier to hear changes in timbre. The distance to the microphone is roughly 2 m. The relative position of the recorder and the violin is the same.

Fig. 2  The black curve is the half way starting point where some changes already have been done. Red curve is after changing the lower bas bar channel under the chin rest. The green curve is after doing small changes to the E-string side inner F-hole wing. The spectra above are produced from the complete melody using Audacity.

 

The following adjustment steps were used

 

#1  Adjust the channel between the lower end of the bass bar and the end block. This makes the tone lighter.

#2  The bridge was made slightly thinner on the side of the G-string. Filed the front under the G- and D-strings. This increases higher harmonics. The arc between the bridge feet was also enlarged slightly on the G-string side (not the whole arc).

#3  The inner wing of the f-hole on the E-string side was thinned. There was a fairly big difference in tap tone between the inner and the outer wing. Making the tap tone better balanced seems to improve the tone. Thinning the inner wing on the other side makes the tone "silkier" which I didn't want to have so I left it alone.

 

It is possible that I will attempt to fix the original problem by adding a layer of varnish on the inside where I unnecessarily re-graduated the top close to the neck. If this turns out good it could be worth another thread. I am thinking of using fairly hard alcohol based varnish or alternatively to add a very thin layer of hide glue in this area. The same methods as used in internal sanding can easily be used to apply layers of varnish or glue anywhere inside the instrument in a very controlled manner.