Installing a Sound Post

July 9, 2015 at 01:46 AM · I have installed only a total of 4 soundposts, and I would like to share my easy method. You will need a twistie, a small flashlight/headlight, and the 5-star tool.

First, make a vertical pencil mark above and below the slot in the soundpost, so you can see the slot easier once it's inside your violin.

Then take a 3 3/4 to 4-inch twistie (the kind you get on a loaf of bread with the thin metal strip inside), and twist one end tightly (just one revolution) around the soundpost above the slot. Tighten it a few times to make sure.

Insert the soundpost thru the larger hole on the treble side, so that the end with the twistie goes in last.

Turn on your flashlight and position the soundpost to your desired spot. You may be able to wedge it in with the twistie alone. You may need your 5-star tool (like I did) to further adjust or wedge the soundpost.

When your soundpost is finally situated, unwind a paper clip (or a long sewing needle would do) to undo the twistie from the soundpost.

If you don't have the 5-star tool, you may be able to unwind a large paper clip and adjust the end so you can move/nudge the soundpost.


Replies (29)

July 9, 2015 at 01:47 AM · Don't try this at home! Unless you know what you are doing.

July 9, 2015 at 02:20 AM · Agreed!

July 9, 2015 at 02:46 AM · Yikes.

July 9, 2015 at 04:29 AM · If you must, get instruction from a pro and then practice many times on a very cheap instrument. Only after that - in an emergency - set a sp on a good instrument. I once complimented a professional maker on a fine-looking bridge and he said "only the first 100 were hard". Don't rush in where angels fear to tread.

July 9, 2015 at 05:57 AM · I would guess this is an emergency operation on a $45 Chinese instrument. If it's worth a $1 more, take it to a luthier.

This is not something that should be encouraged, but even if one manages to do it, one would still have to go to a luthier for minute adjustments, so why bother installing it in the first place?

July 9, 2015 at 04:56 PM · A luthier told me that fitting and adjusting a sound post can reduce a grown man to tears - and that's after he has said all the words that cannot be printed here.

July 10, 2015 at 07:05 AM · I just returned from Claremona - a fantastic 1-3 weeks in Pomona, learning to build a violin. Older technique in a certain country was to use a string and the sound post setter. But placing the sound post is perhaps easier than fitting the sound post, which wasn't described. I am just a beginner here, but I did learn that it is difficult for a beginner, and yes, that's exactly correct: the first 100 or so are the only hard ones. The technique you describe is bereft of all the important steps - where the post is actually positioned (what sound (correction) are you aiming for?, location in relation to the bridge, the height, the grain direction, the fit (the post is not cut evenly) - all of these are as important as the location. You said nothing about the fit, so may I assume you are only trying to replace a fallen post? Even then, the fit might change, and if you don't find the exact spot, or even if you do, the fit will likely be different (stresses on the table may have changed). Any of these done incorrectly could make a perceptively huge difference in sound, never mind causing future damage.

July 10, 2015 at 01:41 PM · Fitting a sound post is one of the most painful steps in violin-making. Setting the neck is also a pain in the neck.

July 11, 2015 at 11:42 AM · I once met a folk fiddler who was fed up with a sound post that was forever falling over when he changed strings so he drilled a small hole in the back plate and used a tiny screw to hold the offending SP in place. Neatly done and unobtrusive, I must admit; at least he hadn't used a hammer and nail as another fiddler I met did.

I think I'm already starting to feel the seismic shudders going through vdotcom!

July 11, 2015 at 04:30 PM · A drop of super glue will work wonders :)

July 11, 2015 at 06:44 PM · Please. Children are reading this.

July 11, 2015 at 07:27 PM · I would agree with the words of caution. As hard as it can be to install a sound post, the real challenge is finding that desirable spot. Not wise for amateurs to attempt this, imho.

July 11, 2015 at 08:16 PM · a twistie, a small flashlight/headlight, and the 5-star tool? Nay, too complex.

Once I observed a fiddler who was changing all the strings, soundpost fell. He used a kitchen fork and a piece of string and had the soundpost back in seconds. Would not recommend trying the same thing on anyone's violin.

July 12, 2015 at 04:44 AM · The easiest way to setup a Sound Post is to have 2 Sound Post Setters as follows :

1. The Sound Post Setter VS-PRO 2. This helps to insert the SP through the f-hole and set the SP straight, positioning it where you want it to stand. Check the grain and the top and the bottom of the SP by marking it with a pencil.

2. The S-shaped Sound Post Setter with a literally 4 pointed start, actually the 4 points are flat. This helps to knock the Sound Post little by little bits when you need to fine tune the position.

There is no Luthiers on my Island. So, I did it myself. It was hard work by trial and error.

Changing Humidity and Temperature were not helping me at all.

Then I decided to plan my Sound Post setting intelligently, thus avoid the trial and error.

a. I drew a straight horizontal line on a piece of paper.

b. I subdivided that straight line into 10 cm form 10, 9, 8, 7 up to 3, 2, 1, 0 starting from right to left. 0 is supposed to fall under the Bridge.

c. So, 1 cm represents the very approximate 1 mm from the Bridge. 2 cm for 2 mm from the Bridge. 3 cm for 3 mm from the Bridge till 10 cm for 10 mm from the Bridge.

d. At each mm I moved the SP, I coded the sound as VB for Very Bright, B for Bright, M for Mellow. This coding may be very subjective from Person to Person, according to his ear and violin quality.

Finally, I have planned my Sound Post Setting. By reading my piece of paper, I could set the SP at the required location. I then fine tuned the SP at its location by tapping it a little bit by a bit with the S-Shaped star SP Setter. Since then, no more headache in my SP Setting !

If you are brave enough to try it, Good Luck !

Do not forget to slightly loosing strings A and E a little when you set the SP / fine tuning it by tapping little bit by little bit.

When my SP fell down, I lie on my back on the bed, and shake the SP out through the f-hole. I hook it out by using the sharp end of my s-shaped SP Setter. When doing this I make sure I shut my mouth so that the SP would not fall into my throat.

July 12, 2015 at 06:31 AM · The ends of the post must be a perfect fit, for tone, and to avoid denting orsplitting the plates.

And if we want to try the post several millimetres further from the f-hole, we must make a longer post with newly fitted ends, otherwise it will be simply a looser, ill-fitting post, invalidating tonal comparison.

Dentist's mirror, lamp, and peering through the button-hole are essential. And a real feeling for softwoods.

July 12, 2015 at 10:49 AM · Hi Adrian !

Good afternoon.

Long time no chat !

Yes, you are right. Unfortunately, I have not yet reached the ability to cut new Sound Posts. So, I am using the one that came with my violins and Viola.

Can I mention the G String on my Viola that was non responsive or suffered a delay under the Bow. Though I changed new G Strings, it did not improved. Finally, I re-adjusted the SP and the G String played fairly well. What I feel strange are :

1. The other 3 Strings on my Viola played fairly well.

2. While the G String not, almost appeared faulty.

3. After re-adjusting the SP, the G String played ok, fairly well

So, why the other Strings C , D, A played rather good, but not the G String. It appeared to me that the G String on my Viola is more sensitive to the precise good positioning of the SP than the other 3 Strings.

What is your opinion ?

Cheers !

July 12, 2015 at 01:00 PM · Hi Judex!

A quick, and safe trial is to move the bridge, from side to side, or up and down the fiddle, re-tuning each time. This will give some idea of subsequent post shifting.

On one decent "student" fiddle, I had to open it to patch up the inside, where the soft spruce wood was dented and cracked by enthusiastic tinkerers of sound posts. Even the hard maple was affected. (A luthier would have charged much more than the value of the violin.)

The balance between the strings varies between instruments, and also according to the weather. It is also sensitive to the side-to side placing of the post, hence my dire warnings...

And the fitting of the soundpost's ends makes a huge difference to the tone; this should be checked visually before any tampering.

And when all 4 strings are slack, the post shoulb not be tight.

The two middle strings can be a bit sluggish on violins too. "Like playing on wet carboard."

July 13, 2015 at 02:54 AM · Thanks, Adrian for your usual good advice / suggestions.

Yes, here the humidity and temperature changes are too much ! I realize that this has made me addicted to re-positioning the SP.

Thanks again, and good day to you.

Cheers !

July 13, 2015 at 04:27 AM · On the violins I take in for repair and set up, 90% have a poorly fitting soundpost, most to the point where they could conceivably do actual damage to the top. By all means get you soundpost checked and if needed refit by a professional, mucking around setting your own soundpost, assuming its properly fit when it is not is just asking for trouble, and can severely damage the inner surface of your violin. The saying "Fools rush in where angels fear to tread" comes to mind!!

July 13, 2015 at 08:40 AM · Judex, the first choice is to stabilize the environment (particularly the humidity) rather than dinking with the soundpost all the time. This is also by far the best thing for the overall health of the instrument.

Where I live, the humidity can vary between 10 percent and 100 percent. But when I keep the environment between 40 and 60 percent, the instruments generally do not require seasonal adjustment. In fact, they can often go for many years without needing any post adjustment at all.

July 13, 2015 at 12:37 PM · Further to Adrian's suggestion of moving the bridge rather than the sound post in order to safely to test the sound changes, a few useful points to keep in mind:

always drop the tension of the strings by between half a tone and a full tone before moving the bridge;

make sure the notches in the bridge and the nut at the end of the fingerboard are well lubricated with soft pencil lead to stop the strings from sticking;

discretely mark the original position of the bridge with two or three small pieces of "sticky note" paper - or, if you can, measure it really accurately from the peg box and one of the f-holes - so that you can safely retrieve your inevitable mistakes ;)

never shift the bridge more than 1mm in any direction when moving it to a new test position - it's surprising the difference to the tone such a small shift is likely to make;

make sure the bridge is properly upright when you re-tune the strings.

July 15, 2015 at 12:17 PM · Thank you very much Lyndon, David and Trevor and to Adrian again.

Your advice are so helpful for Somebody on an Island without a Luthier.

Unfortunately, I have to manage the SP by myself. I understand that when a Violin or a Viola is shipped from Europe to the Tropic, it would need SP adjustment. Is this correct. Guys ? My experience with my imported Violins and Viola tends to make me think so !

Cheers !

July 15, 2015 at 02:15 PM · Maybe yes, and maybe no. As David has said here or elswhere, keeping the instrument in a relative humidity of between 40 and 60 percent will stabalise it, and negate the need for constant adjustments, or any sound post movements.

July 16, 2015 at 07:31 PM · There is an excellent video at that clearly describes in detail cutting, fitting and installing the SP. If you want to get it right the first time you better be a master craftsman.

July 17, 2015 at 04:03 PM · Thanks Peter and Elmer.

On my Island we have 80% to 90 % humidity. I will make a small housing for my Violins and Viola.

Incidentally, I bought my 2 Sound Post Setters at Fiddlers' Shop. I saw the SP Cutter Fiddlerman is selling. I did not buy it because I was not confident enough to do the job well.

Since there is no Luthier here, I will order the SP Cutter and try my hands at it on a couple of cheaper violins.

Thanks again for all your advice and suggestions. You are wonderful People and is a wonderful Community for the String Players !

Cheers !

July 28, 2015 at 10:57 AM · Hi Adrian,

As per your advice I have taken some time to move the Bridge of my Viola. I moved it approximately 2 mm from its initial position in the direction of the tail piece. Actually, every String improved. Playing has become easier and the troublesome G String of my Viola recovered its good sound. Though moving the Sound Post improved the G String, but now moving the Bridge, literally gave it beauty in its sound and also to the other 3 Strings.

So, I am now wondering if the notches of the F-holes are reliable enough as a guide to fit the Bridge Or are the notches are not precise but approximate

Normally how do you fit the Bridge between the 2 inside notches of the f-holes ? Thank you again for your advice.

Cheers !

July 28, 2015 at 11:59 AM · Good point about the accuracy, or lack of, of the f-hole notches. For example, on my 18th-century violin they are not quite in alignment either side of the bridge, so the best way to for me to adjust the position of the bridge is by accurate measurement from the finger-board notches.

July 28, 2015 at 02:06 PM · Here are two methods you can use to check the bridge position against a "standard".

1: For playability and ease of intonation, the ratio of stop length (neck root to f-notches) to neck length (string exits nut to neck root) is 3:2.

Suppose your viola has a neck length of 148mm.

Multiply by 3 then divide by two to get the stop length.

3 x 148 / 2 = 222mm

This is the "standard" distance from the neck root to the f-hole notches.

If your notches are off, you can try shifting the bridge to the computed stop length and see if the strings become more comfortable to play. You may have to adjust the sound post.

2. For string response and tone, some luthiers believe playing string length is empirically linked to the body length.

For violins, string length = .92 to .93 x body length.

For violas, string length = .89 to .90 x body length.

The "theory" is that too short a string and the string cannot pump enough energy into the body to audibly activate the resonances.

Too long a string and the string has to be tensioned higher to tune it up and that alters the resonances of the table (for the worse I presume.)

Measure the length of the body (I usually go from purfling to purfling).

Multiply by .895 to get a typical string length.

Check to see how far off your strings are.

Shift the bridge to get string lengths around this value (+/- 2mm is probably OK).

Adjust the sound post so it is about 3mm behind the foot.

See if the string responsiveness and violin volume and tone improve.

July 28, 2015 at 02:28 PM · Brilliant Carmen,

thank you.

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