Sitar-like sound

Instrument Building
1

Hello all. I’m wondering if anyone can provide insight into a problem my instrument has been developing. A few of the strings have developed a sitar-like twang to them within the last year. It even seems to be slowly spreading to neighboring strings. For example, middle c# and d# have developed the twang while the c, d, and e around them sound normal. This is a bentside spinet I designed and built based loosely on the Goujon spinet in the ( as i recall) Musée de musique, Paris. I’ve been playing it for about five years now. I tried changing string gauges, checking for loose pins, string tail issues, and voicing of plectra. The only thing I have not tried that I can think of so far is the plucking position. My tongues are pretty much smack in the middle of the Jack body. Beech jacks with Holly tongues, boar bristle and wild turkey plectra (dirth of Ravens about). It’s here and a couple more strings above this part of the compass, the strings being pretty close to the breaking point, so the tension should be pretty optimal and the strings around them have good clean tone. If anyone has encountered this phenomenon before and has advice, I would very much appreciate it.

James Young

2

Hi James, Although I’m not a fine connaisseur of sitars, might I suggest you check your bridge and nut profiles? If the strings have slowly sunk ever so slightly into the bridge or nut under the horizontal pressure they exercise, they may be touching the wood now and not coming off the pin for vibration. How far is the crown of the bridge or nut from the pin/string contact point?

Since your plucking point is rather ‘inwards’ the magnitude of oscillation might be enough to cause a buzz.

Sitar sound depends on sympathetic strings, so perhaps your dampers on resonating octaves or 5ths/4ths/2nds have slipped a little?

Hope this helps! Now to get my Ravi Shankar cassettes out from behind the VHS player!

Thomas

04870 St Michel l’Observatoire

(33) 04 92 76 60 81

ProvenceBaroque

3

After five years of satisfactory service I would eliminate a need for a change of string gauge, though a new string of the same gauge and type never hurts. Why c#1 and d#1 are affected and not the d1 which lies betrween them is both a mystery and a clue. Is the weather currently as extreme where you live as it is here in Vienna? Is there a point that you can touch with a toothpick or small screwdriver that makes the effect worse or stops it? Otherwise, Thomas’ suggestions above merit investigation.

Get your Sherlock Holmes magnifying glass out!

David

4

Hi @James apart from playing and making harpsichords I have done a lot of work in classical Indian Music including tours playing the tanpura, the essential drone instrument. Sitar sound does not arise purely from the sympathetic strings for if that were the case then the sarod which also has a large number of sympathetic tuned strings would have the same sound which it does not. Sarod has a tall thin bridge. Sitar and tanpura have very wide nearly (but not quite) flat bone bridges. On sitar this accommodates the very large string bends that are necessary in raga. But the long contact with the nearly flat bridge also adds subtle buzz. Indeed, because you want the tanpura to buzz you put small lengths of cotton between the string and the bridge and adjust until buzz!

What’s the point? ‘Sitar buzz’ is highly likely to be caused by bridge problems. If your strings are under very high tension as it seems you say then they may well have started to bury in the softer wood of the bridge instead of being firmly against the bridge pin. Also, I have seen cases where strings have cut into bridge pins that are not hard enough wire. Note that this effect only need be very small to be audible, and you may well need a magnifier to see it. That would be where I’d be looking first. This is in exact agreement with @JacquesRéelle. I believe this is also consistent with it happening on only a couple of notes. If it were sympathetic vibrations then you’d expect more, e,g, on the octave below as well.

5

Is the undesired sitar sound a buzz (like the brays on a medieval harp) or is the twang more like an undesired/distorted harmonic on the fourth, sixth or seventh? My harpsichord has what seems to be the latter over 5 notes in the bass, similarly impervious to voicing and variations in string gauge. Not caused by changes to pins, etc as the instrument had just been professionally renovated. As I couldn’t change it and it is not unpleasant I have opted to think of it as a part of the instrument’s inbuilt timbre in the bass. I used to think of it as connected with the plucking point of those 5 notes but now am not so sure. I would be interested in knowing if there are ways of adjusting it though.

6

In a spinet the jacks pluck alternately toward and away from the player, but the bridge and nut pins don’t alternate, so the plucked impulses approach the pins as mirror images, some reflecting pushing toward the pins, others reflected pulling away. This may have something to do with the distortions of alternate notes.

In piano technology, considerable attention has been given to the behavior of bridge pins in producing “false beating” strings. False beats are almost never caused by the string, they are usually caused by microscopic wobbling of the bridge pin in a slightly enlarged hole.
The enlarged hole is caused by sloppy drilling and hammering during manufacture, tiny splits in the bridge cap, damaged caused by tapping to “seat” the string (which temporarily improves the sound, but later makes it worse) and…Humidity Slowly Compressing and Relaxing the Wood Around the Pin. (Emphasis intended)

Diagnosis of a loose pin is easy: With the tip of a screwdriver, press the pin toward the string and play the note. If the false sound was caused by a loose pin, it will immediately clear when the pin is temporarily stabilized.

For this hypothesis, the nut pin could be the cause, because it is closer to the plectrum.
[Or perhaps the string has worn into the surface of the nut. Tuning pins may be alternately closer and further from the nut, changing the bearing against the wood, and thus wear and tear.]

In piano work there are two common repairs: 1) Remove the pin, put a tiny bit of water-thin epoxy in the hole, replace the pin, wipe away squeeze out. 2) Apply a tiny drop of very thin CA glue at the base of the pin, quickly wipe away any that is not absorbed. (Caveat: I have never done this repair on a harpsichord. Glue purists should consider that hide glue may make a temporary repair, but would also remain hygroscopic.) Two other repairs, sometimes used: 1) Replace the pin with a larger pin. 2) Drill out the hole, plug with a bit of dowel, re-drill and replace the pin, usually with epoxy or CA glue.

So much for detail. Diagnose First with the screwdriver test! Diagnosis before Treatment! (Clever treatment without diagnosis is the bane of piano technology.)

7

I forgot to add that of course you should look at the nut as well. In fact I’d wager that it is more likely a nut problem. One thing we find is sometimes just banging the nut pin down a bit more to firm it up helps.

8

Ah! Thank you all for your help. I will definitely check the firmness of the pins, especially the nut pin. I looked carefully at the bridge and nut pins this morning and realized that the bridge has a very healthy gap between the crown and pin, but the nut i did not create the same steep angle and the worst offender has almost no clearance between the wood and pin! It has actually settled in and what was already trouble in the making had become worse. I think this is why as Jaques mentioned it has changed. If I’ve exhausted all other suggestions, I think I should at least steepen the downward angle of the nut away from the crown to create a healthy gap between wood and pin. The sitar and sarod insights convince me even more. I love both of those instruments btw…

Further thoughts on this are welcome as well as any advice on replacing new pins into existing holes as I will be removing all the nut pins to plane the top of the nut.

Best wishes, James

9

You and your new-fangled technology!

10

In my experience a hole that is over-large, in the wrong place, or at the wrong angle, can be plugged successfully with a toothpick. Just whittle it until it is the right diameter and press and glue it in (Titebond will do for this job). Then after it has dried you can redrill (having made an indentation with a rounded tool where the hole is to start). For this job I use a small fast dremel-type drill with a small chuck that runs from 12 volts – not a Black and Decker type, as with this it is much easier to be precise.
David

11

As to new pins, we use piano centre pins. Here you can get fine gradations of size:

Here, smaller range but more colours!

https://www.vogel-scheer.de/en/iron-goods/3-5-pins/bridge-pins.html

12

Here’s a tip about bridge and nut pinning. My building colleague and I are fairly convinced that if there is air left at the bottom of the pin hole that it affects the sound, for the worse. Not a lot, but a harpsichord is the sum of dozens of very small effects. You need to bang the pin right down so there is no air gap. This sounds crazy but I am sure you can hear a difference. I mention this because this also applies to filling a hole with a toothpick. Try to make it a pretty good fit. Yes, Titebond will fill any gaps, but I think it’s not the same.

13

Thanks Andrew!

14

Dear All

An interesting topic! James mentions his middle c#’ & d#’ as having a twang, but not the surrounding c’, d’ & e’. But Ed was the first to comment that we are dealing with a spinet, and point out that the jacks face alternate directions.

Spinets share this design feature with virginals, which results in disproportionate string length and varying tension on adjacent notes. (We could consider the harpsichord with its even sweep of string length an improvement in this regard.) And we have all probably noticed the propensity of the stringband of many spinets and virginals to migrate towards the spine, further magnifying the difference in tone between adjacent notes as playing a chromatic scale produces notes which are alternately loud and soft, and requiring careful voicing to iron out alternately long and short quills.

Couple that with the bridge rolling (not along with the solid wrestplank-mounted nut on the spinet) and we can have a rather complicated scenario.

There is next to zero amplitude of the string at its very ends, but contact of the speaking length with the wood of bridge or nut will successfully foul the tone. I don’t think very much clearance is needed between pin and wooden crown of either bridge or nut, but the speaking length of a string must be properly terminated on the metal of the pin for good tone.

So I would be surprized to have this chromatic tone difference arise because of insufficient crown—more likely to be a spinet phenomenon. But assuming you have even downbearing from the nut, before you attempt recrowning the nut, you could try seeing if raising the string height by a toothpick on the tuning pin side of the nut solves the poor tone.

Regards

Carey

15

Ok, so I did the toothpick test (what a good simple idea btw) and no change, so now I’m thinking it is some spinet specific phenomenon. I tried stabilizing the pins with the screwdriver as well. Maybe what I’m perceiving as a twang or buzzing is actually unwanted harmonics standing out. It’s the worst with that c sharp. No matter how I temper it, even as a pure third for A major, it is just stinky! What’s especially strange too is that it wasn’t that way for the first few years. It was sitting unplayed in my bedroom de-tensioned a semitone down for about a year and now that I’m playing it again (up to pitch) there has been this change…I appreciate everyone’s help. I feel like I’ve learned from this.

16

Have you tried switching a few jacks to see if the sound travels with the jack or stays with the string?

17

It’s hard enough troubleshooting computers over the phone but troubleshooting spinets by email is harder! Nevertheless…

I am not sure exactly what you mean by sitar like sound, but now you seem to be saying it may be harmonics related. A couple more things come to mind. Since this was OK for years it can’t be a design issue. One thing I can say is that depending on the type of wire you use, localised rust or corrision spots can cause distortion of the partials structure. The cure for this is a new string, or to give a good clean end to end with 0000 steel wool.

Kinks in the string will also cause this, but it’s hard to see how it would get kinked once having been put on.

One somewhat unscientific trick is to try a heavier gauge wire on that note. At least worth trying.

You also need to be sure there is no varnish or shellac on the bridge pin.

One final observation today is that bridge and but pins should not be too tall. They need to be just the right height. It seems that too long pins absord energy from the overall vibational system too much. Piano makers are very fussy about the bridge pin overheight.

What pitch are you at? What wire do you use?

Do you have very wide plectra? that can be a cause of strange harmonic issues sometimes.

18

James, going back to your first post, you mention using wild turkey quills. Wild turkey quills are about as far from raven quills as you can get, they are very stiff and coarse, but could be thinned. I wonder how flexible they are after 5 years.
If you can forgive my heresies, I’ve been re-plectra-ing my two less than ideal harpsichords with the “very thin” delrin plectra from the Instrument Workshop, who sell delrin plectra in 5 thicknesses. What I notice is that the thin plectra are much more forgiving than the thicker plectra I’m replacing. Since they are thin for their full length, they curve and release more evenly than the thicker, tapered plectra, being in effect “self-correcting.” One of my instruments has jacks that are a little loose in the register, and the thinner, longer plectra even out the sound in a way the stiff plectra could not. The release of the thin plectrum is less violent than the release of the stiff plectrum, so I wonder if this may be exaggerating any differences in the terminations of the strings in your instrument.

19

Here’s an update. I tried switching jacks. No change.

The wire is Malcom Rose from the instrument workshop.

And yes, my pins are actually much taller than they need to be. No varnish on them but there has been some corrosion on the strings.

All of the problematic sounds are from jacks that pluck the string towards the nut pin. The jacks in between, plucking away from the pin sound fine. The string moves away horizontally from the plectrum on the good ones and does not move horizontally on the bad ones during the pluck. I reckon everyone knows that already. I think Carey alluded to that. Outside this octave, there does not seem to be an audible problem. Maybe someone with better ears might notice it there but less intensely.

The turkey quills seem easy enough to voice, but they wear out pretty quick. They split or just partially break about half way out. I think the latter is due to less than careful voicing sometimes. I can get them very thin and softly voiced. I tried voicing the bad notes down very low and i get a very soft version of the bad notes. Playing around with an upside down Jack the bad sound disappears when plucking about an inch and a half from the current plucking point towards the bridge- like four centimeters. This is plucking downward though…

My plectra are tapered to a reasonable width. No wider than necessary to get a good pluck. Like a nice writing quill.

The sound reminds me of a sitar how they sound metallic and buzzy, as if the correct sound is a sarod, but I’m getting sitar. The sourness is there too. My brain may be just perceiving overwhelming bad partials as thin, metallic, buzziness.

Dealing with this has been actually a bit fun with all your help and a great learning experience.

I’ve had a Flemish style going for a while now and am getting back to completing it. I’m planning on using delrin (i think i have medium from the instrument workshop) this time for better reliability.

Just for the hell of it I’m thinking of making a “plucker” that i can use by hand to pluck all those bad strings upward and away from the pin at the plucking point to hear if there’s a difference. I’ll report back on that.

Thanks,

James

20

You must clean the strings.

Can you try as I suggested a heavier gauge? One gauge down may be enough.

And what pitch are you at?

Andrew