Sympathetic Strings - Can we brainstorm?

[KarmaShaman]

Hello all,

I would like to have a conversation about sympathetic strings, and get some opinions from thos emore learned than myself. As a quick bit of background, I want to build a stringed instrument with non-plucked strings that with resonate when the plucked strings are played. Similar concept to the Sitar, or for those to 70's world/jazz fusion, the 'Shakti Guitar' played by John McLaughlin around that time.

As I'm no luthier, nor built an instrument before, the build principles will probably be more in line with a pimped-out cigarbox style, rather than a pro-built instrument. I mention this, because there most definately not be a truss rod through the neck, although it will be well fortifed, perhaps as a multi-piece 'thru-neck' which will work around a steel resonator bowl in the instrument's body.

So I'm hoping for some opinions, or even better, some cold hard mathematical facts, on the best string configurations for both the plucked strings and 'triggering' the non-plucked sympatheic strings.

Consideration 1 - String gauge

Am I correct in thinking that thinner strings hold more tension ? I'm wondering if heavier gauges will be a safer option, to avoid the instrument buckling over time.

Consideration 2 - Configuration

I hope we can examine the merits vs pitfalls of steel vs nylon strings. I would think that at least the sympathetic strings should be steel, to provide more 'twang' (although the outcome is really more of a drone, and the buzzing will be enhanced by a custom designed nut & bridge). Of the four configuration options, what may perform best:

A. Steel Sympathetics & Steel Plucked

B. Steel Sympathetics & Nylon Plucked

C. Nylon Sympathetics & Steel Plucked

D. Nylon Sympathetics & Nylon Plucked

My heart is leading towards Steel + Steel for the best outcome as a droning device, but the concern is the lack of tension support over the length of the neck, so there will be many compromises.

For the record, I'm tentativley planned on a low C, low F, high C, and two more high F's, with the same tuning on the sympathetic strings. I'll need to do some testing to see how strings respond to equal octaves, or whether a low octave will better trigger a higher octave drone. Any ideas on how I can test this ? I was thinking of bolting a speaker to an old Strat (Squire) and feeding a sine wave signal into the body, to see what the best string response is. An acoustic guitar would probably be better for this, being that the instrument build will be an acoustic, but I don't have one that I'm willing to destroy, wheres the strat is a junk guitar already.

Edited January 10, 2014 by KarmaShaman

[curtisa]

Consideration 1 - String gauge

Am I correct in thinking that thinner strings hold more tension ? I'm wondering if heavier gauges will be a safer option, to avoid the instrument buckling over time.

String nension is primarily a function of three things - the mass of the string, the length of the string and the pitch it is tuned to. A heavier (thicker) string tuned to the same pitch as a lighter (skinnier) string over the same length will be under more tension. Increasing the length while maintaining pitch and mass increases tension. Increasing pitch while keeping mass and length constant also increases tension.

There are trade-offs in experimenting with varying the three parameters. Too little tension (by way of pitch, length or mass) tends to make the string sound like rubber bands and don't hold pitch when played. Too much tension and you risk breaking the string or damaging the instrument.

Consideration 2 - Configuration

I hope we can examine the merits vs pitfalls of steel vs nylon strings. I would think that at least the sympathetic strings should be steel, to provide more 'twang' (although the outcome is really more of a drone, and the buzzing will be enhanced by a custom designed nut & bridge). Of the four configuration options, what may perform best:

A. Steel Sympathetics & Steel Plucked

B. Steel Sympathetics & Nylon Plucked

C. Nylon Sympathetics & Steel Plucked

D. Nylon Sympathetics & Nylon Plucked

My heart is leading towards Steel + Steel for the best outcome as a droning device, but the concern is the lack of tension support over the length of the neck, so there will be many compromises.

Steel + steel would have been my choice, but chances are that will require you to construct a neck with a truss rod or similar reinforcement. I am not sure if a genuine sitar uses steel for the plucked and sympathetic strings?

Do the sympathetic strings need to be on the neck? What about mounting the sympathetics on the body as was done on the Jerry Jones Coral Sitar?

Another idea to look at - the Sympitar. The sympathetics run in parallel with the normal strings and up a hollow tube in the neck under the fretboard. Alex De Grassi played one for a while.

For the record, I'm tentativley planned on a low C, low F, high C, and two more high F's, with the same tuning on the sympathetic strings. I'll need to do some testing to see how strings respond to equal octaves, or whether a low octave will better trigger a higher octave drone. Any ideas on how I can test this ? I was thinking of bolting a speaker to an old Strat (Squire) and feeding a sine wave signal into the body, to see what the best string response is. An acoustic guitar would probably be better for this, being that the instrument build will be an acoustic, but I don't have one that I'm willing to destroy, wheres the strat is a junk guitar already.

You can usually excite sympathetic string vibration by plucking single fretted notes on a guitar while allowing the remaining 5 strings to vibrate freely. The lower strings tend to want to resonate at a harmonic of their natural pitch in sympathy with plucked higher strings (eg, 1 octave higher, 1 octave + 5th, 2 octaves, 2 octaves +maj 3rd etc). IME flipping it around the other way and getting a low string to cause the remaining higher pitched strings to vibrate sympathetically is nigh-impossible.

A piano will do a similar thing. For example, hold a low C key down (without allowing it to play - just to get the string damper released) and tap and release a C key one or two octaves above. The undampened low C will continue to resonate in harmonic sympathy with the higher C after the high key has been released.

[curtisa]

IME flipping it around the other way and getting a low string to cause the remaining higher pitched strings to vibrate sympathetically is nigh-impossible.

Actually, after watching a couple of Youtube vids on Sympitars and experimenting a bit at home I found I could get low tuned strings to excite sympathetic vibrations in higher strings. I'm only trying this out on solid body electrics, so it's possible that the characteristic resonances of my instruments are dampening the effect somewhat, leading to my initial conclusion that resonance only occurs harmonically from high strings to low and not the other way around.

For whatever reason I find it easy to get sympathetic vibration from the first harmonic of the open 6th string (E) when plucking the 5th string/7th fret (again, E). Plucking the 6th string/3rd fret (G) only just barely causes the open 3rd string to resonate (G +1 octave) - it's there but really faint.

Edited January 11, 2014 by curtisa

[KarmaShaman]

Thanks for the response. I just picked up a solid-body electric (an ESP roughly in the LP style & weight), unplugged - and found that the low E barely registers on the high E, but the high E most certainly excites the former. I'm working on touch observation only, and feeling the vibration/drone. That may be an important key to my design. Ideally, I would like an instrument, as a tester, to see if the high E excites another high E....... and even how this impacts on the middle range E (of which I would need an open, unfretted sample).

I belive that the sitar is a steel-strung instrument, both plucked and sympathetic. And... no truss rod as far as I know. From what other 'heresay' I have picked up over the years, the sitar isn't exactly a stabilly tuned nor an easily tuned instrument. Thoughout the many tension changes over the neck, it's said to be very hard to 'dial in'.

You mention a 'sympitar'. There's a guy called Fred Carlson who made an instrument much like you described. Sympathetic strings though the guts of the neck, and (very cleverly) tuned on pegs that reside on the headstock... actually Fred's version even has a truss rod. I'm not going to attempt this sort of design, because it's going to be too complicated as a first effort at making an instrument. I'm looking more towards buinding an entire instrument, say 1/2 scale, and installing it into another instrument, that I'll build around it. It'll be a box shape, without a doubt.

[curtisa]

Thanks for the response. I just picked up a solid-body electric (an ESP roughly in the LP style & weight), unplugged - and found that the low E barely registers on the high E, but the high E most certainly excites the former. I'm working on touch observation only, and feeling the vibration/drone. That may be an important key to my design. Ideally, I would like an instrument, as a tester, to see if the high E excites another high E....... and even how this impacts on the middle range E (of which I would need an open, unfretted sample).

Easy way to try that out woud be to replace the B string with the same gauge string as the high E and tune it in unison. To test mid-E for sympathetic vibration just take the D string and tune it up a whole step.

You mention a 'sympitar'. There's a guy called Fred Carlson who made an instrument much like you described. Sympathetic strings though the guts of the neck, and (very cleverly) tuned on pegs that reside on the headstock... actually Fred's version even has a truss rod. I'm not going to attempt this sort of design, because it's going to be too complicated as a first effort at making an instrument.

I think we're talking about the exact same thing. Another one of Fred's creations along a similar line can be seen in action here.

[KarmaShaman]

Having discovered Carlson's 'Taproot' video about two weeks ago, I have lost count of the times I have watched it. That guy is such an innovator, and it's inspirational, even though my own instrument will be rather crude in comparision.

Back on the testing topic, and something I brought up in the opening post. Would a speaker cone bolted to the body of my guitar provide a good amount of energy to stimulate strings, if I were to feed a constant audio signal or sine wave tuned to the precise frequency I'm testing for? If that works, I could jack in and actually measure the output of isolated strings that resonate, and find the absolute best combination. I had thought that simply sitting the guitar on a speaker box would do, but I didn't get much stimulationm from either an electric or acoustic (likely a poor physical connectivity point)

And on the subject of truss rods, there are instances of builds that defy what I believe to be it's purpose. I asked an innovative CBG maker if his neck has twisted or buckled in the three years since his build, and he claims it hasn't. Same too with a woman who built a CBG bass. And of course the sitar has no truss rod, and is under the strain of up to 20 strings. While it's probably not as critical if there were any twisting (the frets are adjustable) I would still think that if there were any neck twists that the some of strings wouldn't evenly terminate at the bridge and nut.

[curtisa]

Back on the testing topic, and something I brought up in the opening post. Would a speaker cone bolted to the body of my guitar provide a good amount of energy to stimulate strings, if I were to feed a constant audio signal or sine wave tuned to the precise frequency I'm testing for? If that works, I could jack in and actually measure the output of isolated strings that resonate, and find the absolute best combination. I had thought that simply sitting the guitar on a speaker box would do, but I didn't get much stimulationm from either an electric or acoustic (likely a poor physical connectivity point)

I would imagine it would work. Another alternative is to fix the speaker to the headstock, similar to as was done using the Sustainiac Model C. You may find however that there is a lot of acoustic coupling between the speaker and pickups, masking any sound made by the resonating strings.

And on the subject of truss rods, there are instances of builds that defy what I believe to be it's purpose. I asked an innovative CBG maker if his neck has twisted or buckled in the three years since his build, and he claims it hasn't. Same too with a woman who built a CBG bass. And of course the sitar has no truss rod, and is under the strain of up to 20 strings. While it's probably not as critical if there were any twisting (the frets are adjustable) I would still think that if there were any neck twists that the some of strings wouldn't evenly terminate at the bridge and nut.

I'll admit I'm out of my depth here regarding Sitar construction. Maybe the strings are light enough to be tuned with low tension? Maybe the neck is overly-thick to compensate for the extra tension?

[KarmaShaman]

Curtis, I just noticed that you're in Oz. I'm also in Australia. Are there many others on this forum that you know of?

The headstock may be an appropriate place - after all, there are clip on guitar tuners intended to pickup on the vibrations at that part of the body. Although I would probably need a flush speaker cone, and may not be able to scavange one that size (although I have some old bookshelf speakers that may have a good sized mid in the sealed box).

I would think that the sitar strings have a lot of tension, at least on the internal strings, to get that much droning going on. The necks are gigantic though, so that probably compensates for any twisting danger. If you look at the image below of the Great Mr. Ravi Shankar (seen here with some guy from a little-known English band in the '60's), a good majority of Shankar's palm is scross the neck face, and still doesn't reach the top.

One thing that comes to mind as I write, is that there are also many, many stories of broken sitars - it seems more westerners who own them have a broken one, usually the gourd cracking - so perhaps that tension without truss support isn't working out so well after all.

[curtisa]

Curtis, I just noticed that you're in Oz. I'm also in Australia. Are there many others on this forum that you know of?

A few. Demonx would be the most active one at the moment. Not sure this project would be up his alley though.

The headstock may be an appropriate place - after all, there are clip on guitar tuners intended to pickup on the vibrations at that part of the body. Although I would probably need a flush speaker cone, and may not be able to scavange one that size (although I have some old bookshelf speakers that may have a good sized mid in the sealed box).

Probably don't need to spend a fortune on a speaker for the task. You're after something that can rattle some strings, not something that is reknown for it's Hi Fi reproduction of Beethoven's Fifth Look for cheap or broken stereos, tape decks, clock radios...there's bound to be something out there for low or no cost to experiment with.

I would think that the sitar strings have a lot of tension, at least on the internal strings, to get that much droning going on. The necks are gigantic though, so that probably compensates for any twisting danger. If you look at the image below of the Great Mr. Ravi Shankar (seen here with some guy from a little-known English band in the '60's), a good majority of Shankar's palm is scross the neck face, and still doesn't reach the top.

Watching some Youtue vids last night of Sitar players I was actually under the impression that the plucked strings are fairly light guage. The bending of the notes appears to be effortless with quite wide intervals spanned with little sideways movement.

[Southpa]

Been suffering will allergies the past while. I remember waking up one morning and walking into the living room. Grabbed a Kleenex and blew my nose....HONNNNNNNNKKKKKK!!!!! The banjo (tuned to Open G) on the stand nearby started singing...sweet!

[Workingman]

You may want to look at harp guitars they were somewhat popular in the 19th Century, particulaly in Germany. Since they predate truss rods they could give you some ideas.