Electric Strings - A Detailed Guide to Electric Violin Construction

My book is now available for ordering.   This book is an in depth, step by step guide from the design process through to the construction of the final finished instrument accompanied by a comprehensive set of photographs of every stage in the making process. The instrument that I am  making and documenting is my Griffin electric violin. The book has 256 pages and has over 145 photographs.

The 'book' is published on a CD in electronic format as an Adobe Acrobat PDF. You will then be able to read or print the book off-line from your computer.

Also on the CD will be:

• The Book in PDF format
• A copy of my web site  so you can explore the site off-line
• A Thumbnail gallery of all of the electric violin designs that I have found on the Internet
• A link to enable you to install Acrobat Reader on your machine if you do not already have it
• A link to enable you to access my web site on-line

By having all of my web site off-line and the Thumbnail gallery you will have access to all of my pages including all of my Newsletters and all of the images of all the electric bowed stringed instruments worldwide. The database list of makers and suppliers will also be there for you to refer to. This will provide you with a complete reference work when you come to designing your own instrument, ordering supplies and seeing how other people have made their instruments.

The cost of the CD is £32 which includes postage and packing.

To order the book (via credit card or UK cheque) click on the CD image on my Home page or on the image below. You will also see the complete table of contents for the book.

Do I need a pre-amp? What is Impedance Matching? Is there an Amp that is specifically for the electric Violin ?

You only need a pre-amp if you need one! By this I mean, if you do not have any problems then you don't need one. If however your sound comes over as thin and off-colour then maybe you do. The most common problems with electric violins is frequency response and impedance matching. Most amplifiers that you will use are designed for the guitar. They have been designed to handle the frequency response of the guitar, not the violin. So the tone controls on the amp may not do what you want and are not very helpful for the violin. To overcome this you can either buy an amplifier that has been designed to work with an electric violin, like the Zeta E-series amp or you could consider an EQ pedal. A 6 band graphic EQ pedal is a very useful box to have. It has 6 sliders to adjust specific frequency ranges to either boost them or cut them. You can therefore shape the sound you make to your own liking with far more control than by using just the amplifier's tone controls.  EQ pedals also have a pre-amp section inside them so you can boost the total output of the signal as well as shaping the individual frequencies. In addition they will often have an impedance matching circuit.

The rule for connecting any pickup to any amplifier or PA is that the socket of the amp must have a higher impedance than the sound source. Most electric violin pickups are piezo electric devices. These are by nature very high impedance devices and therefore the amp needs to have a high impedance socket. Typically a violin pickup has an impedance of 1M ohm or more. If your amp or PA has a socket that is marked 'High Impedance' or 'High Z' this usually means that it is expecting a high impedance microphone (which are around 500k). These inputs may not be high enough for a violin piezo pickup. To overcome this problem (if you have this problem) you need to have an impedance matching device or circuit to match the pickup to the amp. An EQ pedal usually has this type of circuit. So, an EQ pedal is a very useful box - it shapes your sound, boosts the signal and matches the circuit and they are cheap! Set the amp's controls to mid position and do all your sound shaping with the pedal.

The EQ pedal that I use is one of the cheapest, made by Rocktek. Boss and other effects pedal makers also supply them. Barcus Berry have a couple of pre-amp boxes and as I said earlier, Zeta have one of the only amps in the world that is specifically designed for the electric violin and therefore does not need any of these or have any of these problems.

The above discussion is gone into, in more detail in the book that I have authored, Electric Strings : So you want to Electrify your Violin?

DI Boxes can be very useful. The L.R. Baggs Para Acoustic DI box is superb for the electric violin. The specification is brilliant. Low, Mid and Treble controls with an additional Presence control and a Notch filter to help eliminate feedback which is stepped in G, D, A and B which is rather convenient. It has an Effect Loop output and an Invert switch, Runs on a 9volt battery (200+hours) or Phantom Power, has 1/4 inch output and XLR DI connection with a high current buffered output suitable for driving long cables without loss. It gives up to 7db of boost and very importantly takes pickups ups to 10 meg ohms. This means that ALL electric violin pickups are acceptable as well as any other electric instrument (mandolin, guitar etc). The box is small at 5.6" x 3.6" x 1.9" and weight 14.5 oz. With this box you can then easily connect to either an amplifier and a PA system knowing that your signal will be acceptable and controllable. If you are a professional player or an amateur who wants to take control of your sound and remove most of the common problems, then this box is well worth considering. But, as I have often said, 'If you don't have the problem, you don't need the solution'.

The above discussion is gone into, in more detail in the book that I have authored, Electric Strings : So you want to Electrify your Violin?

To anyone who has owned a violin for a while this seems an obvious question. But if you have just bought one, it is a very important basic question. So here goes.

If the electric violin is based on a good sounding acoustic and has a pickup fitted that does not interfere with the acoustic sound then you should stick to the strings that you are using. If the electric violin is a solid instrument or one which is not played acoustically then I would suggest that you fit all metal strings like like Jargar, Thomastic Spirocore, Thomastic Supeflexible etc. and they must have 'ball ends' if they are to go into a standard adjustable tailpiece. Being all metal they stay in tune longer and are not so susceptible to temperature changes like the mixed metal and nylon strings. An electric does not need super expensive strings to gain a better sound. They are transmitting vibrations to the transducer for their sound. (unless of course it is an acoustic that has been fitted with a pickup like an L.R. Baggs, in this case you can get some marginal sound changes by fitting different strings).

Before fitting the strings, slacken off the tailpiece string adjusters. Don't forget to do this when you are replacing any string. Also consider putting some peg paste onto the shanks of each peg if you have any concerns about the pegs slipping or being too tight.

Fit the string ball end into the tailpiece adjuster. Make sure it sits comfortably and true within the claw that holds it. If you have a Puch tailpiece you will also have to ensure that the string will sit in the string guide above the adjuster.

Pass the string up to it peg. Pass the string through the hole in the peg leaving about 1/2 inch visible on the other side. Turn the peg round until the string touches the piece of string just showing. Let the string turn over the end. This will flatten the end of the string to the peg shank and anchor it. Wind 3 turns, on the inner side of the peg (towards the center) and then cross over and you will probably put 2 turns on the outer side of the peg nearest the peg box wall. The string will now probably be just touching the peg box wall.

Tighten up the string and check that the string is still correctly seated in the adjuster and as you tighten up the slack that it is resting on the bridge in its correct groove.

Repeat this for all the strings.

If you do not have one, I suggest you get either a cheap blow by mouth tuner or an electronic one. It will ensure you get the strings up to the correct pitch. Bring each string up to pitch and then CHECK that the bridge is a) still in its correct position (195 mm down from the top curve of the body) and also b) the back face of the bridge is at right angles to the top of the body. As you tune the strings it will try and pull the top over and then make the bridge lean forward. It must not, otherwise it might collapse. The back side (nearest the tailpiece must be at right angles to the surface)

Here endeth your first lesson!

 I had a lady visit me with two violin cases. She said she wanted them tidied up and checked over. When I opened the cases each violin was wrapped in cloth and covered in bow hairs!. Nearly 50% of the hairs were severed about 2 inches away from the bow frog. This was a serious case of Bow Bugs! in fact it was a Violin Case of Bow Bugs!! The bug (and it may only be just one) has the formal name of Anthrenus Museorum or 'museum beetle'. The bug is actually a larva of this insect with a length of 2-3mm. This larva eats the hair. They live on nothing but keratin, the protein material which makes up animal hairs. They do not drink and do not need very much oxygen. In museums they are a scourge as they can eat an entire butterfly collection leaving just the pins or devastate any stuffed animals. Although the larva prefers the dark and hair to eat, the adult insect prefers light and pollen.

This is all very interesting but what should you do if you find that your bow hairs have been 'mysteriously' broken, in a case you perhaps have not opened for some months? Take the case outside with the bows (leave the violin in-doors) and brush out the case well. Vacuum the case with a nozzle. Cut the bow hairs off the bow at the head and frog end and either burn them or put them in the dustbin. Leave the case, open in sunlight or under bright light. Spray the inside of the case with some insecticide or pet flee spray or leave a small piece of insecticide strip in side. The pesky critters should then be sorted out.

Bowed stringed instruments and MIDI are difficult to get working correctly and that is why there are so few makers of MIDI equipment for violin etc. To my knowledge only ZETA have managed to solve the problem. But why is this difficult?

Midi is controlled by an electronic switch. Extend your finger, press a key on a keyboard and you hear that note, only that note and no other note. The key you pressed is a switch that tells the circuitry to generate a specific frequency and send it to the output circuit. Keyboards can do this very easily as they have switches (the keys) that look and feel just like a piano. Guitars can do it because the string (a piece of metal) touches the fret (another piece of metal) and a circuit is made that tells the circuit to generate the required frequency. But bowed stringed instruments are difficult for several reasons. 

You could perhaps make one, like a guitar, as a  fretted violin with lots of wires under the fingerboard but that would make the instrument heavy and would sound like a piano as you slid a finger up the fingerboard. You could use an analogue to Midi converter which takes 'standard' sound and attempts to decide which frequencies you are playing and then electronically cause switches to close to make the desired sound. This has been tried but usually falls down because of the instrument itself. The violin need a lot more circuitry/software and intelligence to translate all the violin effects into MIDI (decrescendo/crescendo, marcato, martele, spiccato, detache, glissando, etc. etc. The sound is rather 'eunuched' without these dynamics). The Zeta equipment is based on a commercially available analogue to digital converter but Zeta add additional hardware and software to support the unique sound and parameters of the bowed stringed instrument. The violin and other bowed stringed instruments are very vibrant. The colour of the string sound is more than just a single note. When you play a note the nature of the instrument is to cause harmonics to sound. How you play a note (the bowing) also varies enormously. If you play a G note on the D string then you will hear the G on the D, the open G on the G string, perhaps a G on the E string and depending on the quality of the instrument you will hear other tonal values that will vibrate in sympathy to the original note being played. This is great and what the violin is all about. This is also the main problem. When you play that note, that G on the D string what do you want the Midi device to play? It will play the note you fingered OK but when the other notes and harmonics come in, sound and fade away you don't want them hitting the loud speaker at the same volume and attack as the main note. But the poor old MIDI device doesn't know this. It has a volume setting for the note you are playing and will trigger these other notes sometimes successfully but more often than not very unsuccessfully and usually very badly. This is called false triggering. Other notes will pop out of the speaker and it might even be difficult for you to understand the relationship of the note being sounded to the original note.

So these are some of the problems that have to be overcome. I know of only the Zeta equipment and can tell you how they have overcome these problems. (If there are any other Violin specific MIDI makers, please let me know)

The Zeta Midi system relies on several parts to produce a brilliant MIDI sound. The Zeta Jazz pickups are the most powerful on the planet. They have 2 transducers per string and together with the circuitry, remove all bowing noise, that background hiss and clonks that many other pickups transmit. This removes a lot of false triggering from the MIDI system. Then the onboard circuit has separate preamps, one per string. Each has tone filters that stop that string sending any redundant information. Each string can only generate the primary sounds of the string. Some harmonics can get through but only from the primary string. No cross over sounds come through. The violin and it's on board circuit is then connected to their MIDI controller. If you do not use MIDI and have one of their instruments, the standard 1/4 inch output is clean, powerful and distinctive because of the circuitry described above.

Their MIDI controller is essential. You cannot use some other makers midi controller or converter. With their Synthony II controller which has a built-in sound module you can control what happens to the sound you are making. Each string could be a different instrument, each note could be a different piece of kit from a drum set or more usually all the strings are set to a single sound type, harmonica, flute, oboe, trumpet, grand piano, rock guitar, sitar etc. etc. You can program many different effects with all the usual midi and guitar based sounds. You can program different sounds and store them as parts of a 'song' and  store many different 'songs'. You can mix the standard output with the midi output and do so many things that would take too long to describe here. (You can download the instruction manual from the Zeta site if you want the full specification). Playing a MIDI violin takes a few moments to get used to. Classically trained players seem to get to grips with it very quickly. This is because they play very positively. There is no doubt about what note they are playing as their bowing movements are positive and even. Like many things you have to give some commitment to the task. Just like playing a 5 string for the first time you need to keep at it to get the desired results. The Zeta midi controller also has a sensitivity setting which you can adjust. This allows the controller to match your playing style to the triggering of notes. Have the setting too high and it will miss-trigger, get it just right and play consistently and you will be fine. The Zeta Synthony II can also provide MIDI to their non Jazz pickups, the Strados and E series pickup instruments. 

Midi however is a solution looking for a problem. If you don't have the problem then you don't need the solution. You have to have a very clear idea of what you want to do and why you want to do to go down this route. If you do and you have the need it is superb and opens up a lot of possibilities.

I hope this explains a bit about MIDI for you.

Whatever amplifier you use it must match the pickup that you are plugging into it. Every pickup will have a certain 'impedance' and the amplifier's circuitry must be able to handle this impedance correctly. Most if not all electric bowed stringed instruments use piezo electric transducers which have a very high impedance. (There are other types of pickups that do not use Piezo electrics but the majority do). The rule that needs to be followed is that whatever you plug into must have a higher impedance that the sending device. So as piezo electric pickups tend to be of the order of 1 to 1.5 Meg ohms impedance, the amplifier must be designed to handle this value. To find out the capability of your amplifier you may need to check the manual specification or contact the supplier. The specification you need to look for will look similar to the following:
Technical Data
Inputs:
    Ch1: Line: unbalanced., 2.2 MEG
    High/Low: -10 dbV
    Ch2: Line: unbalanced., 1MEG
    Mic: balanced., 600 Ohm

What happens if the impedance is too low? The sound you make will be thin, it may sound distorted, it may not be even across the strings. It could be better. It will still work as an amplifier but the sound will not be as good as it should be.
Many PA systems will have 2 inputs per channel, one marked low impedance and the other high impedance (sometimes called Low Z and High Z). Certainly you must use the high impedance input but is it high enough? PA systems are usually concerned with microphone sockets and microphones are not usually very high impedance devices so the high Z input may not be high enough for a transducer to work at it's best.

What can you do if your amplifier's impedance is incorrect? What you need is an 'impedance matching' device. There are units available for this purpose but as most effect pedals have such a circuit in them you may find that by plugging in your instrument into an effect pedal first before you go into the amplifier your problems are solved. In my view the best pedal to get is an EQ pedal as these have an impedance matching circuit within them. I wrote about EQ pedals in Newsletter #1 so if you are unsure about their usefulness read this article. Pre-amplifiers also will have the required circuitry to match impedance so using one of these will help as well.

Having got the impedance correct, what else should you look at or check out? Most amplifiers are guitar amplifiers and as such are designed to handle guitar frequencies and create guitar sounds. The guitar has a frequency range from 82 Hertz up to 698 Hertz whereas a violin has a range from 196 Hertz up to around 2093 Hertz.

Frequency ranges of the Guitar and bowed string instruments against a piano keyboard.
(Red is Guitar, Blue is Violin, Green is Viola, Yellow is Cello, Brown is Bass.
The yellow key on the keyboard is middle C)

The tone controls on the amplifier control these frequencies. But if the amplifier has low, middle and high tone controls, what frequencies are they controlling and how do they relate to the violin? Most of the controls will effect the lower end of the violin and do little for the higher end. This is why most violin/amplifier problems relate to controlling the brightness of the sound. A good EQ pedal can therefore be used to control the frequencies better to your liking. Guitar amplifiers will also be designed for the likes of guitarists ! They may have a 'thick' setting, 'overdrive', 'distortion' and the like. If this is what you need then great but if you do not want these settings then they are a pain and electric luggage you do not want to carry around and manage. If your amplifier (or effects pedal/unit) has an EQ section it is often best to turn it off or put it at a neutral setting and do all of your controls with the EQ pedal.

There are some amplifiers that are called 'acoustic amplifiers'. These often will have a very good EQ section and enable you to create a more natural sound. But nearly any amplifier with a good EQ pedal will do the same.

So where are we? An amplifier for an electric bowed stringed instrument using a piezo electric pickup must have:

a) The correct input impedance - 1.5 to 2Meg ohms
b) Have tone controls that can handle the frequencies of your instrument
c) Do not have unnecessary circuitry that you will not use

Other specifications for your amplifier must be down to personal choice. The power of the amplifier, whether it has line out and other output controls, whether it has any built-in effects (reverb is useful), the weight, size and colour are all down to you to choose what suits you best.

You can choose amplifiers that are designed for piezo pickups. Zeta make one called the AE-12
(http://www.zetamusic.com/products/display.asp?id=27). It has the following specifications:

"INPUT" SECTION

CHANNEL 1 HIGH	This is a "passive" instrument input.
CHANNEL 2 LOW	This is a "padded" input (10db) for use with instruments that have active electronics

"EQUALIZATION" SECTION

LOW	Equalization control that adjusts the amount of boost or cut in the low frequency range (100Hz).
MID 1	Equalization control that adjusts the amount of boost or cut in the low middle frequency range (600Hz).
MID 2	Equalization control that adjusts the amount of boost or cut in the high middle frequency range (2KHz).
HIGH	Equalization control that adjusts the amount of boost or cut in the high frequency range (6KHz).

These four controls are just perfect for piezo electric transducers and bowed stringed instruments and are rarely found on any other amplifier.
But there are other makers and many many different amplifiers out there. (Shipping costs for amplifiers, because they are heavy, can be high so you may have to look around in your own country for a suitable supplier).

Another very good amplifier is made by AER in Germany
(http://www.aer-amps.de/)  with the following input specifications:
Ch1: Line: unbalanced., 2.2 MEG   High/Low: -10 dbV
Ch2: Line: unbalanced., 1 MEG    Mic: balanced., 600 Ohm

Trace Elliot are well known for good acoustic guitar amplifiers but they are also suitable for bowed stringed instruments. (http://www.trace-elliot.com/acoustic/acoustic.html)
The Trace Elliot has an Input specification that includes:
Piezo/Lo-Level - Impedance 10Meg Ohms/Sensitivity 100mV to 8V peak to peak

The above discussion is gone into, in more detail in the book that I have authored, Electric Strings : So you want to Electrify your Violin?

I have been asked how people use effect pedals and the like. Well the straight answer is that everyone sets up their equipment differently and with probably very good reasons, so it is difficult to generalise. However as I have just spent the weekend with Ric Sanders setting up his instruments and equipment ready for Fairport Convention's UK tour, I thought I would tell you how he arranges things.

First of all we both dislike guitar sound processors for several reasons. If one part goes wrong everything in the box usually dies. They usually need some sort of programming and setup which can be good, but on stage is difficult. For example, if you have a delay set up to match the tempo of a tune and it is programmed in, then there is little you can do about it if the rest of the band play the tune faster or slower. My main reason for not recommending them is that they usually have more features than you would sensibly use. Individual pedals, bought individually meet specific needs and you can build a set that is best suited to you and your music.

So what has Ric got on his pedal boards. He has two boards. One he uses all the time and contains his basic requirements. The other board takes any extra pedals that he needs.

The  set he has on tour at the moment is as follows:

Violin===
===Volume Control===MXR pre-amp===MXR 10 band graphic EQ===...

===Boss Vibrato VB2===Boss Octaver===Boss Digital Delay DD5=== ...

===Boss Digital Reverb RV2===Trace Elliot amp

For this tour the violin he is using is one of my classical instruments that is fitted with an L.R. Baggs pickup. He has decided not to use a radio system on this tour as his need to jump around the stage whilst playing is reducing every year!! The violin  goes first to the volume pedal. This enables him to shut everything down in case he needs to re-string or re-tune on stage. The pedal he uses has an additional output that he connects to a tuner. This he powers by battery and not by an external power supply because mains frequencies sometimes cause it to falsely display G#. Using an internal battery avoids this occasional problem.

Then he connects to a pre-amp. He needs this to give his signal more power because everyone else in the band plays so loudly! (It is actually another EQ pedal with all the controls flat and the boost control pushed to max). This box isn't actually technically required but as it has been part of his basic setup for years we tend to leave it there.

After this he goes into a 10 band MXR graphic equaliser. This is an unusual box because of the ten frequency ranges that it covers (I don't think that MXR make them anymore). He trims out the 312, 625, 2K and 4k frequencies. (Piezo pickups often require 2 and 4K trimmed out).

This then goes into a Vibrato unit. He only occasionally uses this and usually when he plays harmonics as it adds more depth and a synth like sound.

The second board has the specific pedals that he uses for various numbers and can be as few as 1 or as many as 6. For this tour he has an Octaver which creates a very good 1 or 2 octave drop from what he is playing.

Then a Digital Delay pedal. This one has a side cable and tap footswitch. You tap in the tempo of the tune and the delay will repeat at that exact tempo. Brilliant - I always wondered what he was tap dancing on behind the stage monitors. Then finally he goes into a Digital Reverb unit which when used subtly can add a lot of presence and grandeur to a tune.

Each of these boxes is powered by it's own transformer, so each box connects to a rail of power sockets.

The effects line then goes into a Trace Elliot amplifier, which he uses as his on-stage monitor. The line out then goes off to the PA equipment.

Nothing very special but hopefully it has introduced you to a few ideas worth trying if you are currently having any problems or are setting up equipment for the first time. The secret with all effects is - use them selectively and sparingly. I have heard many bands who leave a set of effects on for every tune that they play which is not very clever!

The above discussion is gone into, in more detail in the book that I have authored, Electric Strings : So you want to Electrify your Violin?

This month I will tell you a true story. I had a call from a customer of mine. I had sold him an electric violin some 4 years ago and he said he was having a terrible time with it. It was 'sort of buzzing when he played pizzicato and sounded odd in 2nd position'! We discussed various things it could be but, no he said, he had tried all of those. So we booked a time for him to come over. When he arrived we plugged it in and guess what? No buzz, no hum, no problem!! So what was going on. Without all of his equipment available we had to make some guesses. I believe the most likely cause would be his earth. When was the last time you checked the plug on your amp, your PA, your pedal board? Probably never. But, at the end of every gig, you or a roadie pulls everything out and cables get tugged. Earth screws become loose, cable grips slacken off and the potential for buzzing and very dangerous performance becomes possible. 
When one, of any number of earth connections, in your setup becomes loose, apart from a potentially dangerous situation occurring, your cable can become an aerial and stop shielding the signal. Electric guitarist can sometimes point their axe in a particular direction and, with a bad earth, suddenly start picking up taxi calls, police or other signals. The string has become an aerial. This doesn't usually happen with violins but you may experience buzzes or hums. Badly earthed equipment will then allow the pickup wire to sense the mains frequency. If you put your hand near the pickup cable it may turn into a buzz (and perversely, sometimes it can make the hum go away). All sorts of things can happen.
So, when you have a few moments or better still, make some time, check out all of your plugs and their earth connections. Some of the more dodgy places you may play at may also have bad earths in the actual building. Plug your amp in, turn up the volume but don't plug anything in - Is the amp quiet or is there a background hum  present that isn't usually there? Not much you can do about this apart from trying out a different wall socket. The other thing to check is plug adaptors. If you have a 'Christmas tree' of plugs going into an 3 way adaptor you will run the risk of one of the plugs not seating correctly (or coming loose) and the buzz or hum returns. Make up or buy a connector block so that each plug goes into it's own socket.

If you don't put earth to earth you will end up ashes to ashes!

The above discussion is gone into, in more detail in the book that I have authored, Electric Strings : So you want to Electrify your Violin?

I recently purchased my first set of Sensicore Octave violin strings made by Super-Sensitive and fitted them to one of my violins. If you want to steal some of the viola/'cello sounds on your violin they are superb. A wonderful deep sound. Here are some notes to assist you if you intend to fit some to your violin.

First of all make sure you are fitting them to a good and sound violin. When replacing stings it is a good time to check over your instrument. Put peg paste onto the peg shanks, tidy up or tighten up the tailpiece tailon. Check for damage. Clean the fingerboard and remove the rosin dust, mould and sweat from the instrument and from under the fingerboard.
The string holes in your pegs may need to be enlarged to accept the larger diameter strings. I found that a 1.7mm drill was required to enlarge the original holes.
The top nut will need to have the string grooves enlarged to accept the thicker strings. The G string needs care as it is fairly large in diameter it will tend to be higher off the nut. Lower the slot carefully so that the string is still above the fingerboard. You will need a needle file to do this job.
The tailpiece adjuster claws may need to be opened up very slightly to accept the thicker G and D strings.
When you start to tune up, keep checking that the bridge remains vertical and also that it does not slip too much from side to side. When the strings are up to pitch check again the position and angle of the bridge.
The open E string on the Octave set is the same note as the E made by the first finger on the D string of your standard violin.
Finally, you will need perhaps a bit more rosin on your bow to get these thicker strings to respond well at first.

If you are in any doubt about doing this job yourself, please contact your local violin maker/repairer and discuss it with them.

These strings are available from SuperSensitive or one of their dealers.

Silent violins or Ears, Eyes and Wallet!
I am still getting enquiries about silent violin playing. the Yamaha Silent violin and related matters. It is not surprising when you consider the amount of advertising Yamaha have run for their electric stringed instruments or the fact that there seems to be one of their instruments in every (UK) music shop. So lets start with some facts.
If an electric violin does not have a sound box you will hear the innate sound from the strings. This volume is loud enough to hear, loud enough to practice but not loud enough for your neighbours to hear. The comparison best used is that it is like an electric guitar that has not been plugged in. Therefore, any solid bodied instrument by any maker is a silent electric violin. The Yamaha instruments then take this a stage further. Inside the instrument is a small amplifier and a reverb effect which you hear when you plug an earpiece socket into the instrument. Your neighbours will not hear this added volume or the reverb effect but you will through the earpiece. You can then adjust the sound so that it has much more depth and space (to your ears).
Several other makers have also followed this approach (Zeta included). And if you have an instrument that does not use this technique you too can 'join in' by getting an electric guitarists headphone amplifier and connecting it to your violin and any other effects you may have. So (in my mind) there is nothing special about the Yamaha Silent instruments, what is special is their advertising, marketing and bringing the electric violin into many music shops where before it would never have been seen.
When you buy such an instrument the shop salesman will tell you that you have a self contained electric violin which you can practice with, without disturbing the neighbours and an electric violin that you can plug into a standard amplifier and play on stage. What I am saying is that, you can do all of this with any solid bodied electric violin. You also have to consider if you are going to use the violin more on stage rather than at home. If you are, then consider carefully. You will probably not use the inbuilt reverb, you will more than likely use a much better outboard effect unit and probably several of them. Do you want your instrument to sound good in your ear (and no one else's ear) or do you want to sound good on stage and to everyone's ear?
Electric violin choices are down to 3 main considerations (assuming that the build quality, dimensions and playability are the same):
1. The Pickup sound
2. The Design
3. The Price
or Ears, Eyes and Wallet or more importantly, Your ears, Your eyes and Your wallet. Do not be too influenced by other peoples reviews, endorsements or advertising. Always consider what these peoples motives are. It's your choice.