showing posts tagged "bow-response"
15 Apr 2019
tags:  acoustic  electric  bow-response  bridge  soundpost  construction  feedback  

What is Different about the Sycorax

I originally wrote this as a guide for what I would say in an explainer video. However the video isn't going to happen any time soon, so I'm posting it here.

There is considerable overlap with my earlier posts , but sometimes it is good to explain the same thing in different ways.

This post is to explain the Sycorax electric violin and how it relates to conventional acoustic and electric violins.

The Acoustic Violin (really, just the Violin)

An acoustic violin is a fairly simple machine that behaves in a very complex way. I will explain the simple part and gloss over the complexities.

The violin family has a distinct mechanical action and construction that is different from plucked string instruments and also from bowed strings from other cultures.

An acoustic violin has 7 parts involved in making the sound that I will explain briefly.

The string, the bridge, soundpost, bassbar, and the top, back, and internal air.

The string vibrates with a side to side motion as it is bowed side to side:

This moves the top of the bridge side to side.

The bridge sits on the top, which is a lightweight and somewhat mobile piece of thin wood , usually spruce. The top is supported under the treble side of the bridge with the soundpost, which is a 6mm diameter spruce dowel, which extends to the back. The back is made of a stiffer harder heavier wood, usually maple, and is a bit mobile but much less so than the top.

The effect of this is that at the fundamental frequency of the string the treble side of the bridge is held relatively still.

This turns the bridge into a lever with the fulcrum under the treble side, sideways vibration is applied to the top and so the bass side of the bridge is levered up and down. That is what we want as it drives the top in and out which is an effective way to transmit sound to the air.

Glued under the top under the bass side of the bridge is a piece of wood that runs lengthways along the violin, called the bass bar. This helps support the pressure of the bridge on the top and also transmits vibration to the ends of the top further from the bridge.

The main thing to understand about this right now is that the bridge and the parts it is connected to are quite mobile in a complex way with many overlapping resonances.

The top and back have multiple resonances and combine with the internal air resonance to shape the final tone.

What we actually hear in the air is a mixture of the sound emitted from the top, and the internal air resonance through the f-holes with small contributions from the back of the instrument and directly from the strings and bridge.

It sounds quite different depending on where you listen from. Most of the sound is projected out the front, but it is not even.

When amplifying an acoustic violin the only way to get all of that sound is with a microphone in the air, and even then you only get one angle per mic.

Using mics for loud amplification isn't usually very practical because of feedback, ergonomics, and other more subtle reasons.

So amplified acoustic violins often use a contact pickup of some sort that senses the vibration of one part of the instrument. These are often in the bridge, but that doesn't give a very good impression of the overall sound, since it picks up very little from the top and even less from the back.

If you have to choose a single point to sense the vibration of the whole instrument that gives a reasonably balanced summary of the acoustic sound then the soundpost is the best place.

I make a pickup system that uses a soundpost mounted pickup for acoustic violins, and as you will see soon , I use much the same system in my electric violins.

A Typical Electric Violin

A typical electric violin has strings and a bridge much the same as an acoustic. However the bridge is mounted on a rigid body. The feet of the bridge can't move much, or at all.

So the movement at the top of the bridge where the string is driving it, is limited to the flexibility in the bridge itself.

The bridge is small and made of stiff material , traditionally maple, and the flexibility it has is really only relevant at frequencies well above the fundamental frequency of the note.

A regular electric violin has no mobile top or back and no soundpost or bass bar and no lever action converting the side to side movement of the top into an up and down movement of the bass side foot. The bridge just rocks side to side , bending a tiny bit at the waist with its feet held still.

Because the body is rigid and can't move much it doesn't transmit sound to the air as it isn't moving.

Almost all electric violins use a pickup mounted in the bridge or directly under it. There really isn't any other viable option on this sort of instrument since the rest of the instrument isn't vibrating enough to be useful.

There are two main problems with this approach - one is that the sound directly from the bridge, with no additional resonances or complexifying factors, is thin and one dimensional with the characteristic mosquito-like tone of electric violins.

The other problem is the feel - this has two aspects - one is that the rigid bridge feels stiff and unresponsive to make the note speak, and the other is that once the string is moving the rigid bridge reflects more energy back into the string, so the string continues trying to vibrate by itself and it is harder to keep control of it with the bow. This is why electric violins don't just sound different to acoustics but also feel very different under the bow.

The Sycorax Electric Violin

The Sycorax violin is a complete re-imagining of what an electric violin should be like, starting from the mechanical action described at the start that makes a violin a violin.

It has a top, back, and soundpost a lot like an acoustic and this creates the same lever action in the bridge and top as an acoustic.

This means that the motion of the bridge is similar to an acoustic and the sycorax feels flexible and responsive to play rather than stiff and hard to control like a rigid bodied instrument.

Also , the pickup in the sycorax is in the soundpost, rather than in the bridge so it can sense the more complex and gracious tone that exists at that point.

The sycorax is also different from an acoustic in a few important ways.

The differences are to do with how the instrument interacts with the air. On an acoustic the whole purpose is to make the air vibrate with the vibration of the instrument. So there is a relatively large soundboard which moves air and a body of enclosed air which resonates at a low frequency and helps move air at lower pitch.

On a regular electric the air doesn’t get moved much because the instrument itself isn’t moving much , it is built too rigidly to move.

That doesn’t result in the tone I want, so the Sycorax moves like an acoustic, but we don’t want it moving air – and that is why the top and back are small and full of holes – to minimise the connection to the surrounding air.

The sides also have holes partly for this reason, even though they don’t vibrate as much as the top and back.

There is no enclosed airspace like on an acoustic, this is partly because the Sycorax doesn’t need the bass boost of that resonance because of the sound being picked up in the soundpost, and of course also because it would create movement in the surrounding air which we don’t want.

Even more important than making the violin quiet when it isn’t plugged in , is making sure that movement in the surrounding air doesn’t move the violin. On a loud stage an acoustic violin vibrates with all the surrounding sound, not just with it’s own sound, this then gets picked up by the pickup and amplified, which causes feedback. The Sycorax avoids this by interacting with the air as little as possible in either direction.

The Sycorax has a bass bar supporting the top under the bass side of the bridge in a similar way to an acoustic, however this bass bar is a very different design and has a partly different purpose. The bass bar supports the bass side of the bridge in a flexible way allowing it to move, but it’s complex design helps ensure that it doesn’t resonate too much at any one note since if a single resonance dominates we get a wolf note.

07 Apr 2019
tags:  four-string  bow-response  bridge  construction  

What about a 4 string version?

For the last 10 years I have worked primarily with 5 string violins. They now seem entirely normal to me, and I find looking at or playing a 4 string quite odd.

For many or most purposes I think a 5 string is a great option. The extra range is versatile, the low notes are exciting, and there's little reason to do anything else.

However in testing with a fast scottish fiddler I was recently forced to confront the issue that a five string may not entirely replace a four string under all circumstances.

A 5 string has extra pressure on the bridge meaning extra pressure on the top. It also requires a wider, heavier, and generally stronger bridge.

The upshot of that is that it takes more energy to get the violin moving because there is more weight and tension to overcome. Even though a five string bridge and top may be in a sense just as mobile as a four it is mobile at a higher energy level.

This effectively means that the 5 string, all else being equal, will be less quickly responsive at low energy input level. In other words when playing quietly, or (and this is the important bit) when playing the top strings fast and lightly, since they have less mass to drive the bridge and top.

So the response on the E string of a five string violin is slower than on a four. Many players like this as it smooths out the tone and helps avoid a raucous or shrill E string. However if you play fast reels, or Paganini, or anything else fast, high, and showy - you may find that you miss some lightness , sprightliness, or speed of response.

All this applies on an acoustic violin, and also on the Sycorax. On a regular rigid-body electric violin it is less relevant since the body doesn't respond much whatever you do at any speed. The sluggishness and deadness of tone of rigid body electrics is one of the main things I'm trying to overcome with the Sycorax, so it makes sense to pursue this to the limits of speed and light response with a four string.

If you play with a lot of bow pressure or a lot of effects this is unlikely to bother you. Metal players play high and fast, but I'm not sure if they will want 4 strings as a result or not since they are also likely to be playing harder and to want the extended range at the low end. But I can see how some classical or traditional folk players might value the lightest possible response over the extra range.

So this is a longwinded way of saying - the Sycorax violin will be available in a 4 string version eventually.

I plan to wait a few months before doing this, but it will happen.

If you are a player who wants a 4 string version get in touch - I will do it sooner if there is a specific customer who wants one!

18 Mar 2019
tags:  bowed  plucked  distortion  bow-response  theory  

A Violin is not a Guitar

An Electric Violin is not a Funny Shaped Electric Guitar

Am I stating the obvious? Apparently not since most electric violins are built and used a lot like an electric guitar.

What's the difference?

Bowed vs Plucked.

We all know the difference between bowed and plucked. But surprisingly few people have thought through the difference in instrument design that stems from this initial difference.

This is really simplified, but I'm going somewhere with it so bear with me.

A plucked string gets energy imparted to it once per note at the start. It starts off with a sideways movement in the direction of the pluck but quickly settles to a more circular movement as it dies away. How quickly it dies away depends on the mobility of the bridge and soundboard to which it is attached. The less mobile the bridge is, the more sustain but the less volume, as the vibration is reflected back into the string. The more mobile it is, the louder but less sustain as the energy is sucked faster into the body and soundboard. It's a direct tradeoff - this is why a banjo is loud with little sustain - it has a highly mobile bridge because it is mounted on a skin. It is also why electric guitars have more sustain than acoustic guitars - the bridge is mounted rigidly on several kilos of solid wood! Electrics overcome the lack of volume with an amp (obviously). You can make an electric guitar with less sustain by making a more mobile bridge, but since the sustain is musically useful in many situations most electric guitars don't do that.

A bowed string has energy imparted continuously. There is no tradeoff between sustain and volume because the sustain is created by adding more energy rather than by trying to conserve the energy already in the string. In fact making a bowed instrument with a less mobile bridge creating more sustain actually makes it harder to play and control because the energy reflected back into the string causes the string to want to keep resonating by itself, rather than being controlled by the bow.

To complicate matters the stiffness of the bridge will vary with pitch. Most existing electric violins that use a bridge based on a acoustic bridge will have a somewhat mobile bridge at high frequencies since most of the mobility at those frequencies is in the bridge itself - however the bridge is still very stiff at the fundamental frequency of the string(s) since it is attached to a rigid body, and most of the mobility on an acoustic at fundamental frequencies is in the belly, bassbar and air resonance of the instrument, none of which exist on a typical electric violin.

Since it is mostly the fundamental frequency of the note that determines the bow feel on the string the mobility at high frequencies doesn't help much.

The Violorama violin has the exact same action of top, soundpost and bass bar as an acoustic - the only thing missing is the air resonance - if it had that it would BE an acoustic which would defeat the purpose - however the air resonance is substituted for by the resonance of the bass bar assembly which is much more complex than an acoustic bass bar.

Another important difference between plucked and bowed instruments is the direction of the vibration in the string. A plucked instrument sustain quickly settles to an approximately symmetrical movement that moves about the same amount either side of the resting point.

On a bowed string the vibration is offset to one side, because the bow is dragging the string to one side. Furthermore, the direction of the offset changes every time the player changes bow direction. This has consequences for pickups and amplification since the electronics must accommodate the maximum movement to each side even though that is larger than half the maximum peak to trough displacement of the waveform - so we need electronics with greater headroom if we want to ever have a clean sound.

A related issue is that the raw waveform of the string is very different on a bowed string. A plucked string has an initial burst of complexity and harmonics and then settles to a fairly simple tone with fewer harmonics at a lower level. A bowed string is constantly being pushed out of its natural resonance and the waveform has a very different shape, at root rather like a sawtooth wave as the string is dragged sideways by the bow then snaps back suddenly, then does it again. This wave is also fairly simple when considered as a wave - but contains a much higher proportion of harmonics than a guitar wave. Using this bright waveform picked up directly off the bridge as most electric violins do is part of what creates the characteristic mosquito-like tone of many electric violins.

However, even if the wave is allowed to develop into a warmer version of itself though the mobility and resonances and frequency dependent damping of the instrument then the fundamental difference in the harmonic content of the sound needs to be considered at every stage, from designing the preamp through to choosing effects and amps.

Because a bowed string is primarily moving from side to side the violin family has evolved a lever action to convert this to the in-an-out movement of the top that is best for transmitting sound to the air. On an electric we no longer care about transmitting sound to the air - in fact we are trying to prevent it. However the lever action is so essential to the natural movement of a violin that keeping it is necessary to make the electric feel and sound like a violin. Keeping this element of acoustic design in an electric violin also affords us many possibilities for influencing the tone of the instrument, and some locations to have pickups where they can sense a more gracious tone than that directly from the bridge.

Effects in Context

The signature sound of an electric guitar is overdrive / distortion. This is remarkably well suited to the electric guitar since it adds harmonic content to the relatively simple natural tone of the plucked string, and also increases sustain even further. You could even say that it improves the guitar by making it sound more like a violin! Of course that's only partly true, as distortion harmonics have a quite different spectrum profile to the natural violin harmonics.

When you take a violin with a sound that is already bright and harmonically full and add overdrive distortion you get harmonics on the harmonics of the original tone - the sound can quickly become over-complex and unmanageable. This might be useful depending on your style of music. Noise music and music where the primary parameter is texture will find it more useful than it is for music where harmony and melody are primary. It won't easily give you a euphonious melodic lead sound like an electric guitar though.

There's a few things you can do about this:

One is to filter the violin sound down to a simpler tone before adding distortion. Then you shift the tone from noisy overcomplexity to something more like an electric guitar lead tone. However it is difficult to filter the violin tone without also losing articulation and expression. This may or may not matter depending on the style. If you do this filtering with fixed EQ it will only work well in one register and have to be adjusted for a different register.

You can also split the signal and layer distorted tone with clean, or just use less distortion. Or any combination of the above.

The other approach is to abandon the distortion envy and concentrate on effects that work with the existing plentiful harmonics in the violin tone, rather than adding new ones. Wah, phasing, and many sorts of effects based on resonant filters seem very well suited to electric violin. They have so much more to work with than on electric guitar. (Unless the electric guitar has distortion applied first.)

Delay, reverb and other time-based effects are also more audible and effective if the tone they are applied to is clear and articulate - something that is hard to maintain with distortion on electric violin.