The bass bar

The bass bar

The relationship between the bridge and the bass bar is important in sound production. A well placed bar can significantly change the sound of an instrument. There are many advocates of fitting a bass bar onto the table with tension. The question is, how much? We see not avantage to fitting a bar with with tension and we belive that this practice can be detrimental to the instrument. Excessive tension invariably pulls the table arching out of its natural form becouse the mass of the bar will cause the table to conform to the bar arch, not vice versa. Repairman regulary see instruments with sunken arching near the ends of the bass bar. The outline of the bar is sometimes seen quite distincly on the varnish surface of the table becouse the bar was fitted with excessive tension. This is most evident on the tables which were hit treated. The baked wood was a corky consistency and is less able to withstand the pull on the bassbar than untreated spurce.

Funcion

The bass bar is fundamental for the proper funcioning of the front and has a major bearing on the tone of the instrument. It has to support the arching against the tension of the lower string. The bridge rocks about its axis when the violin is played, and the bass bar provide a spring on which the bass foot of the bridge can rebound. Thirdly the bas trasmits the vibration from the bridge across the area which is broken by the bass sounhole. The bar bass should interfere as less as possible with the movement of the plate. The spurs of the bass bar should mach the front closely in terms of its groth line, and should be well seasoned and resonant.

We recomend using split wood for the bass bar,

even if the front is made using sawn wood.

Preparing the bass bar

The lenght of the bass bar is found by measuring the lenght of the front and subtracting 80mm but is normally cut 80mm or so longer to aid the fitting. And the height before fitting soul mately 20mm. Splitt the bass bar from a suitable block, with the grow rings parallel to the side, and around 8mm wide initially. Plan one side of the bar bass flat, removing wood evenly, and then plane the other side parallel down to the filan thickness. If the arching is relatively low, or hte front is of wide grained wood, the thickness of the bar should be 6mm, otherwise the thickness can be reduced to 5.5mm.

Position of the bass bar

The position of the bass bar in relation to the bridge foot is important for a good sound production, and is reflected to the soundpost position. The bass bar is inclined in relation of the centerline and the widest part of the upper botton by seven, and mark a point to this distance from the centerline. Repeat at the widest point of the lower bouts and make an other mark. This establishes the angle of the bass bar and not its position, which can found by moving the bar parallel to the two marks until the outer edge aligns with the mark made at the bridge position. When the bar is positioned in this way, mark the position of the ends.

Fitting the bass bar

The bass bar now need to be accuratelly fitted to the inner curve of the front, with its sides at the rigts angles to the plane of the flat underside, parallel to the ribs and not at right angles to the arching.