In this episode, we focus on fitting the bass bar. This is a vital part of every instrument. The bass bar has two jobs, it holds up and supports one side of the front (with the soundpost holding up the other side), and it also decides the bass response of the instrument. If the bass bar is too hard or soft for the instrument in question, is fitted in the wrong place or left too thick or thin, it affects the strength and sound.
The first job is to sight the bass bar location. This location is decided by where the bridge is to go and how wide it is. This is a large double bass, so we are putting a 165mm bridge and will fit the bass bar accordingly. This means it is located 10cm in from the top and bottom blocks, and 4cm in from the centre joint at the top and 6cm in at the bottom. This can vary slightly depending on the size and location of soundholes, but that is pretty standard for us, fitting to a full-size double bass.
Dan and George discuss the location, and after that, George picks out the most suitable bar to compliment the front. It is a strong and vibrant front that is not too thick. As it is going to be a five-string double bass, the decision is made to put a hard bass bar in but not shape it too high. This will help give a strong bass response and mean that the fifth string has some real power to it.
We make the bass bars around 22mm thick, but this can vary slightly depending on the instrument in question. After we have planed up the bass bar to the correct size, we begin fitting it. We use chalk for this and tend to it by eye. You will see that there are some horizontal cleats on the front covering up some old cracks; this adds a layer of complication to fitting but is no problem to do.
We use a small metal wheel to mirror the shape of the front and draw with a pencil onto the bar. We then cut this out on the bandsaw and begin fitting it by shaping it with a plane. We keep putting it onto the front of the bass to see how it is fitting and plane down the bits that have contact to allow the bits that do not have contact to start to fit. This is repeated until the bass bar fits well.
Once we are happy with the fit, we glue it with hide glue and clamp it in place. This is a complex procedure to get right with all the variables, but our experience allows us to make the right decisions to get the best out of each instrument.
Music: Isabella Stewart Gardner Museum, Boston - www.gardnermuseum.org
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22 авг 2024
