Double Bass Hachez's neck and tail blocks

[Don Harris]

I was at Robertson's a while back checking out Dan Hachez's gold medal bass and noticed that the blocks were very sleek and streamlined to create a smooth inside outline. Seemed like a good idea to me, having studied room acoustics a bit and knowing that corners can do weird things acoustically. So I'm getting ready to cut out my mold and was wanting to try that approach but wanted to get some input first to make sure it wasn't a bad idea. In the pics I have sketched what I remember of the streamlined blocks, there are also lines drawn for the traditional blocks as well as lines indicating the framework of the mold. To me the upside is a nice smooth inside line, the possible down sides are that the blocks get thin on the edges making them possibly prone to crack at some point, and it disables about an inch of the ribs from vibrating (compared to traditional blocks) on each side of the block. However, Traeger mentions that Italian blocks were comparatively wider and that this contributes to the characteristic darkness of Italian basses. Is this accepted as true? By the way, this is from Peter Chandler's Pallotta plans. Traeger also suggests that Italian linings were thinner and narrower, also emphasising lower frequencies, making them dark sounding.

 

[Jake deVilliers]

Looks good Don.

I wouldnt worry so much about the bigger blocks stopping the ribs from vibrating but rather the top and back.

The builder I studied with was really adamant about taking care of the vibrations travelling inside the wood ie rounded corners allowed them to flow whereas 90 degree corners caused the reflected waves to cancel each other out.

Looking inside great-sounding violins and classical guitars seems to bear this out. They are all very smooth in the transitions.

And why stop there - there's no reason you can't round off the corner blocks as well.

 

[arnoldschnitzer]

Traeger mentions that Italian blocks were comparatively wider and that this contributes to the characteristic darkness of Italian basses. Traeger also suggests that Italian linings were thinner and narrower, also emphasising lower frequencies, making them dark sounding.

Isn't that a contradiction? Wider blocks equals less rib vibration. Smaller linings equals more rib vibration. And isn't it a little strange to lump all the makers of one nationality together? Italian basses vary significantly in terms of blocks and linings. And no one has done any testing of smooth vs. square blocks, or narrow vs. wide linings, and their effect on sound. How could you? I am also of the belief that a smoother interior is good for tone, but I have no proof--just a gut instinct. BTW, I hope you plan to install the blocks square and carve them later. Otherwise you will have great difficulty with your clamp-ups.

 

[Don Harris]

Definitely going to install the blocks square. Just thought that the sketch would be the best way to illustrate the question.

Arnold, you're right. Seems like a contradiction, although Traeger says that the wider block limits side to side vibration of the neck creating a less complex harmonic structure with more fundamental. I'm not sure I'm buying that theory, but at least in his mind there are different mechanics involved.