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catnip

#3 finally completed!

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I am pleased with the light golden brown satin finish and I amnow trying to adjust the sound.

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It is much louder than #1 and #2 but the sound is not as focused as I would like. I am hearing some other resonances on each note and also some surface string noise. There was a previous thread about core sound versus a resonance sound which I found helpful. A heavy bow seems to help focus the notes. Any simple setup suggestions... i.e softer strings, heavier bridge ?

Here are some FFT's done with Audacity. The first 4 are bowed notes and the last one is hammered on the bridge.

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Is there some way to bow the strings with a constant speed, pressure, distance from the mic, etc. so that one could use these graphs to compare cross-string evenness? I'm interested in these graphs and what sort of flaws one might find in them and how one could attempt to correct those flaws.

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Looks nice Catnip. I just finished my 3rd as well. It is addicting. I don't have any experience on analyzing sound spectrum graphs, but I made some up of my last to compare with yours. The lower peaks are pretty much at the same numbers, but mine doesn't max out until 864. Maybe mine is too stiff?

The 2nd thru 10th harmonics are higher than the first on my G string. And the 2nd 3rd 5th and 7th harmonics are higher than the first on my D string. Maybe that is just the way the Dominant strings sound? So maybe strings have a lot to do with the sound. That is a profound statement isn't it? Are some strings known to have more of a core sound? Your strings have a strong fundamental, so it doesn't seem like that is the problem. Making might be the easy part.

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What did you hammer on the bridge with? The hammered spectrum appears to drop off steeply at the high frequencies, more so than the bowed notes. Could be due to a too-heavy "hammer"?

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What did you hammer on the bridge with? The hammered spectrum appears to drop off steeply at the high frequencies, more so than the bowed notes. Could be due to a too-heavy "hammer"?

Don,

I enjoyed reading your article in SCAVM on acoustical analysis. I am not sure how to do a proper "hammer" test and I am not sure what I am measuring but here is a picture of my wooden hammer with a cork face with the violin so that you can see is relative size. I just pull it back about a couple of inches and let it go. I am not sure how much of the impulse wave to select for analysis so I zoom in and select just past the initial impact.

Tim,

Thanks, I really do not have a hi-res digital camera that can show enough of the details. I am still using my Sony Mavica FD73. FD stands for floppy disk. Yes, it can save about 25 pictures of 640 x 480 pixels to a floppy disk.

Jezuppe,

I used a very thin flexible scraper for most of the top and back. I only used very fine sandpaper wedges for the corners and little sandpaper "worms" for the outside edge of the channel.

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Well, OK then... that hammer (weight + cork) explains the drop-off at the high end. Here's my method, using a spruce hammer that weighs 0.5 gram (yes, half a gram).

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Smack the bridge several times and analyze the group of smacks. I mike it about 8" away, about vertical from the top at the bridge.

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I chose a spruce hammer to minimize concern when whacking the bridge on someone else's Strad. Less chance of denting. It seems hard enough to get decent high-frequency response; the ultra-light weight helps too. Haven't tried anything harder to compare results, tho.

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