Bass Xylophone - preliminary rough setup

Regarding this article: Marimbas: Exploring The Depths
www.percussionclinic.com/art_mbasa.htm

Great read and that confirmed and expanded on what I've been suspecting.

I'm working on a xylophone (probably my seventh or so) using a very hard wood, I'm pretty sure it is Santos Mahogany (Myroxylon balsamum) which has great sustain but seems to have a limited range. I tried grinding down one bar from E3 165 hz to G2 98 hz and it has an amazing sound when paired with a big barrel shaped resonator. I tried a couple different barrel shapes and it doesn't seem the exact size matters much. I also tried various diameter pipes up to 4 inch and those made no improvement in the volume. As you say, the width is key, and of course this is impractical as the instrument would require jogging left and right to play. I tried building a wide rectangular resonator maybe equivalent to the 4" diameter pipe and it was also useless. The barrels sound incredible though. I think the deal with this wood is it has a narrow range of usefulness but very pure timber with scant harmonics - just the pure root note. I ground them out on a belt sander with just a simple little 1" diameter groove in the center and it doesn't seem important with this wood to pay attention to the harmonics - it's just the pure root note and it sounds much more bassy than other woods. The bar in consideration is the same as the G note played on a guitar on the low E string (first dot on the top of the fretboard) but it sounds incredibly bassy on the barrel resonators. Without the resonator it's inaudible unless an inch or so from your ear (then it's awesome). It has the subjective sound of a stand up bass though it isn't actually very low, the purity of the low fundamentals is such that you feel it in your teeth as much as you hear it.

The solution suggests big gourd resonators, flopping out at angles to allow it all to fit in a reasonable spacing. Actually what I ended up with is a barrel resonator shared by the first three low keys (about 2' deep, 18" diameter) and two big rectangular concrete planters for the rest of the keys (about 12" wide, 3' long, 2' deep) with the drain hole plugged. 22 keys from F2 to D4. A4 through D4 are pretty weak - perhaps I could outfit them with smaller custom resonators. The big soft mallets aren't well suited to that range either (about 1-1/2" diameter super-balls).

The narrow useful range of this wood suggests perhaps using a sequence of different woods for each range of the spectrum.

This pdf has some amazing data on different woods for xylophones:
www.google.com/url?sa=t&rct=j&q=&esrc=s&s...
I've put their chart into a spreadsheet, added some and did a little sorting:
docs.google.com/spreadsheets/d/1pNnfFkN4TpD8KrAhlnk6_CUtb...

The Santos Mahogany sounded weak before tuning (grinding center notch) but improved within a narrow range sounding gorgeous.The mid-range responded well to resonator enhancement, the ones cut very thin sound very low only with huge barrel resonators.

Another wood I tried recently is Padauk - which was really loud pre-grinding - but ridiculously high pitched - then when ground down was quieter but still quite sweet sounding and with delicious long sustain. The mahogany with the barrel resonators also has a great sustain. The Padauk has a much higher and more rich timbre, where the mahogany is ridiculously bassy and pure sounding. I've experimented with many different woods

I finished the mahogany keys today and went through to fine tune them but by the time I finished, the weather had changed and it was out of tune again. A week later: this thing is really fussy to get tuned and sounds bad when it's out of tune. I'm not much of a musician, having more interest in experimenting and exploring so I've been doing a pretty basic boogie-woogie and it just doesn't sound in tune no matter how hard I try refining the tuning. The first boogie-woogie round in low G is OK but when I step up to B, it just sounds off. When I damp the fundamental and strike the second node, I don't hear much to worry about, especially with my big squishy super ball mallets and the oversized resonators, so maybe it is the third harmonic, I think I read that has it's node in the same center point as the fundamental but is transverse? Anyways, that's going to be hard to tune, maybe a stroboscope could help? I'm using a basic free tuning app on my phone and it can be hard to get a good reading. For one thing, it must be done on the resonator, hand held you get a little different note. Sometimes it shows some other wild note that flashes by too fast to read and striking harder or repeatedly eventually I'll be able to see the fundamental. Then, the frequency changes from initial attack, as it fades out. I'm not sure which to tune for. I can see it move as the note plays out.

the way I've mounted these bars is narrow neoprene strips with adhesive tape, intended for weather stripping. This allows sticking them on the bottom of each bar exactly where the salt test shows - even when it's at an angle.then I apply half thick strips on the resonator to match and prevent slipping sideways. The bars are pretty heavy so don't bounce out too easily. I don't have decent pictures yet but will post them here: www.flickr.com/photos/edgehill/albums/72157661781404580

Taken on: December 5, 2015

Sets appears in: • Xylophones • projects

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