Which Timber for Marimba Bars #3 - (Discussions with Stuart Bishop)
-----Original Message----- From: Stuart Bishop Sent: Friday, 11 February 2005 8:45 AM To: firstname.lastname@example.org Subject: woods for MarimbaHi Jim,
Great web pages! Thanks for all you do to help others out.
1. Wood selection. I'm sure this subject has been beat to death, but I haven't found the answer I'm looking for yet. I'm getting ready to build a marimba for use with a church band, and trying to select the type of wood to use. Many sources simply mention Rosewood as the wood of choice, without naming the species. But there are lots of different Rosewoods.
In one of your discussions you mention Honduras
Rosewood as the wood of choice:
... Honduras rosewood is the material from which marimba and xylophone bars are traditionally made. (Platymiscium dimorphandrum) The tree which the Central Americans call "Hormigo" or "Hormiguillo" ...
You also mention Granadillo and African Padauk, but what about the other Rosewoods? In my experience, I think of the genus Dalbergia as being Rosewood.
I've seen mention of another Honduras Rosewood being
the preferred wood for marimba bars:
" ... Honduran rosewood is well known for its tonal properties being the preferred wood for Marimba bars."
Is this the same as the Hormigo you mention?
Also, there are other species of Rosewood. East Indian Rosewood, Dalbergia latifolia, is a more commonly available one. This is also one of the more affordable. Is this a good choice.
In short, if I can't find or afford the Hormigo you mention, should I choose another Rosewood, or go with Padauk?
2. How bar size relates to wood used. To achieve the same pitch, will the use of different woods require bars to be sized differently in a significant way? I'm sure that Padauk and Rosewood, have somewhat different properties that affect tone, such as stiffness, hardness, density, etc. But how much difference in bar size will result? within 5%? 10%? 50%?
3. How about bar length versus thickness. Can't the same pitch be achieved with different combinations of length and thickness? In the low notes, tuning the bars results in the ends being thicker than in the middle. Couldn't the bars be shortened in length, requiring the thickness at the ends to increase? This approach could yield shorter bars and make a more compact instrument. It seems one of the two variables, length, or thickness at the bar ends (assuming fixed thickness in the middle), has to be set (independent), and the other is determined from there (dependent).
If I want to vary my bar lengths linearly, I need to set the lengths of two bars. Two points makes a line. Can you give me some good choices for two bar lengths? To be clear about which two notes, can you either tell me the frequency of the fundamental, or where the note falls on the staff. If you want me to pick, how about middle C (260 Hz) and C (1040 Hz). But any two is fine.
Thanks for any help you can provide.
Get These Comprehensive Plans & Instructions with Video!
1. I'm not a real expert on timber - sounds like you know more about it than me. I'm pretty sure that Dalbergia is the correct genus for rosewoods yes, and I'm also pretty sure that many of these are starting to be used for marimba bars - in particular Dalbergia stevensoni is an old favorite. There are often some changes over the years to botanical classification, so I'm not 100% whether or not its the same tree as Platymiscium dimorphandrum, but I don't think it is. I think I remember (from reading long ago!) that the original "Honduras Rosewood" is not really a rosewood at all, so that would make sense. At any rate, its clear that there are many rosewoods (Dalbergia) that are performing well these days on instruments. That particular one commonly known as "Honduran" is supposed to be particularly good, but like most things, there is a certain amount of myth too. The marimba is really a Honduran instrument - thatís where its roots are - so tradition being what it is..... I have heard marimbas made from other rosewoods and they sound pretty comparable - perhaps SLIGHTLY inferior in the upper register. I couldn't tell you which rosewoods they were though - I suspect something Brazilian. At any rate it is in the upper register where you hear more bar sound and less resonator sound that it is really telling.
If you can get the Padauk I would - it is well known now. Adams make most of their student range, and some of their concert range from padauk - I have two marimbas from padauk and they sound pretty much identical to rosewood. I listened to the same model in rosewood side by side - the same. The only way in which padauk could be considered inferior is that it is not as dense. This means it suffers a little more in the upper register when people use harder mallets - also the smaller bars are lighter so they can sometimes bounce a little with hard playing - itís a matter of good frame / string construction to combat this.
2. I don't think you will even notice a difference between wood types - the ones that work are similar in properties anyway - there can be more variation in wood from different parts of the same tree. Its all the tuning.
3. You are right - you can vary both. It is really worth having a look and a play on some commercial instruments to see what you like. Musser etc have traditionally used shorter/thinner bars at the bottom end whereas Yamaha have used longer bars slightly thicker under the arch - this makes a stronger bar (because Keiko Abe is a VERY strong player) but I think not quite as nice sounding - a little dead. It also makes your instrument pretty wide at the low end - more movement required to get to sharps etc. The choice is yours - choose a length and work/tune from it.
4. 260hz = 367mm & 1040hz = 239mm on my instrument
Hope this helps..
answers by Jim MCCarthy - 02/03/2005
For more help on instrument building you can email Jim.