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Tuning Harmonics in Marimba bars (more questions from Alejandro Suarez)

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-----Original Message-----
From: ALEJANDRO SUAREZ
Sent: 13/02/08 12:38 AM
To: jim@percussionclinic.com
Subject: tuning harmonics
Hi Jim
Iīm Alejandro Suarez from Spain.
Your recommendations about the resonators they were very interesting in my last marimba.
I finish my second marimba project, and iīm really happy with my work. This instrument is a 4 1/3 marimba and it has a good sound in the middle and high register but not so good in the low registry (C3-A2) I always tuning my instruments with the harmonics in a 1:4:10 ratio and iīm very meticulous with the correct 4:10 ratio tuning But after read your article Marimbas - Exploring the Depths, I think thatīs possible that I am mistaken.

For example.

F 1štransversal mode C3 131,4 hz
4 2štransversal mode 2 octaves above the fundamental
10 3štransversal moode 3 octaves + major 3rd above the fundamental

Example:A

Tuner:

     0               0              0
  \  |  /         \  |  /        \  |  /
 \   |   /       \   |   /      \   |    /
\    |    /     \    |    /    \    |     /  
-------------  -------------  -------------
C3             C5             E6    

Itīs correc? or itīs better if I tuning like this.
Example:B

Tuner:

     0               0              0
  \  |  /         \    /         \    /
 \   |   /       \     / /      \       /
\    |    /     \     /   /    \       / / 
-------------  -------------  -------------
C3             C5             E6    

Or 

Example:C 

Tuner:


     0               0              0
  \  |  /         \     /        \     /
 \   |   /       \  \    /      \        /
\    |    /     \    \    /    \  \       /  
-------------  -------------  -------------
C3             C5             E6    

Which is the better form of tunin A-B-C-none?
Itīs the same B and C?
I need to displace the 4 and 10 harmonic a little beat above or below for those harmonics donīt affect to the fundamental in its sound quality?

Iīm going to build a 5 octvs marimba in my next project. Which are your recommendations about the low register before the start

Regards


Hi Alejandro

It might be that your tuning of the harmonics is not responsible for your unsatisfactory low note sound - although it might be if they are a long way from centre (your picture A) AND those harmonics are very prominent relatively to the fundamental. The fundamental can be made relatively stronger with wider bars and especially, wider resonators.

The issues you have with non-fundamental modes in marimbas are different to virtually every other instrument in that they are in no way related to a natural harmonic series. The notes a marimbas harmonics are tuned to are chosen because they ARE musically relevant to the fundamental from a tempered tuning point of view, BUT they WILL NOT resonate in the resonator. The idea is that we want to hear the harmonics as little as possible, and what we do hear of them gets hidden by either blending in with other notes or by being difficult for the ear to separate from the fundamental in terms of pitch.

I would stick with example A from your pictures. This means that the harmonics are in tune with the fundamentals of the higher bars. It also means that they are in tune with our recognition of pitch which tends to be based on equal temperament these days - especially while listening to instruments (like marimbas) tuned with equal temperament.

Your example C is similar to where you might find the naturally occuring harmonics in a vibrating string or air column - but in the case of a marimba that is not really relevant.

Your example B is what you might find on the higher notes of some instruments where stretched tuning is involved. I personally don't know much about stretch tuning so if you are interested you will have to research it - there is an article or two on the percussionclinic.com website. It is not really a relevant topic to your particular low note issue though.

When you ask "do I need to displace the 4 and 10 harmonic a little bit above or below for those harmonics donīt affect to the fundamental in its sound quality?"

Answer: no it won't affect the sound quality of the fundamental, but it WILL affect the overall quality of the sound from that bar - after all, the harmonics contibute to the sound. In particular they will affect our perception of the note's pitch, and purity of pitch.

As for general reccomendations for a 5 octave instrument - definitely exra wide bars at the bottom 8ve + 4th - wider than normal extra wide - I hate having to play hard to get plenty of volumes at the low end! Also there is a trade off between bar length and thickness at the low end - longer bars do not have to be so thin to get down to pitch, so they are stronger and can be hit harder, but i don't think they are quite as responsive or sound quite as good. If using honduras rosewood you can probably go with the thinner bars like musser favour - if using african padoak or something similar then you probably need the extra strength of the longer bars as favoured by Yamaha.

Hope this helps.

Jim McCarthy


answers by Jim MCCarthy - 15/02/2008


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