METHOD TO MUFFLE RINGING OVERTONES

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METHOD TO MUFFLE RINGING OVERTONES

Postby Espresso » Wed Mar 25, 2015 10:53 pm

Hello
I spend some evening to try a solution to MUFFLE RINGING OVERTONES I have on several my drum.
Of course thicker skin help , but with this method You can get better sound and may be You are enough satisfied and avoid to change skin.
I have fix 2 strip of tin on the skin like picture, weight is about 3/4 grams each ,If weight is too much , muffle is too and You lose sound , I used electronic balance.
You have to combine weight , position , and lengt of these strips ; it need a little bit care but You can have good result.
I have got the best result with 2 strip like in the picture , but You can try also with a longer single strip.
This kind of tin is used to produce artistic glass and it have adhesive , but may be You can use glue.
I tryed also with plaster I have stolen to my daughter and may be result is a little better than tin ,but it is impossible to have a permanet fixing, see picture.
I tryed also with silicon , but is is too elastic , may be I will test other kind of gum.
Another intersting thing I discovered is that phisic of sound of drums is much much more complicated than I could think, please see this web site:
https://soundphysics.ius.edu/?page_id=1150
or this experiments on Youtube:
https://www.youtube.com/watch?v=Zkox6niJ1Wc
Skin of drums do not have Harmonics but modes of vibration , the right balance of these give pleasant sound.

Saludos
Attachments
image1.jpeg
TIN STRIPS
image2.jpeg
PLASTER STRIPS
Espresso
 
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby Mike » Thu Mar 26, 2015 6:09 am

A piece of foam which you hang inside the shell is always the easiest solution with best results.
Personally I would never want to stick anything onto the the playing surface, i.e. the skin.
The shell is the culprit after all. Unlike the moongel pads I apply to the drumset skins to eliminate overtones,
my conga skins just remain undampened. As I said, muffling overtones works best with the method mentioned above.

Just my 2 cents.
Peace & drum
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby Espresso » Thu Mar 26, 2015 11:55 am

Hi Mike
Thank to Your prompt remark.
Of course do like You described is well known but I have to say that sometimes I cannot eliminate overtones with this system , so I tried to find an alternative way and operate right where sound is created.
From my side I still have enough space to play all kind of strike I can.
Saludos
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby jorge » Thu Mar 26, 2015 1:39 pm

Tranquilo. You are talking about apples and oranges. There are 2 distinct main sources of overtone ringing in a conga drum. First, the skin itself can ring and this can be controlled by sticking weights to the surface, although the underside may be less intrusive to playing than the topside. As Espresso says, the weight and location of the weights are critical, and this is evidenced by the diagrams of vibration modes of a circular membrane in the links he provided. This technique has been used effectively on iya bata drums as well as bombos and other bass drums and is well accepted.
The second source of ringing overtones is resonances that occur due to reflection of sound waves and the standing waves that are formed inside the cavity of the drum. This is the ring Mike is referring to. These tend to be high frequency ringing that you hear even if you play a muffled slap and make sure the skin is not ringing. This type of overtone ringing is more of a problem with close-mic'ed recordings of congas or heavily amplified live congas. Otherwise, it is unpleasant to the drummer when you are playing, but generally is inaudible over the rest of the music. It can be controlled pretty well by suspending an absorbing material inside the drum, experimenting with size and location of the absorbing material. Too much absorbing material can affect the tone and bass of the drum, so experiment to get it as small as possible and put it in the right place.
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby Espresso » Thu Mar 26, 2015 6:54 pm

Hi Jorge , Hi Mike
I like share informations and ideas because always it possible to learn somethig new.
Of course I have taken ideas from Fardela used on Iya , but I think that weight ratio are different because bata skin is vertical and congas is orizontal , but this is only a little detail.
I would spend a little more consideration , I hope interesting: using weight on skin You modify how this vibrate so You avoid that higher frequece enter to resonate to the cavity of drum.
In the other system You caught these frequence before resonate , but these live a little each strike.
It is like " better safe than sorry".
May be it is stragne but is like bad skin with bad sound become better , I would push to try how I have done because I found really unexpected result.
Let me know , Saludos
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby jorge » Fri Mar 27, 2015 5:39 am

Vertical or horizontal makes no difference. The acceleration of the vibrating skin is way more than the gravitational constant g. It is a mass effect not a weight effect, sticking a weight to the skin would have the same effect even in a weighless state, eg, in earth orbit or outer space.
Also the resonance inside the drum can be excited by an impulse that has no clear frequency, it is not just amplifying the frequency of the ringing skin.
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby Espresso » Fri Mar 27, 2015 6:34 am

I agree with Your more scentific explanation!
So striking with loosen skin we can understand how is the resonance of the shell only , for sure , but I can say that this is not the main component of ringing , it is skin that generate the main unpleasant frequence that we try to eliminate.
Please correct me if it is wrong.
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby jorge » Fri Mar 27, 2015 2:25 pm

Yes, I agree the overtones from the skin tend to be louder and more annoying than the overtones from inside the shell. The pictures of vibrational modes of a circular membrane in the first link you posted are great and are the results of mathematical analysis of the mechanics of the vibrating membrane. The only place I have seen the physics worked out in mathematical detail is in Feynman's Lectures on Physics, I believe in Volume 1. I no longer have this book so can't look up the derivations anymore, but as I remember he identified all the key parameters that determine the shapes, frequencies and relative amplitudes of the different modes. They included, as we would intuitively expect, diameter, mass and thickness of the membrane, its stiffness (resistance to bending), self-dampening of the membrane and tension on the membrane. Of course he made simplifying assumptions like evenness of the thickness and stiffness, circular shape, even tension, etc. Violations of these assumptions would affect the vibrational modes and the sound. Putting manteca de corojo (palm kernal oil) or other oily compounds on the skin increases the mass and self-dampening and reduces the stiffness, all of which would tend to reduce high frequency overtones of the skin. Playing the drum breaks down the microscopic fibrils of the skin over the years and reduces its stiffness, again leading to fewer high frequency overtones. Interestingly, Richard Feynman, a Nobel laureate in physics, also played congas. Judging by the few videos on YouTube, he played pretty badly, but at least he had a great time playing and made some contributions to our understanding of the physics of drum heads.
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Re: METHOD TO MUFFLE RINGING OVERTONES

Postby Mike » Fri Mar 27, 2015 3:54 pm

jorge wrote: the overtones from the skin tend to be louder and more annoying than the overtones from inside the shell

Not necessarily, that depends pretty much on what skin you have on the drum.
I once had some LP fiberglass congas with very thick skins, and what was most annoying was the shell ringing
after closed slaps.

jorge wrote: Playing the drum breaks down the microscopic fibrils of the skin over the years and reduces its stiffness, again leading to fewer high frequency overtones.

Now that is an interesting aspect, and a more accurate scientific explanation of "skins broken in" :)
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