Re: glass xyl/marimba

Rick, One of the glass panes was pulled out by the laborer, so I've
experimented hitting it with my knuckles, a soft-headed marimba
mallet, etc. and it remained solid.

Alison, thanks for the book suggestion; I'll have to find "Sound
Designs" by Banek & Scoville in a local library.

John Chalmers, thanks for your suggestions offline.

One interesting comment I found in an instrument building book I
currently have at home (published ca. 1980?) is that any solid free-
moving bar will have nodes at ca. 1/4 length from each end.

Soundly yours,
Harold Fortuin
http://www.geocities.com/harold_fortuin

--- In MakeMicroMusic@yahoogroups.com, "harold_fortuin" <harold@m...>
wrote:

> One interesting comment I found in an instrument building book I
> currently have at home (published ca. 1980?) is that any solid free-
> moving bar will have nodes at ca. 1/4 length from each end.

i have a vague recollection that a more precise figure for this is
0.225 (i have a strange ability to remember people's phone numbers
without even trying) . . .

You also might want to check this list out:

/oddmusic/?yguid=70544219

--
* David Beardsley
* microtonal guitar
* http://biink.com/db

Harold,

{you wrote...}
>Rick, One of the glass panes was pulled out by the laborer, so I've >experimented hitting it with my knuckles, a soft-headed marimba mallet, >etc. and it remained solid.

I have years of experience with the Partch "Cloud-Chamber Bowls", which were made of Pyrex and were (IIRC) close to 3/8" thick. And the bad news is that they have broken over the years. Once you have your instrument constructed, if it really is going to be made of simple window glass, you might consider hand/soft-mallet playing and have it amplified.

One other thing: resonant qualities of bar instruments are highly influenced by the consistency of the material (i.e. straight grain rosewood will always sound and tune better than wood with cross-grains, etc). If that glass has any variation in thickness, etc, it will make it a tad more of a challenge.

>One interesting comment I found in an instrument building book I currently >have at home (published ca. 1980?) is that any solid free-moving bar will >have nodes at ca. 1/4 length from each end.

That is somewhat dependent on materials, and is also more intricate than simply 25% of the length. Somewhere I have more data on that, and I'll try to post if/when I find it. Until then, DB is right that you should check out the oddmusic group - lot of people there have done bar instruments...

Good luck!
Jon

>

Hello Harold!
Still the best way to find nodes in especially old glass as it will get
thicker toward the bottom with age is by sprinkling
salt or sugar and tapping lightly. I am sure it might be at the very spot Paul
mentions, but one cannot always be sure. this will also give you the idea spot
to drill , it you can figure out a way to do it. i have avaiod ed glkass for
the mere reason that it is just too fragile. Although a thicker glass would
possibly be nice, but then there is kelon which has a very 'china' ( as in
ceramics) like sound.
possibly an instrument where you bowed the sides might be less likely to break
as since even with soft mallets, you will be hitting at it weakest point.

>
> Message: 7
> Date: Wed, 08 Oct 2003 20:59:33 -0000
> From: "Paul Erlich" <perlich@...>
> Subject: Re: glass xyl/marimba
>
> --- In MakeMicroMusic@yahoogroups.com, "harold_fortuin" <harold@m...>
> wrote:
>
> > One interesting comment I found in an instrument building book I
> > currently have at home (published ca. 1980?) is that any solid free-
> > moving bar will have nodes at ca. 1/4 length from each end.
>
> i have a vague recollection that a more precise figure for this is
> 0.225 (i have a strange ability to remember people's phone numbers
> without even trying) . . .
>

-- -Kraig Grady
North American Embassy of Anaphoria Island
http://www.anaphoria.com
The Wandering Medicine Show
KXLU 88.9 FM WED 8-9PM PST

Harold,

Kraig wrote:

>this will also give you the idea spot to drill , it you can figure out a >way to do it.

I also agree with Kraig's use of the time-tested standard of sprinkling something on the bar to find nodes - if the piece is going to be sounding good, you should get a straight line right across the area of least vibration. But that sentence above got me thinking...

When you go to mount it, don't try to drill. You can use a method many have, but I first saw on the Partch instruments. Simply attach a narrow strip of foam rubber across the node with contact cement and then cement it to the instrument stand. With the bar 'floating' on the two strips of foam, in an area with little vibration, you have a nice cushion for the bar and avoid drilling.

Cheers,
Jon

>

I agree with Jon here, you risk losing more than any thing you can gain by
drilling. the salt/sugar/wooddust trick was Harry's. It is more important with
wood where i have seen notes run at slight diagonals and then you have the choice
of going with it or slitting the differance.

>
> From: "Jonathan M. Szanto" <JSZANTO@...>
> Subject: Re: Re: glass xyl/marimba
>
> Harold,
>
>
>
> When you go to mount it, don't try to drill. You can use a method many
> have, but I first saw on the Partch instruments. Simply attach a narrow
> strip of foam rubber across the node with contact cement and then cement it
> to the instrument stand. With the bar 'floating' on the two strips of foam,
> in an area with little vibration, you have a nice cushion for the bar and
> avoid drilling.
>
> Cheers,
> Jon
>
>

-- -Kraig Grady
North American Embassy of Anaphoria Island
http://www.anaphoria.com
The Wandering Medicine Show
KXLU 88.9 FM WED 8-9PM PST