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Author:Reuna, Teemu
Title:Kivi kaiutinkotelomateriaalina
Stone as Loudspeaker Enclosure Material
Publication type:Master's thesis
Publication year:2008
Pages:xiv + 57 s. + liitt. 5      Language:   fin
Department/School:Signaalinkäsittelyn ja akustiikan laitos
Main subject:Akustiikka ja äänenkäsittelytekniikka   (S-89)
Supervisor:Karjalainen, Matti
Instructor:
Electronic version URL: http://urn.fi/urn:nbn:fi:tkk-011892
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark S80     | Archive
Keywords:loudspeaker enclosure material
mode analysis
Prony's method
frequency response
diffraction
bracing
damping material
acoustic circuit theory
kaiutinkotelomateriaali
moodianalyysi
Pronyn menetelmä
taajuusvaste
diffraktio
tukirakenteet
vaimennusmateriaali
akustinen virtapiirianalogia
Abstract (eng):This Master's thesis studies the effect of loudspeaker enclosure material on the sound produced by the loudspeaker.
The idea is to find out, if stone materials are usable as loudspeaker enclosure materials.
For the study a model loudspeaker is bought.
From this model a prototype loudspeaker is built from stone.
Three species of stone are studied and the material for the prototype is selected from these.
To aid this selection, mode analysis is done on the stone materials.
Prony's method is applied in the analysis.
The modal behaviours of the stone materials are studied by measuring their acceleration responses and analyzing these responses.

The thesis introduces also loudspeaker theory especially that of the loudspeaker enclosure.
The big picture of loudspeaker functionality is clarified with the acoustic circuit theory.

The mode analysis was not much of a help when doing the decision on the prototype material, mainly because the measurement results were so similar among the stone materials.
The decision was made based on the density of the material.
The comparision between the model and the prototype loudspeakers was based on frequency responses and power spectra of the loudspeakers.
Also the acceleration responses of the loudspeaker cabinets were compared.
No major differences were found on these measurements.
The most notable differences were due to the front panel of the prototype that differed in shape from the model's baffle.

Stone is a good loudspeaker enclosure material.
Though because its high cost it shoud be used in relatively expensive loudspeakers.
This way the price of the enclosure would be reasonable compared to the other parts of the loudspeaker.
Abstract (fin):Diplomityössä tutkitaan kotelomateriaalin vaikutusta kaiuttimen kykyyn toistaa ääntä.
Tarkoituksena on selvittää, miten kivimateriaali soveltuu kotelomateriaaliksi.
Tutkimusta varten hankittiin mallikaiutin, jonka pohjalta tehtiin prototyyppikotelo kivestä.
Prototyypin materiaaliksi valittiin yksi kolmesta tutkittavasta kivilajista.
Tätä valintaa varten kiville tehtiin moodianalyysi, jossa apuna käytettiin Pronyn menetelmää.
Kivilevyjen moodikäyttäytymistä tarkasteltiin mittaamalla niiden kiihtyvyysvasteet ja analysoimalla näitä vasteita.

Tutkimuksessa käytiin läpi myös kaiuttimen teoriaa, etenkin kaiutinkoteloon liittyvää teoriaa.
Kokonaiskuvaa kaiuttimen toiminnasta tarkastellaan akustisen virtapiirianalogian avulla.

Prototyypin materiaalia valittaessa ei moodianalyysistä juurikaan ollut apua, sillä kivilevyjen tulokset olivat hyvin samankaltaisia.
Päätös materiaalista tehtiinkin tiheyden perusteella.
Prototyypin ja mallikaiuttimen vertailu tehtiin vertailemalla kaiuttimien taajuus- ja tehovasteita sekä vertailemalla koteloiden kiihtyvyysvasteita.
Suurta eroa kaiuttimien vasteissa ei ollut.
Merkittävimmät poikkeamat syntyivät prototyyppikotelon etulevystä, jonka muoto poikkesi hieman mallikaiuttimen muodosta.

Kaiutinkotelomateriaalina kivi on kuitenkin hyvä.
Tosin kustannussyistä johtuen sitä kannattaa käyttää lähinnä vain arvokkaammissa kaiuttimissa, joissa kotelon hinta on järkevässä suhteessa muihin komponentteihin.
ED:2008-09-16
INSSI record number: 36228
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