Difference between revisions of "The Shaping Of The Housing"

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=== Schallausbreitung außen... ===
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=== Sound propagation outside... ===
  
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Bereits in uralten Lehrbüchern gab es Frequenzgang-Abbildungen bei unterschiedlichen Gehäuseformen. Am besten sind alle Formen, die von der Schallquelle (dem Lautsprecher-Chassis) aus eine große Rundung aufweisen. Es hilft wenig, die Seitenwände dekorativ rund zu gestalten. Die unmittelbare Umgebung der Chassis darf keine Kanten, sondern soll große Rundungen aufweisen. Hier, in der unmittelbaren Nähe der Schallquelle, ist der Schalldruck am höchsten und die Beugungseffekte am ausgeprägtesten. <br />
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Even in ancient textbooks there were frequency response illustrations for different cabinet shapes. Best are all shapes that have a large roundness from the sound source (the loudspeaker chassis). It doesn't help much to make the side walls decoratively round. The immediate vicinity of the drivers must not have edges, but should have large curves. Here, in the immediate vicinity of the sound source, the sound pressure is highest and the diffraction effects most pronounced. <br />
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Schallwellen sind Dichteschwankungen der Teilchen in der Luft. Wenn eine sich ausbreitende Schallwelle an einer Grenzfläche (z.B. Schallwand) entlang läuft und sich an einer Gehäusekante abrupt ausbreiten kann, entstehen sogenannte Sekundärschallquellen. Diese breiten sich von ihrem Entstehungsort aus und führen zu Interferenzen mit der Ursprungswelle. Die Folge ist ein ungleichmäßiger Frequenzgang mit einer unter verschiedenen Abstrahlwinkeln ungleichmäßigen Schallausbreitung. Die Sekundärschallwellen laufen auch zu den Chassis zurück und bewirken Änderungen des Strahlungswiderstandes vor den Membranen.<br />
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Sound waves are density fluctuations of particles in the air. When a propagating sound wave travels along a boundary surface (e.g. baffle) and abruptly propagates along an enclosure edge, so-called secondary sound sources are created. These propagate from their point of origin and cause interference with the original wave. The result is an uneven frequency response with sound propagating unevenly at different radiation angles. The secondary sound waves also travel back to the drivers and cause changes in the radiation resistance in front of the diaphragms.<br />
  
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Beim Lautsprecherbau macht man sich daher viele Gedanken um die Schallausbreitung am Gehäusekorpus. Schallwellen sollen sich möglichst ohne abrupten Druckwechsel und den daraus resultierenden Sekundärschallwellen ausbreiten können.
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In loudspeaker design, a lot of thought is therefore given to the sound propagation at the cabinet body. Sound waves should be able to propagate without abrupt pressure changes and the resulting secondary sound waves.
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Vergleichbar ist das in etwa mit der Aerodynamik bei Autos oder Flugzeugen. Im Mittelhochton-Bereich sind die Wellenlängen des Schalls so kurz, dass sie innerhalb der Gehäusedimensionen liegen. Rundungen im Bereich von Mittel- und Hochtöner gewährleisten daher ein hervorragendes Rundstrahlverhalten. Insbesondere die nahen Kanten spielen eine bedeutende Rolle. Alternativ können abgerundete Kanten und mehrere Ecken eine große Rundung ersetzen. Die Fasen an den Kanten der [[Myro Amur Serie]] ergeben zusammen mit dem 108 Grad-Innenwinkel der Seiten nahezu die gleichen Eigenschaften wie ein sehr großer Rundungsradius. Frühere Versuche haben gezeigt, dass ein Radius von 10 cm zu hervorragenden Ergebnissen führt.<br />
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This is comparable to the aerodynamics of cars or airplanes. In the mid-high range, the wavelengths of the sound are so short that they lie within the dimensions of the cabinet. Curves in the area of the midrange and tweeter therefore ensure excellent omnidirectional sound distribution. Especially the near edges play an important role. Alternatively, rounded edges and several corners can replace a large rounding. The chamfers on the edges of the [[Myro Amur Series]], together with the 108 degree internal angle of the sides, give almost the same characteristics as a very large rounding radius. Previous tests have shown that a radius of 10 cm gives excellent results.<br />
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Das Klangbild entfaltet sich im Ergebnis ungestört, ohne zeitversetzte Sekundärschallwellen. Das Resultat ist ein artefaktfreies, völlig klares Klangbild.<br />
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As a result, the sound image unfolds undisturbed, without time-displaced secondary sound waves. The result is an artifact-free, completely clear sound image.<br />
  
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'''Die Mär von der schmalen Schallwand'''<br />
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'''The Fairy Tale of the Narrow Baffle'''<br />
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Viele Lautsprechergehäuse haben in der Nähe der Chassis (z.B. Schallwandkanten) scharfe Kanten bzw. unzureichende Kantenrundungen oder -fasen. Hier gehen der Designwunsch schmaler Gehäuse und die billige Fertigung vor der Akustik. Eine schmale Schallwand ist nur dann eine gute Schallwand, wenn sie in große Rundungen übergeht, wobei man dann eigentlich nicht mehr von einer schmalen Schallwand sprechen kann. Das zeitlos angesagte Bauhaus-Design mit seinen einfachen Geometrien ist den Marketing-Strategen ein willkommenes Argument und freut den Produktmanager wegen der niedrigen Produktionskosten. Diese Gehäuseformen gehören aus akustischer Sicht aber zu den schlechtesten.<br />
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Many loudspeaker cabinets have sharp edges or insufficient edge roundings or chamfers near the drivers (e.g. baffle edges). Here, the design desire of narrow cabinets and cheap manufacturing take precedence over acoustics. A narrow baffle is only a good baffle if it merges into large curves, in which case one can no longer really speak of a narrow baffle. The timeless Bauhaus design with its simple geometries is a welcome argument for marketing strategists and pleases the product manager because of the low production costs. However, from an acoustic point of view, these cabinet shapes are among the worst.<br />
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Fazit: Je näher eine Kante an der Schallquelle ist, desto stärker ist die Auswirkung.
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Conclusion: The closer an edge is to the sound source, the stronger the effect.
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''[[File:Whisky11.jpg]]<br />
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''[[Myro Whisky]]''
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=== Schallausbreitung innen... ===
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=== Sound propagation inside... ===
  
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Für den rückwärtig abgestrahlten Schall gilt prinzipiell das gleiche wie außen. Zudem gibt es innen sehr energiestarke Reflexionen. Dies gilt es durch die Gehäusekonstruktion zu verhindern. Außerdem bestimmt die Innenraumakustik das Feder-Masse-System der Chassis. Zur Vermeidung unerwünschter [[Resonanzen]] (Stehwellen) im Gehäuse werden parallele Gehäusewände vermieden wie zum Beispiel durch Vielecke oder Rundungen. Die Ausbildung einer Längsresonanz (Innen-Höhe) zu unterdrücken, ist bei schlanken, hohen Gehäusen eine schwierige Aufgabe. Von der Konstruktion her ergibt sich bei dieser Grundform immer eine Innen-Höhe, deren Resonanz durch mehrere Zentimeter starke Dämmstoffe nicht mehr absorbiert werden kann. Dickere Dämmstoffe würden den Hohlraum füllen und die Wirkung einer Bassreflexkonstruktion behindern. Man kann sich dann mit einem Trick behelfen durch die Verwendung und Anordnung mehrerer Bassreflexrohre. Hierbei wird die Luftsäule im Inneren an verschiedenen Stellen angezapft.  
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For the backward radiated sound the same applies in principle as outside. In addition, there are very energetic reflections inside. This must be prevented by the housing construction. In addition, the interior acoustics determine the spring-mass system of the chassis. To avoid unwanted [[resonances]] (standing waves) in the enclosure, parallel enclosure walls are avoided such as by polygons or curves. To suppress the formation of a longitudinal resonance (inner height) is a difficult task with slim, high cabinets. By design, this basic shape always results in an inner height whose resonance can no longer be absorbed by insulation several centimetres thick. Thicker damping materials would fill the cavity and hinder the effect of a bass reflex design. In this case a trick can be found by using and arranging several bass reflex tubes. In this case the air column inside is tapped at different points.  
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| [[Datei:Whisky11.jpg]]<br />
 
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''[[Myro Whisky]]''
 
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{| class="wikitable" border="1"
 
{| class="wikitable" border="1"
 
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| [[Datei:Time.jpg]]<br />
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| [[File:Time.jpg]]<br />
 
''[[Myro Time 2]]''
 
''[[Myro Time 2]]''
 
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=== Die Anordnung der Chassis ===
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=== The arrangement of the chassis ===
  
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Die Auswahl der Chassis und das Gehäusedesign mit seinen akustischen und optischen Merkmalen müssen zusammen erdacht werden. ''Myro'' hat seit 1988 Erfahrungen mit der signalrichtigen Wandlung. Allein eine grundsätzlich mögliche Kombination von Lautsprecherchassis zu finden ist ein schwieriges, oft scheinbar unmögliches Unterfangen. Wenn die Chassiskombination nicht von sich aus passt, dann ist ein mittelmäßiges oder gar schlechtes Ergebnis vorprogrammiert. Bei der Wahl der Chassis-Kombination muss man die erforderliche Einbausituation im Gehäuse bedenken. Zugleich muss man eine Idee für die Frequenzweichenschaltung im Kopf haben und eine Vorstellung des gewünschten Abstrahlverhaltens. Jeder Fehler schließt ein richtig funktionierendes Ergebnis aus. Alle Schallanteile zur gleichen Zeit zum Hörplatz abzustrahlen, ist der Sinn einer gebogenen oder schrägen Schallwand. Wer genau hinschaut, wird feststellen, dass die Tieftöner dabei gegenüber den Mitteltonkalotten zusätzlich um ein paar Millimeter vorgesetzt sind. Bei der Wiedergabe von Impulsen entscheiden Millimeter, ob die Schallanteile aller Systeme zueinander passen und zeitgleich die richtige Summe bilden. <br />
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The choice of chassis and the enclosure design with its acoustic and visual features must be thought out together. ''Myro'' has experience with signal-directed conversion since 1988. Just finding a fundamentally possible combination of loudspeaker chassis is a difficult, often seemingly impossible, undertaking. If the chassis combination does not fit by itself, a mediocre or even bad result is inevitable. When choosing the chassis combination, one has to consider the required installation situation in the cabinet. At the same time one must have an idea for the crossover circuit in mind and an idea of the desired dispersion behaviour. Every mistake excludes a correctly functioning result. To radiate all sound components to the listening position at the same time is the purpose of a curved or slanted baffle. If you look closely, you'll notice that the woofers are a few millimetres further forward than the midrange domes. When reproducing impulses, millimetres decide whether the sound components of all systems fit together and form the correct sum at the same time. <br />
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In der Praxis ist der Interferenzbereich der Chassis bei flachen Filtern und spezialisierten Chassis (Hochtöner, Mitteltöner, Tieftöner) in der Regel schmaler als man üblicherweise annimmt. Die Chassis verabschieden sich normalerweise knapp oberhalb und unterhalb der Trennfrequenz mit 18 dB/Oktave oder 12 dB/Okt. durch den Chassisverlauf plus (zum Beispiel) Filter 1. Ordnung (6 dB/Okt.). Diese steilen Flanken sind bei analogen Lautsprechern wegen der starken Phasendrehung ein großes Problem in Bezug auf das Ziel des gleichphasigen, synchronen Einschwingens, der Bildung der original Schallform. Interferenzprobleme treten dabei in erster Linie durch nichtsymmetrische Chassisanordnung, in Bezug zur gemeinsam abgestrahlten Frequenz zu große Chassisabstände und eben durch die erwähnten Phasendrehungen auf.<br />
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In practice the interference range of the drivers with flat filters and specialized drivers (tweeter, midrange, woofer) is usually narrower than one usually assumes. The drivers normally leave just above and below the crossover frequency with 18 dB/octave or 12 dB/oct. through the driver plus (for example) 1st order filter (6 dB/oct.). These steep slopes are a big problem with analog loudspeakers because of the strong phase rotation in relation to the goal of the in-phase, synchronous transient, the formation of the original sound form. Interference problems occur primarily due to non-symmetrical chassis arrangement, chassis distances that are too large in relation to the jointly radiated frequency, and the aforementioned phase rotations.<br />
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Weite Überlappungsbereiche mit linearem Flankenverlauf und minimalen Phasendrehungen sind, sofern man die symmetrische Anordnung und die ausreichend geringen Abstände einhält, sogar relativ unproblematisch. Die Summenbildung funktioniert dann so gut, dass sich saubere Signalformen ergeben.  
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Wide overlapping ranges with linear flanks and minimal phase rotations are relatively unproblematic, as long as the symmetrical arrangement and the sufficiently small distances are maintained. The summation then works so well that clean signal shapes result.  
  
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Findet man bezüglich der genannten Faktoren die richtige Mischung, so ist ein für die Wahrnehmung des Hörers im Abhörbereich gutes Abstrahlverhalten erreichbar. Und zwar ohne auf die richtige Wandlung der Schallsignale verzichten zu müssen.
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If one finds the right mixture with regard to the mentioned factors, a good radiation behaviour for the perception of the listener in the listening area is achievable. And this without having to do without the correct conversion of the sound signals.
  
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*''Bei vertikaler Anordnung der Chassis kommt es unter vertikalen Abstrahlwinkeln zu Frequenzgangunregelmäßigkeiten, wenn die Treiberabstände groß gegen die Wellenlänge sind.''
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*''If the drivers are arranged vertically, frequency response irregularities will occur at vertical dispersion angles if the driver distances are large against the wavelength.''
  
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*''Bei vertikaler Anordnung der Chassis kommt es unter horizontalen Abstrahlwinkeln zu Frequenzgangunregelmäßigkeiten, wenn die Richtwirkung der Chassis sich nicht durch deren Überlappung ausgleicht.''<br />
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*''If the drivers are arranged vertically, frequency response irregularities will occur at horizontal dispersion angles if the directivity of the drivers is not balanced by their overlapping.''<br />
  
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Grundsätzlich sind die Frequenzgangabweichungen unter Winkel relativ zum Frequenzgang auf Achse.<br />
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Basically, the frequency response deviations under angles are relative to the frequency response on axis.<br />
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Bei vertikaler Chassisanordnung ergibt sich für das vertikale Abstrahlverhalten ein weiterer Aspekt. Betrachten wir die Schallreproduktion der Einschwingvorgänge, so sind steilflankige Übergänge bei nichtsymmetrischer Chassisanordnung in der Regel sogar symmetrischen Anordnungen mit flacheren Übergängen unterlegen. Es ist also alles in allem eine Frage der ausgewogenen Abwägung der Faktoren - und der bei einem Lautsprecherkonzept zu erwartenden Aufstellungsbedingungen bei den Anwendern. Jede Anwendung verlangt ein, auf die spezifischen Aufstellungsbedingungen ausgerichtetes Abstrahlverhalten. Selbst die sogenannten Punktschallquellen zeigen jede Menge, teils heftige, Unregelmäßigkeiten im Abstrahlverhalten.
+
In the case of vertical chassis arrangement, another aspect arises for the vertical radiation pattern. If we look at the sound reproduction of the transients, steep-sided transitions with non-symmetrical chassis arrangements are usually even inferior to symmetrical arrangements with flatter transitions. So, all in all, it's a question of balancing the factors - and the user's expected set-up conditions for a loudspeaker concept. Each application requires a radiation pattern that is tailored to the specific installation conditions. Even the so-called point sources show a lot of irregularities in the radiation behaviour.
 +
|}
  
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|}
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==== Sound lines ====
 +
To arrange tweeter sound lines and midrange sound lines next to each other is nonsense. This also applies to individual drivers, which are therefore never arranged horizontally next to each other on the baffle at ''Myro''. If you look at the rising edge of an impulse at different horizontal angles, you will notice that the different distances to the sound sources result in different sound propagation times. The rising edges of the tweeter and midrange sound line (or chassis) arrive with a time delay and can never form the original sound wave. This is particularly critical on the horizontal plane because the seats in the room are distributed horizontally, as armchairs are not on top of each other but side by side. In addition, we listen with two ears that are horizontal to the head. At least one of the ears would receive distorted transients.
 +
Even with a horizontally symmetrical array, these distorted transients result. These systems are all designed for transient conditions, with chassis spacing and co-transmitted wavelengths playing a role. These are pure sound pressure distribution aspects. The transient response of these systems is distorted.
  
 +
=== The surface ===
 +
It is a "lacquer art" to create a surface without ripples with a fine velvety finish. The sense at what degree of drying of a lacquer layer the next layer must be applied is one of the secrets of good piano lacquer surfaces. The lacquer layer has a thickness of ≈1.2 - 1.4 mm. This must be taken into account when milling out the openings or recesses in the chassis.<br />
 +
Compared to silk matt or matt lacquers, high gloss lacquer has the advantage that it can be polished. Spray mist, which is deposited on the rear sides of bodies when they are painted, can be polished away. With matt paints, shiny spots would result immediately. The same applies to abrasion, e.g. during transport or when cleaning the surface. That's why Myro and Michael Weidlich Audio prefer piano lacquer surfaces. The costs for this surface quality are of course higher.
  
  
 
<''zurück: [[Myroklopädie]]''><br />
 
<''zurück: [[Myroklopädie]]''><br />
 
<''zurück: [[Myro]]''>
 
<''zurück: [[Myro]]''>

Latest revision as of 15:58, 12 July 2018

Sound propagation outside...[edit]

Even in ancient textbooks there were frequency response illustrations for different cabinet shapes. Best are all shapes that have a large roundness from the sound source (the loudspeaker chassis). It doesn't help much to make the side walls decoratively round. The immediate vicinity of the drivers must not have edges, but should have large curves. Here, in the immediate vicinity of the sound source, the sound pressure is highest and the diffraction effects most pronounced.
Sound waves are density fluctuations of particles in the air. When a propagating sound wave travels along a boundary surface (e.g. baffle) and abruptly propagates along an enclosure edge, so-called secondary sound sources are created. These propagate from their point of origin and cause interference with the original wave. The result is an uneven frequency response with sound propagating unevenly at different radiation angles. The secondary sound waves also travel back to the drivers and cause changes in the radiation resistance in front of the diaphragms.

In loudspeaker design, a lot of thought is therefore given to the sound propagation at the cabinet body. Sound waves should be able to propagate without abrupt pressure changes and the resulting secondary sound waves. This is comparable to the aerodynamics of cars or airplanes. In the mid-high range, the wavelengths of the sound are so short that they lie within the dimensions of the cabinet. Curves in the area of the midrange and tweeter therefore ensure excellent omnidirectional sound distribution. Especially the near edges play an important role. Alternatively, rounded edges and several corners can replace a large rounding. The chamfers on the edges of the Myro Amur Series, together with the 108 degree internal angle of the sides, give almost the same characteristics as a very large rounding radius. Previous tests have shown that a radius of 10 cm gives excellent results.
As a result, the sound image unfolds undisturbed, without time-displaced secondary sound waves. The result is an artifact-free, completely clear sound image.

The Fairy Tale of the Narrow Baffle
Many loudspeaker cabinets have sharp edges or insufficient edge roundings or chamfers near the drivers (e.g. baffle edges). Here, the design desire of narrow cabinets and cheap manufacturing take precedence over acoustics. A narrow baffle is only a good baffle if it merges into large curves, in which case one can no longer really speak of a narrow baffle. The timeless Bauhaus design with its simple geometries is a welcome argument for marketing strategists and pleases the product manager because of the low production costs. However, from an acoustic point of view, these cabinet shapes are among the worst.
Conclusion: The closer an edge is to the sound source, the stronger the effect. Whisky11.jpg
 Myro Whisky

Sound propagation inside...[edit]

For the backward radiated sound the same applies in principle as outside. In addition, there are very energetic reflections inside. This must be prevented by the housing construction. In addition, the interior acoustics determine the spring-mass system of the chassis. To avoid unwanted resonances (standing waves) in the enclosure, parallel enclosure walls are avoided such as by polygons or curves. To suppress the formation of a longitudinal resonance (inner height) is a difficult task with slim, high cabinets. By design, this basic shape always results in an inner height whose resonance can no longer be absorbed by insulation several centimetres thick. Thicker damping materials would fill the cavity and hinder the effect of a bass reflex design. In this case a trick can be found by using and arranging several bass reflex tubes. In this case the air column inside is tapped at different points.

Time.jpg

Myro Time 2

The arrangement of the chassis[edit]

The choice of chassis and the enclosure design with its acoustic and visual features must be thought out together. Myro has experience with signal-directed conversion since 1988. Just finding a fundamentally possible combination of loudspeaker chassis is a difficult, often seemingly impossible, undertaking. If the chassis combination does not fit by itself, a mediocre or even bad result is inevitable. When choosing the chassis combination, one has to consider the required installation situation in the cabinet. At the same time one must have an idea for the crossover circuit in mind and an idea of the desired dispersion behaviour. Every mistake excludes a correctly functioning result. To radiate all sound components to the listening position at the same time is the purpose of a curved or slanted baffle. If you look closely, you'll notice that the woofers are a few millimetres further forward than the midrange domes. When reproducing impulses, millimetres decide whether the sound components of all systems fit together and form the correct sum at the same time.
In practice the interference range of the drivers with flat filters and specialized drivers (tweeter, midrange, woofer) is usually narrower than one usually assumes. The drivers normally leave just above and below the crossover frequency with 18 dB/octave or 12 dB/oct. through the driver plus (for example) 1st order filter (6 dB/oct.). These steep slopes are a big problem with analog loudspeakers because of the strong phase rotation in relation to the goal of the in-phase, synchronous transient, the formation of the original sound form. Interference problems occur primarily due to non-symmetrical chassis arrangement, chassis distances that are too large in relation to the jointly radiated frequency, and the aforementioned phase rotations.
Wide overlapping ranges with linear flanks and minimal phase rotations are relatively unproblematic, as long as the symmetrical arrangement and the sufficiently small distances are maintained. The summation then works so well that clean signal shapes result.

If one finds the right mixture with regard to the mentioned factors, a good radiation behaviour for the perception of the listener in the listening area is achievable. And this without having to do without the correct conversion of the sound signals.

  • If the drivers are arranged vertically, frequency response irregularities will occur at vertical dispersion angles if the driver distances are large against the wavelength.
  • If the drivers are arranged vertically, frequency response irregularities will occur at horizontal dispersion angles if the directivity of the drivers is not balanced by their overlapping.

Basically, the frequency response deviations under angles are relative to the frequency response on axis.
In the case of vertical chassis arrangement, another aspect arises for the vertical radiation pattern. If we look at the sound reproduction of the transients, steep-sided transitions with non-symmetrical chassis arrangements are usually even inferior to symmetrical arrangements with flatter transitions. So, all in all, it's a question of balancing the factors - and the user's expected set-up conditions for a loudspeaker concept. Each application requires a radiation pattern that is tailored to the specific installation conditions. Even the so-called point sources show a lot of irregularities in the radiation behaviour.

Sound lines[edit]

To arrange tweeter sound lines and midrange sound lines next to each other is nonsense. This also applies to individual drivers, which are therefore never arranged horizontally next to each other on the baffle at Myro. If you look at the rising edge of an impulse at different horizontal angles, you will notice that the different distances to the sound sources result in different sound propagation times. The rising edges of the tweeter and midrange sound line (or chassis) arrive with a time delay and can never form the original sound wave. This is particularly critical on the horizontal plane because the seats in the room are distributed horizontally, as armchairs are not on top of each other but side by side. In addition, we listen with two ears that are horizontal to the head. At least one of the ears would receive distorted transients. Even with a horizontally symmetrical array, these distorted transients result. These systems are all designed for transient conditions, with chassis spacing and co-transmitted wavelengths playing a role. These are pure sound pressure distribution aspects. The transient response of these systems is distorted.

The surface[edit]

It is a "lacquer art" to create a surface without ripples with a fine velvety finish. The sense at what degree of drying of a lacquer layer the next layer must be applied is one of the secrets of good piano lacquer surfaces. The lacquer layer has a thickness of ≈1.2 - 1.4 mm. This must be taken into account when milling out the openings or recesses in the chassis.
Compared to silk matt or matt lacquers, high gloss lacquer has the advantage that it can be polished. Spray mist, which is deposited on the rear sides of bodies when they are painted, can be polished away. With matt paints, shiny spots would result immediately. The same applies to abrasion, e.g. during transport or when cleaning the surface. That's why Myro and Michael Weidlich Audio prefer piano lacquer surfaces. The costs for this surface quality are of course higher.


<zurück: Myroklopädie>
<zurück: Myro>

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