Impedance linearisation

Impedanzlinearisierung

Linearizzazione di impedenza

Bass Impedance Correction Curves
The impedance curve of the big Fun 20 will be the example to explain the impedance linearization module:
- Green: Impedance without linearization,
- Orange: Impedance with cross over impedance linearization but without Low frequency-impedance linearization
- Blue: low frequency impedance linearization put on Low
- Purple: low frequency impedance linearization put on Medium
- Yellow: low frequency impedance linearization put on High
The average Tube amplifiers, in our opinion, need a flat impedance load to get the best sound out of it. The flat impedance allows a more homogeneous sound along the whole frequency spectrum: all our speaker of the big Fun, Genuin and Gioia series have a excludable impedance linearization for the cross-over frequency.

The cross-over impedance linearization is in our experience useful on all tube amplifiers (some people prefer to keep it switched off - question of taste and overall system).
The Bass impedance linearization leads to higher definition and better control in the low frequencies. The fact is that only rare tube and hybrid power amplifier need it, suggests us not to stress the construction to achieve this result.

In fact, each improvement is only useful, as long as the drawback it brings, is smaller than the problem it corrects
Am Beispiel der big Fun 20 ist hier links der Impedanzverlauf zu lesen:
- Grün: Impedanzverlauf OHNE Impedanzlinearisierung
- Orange: Impedanzverlauf mit zugeschalteter Impedanzlinearisierung beim Übergang, OHNE Bass-Impedanzlinearisierung
- Blau: Bass-Impedanzlinearisierung auf Low
- Violett: Bass-Impedanzlinearisierung auf Medium
- Gelb: Bass-Impedanzlinearisierung auf High
Unserer Meinung nach, ist für den Betrieb an Röhrenverstärker wichtig eine flache Impedanzkurve zu erreichen, wodurch keine Bereiche entstehen, die abnormal in bestimmten Frequenzen spielen: in allen unseren Lautsprechern der Serien Genuin, big Fun und Gioia ist eine zuschaltbare Impedanzlinearisierung für den Übergangsbereich eingebaut.

In der Tat, jede Verbesserung ist nur nützlich, solange die Nachteile kleiner sind als die Fehler, die sie korrigiert
La curva dell'impedenza della big Fun 20 sarà l'esempio per spiegare il modulo di linearizzazione d'impedenza dei bassi:
- Verde: curva senza linearizzazione
- Arancio: Impedenza con la linearizzazione nelle frequenze di cross-over inserita, ma senza la linearizzazione nel basso
- Blu: linearizzazione d'impedenza del basso in posizione Low
- Rosso: linearizzazione d'impedenza del basso in posizione Medium
- Giallo: linearizzazione d'impedenza del basso in posizione High
Un amplificatore valvolare, secondo noi, ha bisogno di una curva di carico lineare in modo da esprimersi al meglio. La linearità dell'impedenza permette di avere un suono omogeneo su tutta la gamma delle frequenza: tutti i nostri diffusori della serie big Fun, Genuin e Gioia hanno una linearizzazione d'impedenza escludibile.

La linearizzazione nel campo di taglio è utile a nostro avviso su tutti i valvolari. La linearizzazione nel basso invece non è sempre necessaria, per questo abbiamo deciso di non stressare il progetto introducendo anche questo cambiamento

La linearizzazione del basso da maggiore definizione ed un migliore controllo nelle basse frequenze.

In fondo, ogni miglioramento è un miglioramento solo finché gli errori aggiuntivi che porta sono minori del vantaggio che dà.

Theory behind

Die Theorie

La teoria

Stacks Image 4414
We develop our loudspeakers keeping in mind as well to get the highest linearity in the overall impedance. But all loudspeakers have a complex curve that describes the impedance depending on the frequency (see rough drawing up here). According to the IEC standard, saying that a loudspeaker does have 8 Ω (ohms) impedance, means that the impedance of that loudspeaker does not descend below 6,4 Ω. It does not say anything about the highest possible value that the impedance might reach.


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There is a convention to the use of the term "nominal impedance", and if the impedance over the majority of the bandwidth, specifically covering the range in spectrum where majority of the musical spectral power occurs, it's 8 ohms. A single number cannot tell all there is to tell about an impedance that varies with frequency. You must keep in mind that 'nominal impedance' is not defined in IEC. Indeed, the electronics industry was advised when the Trade Descriptions Act was introduced, that the word 'nominal' should no longer be used in specifications. That is why the IEC concept of 'rated value' is so useful. There is a very detailed definition and explanation of this term in IEC60268-2. The IEC standard (IEC60268-3) allows any "increase" above the rated value, but limits the "decrease". The standard does not allow the impedance to fall below the 80 % of the nominal value at any frequency, including DC.

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Saying that there is a nominal resistance of 8 Ω, does not mean that the impedance is flat 8Ω over the whole frequency spectrum.
One critical range is at the cross over frequency, where normally there is a peak (blue curve in the drawing). Therefore we developed and implemented in our loudspeakers a switchable impedance linearization for the cross over frequency. This flattens the impedance curve in the critical range (green curve in the drawing).
Wir entwickeln unsere Lautsprecher insbesondere auch mit dem Ziel, die höchstmögliche Linearität bei der Impedanz zu erreichen. Dennoch haben alle Lautsprecher aus physikalischen Gründen eine komplexe Kurve, die in etwa den dargestellten Verlauf beschreibt (siehe Zeichnung)! Die IEC-Standards legen fest, dass ein Lautsprecher einen bestimmten Impedanzwert besitzt und angeben darf, falls dieser nicht unter 80% der Nennimpedanz sinkt. Dies bedeutet, dass ein Lautsprecher mit 8Ω ein Impedanzminimum von 6,4Ω haben darf. Dadurch wird jedoch keine Aussage getroffen, wie hoch der Maximalwert sein kann!

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There is a convention to the use of the term "nominal impedance", and if the impedance over the majority of the bandwidth, specifically covering the range in spectrum where majority of the musical spectral power occurs, it's 8 ohms. A single number cannot tell all there is to tell about an impedance that varies with frequency. You must keep in mind that 'nominal impedance' is not defined in IEC. Indeed, the electronics industry was advised when the Trade Descriptions Act was introduced, that the word 'nominal' should no longer be used in specifications. That is why the IEC concept of 'rated value' is so useful. There is a very detailed definition and explanation of this term in IEC60268-2. The IEC standard (IEC60268-3) allows any "increase" above the rated value, but limits the "decrease". The standard does not allow the impedance to fall below the 80 % of the nominal value at any frequency, including DC.

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Wenn man eine Nennimpedanz von 8Ω hat, bedeutet das längst noch nicht, dass sie auch ebenmässig über den gesamten Frequenzbereich verläuft. In der Regel gibt es kritische Bereiche - einer davon ist die Übergangsfrequenz, die ein Maximum aufweist (blaue Kurve in der Zeichnung). Deswegen haben wir eine Impedanzlinearisierung entwickelt und eingeführt. Sie ist zuschaltbar für die Übergangsfrequenz. Das flacht die Impedanzspitze bei der Trennfrequenz ab (grüne Linie).
Noi, da Blumenhofer Acoustics, sviluppiamo i nostri diffusori anche in modo da avere la massima linearità nella curva dell'impedenza. Però tutti i diffusori hanno una curva complessa che descrive l'andamento dell'impedenza in rapporto appunto alla frequenza (si veda lo schizzo qui sopra). Secondo le definìzioni della IEC, un diffusore ha una certa impedenza se il valore minimo dell'impedenza non scende sotto l'80% del valore nominale. Questo significa che un diffusore ad 8Ω ha un impedenza che non scende sotto i 6,4Ω. Non dice nulla a proposito del massimo valore che questa assume


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There is a convention to the use of the term "nominal impedance", and if the impedance over the majority of the bandwidth, specifically covering the range in spectrum where majority of the musical spectral power occurs, it's 8 ohms. A single number cannot tell all there is to tell about an impedance that varies with frequency. You must keep in mind that 'nominal impedance' is not defined in IEC. Indeed, the electronics industry was advised when the Trade Descriptions Act was introduced, that the word 'nominal' should no longer be used in specifications. That is why the IEC concept of 'rated value' is so useful. There is a very detailed definition and explanation of this term in IEC60268-2. The IEC standard (IEC60268-3) allows any "increase" above the rated value, but limits the "decrease". The standard does not allow the impedance to fall below the 80 % of the nominal value at any frequency, including DC.

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Dire che il diffusore ha un'impedenza nominale di 8Ω, non significa che l'impedenza sia piatta ad 8Ω lungo tutto l'arco delle frequenze. Una zona critica è la zona di taglio. Di norma in corrispondenza di essa c'è un picco (curva blu del disegno). Per questo motivo abbiamo sviluppato ed implementato nei nostri diffusori una linearizzazione d'impedenza eliminabile per la frequenza di taglio. L'uso di questo modulo permette di appiattire la curva dell'impedenza in base alla frequenza (curva verde nel disegno) rendendo così questo valore ancora più costante.