[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

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Connor MacLeod
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[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

Δημοσίευση από Connor MacLeod » 25 Οκτ 2008 17:49

RMS = P2P∕2√2

Τι συμενει αυτο?

Ειναι τυπος που εξισονει τα watts RMS με τα watts PMPO.
Τελευταία επεξεργασία από το μέλος Connor MacLeod την 26 Οκτ 2008 11:54, έχει επεξεργασθεί 1 φορά συνολικά.
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Garakatsamol
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[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

Δημοσίευση από Garakatsamol » 25 Οκτ 2008 18:11

Πού το βρήκες?
Γιατί γενικώς δεν υπάρχει τέτοιος τύπος, εξαρτάται από τον κατασκευαστή κι έτσι όπως το γράφεις δε βγάζει και πολύ νόημα


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Connor MacLeod
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[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

Δημοσίευση από Connor MacLeod » 25 Οκτ 2008 18:26

Καπου κατα δω μεσα το βρηκα:
http://en.wikipedia.org/wiki/PMPO
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Garakatsamol
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[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

Δημοσίευση από Garakatsamol » 25 Οκτ 2008 18:35

Δεν τον βρήκα τον τύπο που λες αλλά αν διαβάσεις αυτή την παράγραφο θα καταλάβεις αυτό που σου είπα κι εγώ πιο πάνω, δηλαδή ότι δεν υπάρχει τέτοιος γενικός τύπος
PMPO

Peak Music Power Output (PMPO) (sometimes misused in advertising as Peak momentary performance output) is a much more dubious measure, of interest more to advertising copy-writers than to consumers. The term PMPO has never been defined in any standard but it is often taken to be the sum of some sort of peak power for each amplifier in a system. Different manufacturers use different definitions, so that the ratio of PMPO to continuous power output varies widely; it is not possible to convert from one to the other. Peak power is twice the sine wave power, so, for example, a 5 channel system using amplifiers which can output 10 watts for a few milliseconds with an unspecified percentage for distortion would be specified as '100 watts PMPO'. Sometimes, an extra factor is applied to get an even higher figure. The term PMPO is considered misleading and meaningless by audio professionals. Most amplifiers can sustain their PMPO for only a very short time; loudspeakers are not designed to withstand their stated PMPO for anything but a momentary peak without serious damage. Sometimes the PMPO which can be delivered into an unrealistic resistive load, rather than a real loudspeaker, is quoted. There have been genuine attempts to measure 'peak music power' as described below, but in general the term is not at all useful.[citation needed]

The true power output of an amplifier can be estimated by examining the input current. Linear amplifiers tend to be about 60% efficient at best. A switch-mode amplifier (known as class D) can achieve much higher efficiency, sometimes as high as 95%. A linear car amplifier labeled "500 W PMPO" but fitted with a 5-amp fuse can, at most, deliver an average power of 5 A × 14.4 V × 60%, or about 43 watts. (100% efficiency is always used for PMPO)

Peak momentary power output and peak music power output are two different measurements with different specifications and should not be used interchangeably. Every time a manufacturer uses different words such as pulse or performance they do so to reflect some non standard system of measurement of their own, where only they know what it means. The Federal Trade Commission is putting an end to this with Federal Trade Commission (FTC) Rule 46 CFR 432 (1974), affecting Power Output Claims for Amplifiers Utilized in Home Entertainment Products.
Remembering that neither spec is universally standardized and as stated before different companies use different definitions, The typically understood differences between Peak Momentary and Peak Music Power Output are as follows. Peak Momentary Power Output is measured by the components ability to pass a single peak or a short train of peaks, usually less than ten contiguous wave cycles, without distortion or loss in power output. Whereas Peak Music Power Output is measured by the components ability to pass at least ten contiguous wave cycles without distortion or loss in power output. RADAR amplifiers only care about peak momentary impulse power and CW Linear amplifiers only care about RMS because a continuous sine wave is all they produce.

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GeoStuff
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[Solved] - Ξερει κανεις να διαβαζει αυτη την Εξίσοση?

Δημοσίευση από GeoStuff » 25 Οκτ 2008 19:29

Και λιγάκι παρακάτω είναι το "ζουμί" της υπόθεσης...
To get an idea of the relationship between PMPO watts and watts "RMS", consider the following numbers advertised for some current loudspeakers. These models have been selected at random, and inclusion in or exclusion from this list is neither a recommendation nor a criticism.

* Teac PM-100 3D surround-sound speakers: 16 W RMS, 180 W PMPO
* Kinyo "200 W" PC speakers: 3 W RMS, 200 W PMPO
* Philips Fun Power Plus MMS-102 PC speakers: 10 W RMS, 120 W PMPO (The Philips data sheet mentions only the "RMS" value; the PMPO value is claimed by retailers.)

This list shows that PMPO figures are hugely exaggerated compared with the "RMS" values used by professionals. It also shows that there is little consistency in how much the figures are exaggerated making them almost totally meaningless.
Άρα κοιτάς τα RMS και όχι το στιγμιαίο PEAK...
Κούκλα Μου Φρεγάτα Σκίζεις Τον Ωκεανό... Μοιάζεις Στον Τιτανικό!!!

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