Sujet Activer l'alimentation fantome avec un micro dynamique ou une guitare branchée, dangeureux?
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keyz
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Tout est dans le titre...
Je possède une interface audio (la TC Konnekt8) qui a 2 entrées préamplifiées, mais l'alimentation fantome s'active sur les 2 canaux à la fois. Sachant que j'ai un statique de branché sur la 1ere entrée, est-ce dangeureux de laisser un micro dynamique ou une guitare branchée sur la 2e? Ou faut-il le/la débrancher qd j'enclenche l'alim fantome?
Merci!
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J-Luc
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Il y a deux moyens d’oublier les tracas de la vie : la musique et les chats.
Albert Schweitzer
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lm
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Mais pas les micros à ruban... (sauf certains Royer)
Pour ce qui concerne les guitares, c'est à tester.
Certaines guitares Godin ont des connections XLR qui nécessitent l'alimentation 48V.
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keyz
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Je suis rassuré
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![Christophe - Audio Addict Christophe - Audio Addict](https://static.audiofanzine.com/img/user/avatars/generic.png?w=40&h=40&fm=pjpg&s=0d6213e9da38ef4cab8d0bdd3999c731)
Christophe - Audio Addict
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Citation : La plupart des micros dynamiques supporteront l'alim 48V.
Mais pas les micros à ruban... (sauf certains Royer)
La plupart des micros à ruban "modernes" (et certains vintage mais il vaut mieux ne pas tenter le coup) supporte très bien l'alimentation fantôme.
Personnellement, j'ai longuement tester les Crowley and Tripp que je vends : aucun soucis sur le micro après 12 heures d'alimentation fantôme.
En revanche, ce que les rubans craignent plus, c'est l'alimentation fantôme lors de la connexion du micro au préampli car des micros impulsions électriques passent et peuvent endommager le ruban en fonction de la conception du micro.
Le branchement du micro à ruban sur le préampli (et de tous les micro si possible) doit se faire avec l'alim P48 OFF ! Après, ça doit tenir ;)
Si vous voulez plus d'infos sur les mythes collés aux micros à ruban :
Citation : Myth: "Nothing sounds like/as good/mellow like an old RCA 44, 77, (insert an old mic here)"
Fact: These mics were good and produced excellent sound, but have low output and relatively high noise levels, and are highly variable. Most of the vintage ribbon mics have a steep roll off beginning at 10 KC. If you can put up with unpredictable performance, they may be for you. I have three RCA 77DXs here in the lab at the moment. You can bet they sound good, but different.
Myth: "Such and such has New Old Stock ribbon material (magnets/grille cloth/blueprints/uncle/DNA) which is the best"
Fact: Old ribbon material is likely to be inferior to modern materials. Aluminum oxidizes slowly but corrosion can produce pinholes, while precipitation (age/heat) hardening causes embrittlement, and fracture. Present day aluminum is produced in precise thickness and with better purity than was available even 20 years ago. This is due to demand for thin foils in other parts of the electronics industry, such as capacitors.
The Saggy Baggy Ribbon Myths - Things may droop over time, also with ribbons?
Myth: "Ribbon mics should be stored vertically".
Fact: No. The weight of a typical "large ribbon" is around 0.0018 grams, and a thin ribbon is about 1/4 that. If that is enough to cause sagging, then something is very wrong. Ribbon microphones of any vintage can be used and stored in any position.
Myth: "Just closing the case will blow the ribbon"
Fact: This is quite doubtful. Once again, if the air pressure is enough to damage the ribbon then most of ribbon microphones out there today are already blown. Several manufacturers including us supply ribbon microphones in horizontal cases with top lids. I think you would have to try to slam it very hard, over and over, to show any change to the ribbon tension.
Myth: "Crowley and Tripp uses a vertical storage box to prevent ribbon sagging."
Fact: We did this so you can see it and because we thought it looked better and was more convenient, and that it might cause the user to grab it from the mic locker more often rather than laying flat in the dark recesses of the cabinet. You can lay the box down on its side, turn it upside down - it doesn't matter at all because gravity has only the most minute influence on the ribbon.
Myth: "All ribbon microphones are fragile"
Fact: Modern ribbon microphones are not at all fragile.
Myth: "Move the ribbon mic slowly"
Fact: Nonsense. I saw an intern walking across the studio holding the microphone like it was a lit candle. This was very amusing.
Myth: "Loud sounds will shatter the ribbon"
Fact: Loud? Not loud like loud music loud, at least. No. Detonation of high explosives, maybe. Do not try this.
Phantastic Phantom Myths - Images of smoke, fire and destruction.
Myth: "Phantom power will destroy a ribbon microphone"
Fact: Not usually. Phantom power correctly applied does so evenly, so there is no net force on the ribbon.
Myth "Phantom power will not destroy a ribbon microphone"
Fact: Usually. Phantom power can stretch an aluminum foil ribbon. Any signal that is applied unevenly, such as 1. through a patchbay which is a bad idea anyway, or 2. by hot swapping cables, WILL boink the aluminum foil ribbon in passive ribbon mics.
Myth: "Phantom power will demagnetize the magnets"
Fact: I had to include this one since it was so interesting, and impossible.
Oft-Repeated Mythicisms - merely annoying, or insidiously harmful?
Myth" "Ribbon mics are dark sounding"
Fact: Some are, more modern ones are less so, and a couple are neutral to bright sounding. You choose.
Figure Eight Type Myths - fundamental things about sound in general actually...
Myth: "The back of a ribbon mic is usually brighter than the front"
Fact: This is definitely not so. Most good quality ribbon mics, ours included, are perfectly symmetric in response. The only difference from front to back, of course, is the phase. We think it's slightly embarassing at times to have to explain why this sounds different to people wearing headphones. No offense! Avoid uncomfortable social gaffes and use your phase reverse switch.
Exceptions: Naked Eye is intentionally asymmetrical in response with a 3dB average 8-12 KC presence rise off the back, with no dips, gaps or holes. (recall the embarassing phase cancellation phenomenon causes some people to misunderstand). The so-called "offset ribbon designs" are unintentionally different in tone color from front to back, I suppose because the distance from the mic body and screen to the ribbon varies from side to side. Intentional or not, it can be useful. The RCA 77DX is rather asymmetrical even in the figure eight position. This is a problem inherent in the 77C, 77D and 77DX because the local field around the ribbon motor isn't quite symmetrical to begin with, which is intentional because it is a multipattern mic.
Myth: "Ribbon mics have low output"
Fact: Modern ribbon mics have a HIGHER output than most stage dynamics. Remember that a condenser capsule has NO output and depends on the internal active electronics which are essentially a high gain voltage amplifier.
Myth: "You need a preamp with tons of gain"
Fact: No. Not only is the answer "no" but you can use your preamp wide open and unrestricted because ribbon microphones have extremely low self noise.
Pour plus d'infos, vous pouvez visiter le blog de Bob Crowley : http://microphonium.blogspot.com/
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breizhinours35
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lm
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Merci de ces précisions sur le comportement des différents micros à ruban "modernes".
C'est rassurant.
Je me suis laissé influencer par la mésaventure d'un copain ingé son qui a grillé sous mes yeux un Beyer M160. je suppose que c'est la connection à chaud (alim 48V déjà activée) qui est responsable des dommages et non pas l'alim elle-même.
![Christophe - Audio Addict Christophe - Audio Addict](https://static.audiofanzine.com/img/user/avatars/generic.png?w=40&h=40&fm=pjpg&s=0d6213e9da38ef4cab8d0bdd3999c731)
Christophe - Audio Addict
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Citation : je suppose que c'est la connection à chaud (alim 48V déjà activée) qui est responsable des dommages et non pas l'alim elle-même.
Très souvent c'est le cas (pour ne pas dire toujours).
J'ai entendu dire que les micros Coles avait tendance à être très sensible au 48V mais jamais vérifié personnellement donc...
J'ai quelques copains qui ont grillé des Royer parce que lors de la connection au patch, l'alim' 48V était déjà/encore en route...
![:(](https://img.audiofanzine.com/images/audiofanzine/interface/smileys/icon_sad.gif)
Vraiment, si l'alimentation en elle-même ne représente pas une réelle menace, c'est vraiment au moment de la connection qu'il faut faire très attention.
Pensez-y ;)
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