Bändchenmikrofone – Mythos und Wahrheit

Dieser Artikel von Bob Crowley von Soundwave Research erschien auf seinem empfehlenswerten Microphonium-Blog. Da ich ihn für großartig halte, wiederhole ich ihn hier in voller Länge:

Naked Eye

The Myth of the Ribbon Microphone – Exposed! part one
By Bob Crowley of Sound Wave Research

‚The Knowledge‘ of a London cabbie consists of a complete mental map and image of the the city roads and byways and those with The Knowledge are then qualified to transport via black cab any passenger to any location within London.

The Knowledge of Ribbon Microphones – A Codex inscribed herein for posterity – consists of the true facts and explanations about the mysterious and sometimes ancient mythology of the revered and sometimes reviled ribbon microphone. The Myths are many and the tales told are handed down over the generations of recording aficionados and repeated almost as prayers in the scripture of the ubiquitous message boards, where no false word is ever erased, and lore is mixed with fact, fiction, lies, myths, heresy, pure falsities, and half-truths. And then there is the phenomenon of repetition, whereby the truth is manufactured, where errors are repeated, often over and over, until they become accepted facts, despite the lack of supporting evidence. Like parrots, the falsehood is recanted, passed down through generations, and finally accepted without question.

Here are a few myths to get us started:

Vintage Myths – those myths based on lore, history, and New Old Stock

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.

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1 Antwort auf “Bändchenmikrofone – Mythos und Wahrheit”

  1. 1 Administrator 08. April 2008 um 16:03 Uhr

    Bob hat den Artikel überarbeitet – hier findet ihr die neue Version:

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