After yesterday's long-term recording test, I have good news and bad news.
The good news is that there were no unexpected interruptions during the entire recording process. The bad news is that the 3 minutes warm-up phenomenon occurred again this morning.
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The technical data of the NT1-a include:
Acoustic Principle: Externally polarized 25mm (1”) condenser
Features: True Condenser (externally biased)?
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From a beginner's point of view, I would like to properly understand what "True Condenser (externally biased)" means. Which might be boring for the pros.
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Shure describes it this way:
There are two types of condenser microphones: a permanently biased condenser, usually called an electret condenser, and an externally biased condenser, usually called a true condenser. These days, when people say "condenser microphone", they usually mean, "electret condenser microphone". Probably ninety-five percent of the condenser microphones on the market are the electret type.
The electret has a charged backplate that is created when the microphone is manufactured. A true condenser, on the other hand, continuously requires an external charge. This external charge may come in the form of any external box attached to the microphone, or it may come from the electronics built into the housing of the microphone. To put it simply, true condenser microphones have active electronics that need an external power source.? The basics are that it is a positive voltage (Phantom Power from 12 volts to 48 volts DC) that runs on pins 2 and 3 in an XLR cable. The word phantom is used because the power source is essentially invisible, running through the same cord that the audio signal flows through (Source: sageaudio).?
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Jules Ryckebusch described it very well this way. That voltage charges the mic capsule, which is a capacitor or “condenser” in 1930’s speak.
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According to a Sound on Sound condenser mic life discussion:
A DC-biased capacitor mic should go on forever. There is no inherent deterioration process in the capsule itself. Dirt on the diaphragm (or a very high humidity environment) will cause temporary charge leakage that will reduce the output level and lead to hissing and/or 'frying' noises, but that can be cleaned and performance fully restored by a skilled technician.
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On the other hand, an electret mic can lose the internal stored charge over time and that will also reduce output level and increase noise. Early electret mics (from the 70s and 80s) are much worse for this than modern designs which are vastly improved and can expect a life of 50 years or more.
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If a true condenser sounds dull it could be a contaminated diaphragm -- especially if it has been used a lot on close vocals without a pop screen, or in a smokey environment -- or it could conceivably be because the diaphragm has stretched if used in front of very loud sources (especially kick drums). Alternatively, it could be caused by deteriorating components -- especially aging capacitors -- in the impedance converter electronics.
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In case of the NT1-a I can't say how it was treated. The capsule doesn’t sound dull or noisy at all, as soon as it is operational. So, I’m tempted to conclude that a component in the impedance converter electronics seems to have deteriorated which results in the slow magnetizing process of the diaphragm. My gut feeling tells me that it could be a defective capacitor. But that's pure speculation.
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Since the NT1-a is a 2018 model and my electronic circuit troubleshooting skills are not sufficient to determine the root cause, I should send it to Rode for maintenance.
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If anyone has any other ideas, I would be happy to carry out further error analysis. But I'm afraid I'll definitely need detailed instructions.
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Otherwise I will send it to Rode next week.
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Many thanks to all of you!
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Have a nice weekend.
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Heinz
