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发表于 2022-7-17 07:19:43
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本帖最后由 iggfree 于 2022-7-17 07:21 编辑
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* e! F9 C9 C5 |2 r" F来自海外论坛，谷歌翻译：* M( r8 u9 w: K, B% I( F1 O
IV-SJ 是一种仪器记录仪，因此针对线性进行了优化；这样做的缺点不仅是较低的 S/N 比，而且是较高的失真。在普通的 Nagras 上，录制时还添加了“预失真”，而 IV-SJ 则没有，因此在 IV-SJ 上录制和在另一台机器上播放时可能会出现兼容性问题。
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8 Q G( T0 j- E9 r7 E5 C3 OIV-SJ 是一台不错的机器，但它不是为音频而设计的，所以如果你想要一个 Nagra 用于音乐录制和播放，你会更好地使用标准 IV-S。IV-SJ 因其（通常）更高的价格和类似实验室的衰减器看起来更加华丽，但对于音乐用途，它并不是很适合。有些人可能不同意，但规格不言自明......
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如果您应该选择 IV-SJ，它是一台非常简单的测试机器。磁头部分显然应该没问题，但 Nagra 头部相当坚硬，很少磨损。尤其是仪器记录仪；使用半有缺陷的记录仪进行测量没有多大意义……
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+ T* V4 i! F2 ^0 u& D要注意的一件事是制动器和滚轮的状态；卷轴由一个简单但非常有效的机械反馈回路控制。如果维护不善，张力辊可能会产生“摆动”。通常它并不严重（在轻微的情况下，可以通过用手指轻轻稳定滚筒来消除），但需要注意。幸运的是，服务手册对这些案例非常详尽且内容丰富。
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, g. N# }; @7 d* H; v- C3 `通常，Nagra 绞盘驱动器几乎没有噪音，因此如果驱动器发出隆隆声，最可能的原因是电机轴承损坏。在这种情况下，我建议不要购买它，除非您认识精通 Nagra 汽车护理的人。如果您没有合适的工具，您很可能会在拆卸时损坏电机。但话又说回来：Nagras 很贵，仪器记录仪可能会维护得很好。+ A9 W, g" V1 H e. P% {- {
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除了原始 ATN 电源中的电容器外，很少需要重新加盖。更换电容器简单、便宜且不重要。; H$ x+ q# z! r8 g) y& v. Z
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1 s `& J1 D8 T4 Y+ ?原文： V0 }3 m6 r6 q9 r$ p: i+ u
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As Milan says, the IV-SJ is an instrumentation recorder, and is thus optimised for linearity; the downside to that is not only lower S/N ratio but also higher distorsion. On the normal Nagras there was also "pre-distorsion" added when recording, which isn′t the case on the IV-SJ, so there could be compatibility issues when recording on the IV-SJ and playing back on another machine. ]. o8 N% j9 v. ^ p
4 F" h' J) T: Q1 x& b0 UThe IV-SJ is a fine machine, but it is not built for audio, so if you want a Nagra for music recording and playback, you will be better off with a standard IV-S (pilot or non-pilot, not much difference). The IV-SJ looks more flashy with its (normally) higher price and lab-like attenuators, but for music use, it is not really well suited. Some may disagree, but the specs speak for themselves...! D6 g$ Y( {3 c7 |& m+ j5 s
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If you should go for the IV-SJ, it is a pretty straightforward machine to test. The heads should obviously be OK, but Nagra heads are quite hard and they are rarely worn down. Especially with an instrumentation recorder; there wouldn′t be much point in using a semi-defective recorder for measuring purposes...
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One thing to look out for is the state of the brakes and the rollers; the reels are controlled by a simple, but very effective mechanical feedback loop. If it is not well maintained, the tension rollers might make an oscillating "bobbing". Often it is not serious (can be eliminated by gently stabilising the roller with a finger in mild cases), but it is something to look out for. Fortunately the service manuals are very thorough and informative on these cases.
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Normally a Nagra capstan drive is virtually noiseless, so if the drive make a rumbling noise, the most probable cause is bad bearings in the motor. In that case, I would advise against buying it, unless you know somebody well versed in Nagra motor care. If you don′t have the proper tools, you most likely ruin the motor when disassembling it. But then again: Nagras were expensive, and an instrumentation recorder would probably be well maintained.
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Recapping is very rarely necessary, except for the capacitor in the original ATN power supply. It is simple, cheap and noncritical to change the capacitor.
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。IVSJ也很精密，不能说它是IVS的简化版，用途不同，SJ算仪器级别，磁头的频响范围更广，但这不表明它适合听音乐。