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清兵兄
我猜发信给Tom是问及如何将P101和他的唱头匹配。相信一定是低增益的一类。
Tom 的看法是采用变压器，但这变压器不好找。原因有二：在极低讯号下，变压器需要极佳的屏蔽。P101的输入抗阻是大约1K，輸出端再並联0.03 mf 电容。假如用普通的升壓牛就要改变P101的缐路。用P101你選用的升压牛的抗阻要在1K以下。用这个来举例，你的升压牛的输入抗阻就要 10ohm 才有20db人增益。
另一方法是用前前级，有12db，20db或更高增益。
两者都不容易找到。大部分这些设计都和系统的动磁整合，每每增益太大。
不过还是有些升压牛还是可以发挥，P101的1K抗阻会把讯号减弱，因此达到所需电平。
Dear Jonathan, I would use the transformer in your particular case. The problem is finding one. Due to the the minute signal levels involved requires a very well shielded transformer.The nominal input impedance (" Z ") of the P-101 is about 1k Ohm. This is shunted with a .03 micro Farad capacitor. This will require modification of your P-101 to use a typical step-up transformer. With the present input "Z" of the P101 would need a transformer with an output "Z" of of 1k Ohm or less. A transformer with an output "Z" of 1k and an input "Z" of 10 Ohms would provide 20dB (10X voltage "gain" would work well. FYI: The "Z" ratio is equal the square of the turns ratio or the voltage ratio. For example transformer with with an output "Z" of 600 Ohms and an input "Z" of 6 Ohms would provide a voltage step-up of 10X and have a turns ratio of 10X. Another possibility is to use a pre-pre that has a gain settings of 12dB, 20dB, and higher. It is difficult to find such devices because most transformers and pre-pre(s) were designed to be interfaced with moving magnet phonon designs and as a result provide a large amount of gain. There may be some transformers that will work because the 1k input (z) of the P-101will help reduce the output enough to provide to bring the output level near to the point desired.
我相信关键是动圈唱头的增益。 |
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发表于 2013-2-18 12:08:42
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