Originally posted by

**Helmholtz**View PostThanks, I see. So you have a "pickup" with an inductance of about 100 nanoH looking into a transformer primary of about 4 microH, and so the inductance of the transformer is large enough so that the voltage of the pickup is not significantly attenuated.

In the case you mentioned you have about 25 mH looking back into the transformer secondary with the pickup loop connected. So if the pickup is loaded by the actual input impedance of the mic preamp (assume 2500 ohms), then the high frequency roll off of the system is at

2500/25e-3/2/pi ~ 16 KHz

But there also must be some leakage inductance that we can think of as in series with the secondary of the transformer, and so this lowers the high frequency response some more.

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