increase (mather) impedance?

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I have a GT brick tube preamp which has an input impedance of 600 ohms and i'm connecting an AEA r92 ribbon mic to it which expects at least 1.2k ohm. I recently read an article about how to decrease input impedance with a resistor. is there any way to increase input impedance in this preamp? i'm a newbie so I hope this is the correct forum. thanks! this looks like a great forum.
tweed
 
Without tearing into the amp, you can put a 600 Ohm resistor in series with signal wire (as opposed to ground) of your mike. This will raise the input impedance to 1200 Ohms. There is a price though... it will cut your signal in half... a 6 dB loss.


;)
 
If you can't afford a transformer, which is the best solution, there are other ways--although you may compromise performance, i.e. freq response, SNR especially and so on.

If you use the resistor divider, the good part is that you are staying in the passive electronics realm. But the downside is that your sig loss will mess with your SNR, but it may be acceptable (not much in this case).

The other is an active approach: use a buffer, like a class a emitter follower one stage in order to adapt your source impedence to the your pre.
 
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