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Impedance issues. . mic-mic preamp

Let me try again and refrase it...
I think (but I should say I know) that impedance matching could be key in a lot of recording applications.
It affects the way two pieces of gear interact with each other.
What I am interested in is impedance matching within microphone and preamp.
some mic preamp do have variable impedance (the vipre, UA and some other) I know, but I am looking for someone who could share knowledge about microphone and preamps impedance matching based on experience and experimentation.
you know something like this mic sound great in this amp and sounds like sh*t in this other amp etc.
Bytheway sorry if my english is a little crusty, I am a foreign born bastard :) .

Thanks a bunch


sdevino Wed, 12/17/2003 - 15:41

In the old days of tubes and low impedance gear itwas common to try and match low Z (Z stands for impedance) sources with matching terminations. In other words if you had a 600ohm input impedance on the mic pre, you wanted to use a 600Ohm mic inorder to get the best match and therefor the best voltage transfer from the mic to the pre-amp.

In modern times with contemporary amplifier designs it is possible to design devices which hsave very very low (like less than 1 ohm output impedances, that can drive high input impedances. Many newer mic amp designs have 2k to 10k ohm input impedances.

There are only 3 reasons you care about any of this:
1. lowest noise perfromance is accomplishe when a very low Z feeds a relatively high Z.

2. Voltage transfer: older mics are designed to have a matched load, newr mics want a higher impedance load. These matches will give you the most efficient voltage transfer (i.e. level).

3. SOUND: with modern gear none of this really matters all that much. Low Z mics can drive a very wide range of input Z's. But playing around with the match will not hurt anything and in fact will give you a very wide variation in the overall sound of the mic (which will not be subtle). The Vipre is very cool because you can just about dial in a sound with an older style mic.

In other words.. don't worry about it just experiment and make it sound good.


AudioGaff Wed, 12/17/2003 - 18:13

I had a litle paragrah in my head about this, but Lord Steve, comes in with something even better well said.

In general I have found that only two impeadance selections seem to be needed or make the most difference, And that is 300 or 1200. Many of the orignal Neve modules had a switch to select between these two and a few other mic pres that had those two and more to choose from, it was those two that made the most difference. But as Steve says, it really isn't a big deal anymore these days if your using a modern mic, with a newer, decent mic pre to begin with. Your better off trying to match your mic and preamp based on the sound/tone character that has more of a difference.



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