Mic and Preamp INPUT IMPEDANCE Matching

E

endserenading81

New member
Hi,
I have a Studio Projects C1 Mic, and an Art TPS II Tube Preamp. The preamp has a knob has a knob called "Input Impedance". I can't find the correct settings for this, for matching my mic up to it. Is this very important? Does it change the sound quality?
Could anyone help?
Thanks,
R
 
Plug the mic into the preamp...and then talk/sing into the mic while turning the impedance knob and listening to the changes in sound.
Pick the one you like best.
It may not always be the same choice....it depends on the rest of the music and what you are after.
 
miroslav said:
Plug the mic into the preamp...and then talk/sing into the mic while turning the impedance knob and listening to the changes in sound.
Pick the one you like best.
It may not always be the same choice....it depends on the rest of the music and what you are after.
Click to expand...

Agreed. You can't screw anything up by adjusting the input impedance... You will notice slight changes in the response (mostly in the high end) as you increase the impedance, but you're not going to hurt anything. Good to experiment here.

I typically find my "sweet spot" using the 1:4 rule - Set the input impedance to 4x the mic's output impedance. The C1 has an output impedance of 200 Ohms, so I would start the input impedance on the TPS up around 800 Ohms and tweak from there.

A shameless plug: I just talked a little bit about the variable impedance on the ART units, as well as a tube modding guide on my blog. The OP might find it interesting, or worthless: Modifying The A.R.T. DPS-II
 
Input impedance can have some effect on dynamic mics (eg SM57) or mics with a transformer output. The correct loading resistance for these mics can usually be found in the mic data sheet. A transformer will 'ring' if the loading impedance is too high, and many dynamic mics are designed to work best with a particular termination impedance. Apart from this, use the highest impedance possible for best clarity if using a low impedance output mic (eg condensor).

- Geoff
 
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