Selectable impedance on a pre- how big a deal is it?

[Exocaster]

I've never owned a mic pre with selectable impedance. Is it (or the lack thereof) a "make or break" feature? I don't know much on the subject; I've heard it said a pre with the proper impedance will make a 57 "come to life", and that's about it.

Absolutely necessary, cool to have, or only occasionally useful? Enlighten me.

 

[Metaltastic]

As I understand it, the higher the impedance on a transducer (whether it be a mic, guitar pickup, piezo, etc.), the greater the fullness and range of frequencies are represented. However, this isn't always necessarily a good thing, cuz too much upper frequencies can sound thin and undesirable (hence why in guitars 500k pots are often used, rather than 1 MOhm or higher, even though the latter would give a "better" representation of frequencies from a mathematical perspective). So it is with mics - at least that's my take on it!

 

[greyskull]

depends on the mic really...
does A LOT on ribbons

 

[006]

Yeah it's not something you have to have, but it really does make a difference sometimes. Some mics sound/work so much better if you are able to adjust the impedance on the preamp to the mic's "sweet spot" of sorts. I know on ribbons, as greyskull said already, it can make a night/day difference as I experienced many times with the 121 we had at the old place. And sometimes a certain impedance for a specific mic, say the 121 for example, doesn't give the same results every time, as in a certain impedance worked really well mic'ing up the drum room for one band...for whatever reason a different impedance setting will work better for another band in the drum room. Cool stuff.

~006

 

[colonel kurtz]

nice feature to have, but definitely not make-or-break

it's like getting an extra topping on ice cream...it might make it even better, but it's still gonna be the same flavor underneath it