'Big iron' always necessary? Mics and Pres

I always see this and wonder... sure big iron means better inductance at low frequencies but what about in cases where you want to attenuate the lows such as in a vocal or chain where you'd usually put a high pass on the signal. Wouldn't this be a nice natural attenuation if small iron was used? Say a tube vocal mic or a dedicated vocal mic pre.

In tube guitar amps there are times that a small transformer sounds good as well (Princeton Reverb, Deluxe Reverb, Tweed Deluxe, etc). These are not known as muscular amps... but they sound great for what they do and usually sit well in a mix.

Am I the only one who thinks this? Is it flawed thinking?

It's distortion content and phase response as well.  Not so much about a useful built in HPF.  More complex; it can be a trade off of extreme highs versus lows too.  Many characteristics in play. 

>big iron means better inductance at low frequencies

We should add 'for a given core material and topology' to that statement.

Some modern high-nickel content laminations have much higher permeability than some older lams. Toroidal and cut cores can be more efficient still.

And of course you can adjust the inductance with the number of turns, the payback being increases DCR and possibly high end performance.

z50

zebra50 said:

>big iron means better inductance at low frequencies

We should add 'for a given core material and topology' to that statement.

Some modern high-nickel content laminations have much higher permeability than some older lams. Toroidal and cut cores can be more efficient still.

And of course you can adjust the inductance with the number of turns, the payback being increases DCR and possibly high end performance.

Click to expand...

Yes.  The size just affects your Inductance/Resistance roll-off.

But Inductance in an 'iron' item is a moving target.  eg it varies with frequency and level

What IS consistent is the LF THD and this is probably the best metric to judge a core.  More turns gives more inductance but more resistance but this the higher resistance gives more THD (caveats about source/load/transformer resistance bla bla all to to taken into account)

If  you measure  3% THD (mostly 3rd) in a circuit @ 50Hz 1V, you'll see that 3% @ 100Hz 2V etc

A smaller transformer is a rotten way to limit LF.  It just give more distortion.