totally passive mic pre for loud sources - is this possible?

say i've got a mic input transformer with a high step up ratio, say about 1:10. if i was to mic up , say, a snare drum, couldn't i just plug the mic into the transformer and then straight into a compressor and use the make up gain on the compressor if i need a bit more signal?

is there any impedance issues or anything else i haven't taken into consideration?

will the signal level still be far too low, even after the step up?

Try it!
:guinness:

haha i knew someone would say that!!

i just wanted to know if i was wasting my time before i went to the bother of wiring it all up.

i guess it won't take long though, i'll try to get it cobbled together over the weekend.

But in order for this to work right, you'll need a gain stage (compressor) with relatively high input impedance (at LEAST 10K Ohm)

I've used M147s & M149s straight into the recorder with loud sources. If the signal isn't strong enough I've boosted it after the recording with a line amp (most often in a compressor). Works perfectly. I've also done the transformer thing. With a suitable high input impedance it's workable..

You'll loose the colour of the pre but that can sometimes be nice too :wink:

Didn't someone at TT use a emitter follower after a transformer? That could be cool simple DIY. It would not be balanced out.

lets see a 24V DC supply.

an emitter R of say 10k for about 1.2ma
so we might want a lower R value

If we use say a 1:10 transformer we could bias the EF with a 330k +25 to base 330K base to ground and a cap between the base and transformer hot.

Or a bias transformer hookup like the PRR schematic of a SS preamp from the tt days. Two = resistors a cap from the 1/2V junction to ground. One side of the transformer to that junction the other side to the base.

In the 'old days we used to just play, sing/scream into a big horn. This would modulate a cutting stylus and go direct to disc. No noisy electronics involved.
Sigh... the good old days.

I use Schoeps CM640 Microphones directly connetcted to Digidesign 888/24 I/Os without no problem. (I tried that after the MicPre was allways at 0 dB gain for the singer)

[quote author="BYacey"]In the 'old days we used to just play, sing/scream into a big horn. This would modulate a cutting stylus and go direct to disc. No noisy electronics involved.
Sigh... the good old days.[/quote]

Wow, you're old!!! :green: :guinness:

[quote author="gyraf"]But in order for this to work right, you'll need a gain stage (compressor) with relatively high input impedance (at LEAST 10K Ohm)[/quote]

ok, so what if i wired a 10K:600ohm 1:1 transformer on the back end?

That dosen't make sense..?!?

a 10k:600 transformer would not be 1:1, it would be 4.08:1 (squareroot(10.000/600)

And then there would be little idea in having the step-up transformer in the first place.. :?

Jakob E.

[quote author="gyraf"]That dosen't make sense..?!?

a 10k:600 transformer would not be 1:1, it would be 4.08:1 (squareroot(10.000/600)

And then there would be little idea in having the step-up transformer in the first place.. :?

Jakob E.[/quote]

:shock:

too may of these today :sam: :guinness: :sam: :guinness: :sam: :guinness: :sam: :green:

I did the transformer> emitter follower > transformer > emitter follower > transformer... didn't sound too peachy even though I did get a lot of gain and a very usable freq response. Fun though :grin: .. might try again someday

that's is an old idea I had... what happens if I cascode 3 transformers 1:10, one after another ?
:twisted:

Once I've connected my AT4050 straight to my Motu AD, after a PRR suggestion...

It wouldn't work, think about the impedance :idea: That's why I used zero gain emitter followers, to provide a 100kOhm load to each trannie and a low output impedance to drive the next one..

Quote:
In the 'old days we used to just play, sing/scream into a big horn. This would modulate a cutting stylus and go direct to disc. No noisy electronics involved.
Sigh... the good old days.

I'm not really that old; I just have an image as a crusty old curmudgeon to uphold!