Low End Preamp to Medium End :D

I think a 'millivolts generator' would be closer to reality...

(Anyway: under normal circumstances a 4.7 or 5.6 V zener won't conduct because of the microphone output.)

You would be surprised. I would not like to take the signal level coming from a kick drum lightly.

See the maximum output at below link;

http://www.microtechgefell.com/index.php/en/microphones/studio-a-recording/small-membrane-transistor-mics/429-m-221

THAT corp wrote a pretty good AES paper about input protection. Yes you want to prevent the input devices from zenering (<<7V), but transients from shorted, charged up, phantom supply blocking caps can drive the inputs negative a few tens of volts. Oversized input caps means lots of current must be clamped, too.

JR

So what about my schema?

OK!

I started to draw power supply.I did Preamp and Phantom Power Supply for now.Please look and tell me if it's wrong.

http://dl.dropbox.com/u/91809016/preamp.psu.bmp

Thanks!

JohnRoberts said:

THAT corp wrote a pretty good AES paper about input protection.

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I believe you mean "More Analog Secrets Your Mother Never Told You"? http://www.thatcorp.com/datashts/More_Analog_Secrets.pdf

My recollection was a separate paper just about input protection, but that paper gives it a good treatment, and looks like it has some other useful information worth reading.

Back in the day I learned a lot from the national audio applications manuals. While they always pimp their own products you can still learn a lot of the basics from such sources.

I suspect THAT engineers were forced to rapidly develop expertise about input protection from trying to keep their chips alive inside customer applications. On-chip clamps can rarely handle a full dump from an oversized input cap... bigger must be better right? 

JR

Why no one talks about my schma?

Ok,i did psu of preamp.It's working perfectly!Now i'm working on Phantom power.

rıdvan said:

Why no one talks about my schma?

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No one talks about your schema because you need to work on it some more. The power supply will not produce + and - voltages as you have it drawn. Try running a full wave bridge (4 diodes) from each of the 12 volt windings, to make two separate 18 volt supplies if that's what you want. The phantom supply is somewhat complicated, a full wave bridge and a 48 volt zener is enough for the regulator, at this point.