Hey - I am interested in learning about the internal workings of mic preamp amps. Obviously, one of the best ways to do this is to build one from scratch. after i get comfortable, i want my final project to be a stereo pre. what kind of things really make or break a mic preamp? some of the things i am thinking of adding would be a M/S decoder on one channel, DI on both inputs, switched gain (with continuous knobs for trim), obviously phantom power on both. what else would you add to a preamp to make it stand out ?
My recommendation would be to build a good preamp in kit form first, then consider designing and building your own. The Green preamp is a good compromise between sound quality, features and ease of building.
Good luck, and let us know how you get on!
im asking more about after i learn about the basics, what features would be cool to add(so i can start learning about them now)
z120129 wrote: im asking more about after i learn about the basics, what features would be cool to add(so i can start learning about them now)
"The basics" includes learning about what features are useful and what are not. I would start there.
Actually designing a good preamp with those features is several levels up in competency after you have mastered the basics. Things like switchable HP filters, selectable M-S decoding (which involves two-channels not just one) and variable clip level indicators are all things that feature-rich preamps would offer after the standard items of gain trim and phantom power out.
go to Group DIY and look at the Metta Threads
and as mentioned above
Green Mk1 and Mk2
The Pre-amps I have designed in the past have been pretty simple. The main points I typically concentrate on are:
1)The power supply-very import to get a very clean rail or rails.
2)The differential Input to Single sided converter-Either XFMR or solid-state. OR you could make completely differential amplifier, much more difficult.
3)The Amp itself-Opamp, FET, Tube etc... Your choice
4)Differential out put conversion- xfmr or solid state.
5)The Phantom Power supply- Make sure you have enough current to drive your mics.
6)A Polarity Switch-This one is typically a simple wiring change.
7)A Pad -lower the gain of the amp.
8)A High Pass Filter- Usually tuned at 80Hz typically 2nd order.
After those are good, and then if you still wish to add gimmick features, go for it. Although for your first time I think you will have enough on your plate.
Get access to an oscilloscope, and waveform generator, multi-meter and a decent soldering iron.