what kind of amp do i need?

[Guest kd2cwm]

I am looking to build a home-brew version of a gadget called "the bionic ear"  ( a parabolic microphone, essentially a mic in a parabolic dish hooked to an amp via headphones)_.  I have a  Sony dynamic mic that came from a tape recorder and  i have two smaller  electret condenser mic elements new in box  from Radio Shack.

.I also have several sets of powered P.C. speakers..  can I make this type of device using what I have?  I am thinking the powered p.c. speakers could have the mic hooked into the p.c. plug (green audio plug that goes into back of p.c.)  and run the existing 12volt wall wart to power it..

Is this feasible/possible? or would i need a op/amp circuit dedicated to my microphone/ condenser element?? and which of those is the best choice? im noob here and a ham last 26 yrs but not a expert on this stuff..
any/all help greatly appreciated!

                      Thank You,  KD2CWM  Dan

[audioguru]

The output of a microphone is a very low level, much lower than the level from a pc.
An electret mic needs to be powered properly from a filtered supply through a series resistor.

Therefore you need a preamp suitable for whichever mic you will use.
If you use the pc amplified speaker to drive your sealed headphones then you will need to attenuate its output to avoid deafening yourself.

[Guest Auztra EL]

To  KD2CWM,
Auztra EL.
Your idea of a "Parabolic Mic" needs thorough consideration.
I think you are going to position your Electret Mic at the focus of the Dish.
You will focus NOT ONLY THE DESIRED AUDIO; BUT EVERYTHING AVAILABLE IN THE PARABOLIC SPACE!
You cant discriminate any audible signal unless you use very extensive and elaborate audio filter networks to get signal in a legible level.
Furthermore, the PC Mic input goes to a good Preamp and so will boost the input from your Parabolic Mic to undesirable high levels.

[audioguru]

The parabolic mic will pickup sounds all along the path it is aimed at, including sounds that you don't want.

[Guest swarner11]

But, keep this thing in your mind that on the negative side, parabolic microphones are generally not used for standard recording applications because they tend to have poor low-frequency response as a side effect of their design. This is a direct result of the physical laws that govern sound waves.