[bmwpowere36m3]

I know this is not the typical question for these forums, however the basic circuitry must be similar to that of an op-amp. I've decided to add an external mic to my camcorder (Aiptek A-HD+), since the on-board one is terrible.

I need a mic that can operate in high noise environments and not "clip" and "pop" as the onboard (overly-sensitive) does. From what I understand just using a simple condenser mic with an amplification stage, running on a 9V battery.

I've bought a relatively cheap condenser mic at radioshack:

CB/PA/Mic Condenser Microphone Element (270-092C)
Supply Voltage: 1.5 - 10VDC
Current Drain: 0.5mA (max)
Signal/Noise: 40dB (min)
Sensitivity: -65dB
Output Impedance: 1k

I've seen a circuit like this:

ANy help would be great.

 

[bmwpowere36m3]

Anyone?

 

[Myrdin]

Headphone amp based circuits all add too much noise when modified to provide adequate mic amplification. It makes sense. Microphone signals need about 1000x amplification as opposed to only about 10x for headphones.

There aren't very many DIY mic preamps available. One option is to scour ebay for parted out mixer pre's and then modify it to work as a standalone. Some very nice sounding devices have been made that way. Examples:
Yamaha M916 Mixer Mic Preamp EQ Tamura Trans No Reserve - eBay (item 320301379966 end time Oct-18-08 15:18:33 PDT)
Yamaha PM1000 Rack Project

Be sure to add a deadcat. That should cut down on popping.

 

[cetoole]

How about building something like this: System Test

 

[amb]

It depends on whether your camcorder has a line input or a mic input. If it's the latter then you may not need a mic preamp (it's already built-in to the camcorder). You just need to know whether the electret condensor mic you're considering has the appropriate output level for the camcorder's input.

 

[bmwpowere36m3]

Quote:

Originally Posted by cetoole /img/forum/go_quote.gif How about building something like this: System Test

Looks good, but not interested in something that complicated.

 

[bmwpowere36m3]

Quote:

Originally Posted by amb /img/forum/go_quote.gif It depends on whether your camcorder has a line input or a mic input. If it's the latter then you may not need a mic preamp (it's already built-in to the camcorder). You just need to know whether the electret condensor mic you're considering has the appropriate output level for the camcorder's input.

I'm going straight to the built-in mic, can't use a line-in...

I just wanted to build a simple "pre-amp/buffer" circuit to prevent the mic from overloading and distorting in a high SPL environment. I'm using this camcorder setup for in-car recording, with the windows down and the high general SPL level, the sound is horrible and it clips and pops.

I've tried all sorts of foam/wind blockers to reduce the noise, I just decided to remote mount the mic, but I want it still to be able to handle high SPL's.