Microphone preamplifier

[epilot]

Hi friends,

I am looking for a fair microphone preamplifier circuit that must be used with my car amplifier at 18 to20 volts.
The amplifier chip is able to support that voltage.
The microphones which I want to use are condenser and dynamic microphones.
Is there any guy who knows a suitable circuit for the job?

The amplifier is working ok with the output signals coming from my radio, walkman and PC, so can I use the input of my wanted preamplifier with those devices too or I need 2 inputs, one for my microphones and the other for the devices?

By the way I have few head preamplifier circuits based upon 9411 preamplifier chips too but some guy here said me that those circuits are not good when are use on the common circuitry.

 

[audioguru]

Why do you want to use a microphone with your car amplifier? You will have acoustical feedback howling if the microphone can hear a speaker's output.

A "condenser" microphone needs a 48V supply and is very old fashioned. Maybe you mean an electret microphone which has the 48V charge built-in.

There are millions of microphone preamplifier circuits on the web.

 

[chemelec]

Hi friends,

I am looking for a fair microphone preamplifier circuit that must be used with my car amplifier at 18 to20 volts.
The amplifier chip is able to support that voltage.
The microphones which I want to use are condenser and dynamic microphones.
Is there any guy who knows a suitable circuit for the job?

The amplifier is working ok with the output signals coming from my radio, walkman and PC, so can I use the input of my wanted preamplifier with those devices too or I need 2 inputs, one for my microphones and the other for the devices?

By the way I have few head preamplifier circuits based upon 9411 preamplifier chips too but some guy here said me that those circuits are not good when are use on the common circuitry.

There is a Pretty good Transistor Preamp on my site.
And it will work with a Wide DC Input range of voltages.
Link to my site Below.

 

[epilot]

Why do you want to use a microphone with your car amplifier? You will have acoustical feedback howling if the microphone can hear a speaker's output.

A "condenser" microphone needs a 48V supply and is very old fashioned. Maybe you mean an electret microphone which has the 48V charge built-in.

There are millions of microphone preamplifier circuits on the web.

Well, I want to make an amplifier pack for whole my tests and repairs.
The reason of using a car amplifier is because I have the chip at my junk box.

yea, I meant an electret mic.

yes, I know that there is a lot of preamplifier circuits on the web, but I am not sure and could not find any info that if those preamplifiers are cool for an electret and dynamic mic simultaneously?

by the way, do you know if I can use the input of the preamplifier with other devices or I should use 2 Socket one for the input of preamplifier (just for mics) and the other for the input of amplifier (for devices)?

P.s just to know, how does an condenser mic provide the 48V built-in charge?

 

[audioguru]

Well, I want to make an amplifier pack for whole my tests and repairs.
The reason of using a car amplifier is because I have the chip at my junk box.

You can't use a microphone and an amplified speaker playing its sound in the same room, you will have howling feedback.

yes, I know that there is a lot of preamplifier circuits on the web, but I am not sure and could not find any info that if those preamplifiers are cool for an electret and dynamic mic simultaneously?

An electret mic needs to be powered by a resistor because it has a FET transistor inside. It is unbalanced.
A dynamic mic does not work and might be damaged by the resistor that powers an electret mic. It is balanced. It has an impedance much lower than an electret mic so usually its preamp input also has a low impedance which is too low for an electret mic.
So the two mics need a different kind of input. You can buy a fairly expensive electret mic that has its FET powered by a battery, has a low output impedance and is balanced like a dynamic mic. Then they can share one mic input.

by the way, do you know if I can use the input of the preamplifier with other devices or I should use 2 Socket one for the input of preamplifier (just for mics) and the other for the input of amplifier (for devices)?

You can attenuate line level inputs then feed them to the mic input for a dynamic mic. The inputs need to be switched anyway so why not switch them to a line level input instead?

P.s just to know, how does an condenser mic provide the 48V built-in charge?

Look in Google. The electret material is formed with the 48V charge, something like the way a magnet holds magnetism.

 

[Hero999]

Maybe you mean an electret microphone which has the 48V charge built-in.

Well I wouldn't say an electret is the same as a 48V power supply. It's the difference between a permanent field and a temporary field; like the difference between an electromagnet and a permanent magnet.