A circuit for high quality recording for PC 'mic in'

[Willen]

Uploaded diagram is my simple and direct recording way in PC. I have to make few advertisement audio files. Also, I feel good while recording songs (Karaoke) using sound editing program like CoolEdit, Adobe Audition or Nuendo. But I always feel bore due to poor sound and its irritating noise! Sound is little low and has hum and hiss lot. If I amplified the audio track using software, noise level also amplified. Hiss reduction features also reduces the crisp quality (high frequencies?) in sound... So bored!!
I just want to get nice recording quality using basic and simpler device. It's better if device is very simple. I found a link but actually I don't know what is this... Its unusual output pins and its long articles confusing me... **broken link removed** Please focus on 'Figure- 6' Its simplicity attracted me. No components problems! Or any other there?

 

[Willen]

For simple, I attached simulation files for LTspice. Circuit has low noise 559, 549 transistors but I simulated 547B and 557B. Total circuit has gain of 4 in 5K load (I don't know how much load R should be). Also, it has clear output without distortion. But I don't know what about hum, hiss noises.

 

[ronv]

Your PC has a single ended input so you don't need a balanced output. A good audio op amp might be easier.

 

[audioguru]

Your mic is probably a modern electret type, not an expensive old condenser mic. A condenser mic was powered from 48VDC. An electret mic has the 48V permanently charged on its electret material and has a Jfet impedance converter built-in that uses 0.5mA of current from a few volts.

Your circuit is missing a filtered source of a few volts at 0.5mA to power the Jfet in the mic.

The output of a mic is 2mV to 10mV so its preamp needs a gain of 30 to 150 times for its output to feed a line input. Rod Elliot says if you talk LOUDLY very close then you get 1V or 2V so you need a gain control.
Maybe the input on your pc is already a very sensitive mic preamp? Then it amplifies the noise from the mic and your preamp.

Hum. Is it because your mic is not connected with shielded audio cable or is it hum from a poorly filtered AC-DC power supply?

Hiss. Maybe the pc preamp amplifies noise from your mic preamp.

The 2.2k resistor powering the Jfet in Ronv's electret mic might fry it and its value is so low it reduces the output level from the mic. Use 10k instead.

 

[Willen]

Oh yes, I was thinking to filter voltage source of mic by using low value resistor from +ve, then decoupling this supply by 100uF, 100nF and 1nF caps, then use 10K resistor from this filtered supply for mic. I found my idea is valid because ronv also used same idea on his previous circuit.

Yes, most audio cable I found were without shielding and has just twin wires. Few mic and wires produces lot of noises but few are little nice. So I guessed SMPS is not so bad.

A circuit linked by me and attached by ronv are just an amplifier (input filtered in ronv's)? Because I didn't see any nice audio filters except decoupling caps. I think I will get little loud and clear audio with shield cable using these circuit.

Actually I am inspired by these simple circuit used in professional microphone- (attached) and trying to find almost same thing.