looking for MIC circuit

[ash1412]

Thanks.

if we use a power amplifier in between preamp and speaker, I can also get same response as with PC?

 

[Audioguru]

With a mic, a preamp, a power amplifier and a speaker then you will probaly have acousical feedback howling because the mic will hear the speaker and sounds will go around and around.

If you turn down the volume, space the mic and speaker far apart, point the mic away from the speaker, point the speaker away from the mic and talk very close to the mic then the sound will be good if the speaker is good.

 

[ash1412]

If you turn down the volume, space the mic and speaker far apart, point the mic away from the speaker, point the speaker away from the mic and talk very close to the mic then the sound will be good if the speaker is good.

When I talk very close to the mic, using your preamp ckt the sound quality is good even I am not using any power amplifier.

Any suggested preamp & power amplifier combination circuit, so that I talk at least 1M away from mic.

 

[Audioguru]

When I talk very close to the mic, using your preamp ckt the sound quality is good even I am not using any power amplifier.

The preamp cannot drive a speaker. It is designed to be recorded or drive a power amplifier that drives a speaker.

Any suggested preamp & power amplifier combination circuit, so that I talk at least 1M away from mic.

You do not understand about acoustical feedback howling where the mic can hear the speaker and sounds go around and around.

 

[ash1412]

Thanks.

Regards
Ashwani

 

[ash1412]

Hi,

I would like to know if there is a way to reduce noise after preamp(using your preamp ckt)? I am getting noise and also the signal voice.
Can you tell me how to remove/reduce the noise?

Here is my electret mic data sheet.

 

[Audioguru]

You did not describe the noise.
Is it background sounds from an air conditioner or from traffic outside?
Is it mains hum?
Is it electronic hiss?
Is it acoustical feedback howling (beeeeeep)?

 

[ash1412]

its electronic hiss something like the sounds of radio (it's off or channel /FM signal is not available).

 

[Audioguru]

A TL071 is low noise. It has a small amount of hiss. Cheap carbon film resistors also create hiss. Metal film resistors have less hiss and a better opamp like an OPA134 has less hiss.

 

[ash1412]

ok.
Which one is better among the TL071, LM833, NE5534 amplifiers?

 

[Audioguru]

ok.
Which one is better among the TL071, LM833, NE5534 amplifiers?

Look at the voltage noise numbers on their datasheets. The numbers are 18, 4.5 and 4.0 where the lowest number has less noise.

 

[ash1412]

ya. I got it. I am planning to purchase TI LM833 & NE5534 IC. I have gone thru the TI LM833 data sheet , they hv dual supply Audio preamp reference design.
Do u hv any tested single supply Audio preamp based on LM833 & NE5534 design?

 

[Audioguru]

The single supply circuit I posted works with any opamp. The LM833 is made by National Semi (who was recently bought by TI) and is a dual low noise audio opamp.

 

[ash1412]

Hi Audioguru,

Can I use Tantalum/SMD caps in place of Electrolytic(47uF, 100uF, 22uF) caps. If yes, what would be the suggest values.


Regards,
Ashwani

 

[Audioguru]

Yes you can use tantalum capacitors.
The value of the two filter capacitors depends on how much ripple is on the power supply voltage. These values are for a little 9V battery that has ripple when its internal resistance rises near the end of its life. An AC-DC wall-wart needs to have more capacitance replacing the 100uF capacitor.

 

[ash1412]

Thanks,
can you please suggest tantalum caps assuming using same 9V battery?

 

[Audioguru]

Tantalum capacitors are fine for the 22uf, 47uF and 100uF capacitors when a little 9V battery is used.

 

[xaccto]

can I interrupt here and ask if putting a delay in the mic circuit would eliminate acoustical feedback ?
I mean there are various so called bucket-brigade chips that can be obtained, if they are put in line, causing
a few 10mS(s) delay to stop the feedback?

 

[Audioguru]

If the room is reverberant then you need a very long delay to stop feedback.
Record your voice today and play it back tomorrow. Then there is no feedback.

 

[ash1412]

Hi AudioGuru,

I would like to add mute switch with LED (momentary) in MIC circuit as attached by you in this thread.

pls suggest.

Is it possible to drive power to IC used in attached circuit from O/p of given below circuit(OP1 or OP2)?

**broken link removed**


Thanks in Advance
Ashwani