How to modify the preamp audio circuit ??

[ankan]

Hello Everybody !!

I remember once i discussed a preamp circuit for audio here, ages back.Again,i'm stuck with the same circuit.Please check the circuit attached herewith.

The following circuit works fine with 12V p.s.u.Now to make this circuit work with 5V p.s.u with opamp LM833DT ,i need to change the resistor RA2 to 150 ohms which was around 390 ohms@ 12V.Also if i am using 150 ohms with 12V i found audio cracking while increasing the volume.

Now,could anyone suggest apart from changing RA2 to 150 ohms @5V supply .However to bring your attention on the circuit that changing the value of resistor to 150 ohms at 5V doesn't rectify the audio cracking problemcompletely.Mean to say that it is somewhat random. i.e comes after 2 hours or 3 hours.Where is the loophole?Is there any problem with gain or feedback?What else will be the values of any capacitors or resistors i should change to make the audio cracking completely removed at 5V PSU?

Waiting for earliest replies.

Regards
Ankan

[stratus46]

Originally Posted by ankan

Hello Everybody !!

I remember once i discussed a preamp circuit for audio here, ages back.Again,i'm stuck with the same circuit.Please check the circuit attached herewith.

The following circuit works fine with 12V p.s.u.Now to make this circuit work with 5V p.s.u with opamp LM833DT ,i need to change the resistor RA2 to 150 ohms which was around 390 ohms@ 12V.Also if i am using 150 ohms with 12V i found audio cracking while increasing the volume.

Now,could anyone suggest apart from changing RA2 to 150 ohms @5V supply .However to bring your attention on the circuit that changing the value of resistor to 150 ohms at 5V doesn't rectify the audio cracking problemcompletely.Mean to say that it is somewhat random. i.e comes after 2 hours or 3 hours.Where is the loophole?Is there any problem with gain or feedback?What else will be the values of any capacitors or resistors i should change to make the audio cracking completely removed at 5V PSU?

Waiting for earliest replies.

Regards
Ankan

It looks more like it might be a balanced to unbalanced amplifier but it certainly won't work as drawn as it is incomplete and not biased correctly. In general I find it much easier to work with dual +/- power supplies as it simplifies the biasing immensely.

What is it supposed to do? Gain? How much? Input impedance?

G²

[bear]

what is the purpose of the voltage applied through RA2? seems wrong.

If you want to make a balanced line in to single ended out circuit, there are many that work properly online - some companies even have "all in one" chips that do this job.

_-_-bear