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jaya000 10th April 2007 07:54 AM

suggest preamplifier circuit
I want to make one preamplifier with gain 5~10. The supply voltage is 12v. Input will from a cd player. This is required because the amp to be used hv very low sensitivity. High quality circuit will be prefered.

AndrewT 10th April 2007 09:14 AM

discrete or opamp?
volume control or fixed gain?

5 to 10 times is a lot of gain.
The average signal from a CD player is about 200mV.
Multiply that by 5 and you are sending 1V (average) to the power amp. That is going to get pretty close to maximum output.
The peak signal (ac) from the CD player is usually 2Vac (3Vpk) and now your input to the power amp is going to be 10 to 20Vac. Surely that is overload condition.

Finally, you cannot get 5 to 10 times a CD signal from +12Vdc supply. One would need about +-30Vdc supply or +60Vdc supply.

thanh 10th April 2007 10:27 AM

I think that there are so many pre-amp schematic on internet. I myself can also design a circuit;)
I'm noticing this

I'm not know how to optimize pre-amp for mysefl purpose

A discrete pre-amp. It seem to be a best pre-amp

Nordic 10th April 2007 11:43 AM

Please search for pedja rodgic buffer in this thread... I have tried a bunch of the diy pre's and this is my favourite, also very easy to breadboard, and very cheap.... only a few cheap tranistors and a few caps... but it is almost blameless in quality... very fond of mine

jaya000 11th April 2007 09:50 AM

I searched pedja rodgic buffer, but no response.
waiting for some more circuits.
Discreet or opamp, both ok. with or without volume also ok.
The preamp i want to use will hv 12V supply but amp hv got built in supply. 5 gain will ok. i.e. 200mv signal will be converted to 1V.

AndrewT 11th April 2007 10:07 AM

CDP sends a signal with a peak voltage around 3Vpk.
that becomes 15Vpk into the power amp. It does not go!!!!
and cannot come from a 12Vdc power supply.

volume or not, discrete or opamp. Make up your mind.

juma 11th April 2007 10:21 AM


Originally posted by Nordic
Please search for pedja rodgic buffer in this thread...

It is Pedja Rogic, not rodgic
This is the link to his web page:

jaya000 11th April 2007 01:31 PM

my cd player has low output. The amplifier very low output. hence i thik that the output must be somewhere near 150~200mv. Hence thinking of using gain 5 preamp. Even less will be ok.
Discreet or opamp? I can use any of them which sserves my purpose.
Voume i can use if required.
Hope this clarifies what i want.

Nordic 11th April 2007 01:46 PM

My bad...

Here is the link

palesha 11th April 2007 05:44 PM

nordic, nice link. I want to use the same for my small preamp in fm modulator. Almost similar application as in this thread. The modulator IC TDA5664 is having low sensitivity in audio. so i want to add gain of 2~3. So i am also interested in this project.

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