Preamp using LM386

JordiGPS · 2nd January 2008, 10:50 PM

Hi everyone.

First of all, this is my first post. Before posting this I've read a lot around here but I could solve my problem. Please help...

OK. Here we go. I need a preamp to raise output vol out from my CD changer before it is fed in the car HU. Before that, a "CD interface" (so are called...) does media interface (DIN 8 jack to radio input harness).

The problem in the chain CD changer- CD interface - Radio HU is that the sound level is too low. So I decided to implement a preamp before the CD interface.

My first design was based on LM386:

The results have been VERY disappointing. White noise was unacceptable (it was rather a hiss...).

My question would be: What if I used a MUCH better IC such as LME49710?

The above delivers 40 dB which is enough.

What do you think?

Minion · 2nd January 2008, 11:23 PM

The LM386 isn"t idealy suited for a low noise preamp...The LM386 is actually a low Power amp IC which is Internally Biased for single Supply opperation, They are used quite a lot in Distortion pedals because of there High current output and they actually sound OK when Clipped which is also probably why they are used in Distortion pedals but not good for a Low noise pre-amp.....

You should get better results with just about any Audio grade op-amp like the NE5534 or TL071 Or OPA134 or OPA627 or LM4562 ect.....

Nordic · 3rd January 2008, 11:13 AM

I agree , those are suitable for electric guitars etc... not hifi...

Pedja Rogic's J-fet buffer for dummies.

Have a look at the attached link for the best GC preamp, in my opinion... very low build cost... very high performance...

DJ Exprice · 3rd January 2008, 10:04 PM

Ew, LM386

2nd January 2008, 10:50 PM	#1
JordiGPS diyAudio Member Join Date: Jan 2008	Preamp using LM386 Hi everyone. First of all, this is my first post. Before posting this I've read a lot around here but I could solve my problem. Please help... OK. Here we go. I need a preamp to raise output vol out from my CD changer before it is fed in the car HU. Before that, a "CD interface" (so are called...) does media interface (DIN 8 jack to radio input harness). The problem in the chain CD changer- CD interface - Radio HU is that the sound level is too low. So I decided to implement a preamp before the CD interface. My first design was based on LM386: The results have been VERY disappointing. White noise was unacceptable (it was rather a hiss...). My question would be: What if I used a MUCH better IC such as LME49710? The above delivers 40 dB which is enough. What do you think?

3rd January 2008, 10:04 PM	#4
DJ Exprice diyAudio Member Join Date: Mar 2006 Location: San Francisco, California	Ew, LM386 __________________ The DIY Life "The "free energy" is used to power DVD rewinders and for bending spoons with one's mind." -DCPreamp

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2nd January 2008, 11:23 PM	#2
Minion diyAudio Member Join Date: May 2006	The LM386 isn"t idealy suited for a low noise preamp...The LM386 is actually a low Power amp IC which is Internally Biased for single Supply opperation, They are used quite a lot in Distortion pedals because of there High current output and they actually sound OK when Clipped which is also probably why they are used in Distortion pedals but not good for a Low noise pre-amp..... You should get better results with just about any Audio grade op-amp like the NE5534 or TL071 Or OPA134 or OPA627 or LM4562 ect.....

3rd January 2008, 11:13 AM	#3
Nordic diyAudio Member Join Date: Sep 2005	I agree , those are suitable for electric guitars etc... not hifi... Pedja Rogic's J-fet buffer for dummies. Have a look at the attached link for the best GC preamp, in my opinion... very low build cost... very high performance...

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