Audioguru's fabled preamp, plus more! A query

[lordfiend]

Hello All!

First of all I would like to thank Audioguru for making his TL071 circuit available to us and all forum members for being helpful for all the questions. I have been stalking the forums and finally made an account to ask a question. I am no electrical engineer and its been while I worked with them.

I want to scale the circuit using TL074 and make 4 channel preamp. 4 electret mics output 4 different outputs. I went this way instead of using 4 TL071 circuits just because this has only one IC. I wanted to know what changes do I have to make in the TL071 circuit if at all. Do I replicate the components used by the mics or is there some smart way to minimize the components.

Thanx in advance

Regards

 

[ronv]

You should be able to share some components. Post the schematic and we can have a look at which ones.

 

[audioguru]

Here is the original single preamp using a TL071 single opamp and it modified with four opamps using a TL074 quad opamp:

 

[lordfiend]

ronv - Sorry I was going to upload the circuit I came up with today but looking at audioguru's circuit, mine looks like a juvenile fatal attempt.

audioguru - Thank you for the schematic. I forgot to mention I made 071 and it works like a charm. I will try this and give feedback. I intend to convert the signal to digital and use speech recognition to convert speech to text and if I use LME49740 will it make a lot of difference?

Thank You

 

[audioguru]

The LME49740 is an excellent quad audio opamp, much better than the TL07x opamps. But its very high frequency response might cause oscillations if its circuit is built on a solderless breadboard. Its high frequency response also causes ringing and maybe oscillation if it drives an audio cable with a capacitance higher than 100pF so add a series 100 ohm resistor to its output when it drives a shielded audio cable.

Hee, hee. The LME49740 is not very old but its datasheet shows it being used as a record player or tape player (remember them?) preamp.

 

[abimanyu5]

you should minimize the existing components**broken link removed**

 

[audioguru]

you should minimize the existing components**broken link removed**

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