Opamp for Mic preamp

-_nando-_ · 11th August 2011, 06:07 PM

Hi there!

I'm about to design a microphone pre-amp based on a typical "3 amp instrumentation amplifier". Cost is a big concern. For an input impedance of 600Ohms, which opamp would be quieter, the NE5532 or TL072?

Thanx!

simon7000 · 11th August 2011, 08:37 PM

5532 would be quieter but will pick up RFI.

-_nando-_ · 11th August 2011, 09:27 PM

Well, I use to put a ferrite bead and capacitors at the input, I think that it can fix the RFI problem. I'm more concerned about which one has better CMRR and is more silent using a low impedance at the input. Any ideas and opinions are welcome!

SY · 11th August 2011, 09:34 PM

Quote:

Originally Posted by -_nando-_

Hi there!

I'm about to design a microphone pre-amp based on a typical "3 amp instrumentation amplifier". Cost is a big concern. For an input impedance of 600Ohms, which opamp would be quieter, the NE5532 or TL072?

Thanx!

An SSM2019 or THAT1512 is still pretty cheap and will perform enormously better.

Michael Bean · 09:36 PM

Ne5532 is the best choice of the two. But SYs suggestion is better than either.

Mike

-_nando-_ · 12th August 2011, 02:25 AM

Quote:

Originally Posted by SY

An SSM2019 or THAT1512 is still pretty cheap and will perform enormously better.

In which terms you mean? Noise only? Because these specific chips are nothing more than the typical 3-amp configuration, but of course, with laser trimmed resistors. I think I can get away with the NE5532 + 0.01% resistors and it will be better than many mic pre-amps out there...

SY · 12th August 2011, 02:56 AM

Noise, distortion, common-mode rejection. And no need for 0.01% resistors- the internal matching and thermal tracking is better than you can do with discrete (unless you want to get super exotic and expensive).

stellavox · 12th August 2011, 11:55 AM

I've just finished a THAT1510 design and can say that it sounds wonderful. PLUS, their website has a number of great application notes about the intricacies of mike pre designs - keeping high CMRR; balanced / unbalanced operation; phantom power; etc.

Charles

11th August 2011, 09:34 PM	#5
Michael Bean diyAudio Member Join Date: Sep 2004 Location: Minneapolis, Minnesota, USA	Ne5532 is the best choice of the two. But SYs suggestion is better than either. Mike Last edited by Michael Bean; 11th August 2011 at 09:36 PM.

12th August 2011, 02:56 AM	#7
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Noise, distortion, common-mode rejection. And no need for 0.01% resistors- the internal matching and thermal tracking is better than you can do with discrete (unless you want to get super exotic and expensive). __________________ “There are no greater liars in the world than quacks, except for their patients.” - Benjamin Franklin

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11th August 2011, 08:37 PM	#2
simon7000 diyAudio Member Join Date: Nov 2008 Location: Oakmont PA	5532 would be quieter but will pick up RFI.

11th August 2011, 09:27 PM	#3
-_nando-_ diyAudio Member Join Date: Dec 2005 Location: Sao Paulo	Well, I use to put a ferrite bead and capacitors at the input, I think that it can fix the RFI problem. I'm more concerned about which one has better CMRR and is more silent using a low impedance at the input. Any ideas and opinions are welcome!

12th August 2011, 11:55 AM	#8
stellavox diyAudio Member Join Date: Jan 2007 Location: Oneonta, NY; USA	I've just finished a THAT1510 design and can say that it sounds wonderful. PLUS, their website has a number of great application notes about the intricacies of mike pre designs - keeping high CMRR; balanced / unbalanced operation; phantom power; etc. Charles

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