Need Opamp Mic Preamp Circuit - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th July 2003, 12:34 PM   #1
diyAudio Moderator
 
JojoD818's Avatar
 
Join Date: Mar 2003
Location: searching...
Default Need Opamp Mic Preamp Circuit

Hi all!

I am in need of a circuit that would be used to amplify a microphone so that it can be connected to an amp. An opamp based preamp is what I need.

Any circuit schematics would be very helpful.

Thanks
JojoD
  Reply With Quote
Old 19th July 2003, 03:06 PM   #2
diyAudio Member
 
Join Date: Aug 2001
Location: Bath, UK
Hello JojoD,
Eric Wallin has a mic pre amp on his page. It uses four op-amps: one to buffer the voltage reference, one to do the amplifing and two to show clipping, all running off a single rail. It can be found here:
http://www.gti.net/wallin/audio/preamp2/preamp2.html

I've got a pre-amp on my webpage but the write-up isn't finished. It's a single op-amp running from a split rail. It can be found here (you want the circuit in the lower left corner):
http://www.apcl43.dsl.pipex.com/SW_jig.htm

R12 and C6 form a switchable gain stage and can be omitted if not needed.

Nice one,
David.
  Reply With Quote
Old 19th July 2003, 08:41 PM   #3
diyAudio Member
 
Edu Silva's Avatar
 
Join Date: Jan 2003
Location: Brazil
Default Re: Need Opamp Mic Preamp Circuit

Hi Jojo and all,

Quote:
Originally posted by JojoD818

Any circuit schematics would be very helpful.
You'll find something useful here:

http://www.epanorama.net/links/audio...ts.html#micamp

Hope this helps
  Reply With Quote
Old 20th July 2003, 02:46 PM   #4
diyAudio Moderator
 
JojoD818's Avatar
 
Join Date: Mar 2003
Location: searching...
Default Thanks!

Hi guys!

Thanks for the post, any other hidden schematics?

JojoD
  Reply With Quote
Old 20th July 2003, 07:59 PM   #5
Pedja is offline Pedja  Serbia
diyAudio Member
 
Join Date: Jun 2002
Location: Belgrade
JojoD, you did not tell us what the actual purpose of your mic preamp is.

Anyway, you can find one here.

Pedja
  Reply With Quote
Old 21st July 2003, 02:43 AM   #6
diyAudio Moderator
 
JojoD818's Avatar
 
Join Date: Mar 2003
Location: searching...
Default Hi

Hello,

I really forgot to post where I will use the mic preamp. Anyway, it's going to be used for a mixer that is a part of a PA system. They will use 600 ohms mics. It is preferable if the circuit is low distortion and uses an opamp (for ease of construction) and uses +/-15V.


JojoD
  Reply With Quote
Old 21st July 2003, 03:01 AM   #7
diyAudio Member
 
Edu Silva's Avatar
 
Join Date: Jan 2003
Location: Brazil
Default Re: Rane pro audio schematics

Hi, jojo and all

Quote:
Originally posted by JojoD818
Anyway, it's going to be used for a mixer that is a part of a PA system.
All you need is here:

http://www.rane.com

Select a product, scroll down to the end of the page and click on the schematic link.

Have fun!!
  Reply With Quote
Old 21st July 2003, 08:51 PM   #8
diyAudio Moderator
 
JojoD818's Avatar
 
Join Date: Mar 2003
Location: searching...
Default Hi again!

Hello!

I've already seen those mixers from rane and they really are great. I guess I'll just try some of their mic preamps.

Thanks again to all.

JojoD
  Reply With Quote
Old 24th July 2003, 05:48 PM   #9
diyAudio Moderator
 
JojoD818's Avatar
 
Join Date: Mar 2003
Location: searching...
Default more confusion

hi, i'm a bit confused...

I will be using a "dynamic microphone" for the preamp(schematic) i am asking everyone about. the question is this, a dynamic mic = unbalanced right? can I use this for a mic preamp that has a balanced input design? such as those used by rane?

i see that there are 3 pins from the bottom of the mic and 3 pins from one end of the wire that came with the mic. but the 1/4" phone plug at the other end of the wire only has 2 connections. tip and sleeve only, NOT tip-ring-sleeve.

this means that pin #3 from the mic is "ground", then if I plug this to a balanced input preamp, then the "negative" input of that preamp will be grounded right? is that the way it's done?

thanks in advance

JojoD
  Reply With Quote
Old 24th July 2003, 05:59 PM   #10
diyAudio Member
 
Sparhawk's Avatar
 
Join Date: Sep 2002
Location: Ontario, Canada
Default Re: more confusion

Quote:
Originally posted by JojoD818

i see that there are 3 pins from the bottom of the mic and 3 pins from one end of the wire that came with the mic. but the 1/4" phone plug at the other end of the wire only has 2 connections. tip and sleeve only, NOT tip-ring-sleeve.
The 3-pin connector on the bottom of the mic is a balanced XLR connector. Ideally, you would use an XLR <-> XLR cable, and plug it into a balanced mic input. The cable you have is converting the balanced connection to unbalanced, by connecting one of the balanced lines to ground, as you suggested. This will work, but will be much more likely to pick up noise and interference, especially with long cables.

If you're building your own preamp, you would be much better off building a balanced design and replacing the cable. You could probably just replace the 1/4" connector with an XLR, as long as the cable has two conductors plus ground.

You might also want to look at this thread.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simple 'treble cut' opamp circuit needed. HankMcSpank Solid State 10 20th July 2008 08:03 AM
TL071 opamp circuit needed space2000 Solid State 19 23rd May 2008 07:20 AM
Can anyone help with this opamp circuit? lt cdr data Solid State 4 20th May 2005 11:12 AM
Transistor/opamp circuit soundNERD Chip Amps 12 15th September 2004 03:16 AM


New To Site? Need Help?

All times are GMT. The time now is 02:16 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2