Microphone preamp vero layout

[Freppo]

Hi there fellows

I made a layout for a nice microphone preamp and I though I'd share.

I realize that this might be alittle out of place for this forum..
But it would not have been possible for me without all the knowledge I've gathered from here. Maybe someone can get some use out of ut. :)

[Freppo]

It's based on the so called "5 dollar mic pre" which is a nice preamp. Better then most preamps that comes with your soundcard/interface. Check out the blind shootout on gearslutz where many choose this preamp over a very expensive (500$ +) preamp.

I modified it with an electronically balanced output which gives you about +6db extra output, which is in fact double the volume! Which also means reduced noise as you won't have to drive the preamp as hard (most preamp gets noisier at the top of the gain-range)

However, I wanted to keep it simple so I omitted the +48v components and the optional DC control loop.

Both IC's are avaliable as free samples from Texas Instruments.

Here is the layout


It's verified and sounds very good. I tested it with my regular +9v pedalsupply through a 18v changepump and a negative voltage inverter from Marks layouts. I haven't boxed it yet though, because i'm building a full channeltrip with EQ. Layout in the works for a Line Level EQ with sweepable midrange. Will share that one too when I have verified it.

[Freppo]

Oh, I almost forgot.

I though I would include a switchable -20 db PAD in my build.
Very useful when plugging in hot sources.

Here is how you make a -20db pad on a switch

cheers!
/ Fredrik

[adstrum]

Hey, very interesting  stuff.

One question: could you connect an electret microphone insert directly to the in+ and in- rails, or would you need to find some other way of powering the electret before connecting it?

[Freppo]

Hi

Good question. I don't think that will work, but i'm not sure.

[PStevenson]

no, you can't connect and electret straight to it because they need external power sources
I happened to do a similar microphone preamp a couple of years ago however you only need single supply to run it http://www.paulinthelab.com/2012/04/balenced-to-line-microphone-preamp.html