Author Topic: Looking to build a mic preamp  (Read 10689 times)

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TimWaldvogel

Looking to build a mic preamp
« on: November 17, 2010, 01:51:01 AM »
I want build a semi simple mic preamp. Balanced xlr in and out. Something with a simple power supply
I can buy from radioshack or use a guitar power supply up to 24v.
Preferably a transformerleas design but I wanna see those too.
Something that will pass or potentially produce phantom power.

I am also curious if there are any mic preamp kits where I can only buy the PCB and parts list. Then I can purchase my own parts.
Please help, thank you.
YOU KNOW WHAT THEY SAY ABOUT LARGE PEDALBOARDS....

.... I BET YOU WISH YOUR PEDALBOARD WAS AS LARGE AS MINE

Cliff Schecht

Re: Looking to build a mic preamp
« Reply #1 on: November 17, 2010, 03:38:59 AM »
Paia sells a cool tube mic pre kit ;).

mth5044

Re: Looking to build a mic preamp
« Reply #2 on: November 17, 2010, 10:10:29 AM »

Top Top

Re: Looking to build a mic preamp
« Reply #3 on: November 17, 2010, 03:18:37 PM »
The funny thing about the "$5" preamp is that if you add it up, he is suggesting you use NINE 9v batteries (four for the +/-18v and five for the phantom power).

That brings the total up to considerably more than $5  :icon_lol:

malrock75

Re: Looking to build a mic preamp
« Reply #4 on: November 17, 2010, 04:06:07 PM »
I've built 3 of these and they are an easy build.

http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=6

They are like a neve on steroids. Down the bottom of the page you have options. I went with the jlm14 and 99v op. You don't need a transformer they have a load of gain.
Mal

mth5044

Re: Looking to build a mic preamp
« Reply #5 on: November 17, 2010, 06:39:35 PM »
The funny thing about the "$5" preamp is that if you add it up, he is suggesting you use NINE 9v batteries (four for the +/-18v and five for the phantom power).

That brings the total up to considerably more than $5  :icon_lol:

Ehhh don't ya know everyone has a battery drawer?  :icon_lol:

Just kidding.. at the price ya might as well get the $30 one from MF, even if the tube might be a gimmick.

TimWaldvogel

Re: Looking to build a mic preamp
« Reply #6 on: November 17, 2010, 07:18:09 PM »
I like the idea of the cheap 5 dollar mic preamp. But it doesn't have a balanced output it seems. Any schematic where people have changed this?
Another thing is I would prefer not to build a power supply. I don't understand it very well as far as a power supply
YOU KNOW WHAT THEY SAY ABOUT LARGE PEDALBOARDS....

.... I BET YOU WISH YOUR PEDALBOARD WAS AS LARGE AS MINE


.Mike

Re: Looking to build a mic preamp
« Reply #8 on: November 18, 2010, 06:31:22 PM »
There's a DIY Green Pre page here that I have thought about building.

It has a single-sided transfer (archive) so you could make your own board. It does, however, require a +/- 15V supply.

:)

Mike

If you're not doing it for yourself, it's not DIY. ;)

My effects site: Just one more build... | My website: America's Debate.

therecordingart

Re: Looking to build a mic preamp
« Reply #9 on: November 18, 2010, 08:46:02 PM »
Hard to beat the JLM Audio Baby Animal pres or anything from Seventh Circle Audio. I've spent many hours building some snobby mic preamps, and I can't say enough good things about JLM Audio.

If you are on a budget you probably won't be able to build anything for less than you can buy the ART Tube MP (like $29). Like it has been pointed out, the "$5 mic preamp" costs much more than $5. You can build preamps similar to those that cost $500-$1000 per channel retail for about $200-$250 per channel (think Neve 1272 using Carnhill transformers).

« Last Edit: November 18, 2010, 08:50:27 PM by therecordingart »

Salvatore

Re: Looking to build a mic preamp
« Reply #10 on: November 19, 2010, 10:48:05 AM »
24 Volts ?

This is an interesting one, good quality and can be configured in many ways.

http://home.comcast.net/~markfuksman/hamptone.jpg

Mark Hammer

Re: Looking to build a mic preamp
« Reply #11 on: November 19, 2010, 11:05:55 AM »
Check out the manuals at the Rolls site.  A lot of their boxes include simple mic preamps and the manual includes the schematic.

TimWaldvogel

Re: Looking to build a mic preamp
« Reply #12 on: November 19, 2010, 08:26:04 PM »
lets say i DO decide to go with something i can operate on lower voltages using transformers. can someone recommend a way of getting some dirt cheap mic input and output transformers that sound pretty good?

cause a mic input and output transformer basically turns a balanced signal into a unbalanced and then the output transformers job is to put it back to balanced correct?

other than that its a fairly simple quiet opamp based gain circuit? maybe some cascaded opamps for  quieter gain.

but the transformers usually are passive correct? meaning i can simply run the opamps at close to their max voltage for high headroom and thats the key behind the whole thing?

maybe i should look into it more and someone could recommend me to an article where i could better understand the science behind it all

and PLEASE post some URLs for afforadable transformers


maybe this i found would work???

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=242-905
« Last Edit: November 19, 2010, 11:50:49 PM by TimWaldvogel »
YOU KNOW WHAT THEY SAY ABOUT LARGE PEDALBOARDS....

.... I BET YOU WISH YOUR PEDALBOARD WAS AS LARGE AS MINE

TimWaldvogel

Re: Looking to build a mic preamp
« Reply #13 on: November 19, 2010, 08:46:34 PM »
« Last Edit: November 19, 2010, 10:59:02 PM by TimWaldvogel »
YOU KNOW WHAT THEY SAY ABOUT LARGE PEDALBOARDS....

.... I BET YOU WISH YOUR PEDALBOARD WAS AS LARGE AS MINE

Salvatore

Re: Looking to build a mic preamp
« Reply #14 on: November 25, 2010, 09:20:45 AM »
As there are countless choices of different output/input transformers in all values, I would first choose a good schematic to build, and then buy a transformer with the exact specs the design needs.
A manufacturer of transformers who has a pretty good reputation for making ok transformers for not to much money is this one..

http://www.edcorusa.com/Products.aspx