Hodge-podge Mic Preamplifier

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

fuzzedout

New member
Joined
Aug 10, 2012
Messages
2
Greetings,

I was recently given a couple of input transformers and monolithic TOA audio opamps salvaged from a TOA board. Is it possible to cobble these together and make an very primitive (lo-fi) API style mic preamplifier on the cheap? I have a 500 series lunch box with two open spaces and would love to have it fully loaded. The only problem is that I don't know where to begin. I know that Eisen Audio had a DIY 500 series kit a while ago but it was discontinued in 2010...

Any help would be highly appreciated!

Thanks,

fuzzedout
 
It's definitely possible.  Since they were given to you, it can't hurt to try. Also since you already own a rack, the difficulty of the power supply is taken care of.

Do you know anything about the unit they were salvaged from?  A little backstory would go a long way to help you know if the transformers are line input 1:1 ratio or mic input - 1:8 / 1:10 or thereabouts.  In a best case scenario, the input transformer and opamp were made to go together to form a mic pre. If that's the case, you can probably follow the basic API 312 schematic and cobble something together.

You could use a API style breadboard, like the one from AML:
http://www.diyrecordingequipment.com/projects/aml-500-series-51x-alliance-breadboard/

Although that may not be economical given the current euro-to-dollar ratio and shipping from the UK. Perhaps just the edge card adapter and some other flat board would do. Like this one from Jeff:
http://classicapi.com/catalog/product_info.php?cPath=87_88&products_id=164
Along with an L-bracket:
http://classicapi.com/catalog/product_info.php?cPath=87_88&products_id=181

Are you still considering doing it? If so, post here, we'll walk you through it.
 
Back
Top