Jung/Markell Pre finished

I finally finished this pre, after putting it away for about a year. I designed a two channel board and had ExpressPCB make a few. I learned a lot about PCB design, mostly what no to do. The power supply is a home etch of Keef's dual rail supply.

I ended up using the recommended Jensen input transformers, JT16A, and switching jacks for unbalanced or balanced (via Edcor WSM600:600 transformer) outputs. I will be testing the difference between the outputs later.

This is a great sounding pre. I used it for makeup gain after my passive summing mixer, and tested on vocals with a heavily modified ADK tube mic and a ShinyBox 46 ribbon mic. Sorry, no pics or samples yet. I just wanted to say "HOT DAMN this sounds good!"

Background in this thread:
http://www.groupdiy.com/index.php?topic=8626

Edit: I can't believe I forgot to say; Thanks to everybody who offered analysis and advice! Thanks to Misters Jung and Markell for a great design, pstamler for explaining input transformers to me, bcarso for advice on the current source semi-diodes, dale for actually building it long ago, and peterc for collaboration, encouragement, and trying to understand my first attempt at the PCB design. Thanks everybody!!!

Is this the schemo ? (the links in the thread you mentioned are not working here.)

http://waltjung.org/PDFs/LT1115_Mic_Preamp.pdf

=FB=

edit: I have some MCI output Xformers. I'm looking for a pre to build...maybe the one you did, or with an ad815ay, but that's a bit off-topic...page 13...
http://www.ortodoxism.ro/datasheets/analogdevices/163971262AD815_b.pdf

Yep, that's the one. I did some brief testing, and I think the unbalanced, transformerless outputs will be used most of the time.

I see several differential conversion schemes in that AD815 sheet, are you thinking a transformerless input?

The Jung/Markell is such a clean amp that you could put different transformers on the ins or the outs, and you would know that any coloration is from the transformers. That was my thinking with the inexpensive Edcor option on the outs.

Overall, this is a really inexpensive preamp for its performance. I spent $17 on the ICs, $35 to have the boards made, maybe $20 on caps/resistors/switches/regs, and $2 for a case. The only pricey part is the transformers, which I spent about $140 on. You could get a pair of Cinemag CMMI-2 for less, and I'm sure the performance would be on par.

[quote author="Freq Band"]Is this the schemo ? (the links in the thread you mentioned are not working here.)[/quote]
Yep, I removed these files when Walt Jung showed up here and indicated he rather provided them himself. His article-version is cleaner as well.

Bye,

Peter