New preamp builds Jung-Markell and THAT1512 - Samples added!

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skipwave

Well-known member
Joined
Jul 8, 2005
Messages
1,416
Location
Los Angeles
A couple new boxes finished. These both sound amazing, I'm very pleased, although the Jung-Markell stands out. In a brief test on acoustic guitar it really captured all of the natural overtones and harmonics that other preamps don't translate. The THAT1512 pre was close, very fast and clean, maybe just a touch bright sounding because of the speed and surgical precision of it.

THAT1512 pres on top, PCBs from mcs. Unbalanced outs, but plenty of room for add on balancing measures, thanks to Mikkel's great board layout. More people should consider these for a project, his kits are inexpensive and a quick build, despite the SMD gain setting resistors. I was proud that I only lost one (though I was scouring the floor at least three times for runaways), and easily subbed a regular leaded resistor.
Kits here, click "THAT Preamp":
http://electronics.dantimax.dk/Kits/Preamps_-_poweramps/index.html

Jung-Markell pre on bottom, my PCB design (and not a very good one at that, was difficult to work with). Jensen input transformers, Edcor outputs, with unbalanced output via switching jacks.
http://waltjung.org/PDFs/LT1115_Mic_Preamp.pdf

jung_that_pres.jpg


that_pre_inside.jpg


jung_pre_inside.jpg
 
Full details on the THAT pre in this thread:
http://www.groupdiy.com/index.php?topic=10417&start=30

And its evolution into a mixer design in this:
http://www.groupdiy.com/index.php?topic=19888&start=15

The THAT pre really does sound good, and the kit makes it a quick build. I hope people consider it along with the usual suspects for a transformerless preamp, like the GreenPre.

The Jung-Markell also delivers amazing quality for low cost and non-complexity. I might build another pair with Cinemag CMMI-2C, which are probably right on par with the Jensen and considerably less expensive. Although, it would be really nice if someone offers quality PCBs. I used one that I designed and had ExpressPCB make. It really made me appreciate the luxury of professional PCBs, with solder mask, plated through holes, and more spacious layouts.
 
Nice job, Skipwave!

Any project that gets finished and working is a GOOD project, imo. And not a bad job for your first layout! You should try home etching...that's a lot more "fun".

Peace!
 
Thanks guys!

I plan to home etch some simpler designs, but the Jung-Markell pre really needed dual layer, ground plane construction. I came off overly critical of my PCB layout, it works well, I just wanted to preempt any requests for the layout, because it should be reworked a little. The Jung-Markell design really does sound great!

The 1512 is impressive. I'm thinking of adding the THAT1646 on the output, after reading about all the cool things Roger and Wayne are doing with it. For now I just run it to 6k-10k inputs.
 
Nice to see my boards used in projects other than my own :grin:

Glad you like them!

I'm currently finishing the 10-channel mixer version...

Best regards,

Mikkel C. Simonsen
 
I noticed this post earlier today and figured since I didn't have anything else going on I'd design a PCB for the LT1115 pre.

Here is the schem and PCB:




If anyone notices a problem with these let me know and I will fix it. Any and all suggestions are welcome. I don't have the finances to get a batch made but I will post the gerbers and and artwork for anyone who wants them.

JL

I updated the images. I'm etching a prototype and ordering the parts. I'll let everyone know how it's going. Once I have it built I'll put it on the Neutrik A2 and see how it specs out. If everything is okay I'll put together an order for some PCBs if anyone is interested.
 
You might try doing what I did on the Gamp supply board and am now doing on the Tri-Way supply board: put together a one-time group buy with other forum participants. The more people sign up, the cheaper each board is. That way we share the set-up costs.

Peace,
Paul
 
Bigugly - That layout looks pretty similar to mine, though better component distribution. I squeezed a pair of pres onto a small board.

Paul - I owe you special thanks for answering my questions in the original Jung-Markell discussion thread. I learned a lot from tackling this design.
 
Samuel,

I don't know. I really didn't study the schematic. I just copied it, from the pdf, verbatim into Proteus so I could make a PCB layout. I thought it was odd too, but I figured the original designers knew what they were doing so I left it in.

James
 
[quote author="guavatone"]Thanks, that was quick! 2 small problems though..... both files are not dl-ing[/quote]

EDIT: Like I said; Samples gone.
 
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