rafafredd
Well-known member
EDIT:
As requested, here are the schematics:
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_input_Bodanga_BD180-P4.gif
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_amp_Bodanga_BD180-P4.gif
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_out_Bodanga_BD180-P4.gif
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I was looking at my pictures and found these. Been quite a while I completed this one, but I never posted it, so here it is:
designing:
boards:
got some really small things I call the "mini bloaks" made (16 of them) just to use the cut space of the DI input jack. Still saving these for a later project.
And the thing, finally done:
Internals:
components on both sides, YEAH!
Pretty crazy, hum? It is a simple discrete opamp schematic, but it has all you could think of in a single card with onboard power supply, FET DI and many options as output bias for nulling DC, transformer and impedance balance outputs, and lytics caps with proper DC float for good polarization. It was made to be cheap, so I had to go single board, and layout components on both sides. YES!
You can use any type of discrete opamps on it. mine is DIY Jensens 990s.
Input transformers must have dual primaries, like 50+50=200 ohms rated, so that the impedance option will work right. Channel 1 and 2 are using Hammond input transformers and 3 and 4 have TAMURAs. All outputs are PTC (Prototype Transformer Company) 1:1:1:1. I think these are quadfillar. Having more than four thousand audio iron collection, I had never heard of these before. Came from some vintage Hi and Low pass filters I have taken apart that came from Neil Young's old studios (they were in storage for years in fact). Measures very good and sounds wonderful.
The DI sounds trully fantastic, and you can use many types of FETs and BJTs for these. I am using 2n5457 and BC560B. Sounds good. I may try the toshiba transistors in the next build. I still have three boards left.
Tamura channels gets more use in the studio, but Hammond channels are far from bad. Did I ever metioned how much I love japonese iron???
Anyway, with all the big names we have in the rack nowadyas, like Altec, Gates, Langevin, UA, Brent Averil, Manley, Amek, Truesystems, etc, it's good to know that this preamp and DI is the most often used for tracking. 8)
That is it! Hope it inspires more DIY!
As requested, here are the schematics:
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_input_Bodanga_BD180-P4.gif
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_amp_Bodanga_BD180-P4.gif
http://img.photobucket.com/albums/v172/rafafreddy/TechTalk/audio_out_Bodanga_BD180-P4.gif
-------------
I was looking at my pictures and found these. Been quite a while I completed this one, but I never posted it, so here it is:
designing:
boards:
got some really small things I call the "mini bloaks" made (16 of them) just to use the cut space of the DI input jack. Still saving these for a later project.
And the thing, finally done:
Internals:
components on both sides, YEAH!
Pretty crazy, hum? It is a simple discrete opamp schematic, but it has all you could think of in a single card with onboard power supply, FET DI and many options as output bias for nulling DC, transformer and impedance balance outputs, and lytics caps with proper DC float for good polarization. It was made to be cheap, so I had to go single board, and layout components on both sides. YES!
You can use any type of discrete opamps on it. mine is DIY Jensens 990s.
Input transformers must have dual primaries, like 50+50=200 ohms rated, so that the impedance option will work right. Channel 1 and 2 are using Hammond input transformers and 3 and 4 have TAMURAs. All outputs are PTC (Prototype Transformer Company) 1:1:1:1. I think these are quadfillar. Having more than four thousand audio iron collection, I had never heard of these before. Came from some vintage Hi and Low pass filters I have taken apart that came from Neil Young's old studios (they were in storage for years in fact). Measures very good and sounds wonderful.
The DI sounds trully fantastic, and you can use many types of FETs and BJTs for these. I am using 2n5457 and BC560B. Sounds good. I may try the toshiba transistors in the next build. I still have three boards left.
Tamura channels gets more use in the studio, but Hammond channels are far from bad. Did I ever metioned how much I love japonese iron???
Anyway, with all the big names we have in the rack nowadyas, like Altec, Gates, Langevin, UA, Brent Averil, Manley, Amek, Truesystems, etc, it's good to know that this preamp and DI is the most often used for tracking. 8)
That is it! Hope it inspires more DIY!
