DIY Line Output Converter W/ DSP Module
#1
DIY Line Output Converter W/ DSP Module
Sticky? ![thewave](https://g35driver.com/forums/images/smilies/th_wave.gif)
Credit goes to minivanman over on mobilesoundscience
I don't know if this falls in the low cost necessarily, but it is high value. Here is a complete module that operates as a line output converter (LOC), and a digital sound processor (DSP)
The goal of this project was to build a unit that could convert the speaker level outputs of my stock head unit and supply a line level signal to a miniDSP module.
http://www.minidsp.com/onlinestore/c...7/minidsp-kits
http://www.mobilesoundscience.com/f4...-work-you-257/
Typical car audio branded LOCs generally have a limited bandwidth, and even within that bandwidth, the signal isn't very flat. All an LOC is is a group of small transformers that step down the voltage to a line level, and provide ground isolation. Since consumer car audio LOCs utilize such small, and inexpensive transformers, you'll get the limited bandwidth I was talking about. For example, David Navone brags that his LOCs exhibit bandwidth extending down to 80 hz. Roll off after that occurs at 12 db/oct, so by 20 hz, you're 24 db down in output. Usable, but we can do better, albeit with a considerably higher cost.
Now in come the pro grade transformers. These are not cheap, but they exhibit a full audio bandwidth between 20-20khz, and the signal is flat. The most respected, and popular are made by a company called Jensen (not to be confused with Jensen Car Audio).
http://www.jensen-transformers.com/
I decided to use a JT-10KB-D transformer for this project based on a very simple schematic that Jensen provides on their website for a LOC. The schematic is listed under application AS068.
http://www.jensen-transformers.com/apps_sc.html
Since the power being supplied in this application is fairly small, it was very easy build. In fact, technically, you could just run this transformer without any additional resistors. I put some on the back purely for protection sake.
![](http://img.photobucket.com/albums/v641/glevii/hpim2176.jpg)
Here are the transformers. You can fit about 4 transformers from a car audio branded LOC into one of these.
![](http://img.photobucket.com/albums/v641/glevii/hpim2178.jpg)
Here's the input plug. Simply two runs of speaker wire, and a 12 volt power, and a ground wire.
![](http://img.photobucket.com/albums/v641/glevii/hpim2179.jpg)
Output side.
![](http://img.photobucket.com/albums/v641/glevii/Measurements/hpim2180.jpg)
Total this project costs about $225.00. With another DSP module this could easily run a full 4-way setup for under $350.00.
![thewave](https://g35driver.com/forums/images/smilies/th_wave.gif)
Credit goes to minivanman over on mobilesoundscience
I don't know if this falls in the low cost necessarily, but it is high value. Here is a complete module that operates as a line output converter (LOC), and a digital sound processor (DSP)
The goal of this project was to build a unit that could convert the speaker level outputs of my stock head unit and supply a line level signal to a miniDSP module.
http://www.minidsp.com/onlinestore/c...7/minidsp-kits
http://www.mobilesoundscience.com/f4...-work-you-257/
Typical car audio branded LOCs generally have a limited bandwidth, and even within that bandwidth, the signal isn't very flat. All an LOC is is a group of small transformers that step down the voltage to a line level, and provide ground isolation. Since consumer car audio LOCs utilize such small, and inexpensive transformers, you'll get the limited bandwidth I was talking about. For example, David Navone brags that his LOCs exhibit bandwidth extending down to 80 hz. Roll off after that occurs at 12 db/oct, so by 20 hz, you're 24 db down in output. Usable, but we can do better, albeit with a considerably higher cost.
Now in come the pro grade transformers. These are not cheap, but they exhibit a full audio bandwidth between 20-20khz, and the signal is flat. The most respected, and popular are made by a company called Jensen (not to be confused with Jensen Car Audio).
http://www.jensen-transformers.com/
I decided to use a JT-10KB-D transformer for this project based on a very simple schematic that Jensen provides on their website for a LOC. The schematic is listed under application AS068.
http://www.jensen-transformers.com/apps_sc.html
Since the power being supplied in this application is fairly small, it was very easy build. In fact, technically, you could just run this transformer without any additional resistors. I put some on the back purely for protection sake.
![](http://img.photobucket.com/albums/v641/glevii/hpim2176.jpg)
Here are the transformers. You can fit about 4 transformers from a car audio branded LOC into one of these.
![](http://img.photobucket.com/albums/v641/glevii/hpim2178.jpg)
Here's the input plug. Simply two runs of speaker wire, and a 12 volt power, and a ground wire.
![](http://img.photobucket.com/albums/v641/glevii/hpim2179.jpg)
Output side.
![](http://img.photobucket.com/albums/v641/glevii/Measurements/hpim2180.jpg)
Total this project costs about $225.00. With another DSP module this could easily run a full 4-way setup for under $350.00.
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