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FREE PCB for 4-channel gain stage with onboard power supply

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I developed a 4-channel gain stage PCB that has an onboard PCB. Info and performance measurements can be found at the end of this thread:
http://www.diyaudio.com/forums/mini...in-stage-dc-servo-minidsp-11.html#post4161804

Since it's the holidays I have decided to offer the PCB for free (for now). You just pay the shipping cost. I will Email a copy of the BOM using Mouser part numbers but you are welcome to get the parts anywhere you like. In return for the free PCB I would ask that you build the board, give it a try, and then give me your feedback.

Send me a PM or EMail if you are interested.

Happy Holidays!

-Charlie
 
Description and Background of the gain stage board:

This was originally designed for the purpose of increasing the maximum output voltage of a miniDSP 2x4 crossover. The circuit provides additional gain and headroom with low distortion and noise, and makes the 2x4 work better with your amplifier. The builder can choose the gain level. Choose enough to raise the voltage level as needed, keeping in mind that this also raises the noise floor from the upstream components (e.g. the miniDSP) by the same amount.

The board can be used as a gain stage for any purpose, for instance as part of an analog preamp. If only 2 channels are needed, you can populate the board with only one of the op-amps and associated components.

The board has "DC power" connections. When the PS components are included, the power connections can be used to power other circuits. The onboard PS uses 317/337 regulators and employs CRC arrangement of the smoothing caps to reject power supply related noise and harmonics. The builder can choose the voltage of the supplies to match their needs and/or the transformers that are used. Alternatively, an external power supply can be connected at the "DC power" terminals to power the board. In that case only local 220uF reservoir caps are used and the other PS components can be omitted.

The board measures 4"x4" (102mm x 102mm). A picture of an example of the board, with PS components, is attached.
 

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Hi Charlie,
This is awesome. I'd like to buy a board or two, if they're still available. Before I do, I'd like to run my use case past you and see if it makes sense.

I'm building an integrated amplifier with four channels of MyRef RevC amplification. Within my integrated amp, I plan to use a miniDSP 2x4, kit version, as an electronic crossover. I'm using a Twisted Pear Darwin to handle input selection. Output from the Darwin will feed a Pass DIY B1 buffer which will feed the miniDSP 2x4. The outputs from the miniDSP will feed my four channels of amplification.

Reading about the miniDSP, I've been hearing cases of distortion and overdriving of its outputs. Your board seems to be the perfect solution to these problems.
thanks,
Marc Brown
 
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