PI7293

PCB

The layout of the PCB is well-spaced, with the important components as near to the 3 TDA7293 ICs as possible. Having a professional-done PCB means that we can use double-sided PCB, thus allowing us to use almost no jumpers yet have a short path for the signal. The input signal have a very short path to the master TDA7293 IC.

Even though it looks spacious, the size of the board is only 16.5x7.3cm.

The design highlight of the layout is in the very careful layout of the ground returns. Note in particular the very explicit "star" ground you see in the lower half of the board.

The construction of the amp is very straightforward; it can take less than 10 minutes to populate a board.

The PCB is available here.

Power Supply

We use individual diodes as bridges, having 2 bridges for each channel. Any series of the MUR can be used, as long as the diode reverse voltage is above the voltage of the transformer output. We chooses MURs from onsemi due to their fast recovery time, and low voltage dropout. However you can use any other diode you like. Heatsinking the diodes is optional, as they do not get warm at all.

The PCB of the power supply allows us to use any size of caps after the bridges, up to 4 20000uF as long as they fit well on PCB. We can add another 2 smaller caps when needed.

This power supply board can also be use for other purpose if needed, e.g. other DIY amps or other preamps that I might build in the furture.

I etched the PCB at home using photosensitive boards. The size of the board is 15x10cm.

Construction

As I am still constructing my DI-Pre, another friend of ours, CGH, have completed the amp before I could even start with mine, the pictures of his completed amp can be seen here. After hearing it, I like it a lot that I will be building mine soon (as soon as I find time)

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