My DIY UcD400AD based Power Amplifier

Info: has been disassembled. Please see http://www.ulriklund.dk/?q=node/28

This Power amplifier utilises the UcD400AD modules, see also www.hypex.nl. The modules are based on the PWM-technology also known as class D. In Denmark the modules are resold by www.frequence.dk, where a discount can be achieved.

Figure 1: The fully operational and playable power amplifier. Soft starter, front
plate and final finish are not done yet.

The power amplifier is designed as a dual mono block with two separate power supplies where the only things shared are the soft starter, DC-filter, fuse and main power inlet. The power supply is somewhat over-dimensioned, see specs of the UcD module. The hole amp is fitted into a 19" 2U rack cabinet and is expandable to 5 channels. Furthermore most of the circuits' design have been found on the internet, as I saw no reason to reinvent the wheel ;-)

The used modules are as mentioned the UcD400AD modules from Hypex and can be seen on the two pictures below.


Figure 2: The modules seen from the front and back side

In order to transfer the heat from the modules and give them a solid base, they are mounted a piece of copper as seen below.


Figure 3: The UcD modules mounted on a piece of copper

Regarding the power supply different topologies are discussed at www.tnt-audio.com and the last one in part 3 is used.


Figure 4: The linear power supply, see also www.tnt-audio.com diagram 4

With reference to the article at tnt-audio the following main components were used (Total number of components for 2 channel):

* 2 x 625VA, 2x40VAC produced by Telema, see also www.el-supply.dk.
* 4 x std. rectifier bridges of 25A, 200V.
* 8 x 10.000 µF 63VDC capacitors, BHC Arevox, marked by yellow in the datasheet,
nothing special.

The rest is described at tnt-audio. My final PCB can be seen on the picture below and figure 1.


Figure 5: The final two power supply modules (everything after the rectifier bridges)

The design of the DC-filter has been taken from Per-Anders Sjöström and fitted to the components I had.
Components used:

* 2 x 10.000uF, 63V, Blue Roe capacitors
* 6 x ?? rectifier diodes

good picture needs to be taken
Figure 6

The internal wiring from the RCA plugs to the modules is solid CAT 5 Ethernet cable and the wiring for the modules to the speaker plugs is 6 mm² solid OFC Holfi speaker cable. The internal speaker wiring is soldered at both ends.

The sound

In short, when comparing the amplifier to my old integrated Holfi Integra there is simply more of everything, resolution, bass.... it simply sounds better in my ears and I like my new amp :-)
(more to come...)