Power amplifier based on dx1000 class D amp


2010-05-16 7:05 pm
Here I wanna to share with you my new construction - class D power amp based on dx1000 amp. Let's get straight to the point :)

Giver housing was broken amplifier QSA . It didn't require too many alterations and it has enough space. Another advantage is that it is ventilated and has all needed inputs/outputs - input jacks ( XLR jack 6.3 ) output sockets / speakons, the preamp section with limiter.


I bended a little the plate, which was inside . I could say that it serves as a shield and a handle for attaching cables.


Power supply
I used serial switching power fromt the QSA amplifier, which immediately after purchase required minor repair - replace rectifier bridge - because he was flying a frivolous housing . ; ) As for the SMPS design, it looks like a half bridge with core etd49, I don't know which power switches was used – since model are wiped out . It is assumed that the standard sg3525 + driving transformer + secret power switches.

Power amplifier
Finally I decided to built dx1000 . Why? Because this is tiny, furiously red and for this size hellishly strong amp - apparently without hesitation reaches 1000W / 4ohms and it sound so good as AB class amplifier or even better.

Power amplifier modules
Both amplifiers started working almost immediately. What I like is that I didn't have to choose elements, pair transistors , etc . etc. - of course, I used the elements exactly as in the specification – DX audio don't recommed to replace some of elements such as transistors or drivers , because the rise time , the gates capacities , etc. etc. Original parts are available, so don't care.

And what I liked the most is that you don't have to do ANY type of calibration such as dc -offset, or adjusting bias so hated by many electronics hobbyists.


Some photos from assembling


Protection systems
dx1000 has own, onboard protections, but for safety I added DC-protection using relay and UPC1237 IC


Mounted amplifier



The first test and listen
Amplifiers has started working up without any problems. Large resistors and radiator heats up quite significantly, but in conjunction with the fan their temperature drops. Also output choke considerably heats up but DX said this is normal.

I made a test of power with dummy resistive load of 4 ohms, with a supply voltage of approx. 2x80VDC amplifier generates approx. 600W in the whole bandwidth. At the "bottom " band I noticed very minimal buspumping. Given the fact that it is compensated by the drop voltage power supply, it does not have to worry about.

I also tested it with speakers – it sound really really good with excellent dynamic and great low tones. The rest of the band is also very selective. The amplifier minimal hisses but with these powers is rather normal.

Link to the amplifier website project dx1000

Now I'll be gratefull for any comments and tips ;)
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