Need PSU advice for 2x Class D amp modules

[thommy]

Hi,

I'm starting my first project - an integrated usb dac/dual mono class d amp.

I don't have any in-depth electronics knowledge but am handy with a soldering iron so it shouldn't be too difficult to get working and i have the dac/pre section running fine on the desk right now.

I'm looking for advice on what to use to power 2x L15D or CxD300 mono modules. The pre takes 12v so it would be nice to have provision to run that too. I am confused between smps and the use of transformers, and also even the word power supply sometimes - like what are these boards of capacitors that i have seen sitting in between toroidal transformers and amp boards?

As you can see I'm a bit of a newb, so any help is going to be much appreciated.

 

[nigelwright7557]

I prefer a linear supply to a SMPS.
A linear supply is less noisy.

You will need 400va transformer for each class d amp.

The pcb's with lots of capacitors on are the smoothing capacitors for a linear supply.

 

[thommy]

Thankyou Nigel.

400va per amp board. I assume that they would be taking DC so that's 400w for a 200w board? Please excuse my ignorance.

200w per side is far more than enough in terms of volume levels, but they were the smallest boards available for a dual mono configuration. If I never plan to run the amps at over 50% of their output would that still require 400w per side?

 

[nigelwright7557]

I assumed cd300 was 300 watts so add 25% for losses.

If it 200watts then 250VA per amplifier would be fine.
Or you could use one 500va transformer.
Some people prefer 2 transformers and others think one is OK.

 

[thommy]

Thankyou, that makes more sense. It's true that two individual supplies would give higher audio quality by increasing separation and stereo width, but at a less than £300 total cost for this project, the casing size and overall power consumption are more likely to be deciding factors than pure audio quality.

Therefore, a single 500va supply would serve both amps well for my needs, and is it as simple as wiring the +ve, -ve & gnd to both boards in a parallel configuration?

 

[nigelwright7557]

Use a bridge rectifier and at least 2 * 10,000uF capacitors for the supply.
Then as you say +, - and gnd go to both boards.

 

[thommy]

Thanks for your help Nigel