PSU for Tripath Amp3, where to start?

[michaelconnor]

Greetings all,
I've just finished assembling my 41Hz Amp3, and now I'm trying to decide how to power it. From all of threads I've pored through, it looks like the options are a 12v SLA battery with some input caps, or a 12-14.6v linear/switching regulated PSU.

The battery option seems simple enough, and supposedly it can last for several days of continuous use before it needs recharging. But that raises the issue; am I going to have to tear down my amp once a week to charge it? ..or are you guys installing some sort of a concurrent or switchable recharging circuit in parallel with the battery?

On the other hand, I feel pretty lost over all the regulated PSU's out there. I know this is the DIY forum, but building one from scratch seems a little intimidating to me. Are there any specific commercially-available PSU's that really unleash the full potential of the Amp3? What are you guys using?

I'm sorry if this has all been discussed at length before, but I've spent the last two weeks just reading through thread after thread and haven't found a clear consensus on what works best. I'd really appreciate some guidance. Thanks!
-Mike

[Pano]

Originally posted by michaelconnor
I've spent the last two weeks just reading through thread after thread and haven't found a clear consensus on what works best.

That's because there isn't one!

Go get one of these, they work really well. There are improvments you can make, but it will get you started down the right path.

BG Micro supply

[michaelconnor]

Originally posted by panomaniac

That's because there isn't one!

Thanks! I was beginning to suspect that is the case.

Are there any other components I should throw into the power line? There are (what appears to be) two radial input caps already integrated into the Amp3 board, so I shouldn't have to add any additional caps right? I just want to make sure I've covered all the bases.

[deandob]

For my amp3 I had a big improvement in the dynamics when I added a 1,000uF Panasonic FM capacitor with a parallel snubber (0.47uF polystyrene in series with 0.5 ohms) on the power supply input on the AMP3. As the quality of the power supply is important for Class D amps, this combination allows you to use a cheaper power source and still get a decent sound.

Its important that you mount these components close to the amp3 board.

You could also change the power supply decoupling caps on the amp3 board to better ones.

Regards,
Dean

[mourip]

Originally posted by michaelconnor
Greetings all,

The battery option seems simple enough, and supposedly it can last for several days of continuous use before it needs recharging. But that raises the issue; am I going to have to tear down my amp once a week to charge it? ..or are you guys installing some sort of a concurrent or switchable recharging circuit in parallel with the battery?

-Mike

Hi Mike,

I wired a charger to the case via a panel mount jack. Wire it internally to switch the battery between either the amp or the charger. If the amp is not on then the battery is charging. Here is a link to Batterymart.com which has good deals on sealed lead-acid (SLA) batteries.

http://www.batterymart.com/battery.mv?p=SLA-12V2-3

They usually have an appropriate charger listed at the bottom of each page. Don't forget to buy a cable with the charger. You can go as low as 1.3AH but 2 to 3AH is a nice size for a small case and still have good staying power. I have been running a tweaked SI T-Amp and a Scott Nixon DAC from SLAs for about a year and it works very well.

Having said all of this I just bought a 10A 12volt SMPS power supply from EBAY to see how that compares. Some folks feel that it sounds even better than batteries.

Half the fun is in trying different things out...

Good luck,

Paul

[michaelconnor]

Cool. I'll have to try that out.
What you're describing should look something like below, right?

......Vs ---|------------|---------------Vin
...............|................C (0.47uF)
...............C (1kuF)......|
...............|................R (0.5ohm)
...............|................|
....GND----|------------|--------------GND

[michaelconnor]

Okay, this should be fun. Since I despise wall-warts, I'm going to try and fit the DVE PSU, this battery and a charger into a hammond case. This way, I can experiment with sources, have portability, or use the PSU while the battery is charging. I'll have to post some pics when I get everything assembled.

I did the layout right on my desk because I'm feeling impulsive

It looks like some components will have to get a little comfortable, but we shall see...

[deandob]

Michael, yes, that is the config I use. Try it with & without, it made a difference for my setup but YMMV.

Regards,

[michaelconnor]

Getting there...

Well, I've started assembly, but I'm still waiting on a few parts, namely the AC supply. So far, the only problem I've encountered is that I've underestimated how much space would be needed to fit everything. To resolve this, I ghetto-rigged a wall-wart case to fit the lead-acid recharging transformer. It's all not quite what I was going for, and perhaps I was a little ambitious with the integration, but i suppose this is my first audio-amp build.

[Pano]

Hey, looks nice but...
That RCA next to the IEC worries me. For both safety and noise reasons. Can't you put the RCAs somewhere else?

If not, be sure to use good shielded cable and don't get your 120V into the signal lines!