[KevC]

I'm looking to build a DIY Power Supply for my Fubar II. I personally have zero soldering experience but my friend has his whole physics lab at his disposal so that should be good.

What makes a good PSU? The requirements for the Fubar II (looking at the Supplier) is a 24VDC; 500mA max. output. I wont be taking her overseas so all I need is 110V input.

I heard you should avoid switchable PSUs?

How about building a good PSU for a T-Amp? What components are necessary?

 

[Garbz]

If you have no experience I would highly suggest you should try something that can not KILL you if you make a mistake. I'm not joking either, there are a lot of people who in the quest for good sound on forums do downright stupid things like disconnecting the safety ground not knowing any better. Even if it does improve the sound if this is your thinking you should not attempt a mains project.

Now that little disclaimer is out of the way your basic PSU is simple. 240V input, stepdown transformer, filter capacitor, regulator. This can ofcourse get very complicated if you wish it to adding things like mains filters, constant current sources, etc, but the basic principles still apply.

An ideal powersupply will deliever its voltage regardless of conditions. These unfortunately do not exist. There are always limitations on current noise impedance etc.

An audio powersupply should ideally be of a low noise, low impedance design. Switching supplies have noise in the Mhz range, and while it can work pretty well the mere principle of its operation normally makes it taboo for audio electronics. Also in the worst case I think it may be able to push an device into instability.

The STEPS or TREAD powersupplies at www.tangentsoft.net would be a good start.

 

[tangent]

Quote:

Originally Posted by KevC What makes a good PSU?

Low noise in the audio band, and low output impedance so the varying current load can't modulate more noise into its output. This implies that it be regulated.

Quote:

I heard you should avoid switchable PSUs?

"Switchable" is an ambiguous term.

If you mean switching power supplies, then no, don't rule that out absolutely. It all depends on quality and design choices. I built a DIY switcher once that had only a 30 kHz operating frequency, and you could clearly hear a buzz in the headphones; totally wrong for audio. On the other hand, Kevin Gilmore specified some high-end switchers about a year ago for one of his amps, and Gilmore wouldn't do something like that if he didn't know it sounded good.

If you just mean a DC power supply with switchable output voltages, the only reason to avoid those is that they're ususally either unregulated or low-end switchers.

Quote:

How about building a good PSU for a T-Amp?

You want decent performance at high-frequency as well as in the audio band, because that's a digital amplifier. Because it will be sending noise back to the power supply at high frequencies, I would seriously consider using a power supply with an AC line filter on it to prevent that noise from being pushed back through the power supply and onto your home's power system, where it will get into all the other audio equipment.