[steinba]

I'm putting together a "laptop sound survival box" consisting of a Tread, a pimeta and a Bantam dac. I'm going to pick up a wallwart/psu for it. Would something like this be OK?

Clas Ohlson - Batterieliminator, batterieliminatorer

(Sorry about the norwegian)

It claims to output max 2,75A at 24V. "Stabilized voltage".

I assume it outputs DC. I don't know if it's a switching psu or whatever. Does it matter?

If switching is OK, then how about this;

...Er, sorry. Can't link directly. Look at https://www1.elfa.se/elfa~ex_en/b2b/start.do and search for 69-847-79 please.

Oh, and BTW: what current/power will the wallwart have to deliver? Will 10VA suffice? 500mA? Please bear with a noob and explain this to me, someone.

Thanks in advance.

 

[Juaquin]

Switching is ok if you're going to filter through the TREAD, although I wonder why you don't just use USB power if you want a portable laptop rig - Tangent's PIMETA2 page says "Supply voltage can be as low as 5 V, with suitable part selection". You could also use a boost converter and boost the USB 5V to something higher if you don't want to use the low voltage parts.

Either way, I can't imagine the PIMETA drawing more than 300mA so just about any power supply out there should work ok if you go that route.

 

[steinba]

Thanks. No, it won't be portable. It'll stay on my desk at work. Anyway, it's an interesting thought.

 

[tangent]

No, don't use a switcher. A TREAD's regulator is not fast enough to clean up high-frequency noise. It is designed to go after audio frequency noise, particularly AC line frequencies and the first few harmonics. That means you want an unregulated wall wart. That will be cheaper than a switcher, anyway. Plus, many switchers aren't isolated.

And no, don't use USB for powering a TREAD and/or PIMETA. Again, not isolated. It's tied to the same ground as the DAC's audio source, so it's likely to collapse the PIMETA's vground when you hook the two together, unless you do something like use a TosLink connection to the DAC.

These questions have been asked again and again, Steinba. Please search the archives.

 

[steinba]

Quote:

Originally Posted by tangent /img/forum/go_quote.gif No, don't use a switcher. A TREAD's regulator is not fast enough to clean up high-frequency noise. It is designed to go after audio frequency noise, particularly AC line frequencies and the first few harmonics. That means you want an unregulated wall wart. That will be cheaper than a switcher, anyway. Plus, many switchers aren't isolated. And no, don't use USB for powering a TREAD and/or PIMETA. Again, not isolated. It's tied to the same ground as the DAC's audio source, so it's likely to collapse the PIMETA's vground when you hook the two together, unless you do something like use a TosLink connection to the DAC. These questions have been asked again and again, Steinba. Please search the archives.

Thanks.

Sorry, but I did search. Maybe I gave up too easy.

So, a simple, cheap and unregulated "24V/550mA" DC wall wart like 69-812-60 on www.elfa.se will do, then?

 

[shake]

A linear regulated power supply is most idea.

 

[Juaquin]

Thanks to Tangent for correcting me about using USB power - forgot about the virtual ground.

This is a little off topic, but what if you used a boost converter from USB to say 12V? Most boost converters are isolated, correct?

 

[tangent]

Quote:

Originally Posted by steinba /img/forum/go_quote.gif Maybe I gave up too easy.

That seems probable.

Quote:

69-812-60

Looks sensible.

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif what if you used a boost converter from USB to say 12V? Most boost converters are isolated, correct?

I don't have a huge amount of experience with DC-DC converters. Most of the ones I remember looking at are not isolated, but if you found one that was, then yes, that should fix the problem. But then you have to deal with the noise the converter creates.