|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.189.134.122
The Teradak U9 linear ps finally arrived. Using the usb out (5v @ 800ma) I was underwhelmed.
I know this is a bit underpowered (the specs call for 2.1 ah I think) but I don't have anything plugged into the Rpi other than the dac. The Rpi does not power the dac and even the 5v signal comes from a battery (via split usb)
Anyway, the Teradak sounds too hifi and a tad mechanical. I prefer the apple iPad 10w power supply.
Who would of thunk it?
I do remember someone doing some research and coming to the conclusion that the Rpi sounded best with a switching ps.
I think I'll try an iFi next.
Follow Ups:
Some information that you might find useful. Not a complete copy due to the usual legal issues, but enough.
" ...
OK, we threw the Teradak PSU on the scope today ...
Whilst I didn't drag my SBTalong for testing the output of its USB port when fed via the SBT switching PSU, we did have an apple 5V USB power supply and a generic 5V USB power supply.
The generic power supply revealed around 250-300mV of noise under no load, and an increase over this figure when under load.
The Apple power supply revealed around 80mV of noise under no load, and an increase over this figure when under load.
The Teradak linear PSU showed 2mV of noise... but unfortunately this was the limit of our testing, as there was 2mV of noise with nothing connected to the scope. ..."
The Teradak is a rather basic PS and you shouldn't expect much from it.
It shouldn't sound bette than an Apple 10w iPad charger?
It's how your system interacts with it. A better PS can reveal gremlins elsewhere.
I'll try to comment being as cryptic and unhelpful as possible and yet still post something. ;-)
It could be that the 5V USB out on the U9 is an afterthought and not exactly worth the money if that's all you are going to use it for.
More interesting is that 'some' but not 'all' of the TeraDak supplies have a small blue pot inside that can be used to adjust the main (9V) output from some low number (less than a volt?) to 9V max.
If that's the case and you have a VOM handy...
Link below:
You can do much better if you DIY. The key is to start with a reasonable size TRANSFORMER. Then, you can order a stuffed and tested PCB from China and an aluminum case and you will still be out about $60.00 and some effort. The tricky part is finding the transformer. I bet there are a lot of discarded electronics from the 80's with good transformers in them.
I do remember someone doing some research and coming to the conclusion that the Rpi sounded best with a switching ps.Such is contrary to my experience with either the SB Touch or RPi. Or any audio component for that matter.
As for Teradak, this is the one I used for a while. A bit more than $44 though. :)
edit: As a point of reference, I have two lipstick sized batteries with 1A capability. You might try spending ten bucks on one of those.
Edits: 05/26/17
I'm 99% sure it was Larry Moore of Ultra Hi-Fi. I'll look tonight and see if I can find it.
Those batteries have nasty voltage regulators in them.....isn't that defeating the whole point.
I know it doesn't make any sense....but as son as I put the apple back in, everything sounded more natural. Obviously this is just my take,,,,no flaming arrows please.
There are also differences between batteries!
Some sound like crap others do quite well.
E.g. My Ankers sound much better than my Easy Accs.
Bottom line. You can't just talk about "Batteries" in general.
For sure these devices will kill your ground loops.
It's again about compromises and tradeoffs.
And then the regulator in a pre-DC stage is IMO of minor concern first of all. That's why I e.g. consider an LPS-1 nonsense.
If you're concerned about HF interference put a ferrite bead on the DC line and keep the cable short.
And again. My iFi iPower is better than any battery I had around.
But the battery was better then several linear supplies I had in my hand.
Enjoy.
The Anker showed up today. You are right. It sounds good.
I believe there is a way to power an Rpi (if you are using a hat) directly from the hat..bypassing the internal regulator of the Pi....I think
My Ankers sound much better than my Easy Accs
No idea why but I found the same. When I first tried an EasyAcc as a replacement PS for various devices, I quickly reverted to the linear PS but, when I later tried an Anker PowerCore 20100, I found that it sounds significantly better than even a decent C-L-C linear PS.
And then the regulator in a pre-DC stage is IMO of minor concern first of all. That's why I e.g. consider an LPS-1 nonsense.
I'm not sure what you mean by "the regulator in a pre-DC stage" but I am sure that it's nonsense to dismiss (yet again) a device you haven't tried or, I suspect, even seen.
I haven't tried the LPS-1 or the Anker on a RPi but I have compared them on several other devices, inc clocking and supposedly PS-immune isolation circuits. If there's one thing here that I am sure of, it's that there really is no comparasion between the two. It's fair to argue that the LPS-1 is too expensive for you to justify its use in your system but, honestly, if your RPi boxes don't sound better when driven by one rather than the likes of an Anker charger, something is amiss.
If you're concerned about HF interference put a ferrite bead on the DC line and keep the cable short.
Better than nothing I suppose but it's neither hard nor expensive to improve on that. See e.g. recent discussions of quad-core cables.
I'm actually not questioning the LPS-1 as a product (not in this post ;) ) , I'm questioning it as a technical solution.
Therefore there's IMO no need to even try it.
I'm questioning highest quality regulation in the first stage - and that's where e.g. an LPS-1 gets used - of a potentially 2 to 3-stage supply chain.
That just leads to "overregulation" of the whole chain. It just slows things down.
The probably much better approach would be to offer just the supercap buffer on the output - maybe as an option - the way a battery would be used.
Basically that's the way I'm running my supplies - after trying all kind of stuff over the years.
Enjoy.
I'm questioning [the LPS-1] as a technical solution. Therefore there's IMO no need to even try it.
There being no logical defence against solipsism, I'll not try to provide one.
That just leads to "overregulation" of the whole chain. It just slows things down.
If, as here, the OP impedance of the first device in the chain is lower than that of subsequent devices by an order of magnitude or more, your argument fails. Think about it.
Basically that's the way I'm running my supplies - after trying all kind of stuff over the years.
Absent detail, argument from authority doesn't impress. I stand to be corrected but, for all your undoubted expertise, you don't seem to grasp how a supercap device works or why they're unlike older PS designs.
"Those batteries have nasty voltage regulators in them....."
True. Not just nasty voltage regulators but switching regulators. You are not running purely on battery power with those USB battery devices.
....isn't that defeating the whole point. "
Sort of in terms of quality DC power.
The main technical advantage I can see in using a USB battery is that it is isolated from the AC mains. But you can achieve the same or better with a quality switching power supply or linear power supply on an AC power regenerator. I have the old PS Audio Power Plant P300 for AC power regeneration and isolation.
Those batteries have nasty voltage regulators in them.....isn't that defeating the whole point.is based upon the audible results, not an examination of the architecture.
I find the biggest difference in power supplies lies at the top - largely in terms of better ones lacking a sense of "false brightness".
Obviously this is just my take,,,,no flaming arrows please.
Whatever works! I'll have to give that a try for reference. :)
edit. BTW, one of the challenges with switchers is they tend to spew their noise back into the AC to be picked up by other components.
Battery supplies are isolated from such...
Edits: 05/26/17
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: