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diy hi end usb power cheap and easy

post #1 of 10
Thread Starter 

you need a Belkin F5U404v usb hub. OfficeMax,office depot,cdw etc. have it. it comes with a good linear psu. it also comes with a cable, a to mini. with the a side(to computer) of the supplied cable facing up towards you so you see the pins put a little piece of scotch tape on the pin all the way to the right. make sure the pin is completely covered with tape. now plug everything in as normal and use the usb cable of your choice. I recommend Belkin gold with this. you now have clean linear isolated +5v power that is not coming from the computer. even if your dac has self power it most likely still needs +5v from the cable to sync. do not tape the ground on the left. you can also use this trick to make a data only cable if you wish. they rarely work though. now for 20 bucks you have a comparable device others sell for $200+.. good deal. there is one caveat, with jriver at least sometimes I get an error once on start and it works the second time. do not plug anything else into the hub for best sound. it sounds real good.

post #2 of 10
Quote:
Originally Posted by music_man View Post
 

you need a Belkin F5U404v usb hub. OfficeMax,office depot,cdw etc. have it. it comes with a good linear psu. it also comes with a cable, a to mini. with the a side(to computer) of the supplied cable facing up towards you so you see the pins put a little piece of scotch tape on the pin all the way to the right. make sure the pin is completely covered with tape. now plug everything in as normal and use the usb cable of your choice. I recommend Belkin gold with this. you now have clean linear isolated +5v power that is not coming from the computer. even if your dac has self power it most likely still needs +5v from the cable to sync. do not tape the ground on the left. you can also use this trick to make a data only cable if you wish. they rarely work though. now for 20 bucks you have a comparable device others sell for $200+.. good deal. there is one caveat, with jriver at least sometimes I get an error once on start and it works the second time. do not plug anything else into the hub for best sound. it sounds real good.

Sorry, but maybe you should look up the definition of a linear-regulated wall adapter.  The Belkins come with typical switcher power supplies.  (It's the only way you can get 2.6 Amps into such a small walwart.)  Also, AFAIK, connecting the power adapter into the USB hub already disconnects the USB source power supply.  So, I'm not sure this really accomplishes anything. ;)

post #3 of 10
Thread Starter 

the wall wart is just an xformer and capacitor. same thing as ifi basically. the regulation is in the device. which is why I recommended this specific model. if you remove the wallwart it still operates on bus power. presence of the wallwart does not lift the +5v rail from the bus. it is a notch filter. taping the +5v rail made a large reduction in jitter per scope. excuse the Chinese.....http://www.cslog.cn/Content/usb-hub-charger/    keep in mind this is less than 15 bucks and made a measurable difference.

 

edit: I see that you know your way around a pcb so I did not mean to insult you. if you see something different than I do please say so. nonetheless as I mentioned it made a measurable difference in the noise floor.

 

the ifi psu is the same thing pretty much even though they would like to think not. I posted the internals of the isubpower elsewhere. the regulation is also in the device as well. not in the wallwart as with this Belkin. of course the ifi is better.  https://www.facebook.com/notes/ifi-audio/ifi-audio-ultra-low-noise-acdc-adapter/483150281720719


Edited by music_man - 2/5/14 at 8:55pm
post #4 of 10

OK, here's the thing: I apologize for stating that perhaps you didn't accomplish much.  That was an over-reaction by me and I shouldn't have said it.

 

However, I get worked up when someone throws around terms that are premium features in the audiophile DIY community.  "Linear-regulation" or a "linear" power supply is one of those terms.

 

The Belkin USB Hub that you reference has a switcher power supply, plain and simple.  Here's why:

  • The only chip on the USB hub's PCB is the GL850-series hub controller chip.  (You need some mix of transistors or an integrated circuit chip to provide a regulated circuit.)  The only chip on that hub's PCB has nothing to do with power regulation.
  • The power supply outputs 5V DC.  It can't be "just a xformer and capacitor" or it would be impossible to get DC.
  • The power supply is small.
  • The power supply has no cooling vents.
  • It's rated at 5V and 2.6A.  That's 13 Watts.  You would need a significant heat sink if the power supply was linear-regulated at that kind of current, or lots of vents in the adapter box.  A typical 24V, 0.5A linear-regulated power adapter  (that's 12 Watts) weighs over 1 lb. and is a 2" x 2-1/2" x 3-1/2" brick.  You can look at one here:

http://www.jameco.com/Jameco/Products/ProdDS/174861.pdf

It uses the 7824 power regulator.  The heat sink is part #18 in the datasheet and it's at the bottom of the adapter's box where all the vents are.

 

Now, I don't doubt that perhaps you've gained a measure of performance improvement and it shows up on your scope.  It's not linear-regulated, though, which offers magnitudes higher noise improvement when used in audio.

post #5 of 10
Thread Starter 

actually you are correct. I was mistaken and now I must apologize. i would like to know something. i do have two linear regulated power supply's on hand. both 1 amp and both weigh like 3 pounds. the problem is that one is 4.5v and the other is 6v. would either of these be okay to use? i don't know about undervolting or blowing it. i understand the usb hub is not as nice as your projects but heck i have the two psu's if i can use one. i think it will deal with 4.5,6 might kill it because you are correct there is no regulation on the pcb as i had thought. i swear i saw a set of zener diodes but i have to admit i was drinking last night. sorry. i understand this is not at all like your device, i did not insinuate a comparison.  i have the psu's so other than the wrong voltage i would like to see what happens.

thanks

 

wait, i just noticed my 15 year old psu's are from reliapro! what i am concerned about is i blow my new dac!


Edited by music_man - 2/6/14 at 4:58pm
post #6 of 10

4.5 volts is too low to meet the standard and 6 volts is way too high.

5 volts +/- 0.25 volts is the standard for USB 1 and 2 devices.

USB info

post #7 of 10
Thread Starter 

thank you. I have to hand it to you guys for making good stuff unlike this junk. the regulated psu is not so regulated. under no load on the 4.5 one I am reading 4.80 which should be fine. on the 6 volt one I am getting 6.34 which should kill something right quick. the psu that came with the usb hub is putting out 5.32vdc under no load. the regulated psu at least  I put a 500ma dummy load and it only dropped .05. also I do not see how the Belkin adapter is really 2.6 amps when a real 1 amp psu is five times it's size. obviously not quality stuff.

 

I was going to use the one that is putting out 4.80vdc/1amp at no load but I am guessing that is a bad idea. if I inadvertently plug something else into that hub.

 

 

--so I went ahead and used it. it did in fact make even more of a difference. the voltage is within spec. I swear I saw less than 1ps jitter out of this but I am in disbelief myself. this psu draws more ac current than the Belkin psu. in fact the Belkin says .5a in and 2.5a out. some sort of magic. I am not worried about a real 1 amp either. it only takes 300ma to charge a 18650 li-ion battery. I bet if I try to draw 2.5a out of it it explodes. however the usb spec does allow for 500ma per port. there are 4 ports. which I taped 3 of so I don't inadvertently use them. the dac I have only needs to see power to initialize. it is self powered anyways but I don't need to pollute it. I measured big differences at the port and out of the dac. I feel I really can hear it. for one thing doing this increased the dacs volume by 6db. I have no idea how that happened. I am pleased with this for almost no time and $15. nonetheless I am sure there is better.

 

I appreciate that you guys spoke with me regarding this. I saw your very nice projects.


Edited by music_man - 2/6/14 at 8:24pm
post #8 of 10
Thread Starter 

oops. my creation measures better than this $200 device. http://aqvox.com/usb-power_en.html probably due to the very good psu I just used. undervolting it does not seem to be a bad idea either. it is still within spec. make sure the usb settings in control panel if using windows are set right too.

still I think data isolation is the next step. I think I might build something of my own as well.


Edited by music_man - 2/7/14 at 6:43pm
post #9 of 10
Quote:
Originally Posted by music_man 

I swear I saw less than 1ps jitter out of this but I am in disbelief myself.

1 picosecond is equivalent to a resolution of 1 million megahertz.

1000 gigahertz.

What kind of equipment do you have that is supposed to see this small?

Think before you post, because people will soon lose patience with impossible claims.

I think your idea is fundamentally sound. If I were concerned about PSU noise on USB I would take a USB hub and supply it with a low-noise PSU, but the overall impression I get from your posts is not one that leads me to want to rely on your competence.

w
post #10 of 10
Thread Starter 

Tektronix. not mine. as i said i obviously read it wrong. seeing as that is beyond its resolution! therefore i don't know why i mentioned misinformation. honestly i would probably advise you to not always rely on my competence. i do not try to make purposefully false claims. i just tend to be careless. i am pretty handy with electronics but i rush things and often screw them up. i would ask that no one dismiss me as an idiot. just to use their own head. i did say i thought i was incorrect.

other than that i am glad you agree with what i did. i would like to filter the data as well. i feel it already equals many retail solutions of the like.

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