UREKA! UREKA! - USB Ports Dont Sing The Same

[kaushik]

I while ago i was fitting speaker banana plugs to the speaker cables ..obviously DAC was disconnected along with amp,
after the bannaas fitted i pluugged the dac to nearest USB port on my laptop .
whoa ,what happened to my wide open sound stage ? ! tried removing the plugs etc ...ah not at all mydaily source of music ....
as if some one have removed all good caps on amp and fitted 20 for 10 Rs capacitors ,i was about to conclude it my mistake but ...

after a while i plugged dac to leftside of laptop where i always listen from , wah :clapping:the dac guy started showing as many details i always get ..

so in short not all usb ports give good audio..... may be internal interface
makes this variation ..

happy for it

 

[BLASTO]

Check if the first USB is 1.0
Otherwise both are same. They transfer only bits..

 

[kaushik]

probably the bus interface matters , the one good sounding may be provided by a host controller part of main processor bus... other one is daisychained another root hub...probably it it the latency of usb commands or the internal power save modes of the Usb HC here playinga bad role...

this article in computer audiophile confirms same :A USB Port is Not a USB Port | Computer Audiophile

 

[Shivam]

I too have noticed the same thing and I always thought that it was due to my defective computer !!!

 

[Thad E Ginathom]

It may be. Defective by design, I'm afraid. See the comment on the above link relating to Intel design, and the stuff about DPCL, referred below.

probably the bus interface matters , the one good sounding may be provided by a host controller part of main processor bus... other one is daisychained another root hub...probably it it the latency of usb commands or the internal power save modes of the Usb HC here playinga bad role...

this article in computer audiophile confirms same :A USB Port is Not a USB Port | Computer Audiophile

Whilst it is very Mac-specific, I don't see why the solution should not apply to PCs too.

Check if the first USB is 1.0
Otherwise both are same. They transfer only bits..

Absolutely true, except when they don't

If anyone claimed more air, or whatever, from one USB port over another, then my scepticism would be to the fore, but this is not some audiophile angels-on-a-pin-head question: the sound is actually dropping out, ie those only-data bits are not getting transferred.

Googling DPC latency will come up with one reason for this kind of problem on PCs. If you have it, it's a nightmare. In fact, I have a thread about suffering it.

 

[kaushik]

Thad,
I have seen your informative thread,
some latency thingy i can assume

being a believer of KISS :keep it simple stupid principle ..i will not dig more for now as the better port is still Alive to sing for me

regarding USb 1.1 or 2.0 , the dac is 1.1 so this case is ruled out

 

[Thad E Ginathom]

being a believer of KISS :keep it simple stupid principle ..i will not dig more for now as the better port is still Alive to sing for me

Stick with what works for you, being glad that it does!

Despite the fact that PC audio is my main area of interest on the forum, I actually do not like getting down into that level of technology at all. I have had to, both with this DPC latency thing, and with getting a firewire audio device to function with Ubuntu. Having found, eventually, a plug-and-play solution to that problem, I was quite happy to forget all the stuff about interrupts, interrupt latency, interrupt priorities that I had had to dig into. Like maths, if it turns you on, it's fascinating: if it doesn't, it's tedious!

 

[matbhuvi]

I have noticed such things not in music but in the usb chargers. Some USB chargers were very picky about the USB ports. I have about 8 in my PC. The charger will not work in the USB port in the front. But, it will work fine in any of the USB ports in the rear. I am assuming that the defective USB is not providing enough voltage.

 

[theironhorse]

I have noticed such things not in music but in the usb chargers. Some USB chargers were very picky about the USB ports. I have about 8 in my PC. The charger will not work in the USB port in the front. But, it will work fine in any of the USB ports in the rear. I am assuming that the defective USB is not providing enough voltage.

theoritically you can connect upto 120 usb to a mobo but practically it wont happen for the mobo will not have enough juice to power 8-10 devices..

the front ports are generally connected via thin cable to the ports ove the mobo and will happily work with external powered devices like printer/3.5 ext hdd.. rear ports will be able to power the devices but they will max out too..

it also depends on what mobo and what power supply you use... 20 pin molex or a 24 pin..

usb chargers generally dont work for the same reason.
the power you get from a PC based usb charging is around 600 mah. however if your device needs more power it will not charge or might just say that device unable to charge for low on power.. you would then specifically need to use the higher power wall charger..


i have also seen that cheapo cables getting faulty after a few days of use.. try using diffrent USB cable...

update the drivers. use the rear port and a better cable and that should do it...

personally the best cables i figured out of my little exp were the cables that came along with motorola /blackberry and dell printers..

thick and well insulated. never gave a problem..

 

[theironhorse]

probably the bus interface matters , the one good sounding may be provided by a host controller part of main processor bus... other one is daisychained another root hub...probably it it the latency of usb commands or the internal power save modes of the Usb HC here playinga bad role...

this article in computer audiophile confirms same :A USB Port is Not a USB Port | Computer Audiophile

i agree to the fact that what is stated in this article is true for a reason.
lots of r&d goes to make the laptop consume lesser power and this is the reason.

most of the laptops will give you 3 usb's however 2 of them will always be able to power devices. third is always there for more verstality but you will be able to use it only with a self powered device..

try connecting 3 non powered devices to a laptop and i bet one of them atleast will give troubles with either not getting detected or being erratic or bare minimum of extreme slow transfer rate...

2 of the side ports are generally inegrated over the mobo with power and the third one is suppose to be just the data bus with very little amount of power to transmit data..

 

[cmsajith]

I dont think the power supply is the issue, if at all a difference is there. The external dac doesnt need any power from the usb port. Moreover some audiophiles are removing the power wire from the usb cable to remove the interference because of that(dont know about the effectiveness of this mod)

 

[kaushik]

I have noticed such things not in music but in the usb chargers. Some USB chargers were very picky about the USB ports. I have about 8 in my PC. The charger will not work in the USB port in the front. But, it will work fine in any of the USB ports in the rear. I am assuming that the defective USB is not providing enough voltage.

usb specs say dont give more than 100mA, a max about 500mA that too after device discovery ! some ports comply ,
@ironhorse
usb lines connecting to the controller has no role to play .. funny assumptions !

but usb has been misused [includes me for my phone ] ...for charging even running fan and fridge..some Host controllers allow that more current drain.

Anyways this no where relates to the DAc sound , yup the noisy usb power can be avoided , too lazy to do that

 

[square_wave]

Theory is all fine but all USBs dont sound the same. Many of us have been checking on this for a long time.

Computers do not make USB for audio. It is a general purpose solution. USB dac designers have been fighting this problem along with the issue of isolating the usb receiver (in the outboard DAC) from the ill effects of computer hash. Many years of research has already gone into this. If you interested, go to the audio asylum pc audio section to read up.

 

[kaushik]

i agree to the fact that what is stated in this article is true for a reason.
lots of r&d goes to make the laptop consume lesser power and this is the reason.

you cant confirm that by your 'feeling'

try connecting 3 non powered devices to a laptop and i bet one of them atleast will give troubles with either not getting detected or being erratic or bare minimum of extreme slow transfer rate...

usb transfer rate is is different story , God!! power drainage is NOT related to transfer rate , if it is a isochoronous transfer the bandwidth is guaranteed.
I many time have 3 min devices powered from usb , my wireless mouse, the dac , BT adapter ..no issues at all!

2 of the side ports are generally inegrated over the mobo with power and the third one is suppose to be just the data bus with very little amount of power to transmit data.

please read a little on uSB , each USB port is provided by as HCD sitting on peripheral bus , or like a leaf end .Data bus of processor is neva exposed ,moreover the USB lines are( D+ -) differential not just tristate lines ..


come on ...

 

[theironhorse]

you cant confirm that by your 'feeling' ...

its not about the feeling. companies do r&d for lesser power. i guess the recently released AMD brazos is a good example for the same running over 9 watts. same goes with other components used in computers.

usb transfer rate is is different story , God!! power drainage is NOT related to transfer rate , if it is a isochoronous transfer the bandwidth is guaranteed.
I many time have 3 min devices powered from usb , my wireless mouse, the dac , BT adapter ..no issues at all! ...

try connecting three portable HDD's at once and i bet you will not state the same thing again.

please read a little on uSB , each USB port is provided by as HCD sitting on peripheral bus , or like a leaf end .Data bus of processor is neva exposed ,moreover the USB lines are( D+ -) differential not just tristate lines ..

come on ...

i will check on the same however my purpose was not to misguide anyone.
also things dont work exactly the way they show on paper all the time. real life scenario's are all together diffrent. keeping that in my head and what i have seen in real time. i quoted few stuff.

 

[theironhorse]

usb specs say dont give more than 100mA, a max about 500mA that too after device discovery ! some ports comply ,
@ironhorse
usb lines connecting to the controller has no role to play .. funny assumptions !

but usb has been misused [includes me for my phone ] ...for charging even running fan and fridge..some Host controllers allow that more current drain.

Anyways this no where relates to the DAc sound , yup the noisy usb power can be avoided , too lazy to do that

The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V5%) between the positive and negative bus power lines. For USB 3.0, the voltage supplied by low-powered hub ports is 4.455.25 V.[40]

A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0. There are two types of devices: low-power and high-power. A low-power device draws at most 1 unit load, with minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0. A high-power device draws the maximum number of unit loads permitted by the standard. Every device functions initially as low-power but the device may request high-power and will get it if the power is available on the providing bus.[41]


try connecting 3 non self powered devices to the ports that might pull 500 mah from all the ports .

lets say three devices needing 500 mah are connected and 3 ports are unable to provide current of that amount at a time. logically one device will suffer and run low on power. how do you justify that it will still work the way its supposed to. ????

 

[Kannan]

It is usually the power issue.
Since laptops come with muliple ports, each port is powered internally.
Usually depending on the location of the port on the motherboard (design issues), some USB ports misbehave which is usually due to power issues.
Many a times something as simple as a pendrive or even a mouse may not work on a particular port.
This almost never occurs with powered USB hubs as they have dedicated external power sources.

 

[msagar]

When I connect my MacBook Pro to the DAC, the USB port near the power supply (left of the laptop) sounds better than the ports that are to the right of the laptop.

 

[theironhorse]

When I connect my MacBook Pro to the DAC, the USB port near the power supply (left of the laptop) sounds better than the ports that are to the right of the laptop.

for macbook pro 15 in.. people suggest not to use the left port and the same goes with the 17 as well.. use the ones on right and you will find it to be better sounding.

 

[kaushik]

try connecting 3 non self powered devices to the ports that might pull 500 mah from all the ports .

lets say three devices needing 500 mah are connected and 3 ports are unable to provide current of that amount at a time. logically one device will suffer and run low on power. how do you justify that it will still work the way its supposed to. ????

:sad: where from three HDDs came from ????
we are talking about a tiny tiny daC , some 70mA or so drainage.

again guys ..whoever telling power power ...it is NOT
please read more on USB!