usb/spdif converter, sound dropouts - SOLVED

[skepticalnewb]

Hi!
 
I have a problem and maybe there are some techies here that can advise.
I got an usb/spdif converter the other day, made by a friend - so not really a brand but he's an audio techie. I am connecting it to a usb cable and the other end is plugged directly into a dac on rca spdif connector.
 
I tried using it through a 5 m cable but I am getting dropouts every few seconds - 5 or 10 or so, irregularly. I tried cheap cables for now, 4 of them different brands and having different specs but the result is same.
No matter if I connect my desk pc or notebook it's the same.
 
I tried a 1.8m cable and it worked just fine.
I thought it might be some power issue, but with the long (4.5m to 5m) cables my notebook is having same problem if running on batteries, too.
I wondered if it's a power issue, one of the cables is a Belkin pro that is supposed to have awg20 power wire inside (thickest for usb, normally it's 24 or so in other cables... thinner).
I also checked the USB device (running on default windows driver, requires no specific driver). The device is connected at 1.1 full speed so the usb specified max should be 5m of cable (if it was low speed, 3m would be max but it isn't the case).
Some of the cables are thicker or thinner than others so there's a shielding (or lack of) difference between them but doesn't seem to matter.
 
I know there are super expensive cables out there that makes people's jaw drop when listening to, but for now I'd rather have a dry, technical approach to the problem.
What do you think is causing the dropouts? I realise some off-spec chinese cable might behave bad but that's why I got 4 cables, I don't think none of them meet the usb specifications.
Can it be a power issue (I'm no good in physics)? Or what else?
 
There are a couple people using same device, one with 4m, other with 4.5m cable, they did have this problem at some point in time but switched to other cheap pc usb cable and it works now. Those are also just random cables that don't even have brand on them just the usual usb specification stuff (28awg/24awg etc.)
 
Appreciate any input.
 
ps. the device is using isochronous transfer mode, if it matters.

 

[HeatFan12]

What player are you using on the PC?

 

[skepticalnewb]

foobar2000, ds mode, pretty much default settings. Previously I was connecting the pc to dac with spdif coax cable and it was working fine (audigy 2 zs platinum pro output), it's just sounding better on usb.

 

[HeatFan12]

No worries then.  Most dropouts come from the buffer length setting in Foobar.  Drop it under 200 ms and that should do it....I keep it usually on 100-150...I usually use WASAPI and KS though.
 

 

[skepticalnewb]

Hi,
 
Thanks for the ideas. Unfortunately buffer setting, low or high doesn't seem to do a thing. I have installed asio4all and used asio output over the usb and it was exactly same result, intermittent playback, a very very short click/pop/interruption every few seconds, sometimes 1 second, other times 10 seconds from previous one. Did I say that this doesn't happen on 1.8m usb cable? But I can't move my desk with the pc closer, I tried that just for testing purposes... It probably has to do something with the cable, but in days of browsing various threads on the internet I did not find any useful information. If I only knew the reason I could try and do something about it. I thought of trying with a usb hub/repeater cable (again one of those things that I buy and won't help perhaps), with the 1.8m cable connected to it, if it is signal degradation or power diminution problem that may help, bit I don't have a clue if that has any other effect (like screwing up isochronous clock or something, sorry if I said something stupid).
 
ps: I tried kernel streaming component, it acts a bit weird (gotta press 2 times pause for it to start) then it starts playing and exact same symptom appears. That seems to kinda rule out player software... something btween usb controller and converter is not OK.

 

[joe_cool]

How does it work using Direct Sound?
Can you use an external power supply for the USB / SPDIF converter?
Have you checked your PC latency? Are you using a wireless NIC?

 

[JRG1990]

You aren't using a usb hub or anything???, unless the usb cables you used were seriously rubbishy and not built to specification there is no reason why they shouldn't work to 5metres, wireworld make a usb cable that they say will work up to 7metres http://www.wireworldcable.com/products/57.html , it's quite pricey but since it goes up to 7metres theres no reason the 5metre shouldn't work.

 

[RonaldDumsfeld]

skepticalnewb, post count 1, wrote:-
 
Quote:

I tried using it through a 5 m cable but I am getting dropouts every few seconds - 5 or 10 or so, irregularly. I tried cheap cables for now, 4 of them different brands and having different specs but the result is same.
No matter if I connect my desk pc or notebook it's the same.
 
I tried a 1.8m cable and it worked just fine.

 
Obvious troll is obvious.

 

[skepticalnewb]

Thank you all for your input.
 
My pc shows good latency for the most part, with some spikes nearing 1000 but always under, it's always green. And spikes don't come together with sound interruptions.
I am not using usb hub.
I don't have a wireless card on my desktop pc (there is one on notebook).
I tried so far with DS, KS, Asio4all in WinXP, also Ubuntu Studio and it shows exact same problem with the 4.5m to 5m cables.
For one test I disabled nvidia driver, network driver, and I stopped pretty much all services I could stop (with maybe 5 remaining).
 
None of these mattered. But as I said I tried with a 1.8m cable and then it worked so I'm assuming it has not much to do with PC and a lot with cable?
 
The 4 long cables I tried are just regular PC cables. 3 of them have the usb 2.0 logo. One of these is a Belkin Pro which is supposed to have an AWG20 power wire (thickest by USB specification) - I hoped this will work if power is the problem (less resistance).
But maybe signal is degrading, not sure, would be nice if I knew electronics enough to figure it out.
 
Unfortunately the converter cannot be powered externally, it's just a closed box with the usb / spdif coax connectors.
 
For a few days I browsed the internet, even read USB specifications document (well parts of it) trying to figure out what can it be.
I am aware that there are $200 - $2000 usb cables I was just hoping to find a real reason instead of just going the faith way.
 
In theory cable length should not be an issue, since USB 1.1 full speed allows for 5m cable and that's not conductivity but signaling limit (round-trip delay).
 
Right now I connected the converter with the 1.8m usb cable, and I added a 5m coax to the other side and it works fine, would have just preferred to have usb all the way to the dac (with converter plugged in directly).
 
About the 1 post, what's the problem with it? I registered to ask this question. I found the site using google and read many threads previously, as I did on many other sites as well.
 
I feel I should ask someone that's an expert in cabling / usb but did not find a working forum about these topics... there's gotta be a perfectly logical, scientific explanation...
 
Thanks again for everyone for your assistance.
 
PS: the Belkin cable is this:
http://www.amazon.co.uk/Belkin-PRO-Hi-Speed-Device-Cable/dp/B000EOTDQ4/ref=sr_1_5?ie=UTF8&qid=1297724916&sr=8-5
 
I did not want to stretch too far but I ordered this cable yesterday:
http://shop.delta.co.at/usb-20-kabel-typ-ab-premium-gold-5m-p-2819.html
 
These days searching Internet I found out about Kimber cable's usb, Furutech, Audioquest, Wire world but since these are much more expensive I didn't want to spend more on the cable than on the converter+dac... for other cabling I just use custom made silver plated copper speaker cables, inakustik ICs etc. and I'm ok with that (my whole system is maybe a bit over $1000 in value, bought most of it used).
 
edit2: sorry for the german, the cable I ordered is this:
http://www.lindy.co.uk/5m-premium-gold-usb-2-cable-type-a-to-b/37654.html
I doubt at this price is sub-spec... if it doesn't work, then there's good chances other won't either, dunno.

 

[kiertijai]

I recently purchased one HRT streamer plus and had to use the llong USB cable about 4 m length
because the digital coaxial that I would like to use was only 1 metre long.  I had emailed and asked
Kevin Halverson and he answered back that the power supply to the streamer may not be enough
for the long USB cable and he advised me to use the powered USB hub between the usb cable and the
digital coaxial.  Can it be the case heare?  if it is, you need to purchase the D-link powered USB hub.

 

[skepticalnewb]

It can very well be the case.
In a few days  will try my new usb cable and if it still doesn't work I will attempt with an usb hub. Some say it worked for them, others say it didn't, so it will be just another test.
 
I just wonder, one of my USB cables is a very thin one, doesn't have usb 2.0 label and it functions exact same way as the Belkin, while the Belkin has the thickest power wire USB standard specifies. If it was voltage drop, there should be a difference between these 2 cables since a thicker power wire is supposed to have less resistance (so I'm told).
 
While my dpc latency shows green, over 500 is not really low, I wonder if usb performance over a long cable can be affected by it. I opened a ticket with Gigabyte, maybe they can give me a fixed BIOS with lower dpc latency (google says some people fixed their latency like this).
 
I still have hope, many things to try. I was just googling to see if anyone made and tried off-spec usb cables with both thicker power and signaling wires but no luck yet.

 

[skepticalnewb]

Solved! (in case anyone finds this thread and need a similar solution)
 
I bought an 5m usb repeater cable (an extension cable with a small box at the end, not powered externally).
When I opened the box I was a bit confused since cable says it has awg28 power wire - this type of cable usually has awg20 ones.
Connecting it to the pc, it detected it as an usb hub.
 
There are no dropouts anymore, for a quick test everything works as it should, it seems.
 
I don't understand why, I used some online calculator and on this length an awg28 cable is supposed to have a voltage drop of around 1 which is a lot and should not be tolerated by usb devices (specification says a minimum of 4.75 volts).
 
So unfortunately I don't understand what happens, but the most important thing, it works.
 
Thanks for everyone for their input.