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Scott Dorsey Scott Dorsey is offline
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Default USB hum/noise isolation?

w_tom wrote:

Currently we don't even know is the noise is differential mode or
common mode - and in what electrical loop (circuit). Get a 6 ft USB
cable and perform the test; to answer those unknowns.


From his description, it's neither.

He says he hears the noise in headphones plugged into the interface,
with nothing other than the computer plugged into it.
--scott
--
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Richard Crowley Richard Crowley is offline
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Default USB hum/noise isolation?

"w_tom" wrote...
"StudioDog" wrote:
OK, gentlemen.....
I'm going to go play some Paddy's Day gigs while you two carry on
****ing in each other's cornflakes..... if you must.


No problem. Meindert is finished confusing the issue. And I am
finished trying to explain to him so many times over why his posts are
irrelevant to your problem.

Currently we don't even know is the noise is differential mode or
common mode - and in what electrical loop (circuit). Get a 6 ft USB
cable and perform the test; to answer those unknowns.


Remember that just because the OP calls it "ground loop"
or even "hum" doesn't make it so. His description sounds
more like high-frequency digital hash than anything like
"traditional" ground-loop 60Hz power mains hum.

Remember he said he still hears it with no inputs connected,
and he still hears it with only headphones. Either of those
casts significant doubt on "traditional ground loop" as the
primary issue.

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Scott Dorsey Scott Dorsey is offline
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Default USB hum/noise isolation?

Richard Crowley wrote:

Remember that just because the OP calls it "ground loop"
or even "hum" doesn't make it so. His description sounds
more like high-frequency digital hash than anything like
"traditional" ground-loop 60Hz power mains hum.

Remember he said he still hears it with no inputs connected,
and he still hears it with only headphones. Either of those
casts significant doubt on "traditional ground loop" as the
primary issue.


If he hears it without only headphones, it's not a ground loop, because
there is only one single ground path. (Well, it COULD be internal grounding
issues inside the box, but there's nothing he can do about that.)

And if it's not a ground loop, fiddling around with cables isn't going to
improve anything.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Meindert Sprang Meindert Sprang is offline
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Default USB hum/noise isolation?

"Scott Dorsey" wrote in message
...
If he hears it without only headphones, it's not a ground loop, because
there is only one single ground path. (Well, it COULD be internal

grounding
issues inside the box, but there's nothing he can do about that.)


Was that interface powered by USB or did it have it's own power supply?
There could be a loop.

The best way for him to try is to connect the interface to a laptop running
on it's battery. Headphone on the interface and nothing more. This ensures
there is absolutely no ground loop. If the hum/noise is still there, it must
the interface itself.

Meindert


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Richard Crowley Richard Crowley is offline
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Default USB hum/noise isolation?

"Meindert Sprang" wrote ...
Was that interface powered by USB or did it have it's own power
supply?
There could be a loop.



I thought the external power supply was a wall-wart with a
2-prong power mains plug.



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Meindert Sprang Meindert Sprang is offline
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Default USB hum/noise isolation?

"Richard Crowley" wrote in message
...
"Meindert Sprang" wrote ...
Was that interface powered by USB or did it have it's own power
supply?
There could be a loop.



I thought the external power supply was a wall-wart with a
2-prong power mains plug.


No loop through ground then. But even then it should best be plugged in the
same power strip as the laptop.
Just the other day I had a mixer in one outlet (grounded) and a drumcomputer
in an other (wall wart), which whas on a drifferent mains group of a 3phase
system. Huge 50Hz hum.

Meindert


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StudioDog StudioDog is offline
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Default USB hum/noise isolation?


Hi all. To clarify power supplies:

external USB interface is USB powered- no external p/s
mixer's intertnal USB interface is powered by mixer psu, which is 2-
pring wall wart. (Alesis multuimix 8USB).
all other gear is 3-pring IEC cable

I have also just added an ART PB4x4Pro power conditioner to the rack -
seems to quiet the noise somewhat when I use the external USB
interface, but no difference using the Alesis mixer's built-in
interface.

I'm game to try the USB cable experiment that generated so much
traffic here. I opened a spare usb cable to find : a RED wire, a BLACK
wire, a GREEN wire and a WHITE wire. I believe these wires are
assigned as: Red - power, White - Data neg. Green - Data pos, and
Black - Ground.

Can someone back me up on this before I cut the wrong wire? Also, if
grounding is an issue, as I gather it is/may be from the earlier
flurry of posts, if I cut the red wire but leave the ground intact,
would this maintain the ground between the computer and the USB
interface?

If someone can confirm the wiring assignment, I will conduct our
little experiment tonight and post results asap.

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Default USB hum/noise isolation?

"StudioDog" wrote in message
oups.com...
I'm game to try the USB cable experiment that generated so much
traffic here. I opened a spare usb cable to find : a RED wire, a BLACK
wire, a GREEN wire and a WHITE wire. I believe these wires are
assigned as: Red - power, White - Data neg. Green - Data pos, and
Black - Ground.


These colors are correct.

Can someone back me up on this before I cut the wrong wire? Also, if
grounding is an issue, as I gather it is/may be from the earlier
flurry of posts, if I cut the red wire but leave the ground intact,
would this maintain the ground between the computer and the USB
interface?


Yes.

Meindert


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StudioDog StudioDog is offline
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Default USB hum/noise isolation?

Meindert

I snipped the red wire to cut the usb power and connected the mixer's
internal USB port to the USB hub that connects to my computer in the
next room. I didn't get any response from the computer ie. the
computer did not recognize that I had plugged a device in, Thus, no
driver instal, and no sound....

Any suggestions? I can't imagine why the Alesis mixer would need to
power its usb interface via the usb bus, as the mixer is powered by
wall wart AC....

I'm not sure exactly how to continue diagnosing this issue, as my
other usb interface (Behringer UCA202) is USB Bus powered, with no
option for AC, so I can't use it with a cut Vcc lead in the cable.

My thanks in advance for any advice.




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Richard Crowley Richard Crowley is offline
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Default USB hum/noise isolation?

"StudioDog" wrote ...
Meindert

I snipped the red wire to cut the usb power and connected the mixer's
internal USB port to the USB hub that connects to my computer in the
next room. I didn't get any response from the computer ie. the
computer did not recognize that I had plugged a device in, Thus, no
driver instal, and no sound....

Any suggestions? I can't imagine why the Alesis mixer would need to
power its usb interface via the usb bus, as the mixer is powered by
wall wart AC....

I'm not sure exactly how to continue diagnosing this issue, as my
other usb interface (Behringer UCA202) is USB Bus powered, with no
option for AC, so I can't use it with a cut Vcc lead in the cable.


It would appear that the USB port/driver depends on seeing
a load on the power source to detect when a device is
connected. Not programmed to call unless it thinks somebody
is home. Well, that knocked that experiment right in the head.

Of course, we are assuming that the colors connected to
what we think they should. Note that if you are making cables
(especially molded ones which likely nobody will ever peek
inside of), it doesn't really matter which color you use, as long
as it is the same on both ends. I would have confirmed the
pinout before cutting anything. You can stick a straight pin
(or safety-pin) through the insulation to test which color is
connected to which pin. etc. before cutting anything.

Did you ever mention whether there was any change in
symptoms when all the equipment was together in the
same room? Without any extensions of any kind?




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Meindert Sprang Meindert Sprang is offline
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Default USB hum/noise isolation?

"StudioDog" wrote in message
ups.com...
Meindert

I snipped the red wire to cut the usb power and connected the mixer's
internal USB port to the USB hub that connects to my computer in the
next room. I didn't get any response from the computer ie. the
computer did not recognize that I had plugged a device in, Thus, no
driver instal, and no sound....


Two possibilities he either the USB interface is bus powered and gets no
supply.
When it is self powered, the USB standard requires a device to connect D+ to
VBus through a 1k5 resistor. Without Vbus (you cut the wire) the computer
will not detect the device.

Any suggestions? I can't imagine why the Alesis mixer would need to
power its usb interface via the usb bus, as the mixer is powered by
wall wart AC....


To prevent ground loops? It is perfectly feasible that an audio device has
an isolated USB interface to prevent any ground loops. The USB interface can
then be bus powered and the link with the rest of the electronics can be
made through high-speed opto-couplers.

I'm not sure exactly how to continue diagnosing this issue, as my
other usb interface (Behringer UCA202) is USB Bus powered, with no
option for AC, so I can't use it with a cut Vcc lead in the cable.


Try to eliminate things. If your Behr also produces noise with only a
headphone connected, the noise can either come from the interface or it is
produced in the computer. Swap the computer/laptop and check again. Is the
noise in the recordings or is it just produced by the headphone amp? I know
My FireBox has a little high frequency hiss on the headphone output, but the
recorded material is clean. When I play it through the line outputs to a
headphone amp or mixer, it sounds clean.

Meindert



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Default USB hum/noise isolation?

"Richard Crowley" wrote in message
...
Of course, we are assuming that the colors connected to
what we think they should.


These colors are dictated by the USB standard, as are a whole bunch of
things, like wire gauge, mechanics etc.

Meindert


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Richard Crowley Richard Crowley is offline
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Default USB hum/noise isolation?

"Meindert Sprang" wrote ...
"Richard Crowley" wrote ...
Of course, we are assuming that the colors connected to
what we think they should.


These colors are dictated by the USB standard, as are a whole bunch of
things, like wire gauge, mechanics etc.


Of course. But that is not the same as saying that all USB
cables consientiously actually use the proper colors.

I suspect that if you were some production manager under the
gun somewhere in interior China somewhere you wouldn't stop
the production line because your latest shipment of wire had blue
instead of green. Its not as if it actually affects the functionality or
performance.

The USB standards also prohibit A-to-A or B-to-B or "extention"
cables, but that doesn't prevent people from making and selling
them everywhere without apparent consequenses.


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Default USB hum/noise isolation?

The noise appears with whatever computer I use. I have tries it with
an IBM Thinkpad laptop, a generic P3, and my new AMD 64x2 3800+ dual
core system. All produce this noise (although the laptop, ironically,
is the quietest - just doesn't have the brain-power to handle much
audio processing).

I have also swapped out usb interfaces - tried the Alesis' on-board
interface (that's why I bought the mixer after all!), and then the
Behringer UCA202, which is quieter. I have also tries using a brand-
new Behringer Xenyx 1204 mixer that came bundled with a UCA 200 usb
interface (essentially a UCA202 without a headphone output). All setup
variations give me the noise.

I'm stumped, really. My guess, if I had to make one at this point, is
that the computer is generating the noise - perhaps a power supply
issue? Perhaps a feedback loop in the circuitry? No idea how I'd test
for that, either.

I'll keep tinkering with things, and post back if I get lucky! I still
haven't heard anything useful from Hewlett Packard as to whether there
may be a fault with the computer itself, but I think that's a long
shot. HP's not likely tp take responsibility for this one!

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Chris Hornbeck Chris Hornbeck is offline
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Default USB hum/noise isolation?

On 19 Mar 2007 17:29:06 -0700, "StudioDog"
wrote:

The noise appears with whatever computer I use. I have tries it with


I have also swapped out usb interfaces - tried


All setup
variations give me the noise.


Then, beyond the language barrier, there's something you're
not telling us. Whatever could it be?

What else is connected to these computers? List everything,
or risk wasting another week.

Chris Hornbeck


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Default USB hum/noise isolation?

The red wire should have been the correct wire. But more important
was which wires are twisted and untwisted. Two wires twisted around
each other are the wires to not cut. You must cut both untwisted
wires. Leaving a ground wire discovers nothing. Cutting the ground
wire is necessary to make the experiment work. You want both
untwisted wires cut between computer and mixer. Ignore everything
Meindert was posting about grounds. It was all totally irrelevent.

Why no response? Well if the red wire was a twisted pair wire, then
you have killed the signalling. Meanwhile, it does not matter whether
computer push music through the mixer. That noise will be there
anyway.

However you can continue to experiment. Simple strip and twist
those two untwisted wires together. Make the connection. With noise
still there, disconnect only two untwisted wires. Does noise
disappear? That is useful information.

However before doing any of this, first confirm the red and black
wires are the untwisted wires and that other wires (green and white?)
are twisted. Cut and strip the untwisted wires. Reconnect those
wires. Setup the USB test. Listen for noise. Learn what happens to
that noise as those untwisted wires are disconnected while live. And
again, don't worry about any posts about potential damage. Those
warnings would be bogus and irrelevant.

Now once those untwisted wires are disconnected, the computer may
then report the disconnect. But that is also useful information. USB
detection for connection, bus speed, and disconnection are all
performed on the signal (twisted) wires. If both boxes have their own
power, then voltage power on untwisted wires is not necessary.
Removal of that unnecessary power should cause no disconnect detected
when untwisted wires are disconnected. What happens when you perform
that experiment will be very informative.

I am not lost. What makes sense is that, as Chris(?) suggested,
wire color codes are wrong. That is why I did not list any colors -
why instead I was careful to only call the wires 'twisted' and
untwisted'. Believe me. I have been very careful in what I posted
which is also why Meindert's warning had long ago been considered
(before he even posted) and discounted.

Go back to verify every wire in the setup is are defined so many
days ago. Also verify which wires are twisted and untwisted. Then
perform the experiement with untwisted wires temporarily connected
when USB cable is powered; verify noise exists; disconnect untwisted
wires; and report those details.

On Mar 19, 5:34 pm, "StudioDog" wrote:
I snipped the red wire to cut the usb power and connected the mixer's
internal USB port to the USB hub that connects to my computer in the
next room. I didn't get any response from the computer ie. the
computer did not recognize that I had plugged a device in, Thus, no
driver instal, and no sound....

Any suggestions? I can't imagine why the Alesis mixer would need to
power its usb interface via the usb bus, as the mixer is powered by
wall wart AC....

I'm not sure exactly how to continue diagnosing this issue, as my
other usb interface (Behringer UCA202) is USB Bus powered, with no
option for AC, so I can't use it with a cut Vcc lead in the cable.

My thanks in advance for any advice.



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w_tom w_tom is offline
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Default USB hum/noise isolation?

On Mar 19, 5:34 pm, "StudioDog" wrote:
...
I'm not sure exactly how to continue diagnosing this issue, as my
other usb interface (Behringer UCA202) is USB Bus powered, with no
option for AC, so I can't use it with a cut Vcc lead in the cable.


BTW, when doing the 'temporary spliced together' test, use scotch
tape to keep those wires from accidentally shorting to each other or
to anything else.


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"w_tom" wrote in message
oups.com...
Now once those untwisted wires are disconnected, the computer may
then report the disconnect. But that is also useful information. USB
detection for connection, bus speed, and disconnection are all
performed on the signal (twisted) wires.


Yes, but in conjuction with the power wires. From VBus drives internal
circuitry which in turn injects for instance +3.3V on D+ to indicate a
device is full speed.. Without the presence of VBus, the device will not
send ANYTHING on the data wires and will therefore not be detected. And
since the Ground wire is needed to reference any of thos signals against,
cutting either wire will report the device as disconnected. Apart from that,
cutting the ground wire of the usb cable alone, is makeing the entire supply
current of the device through the datalines with will be detected as a fault
situation in the host port which will be shut down.

If both boxes have their own
power, then voltage power on untwisted wires is not necessary.


One had, the other didn't. And as you could have read, cutting the VBus wire
to the Alesis did also 'disconnect' the device.

Removal of that unnecessary power should cause no disconnect detected
when untwisted wires are disconnected.


Wrong by the USB standard, proven wrong by SoundDog.

You now better stop making a fool of yourself by constantly ignoring and
denying expert advice.

I am not lost.


We are. If SoundDog tells us that even the bus powered device produces noise
on a headphone, there are no groundloops anymore that could cause this. If
computers swapped still produce the problem, it cannot be the computer.
Besides, the sound in the computer is digital, so interference in the
computer can affect that data and not crash the computer. Power supply noise
of the computer cannot affect the digital datastream. There is something
else going on which we are not told yet.

Meindert


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Default USB hum/noise isolation?

On Mar 19, 11:56 pm, Chris Hornbeck
wrote:
On 19 Mar 2007 17:29:06 -0700, "StudioDog"
wrote:

The noise appears with whatever computer I use. I have tries it with
I have also swapped out usb interfaces - tried
All setup
variations give me the noise.


Then, beyond the language barrier, there's something you're
not telling us. Whatever could it be?

What else is connected to these computers? List everything,
or risk wasting another week.

Chris Hornbeck


Chris. Hi. There is nothing else connected to the studio computer (and
no language barrier, btw, only crappy typing!). As I said before, even
stripped right down to the barebones computer --USB interface--
headphones configuration, the noise is present on any computer I

try.


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Default USB hum/noise isolation?

On Mar 20, 12:48 am, "w_tom" wrote:
The red wire should have been the correct wire. But more important
was which wires are twisted and untwisted.


I understand what you're saying, but is it possible we're talking
about different cables? Is there a difference between a USB 1.1 cable
and a USB 2.0 cable? I have not found any twisted pairs in the cable
I'm dissecting. All four coloured wires in my cable are singles, made
up of mutli-stranded steel-coloured wire. It's a USB A male to USB B
male cable, btw - probably came with the Alesis mixer, which is USB
1.1.




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Arny Krueger Arny Krueger is offline
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Default USB hum/noise isolation?

"StudioDog" wrote in message
oups.com
On Mar 20, 12:48 am, "w_tom" wrote:
The red wire should have been the correct wire. But
more important was which wires are twisted and untwisted.


I understand what you're saying, but is it possible we're
talking about different cables? Is there a difference
between a USB 1.1 cable and a USB 2.0 cable?


Clearly, a USB 2.0 cable has to pay more attention to the usual details -
the potential data rate is what 40:1 higher?

IME USB 1.1's max 12 Mb/s data rate isn't a license to be completely
sloppy, but 480 Mb/s is clearly much more demanding. It's 40 times faster!

USB 1.0 was only 1.5 Mb/s and that is more of an "anything goes" situation
for typical consumer lengths of cable.

I have not found any twisted pairs in the cable I'm dissecting.


There are more than one ways to come up with the right impedance.

All four coloured wires in my cable are singles, made up of
mutli-stranded steel-coloured wire. It's a USB A male to
USB B male cable, btw - probably came with the Alesis
mixer, which is USB 1.1.



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"StudioDog" wrote in message
oups.com...
Chris. Hi. There is nothing else connected to the studio computer (and
no language barrier, btw, only crappy typing!). As I said before, even
stripped right down to the barebones computer --USB interface--
headphones configuration, the noise is present on any computer I

try.


That suggests that the hum is produced somewhere in the analog output
circuit of the USB interface.
Is the noise also present when you don't playback a track?

Meindert


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Richard Crowley Richard Crowley is offline
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Default USB hum/noise isolation?

"StudioDog" wrote ...
"w_tom" wrote:
The red wire should have been the correct wire. But more important
was which wires are twisted and untwisted.


I understand what you're saying, but is it possible we're talking
about different cables? Is there a difference between a USB 1.1 cable
and a USB 2.0 cable?


At DC, there is no difference between USB1.x and 2.0 The major
difference is likely that the (differential) data pair is likely twisted in
a 2.0 cable (to maintain somewhat better impedance at higher data
rates). Same kind of thing used in Cat5 network cabling, etc.


I have not found any twisted pairs in the cable
I'm dissecting. All four coloured wires in my cable are singles, made
up of mutli-stranded steel-coloured wire. It's a USB A male to USB B
male cable, btw - probably came with the Alesis mixer, which is USB
1.1.


If it were a 2.0 USB cable, more likely for the data pair to be twisted.
But for your purposes, probably of no consequence.


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Laurence Payne Laurence Payne is offline
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On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley"
wrote:

If it were a 2.0 USB cable, more likely for the data pair to be twisted.
But for your purposes, probably of no consequence.


Is there evidence that two types of USB cable are made?
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On Mar 20, 11:43 am, "Meindert Sprang"
wrote:
"StudioDog" wrote in message

oups.com...

Chris. Hi. There is nothing else connected to the studio computer (and
no language barrier, btw, only crappy typing!). As I said before, even
stripped right down to the barebones computer --USB interface--
headphones configuration, the noise is present on any computer I

try.


That suggests that the hum is produced somewhere in the analog output
circuit of the USB interface.
Is the noise also present when you don't playback a track?

Meindert


hi Meindert.

That's probably an important piece of info which I thought I had
already posted, but I just rechecked all my posts and I seem to have
omitted it! Whoops!

Yes, the noise is present as soon as I open Cubase or any other
recording software that accesses the usb audio drivers. It doesn't
matter which driver I use (ASIO DirectX Full Duplex, ASIO Multimedia
Driver, usb-audio.de, etc). All pass on the noise as soon as Cubase
boots, and continue the noise until I shut Cubase.




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Scott Dorsey Scott Dorsey is offline
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Laurence Payne lpayne1NOSPAM@dslDOTpipexDOTcom wrote:
On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley"
wrote:

If it were a 2.0 USB cable, more likely for the data pair to be twisted.
But for your purposes, probably of no consequence.


Is there evidence that two types of USB cable are made?


The Hitachi cable catalogue lists two pages of different types of USB
bulk cable. I am not sure what the various merits and demerits of each are.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Default USB hum/noise isolation?

"StudioDog" wrote in message
ps.com...
hi Meindert.

That's probably an important piece of info which I thought I had
already posted, but I just rechecked all my posts and I seem to have
omitted it! Whoops!

Yes, the noise is present as soon as I open Cubase or any other
recording software that accesses the usb audio drivers. It doesn't
matter which driver I use (ASIO DirectX Full Duplex, ASIO Multimedia
Driver, usb-audio.de, etc). All pass on the noise as soon as Cubase
boots, and continue the noise until I shut Cubase.


And does that happen with both the Behringer interface and the Alesis used
as output device?

Meindert


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"Laurence Payne" lpayne1NOSPAM@dslDOTpipexDOTcom wrote in
message
On Tue, 20 Mar 2007 09:29:39 -0700, "Richard Crowley"
wrote:


If it were a 2.0 USB cable, more likely for the data
pair to be twisted. But for your purposes, probably of
no consequence.


Is there evidence that two types of USB cable are made?


I've certainly seen cables that would work fine for USB 1.1 connections, but
fail to work for USB 2.0 connections.

Type of device most likely impacted: USB flash memory.

Experiment:

Attach USB 2.0 flash memory 1 directly to computer USB 1.1 port. It works.
Attach USB 2.0 flash memory 1 to computer USB 1.1 port through extension
cable A. It works.
Attach USB 2.0 flash memory 1 directly to computer USB 2.0 port. It works.
Attach USB 2.0 flash memory 1 to computer USB 2.0 port through extension
cable A. It fails to work.
Attach USB 2.0 flash memory 1 to computer USB 2.0 port through extension
cable B. It works.

Attach USB 2.0 flash memory 2 directly to computer USB 1.1 port. It works.
Attach USB 2.0 flash memory 2 to computer USB 1.1 port through extension
cable A. It works.
Attach USB 2.0 flash memory 2 directly to computer USB 2.0 port. It works.
Attach USB 2.0 flash memory 2 to computer USB 2.0 port through extension
cable A. It works.
Attach USB 2.0 flash memory 2 to computer USB 2.0 port through extension
cable B. It works.

USB extension cable A is one of those wind-up affairs.
USB extension cable B is standard, specfically rated for USB 2.0.


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StudioDog StudioDog is offline
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Default USB hum/noise isolation?

And does that happen with both the Behringer interface and the Alesis used
as output device?

Meindert


Yes. The noise comes through either interface as soon as I boot
Cubase.



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Arny Krueger Arny Krueger is offline
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Default USB hum/noise isolation?

"StudioDog" wrote in message
oups.com
And does that happen with both the Behringer interface
and the Alesis used as output device?

Meindert


Yes. The noise comes through either interface as soon as
I boot Cubase.


Nothing attched to the interface but the computer?


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StudioDog StudioDog is offline
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Default USB hum/noise isolation?

On Mar 20, 2:07 pm, "Arny Krueger" wrote:
"StudioDog" wrote in message

oups.com

And does that happen with both the Behringer interface
and the Alesis used as output device?


Meindert


Yes. The noise comes through either interface as soon as
I boot Cubase.


Nothing attched to the interface but the computer?


Again, no. I can remove everything down-stream of the Behringer UCA202
interface and listen through the unit's headphone output. The noise is
present as soon as I boot Cubase.

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Arny Krueger Arny Krueger is offline
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Default USB hum/noise isolation?

"StudioDog" wrote in message
oups.com
On Mar 20, 2:07 pm, "Arny Krueger"
wrote:
"StudioDog" wrote in message

oups.com

And does that happen with both the Behringer interface
and the Alesis used as output device?


Meindert


Yes. The noise comes through either interface as soon as
I boot Cubase.


Nothing attched to the interface but the computer?


Again, no. I can remove everything down-stream of the
Behringer UCA202 interface and listen through the unit's
headphone output. The noise is present as soon as I boot
Cubase.


So, how far to the nearest radio transmitter or other strong EMI source?


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Meindert Sprang Meindert Sprang is offline
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Default USB hum/noise isolation?

"StudioDog" wrote in message
oups.com...
And does that happen with both the Behringer interface and the Alesis

used
as output device?

Meindert


Yes. The noise comes through either interface as soon as I boot
Cubase.


Then it cannot be a problem in both interfaces, I'd say. No ground loop
either. The thing that puzzles me most is that it starts the moment you
start up Cubase. It does not make sense. The only thing I can think about is
that when Cubase is not active, neither sound interface is active and cannot
pick the noise from some unknown nearby source.

Does the noise change when you move things aroud physically? Try to turn the
Behr and the Alesis in all three axes, just to see if the noise is some
interference picked up by the circuits.

Meindert


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Meindert Sprang Meindert Sprang is offline
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Default USB hum/noise isolation?

"Arny Krueger" wrote in message
. ..
"StudioDog" wrote in message
oups.com
On Mar 20, 2:07 pm, "Arny Krueger"


So, how far to the nearest radio transmitter or other strong EMI source?


Thought about that too, but why is it only present when Cubase is started?

meindert




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StudioDog StudioDog is offline
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Default USB hum/noise isolation?


So, how far to the nearest radio transmitter or other strong EMI source?-


radio transmitter? 5 Km, maybe? there's nothing in the house that is
an obvious culprit, or I would have found it already. the studio is on
a separate electrical circuit in the house...there may be a power
cable in the stud space adjacent to the cable conduit passing through
to the computer (PC tower is in separate room to combo control room/
recording space), but I've also tried setting up with the computer in
the same room, no extensions. Still get the noise.

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w_tom w_tom is offline
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Default USB hum/noise isolation?

On Mar 20, 10:30 am, "StudioDog" wrote:
On Mar 20, 12:48 am, "w_tom" wrote:
I understand what you're saying, but is it possible we're talking
about different cables? Is there a difference between a USB 1.1
cable and a USB 2.0 cable? I have not found any twisted pairs in
the cable I'm dissecting. All four coloured wires in my cable are
singles, made up of mutli-stranded steel-coloured wire. It's a USB
A male to USB B male cable, btw - probably came with the Alesis
mixer, which is USB 1.1.


USB is actually three different types - low speed, full speed, and
high speed. First two are USB 1.1. Only low speed cables can have
signal wires untwisted. Also "color used for the cable assembly is
vendor specific". Only three colors are 'recommended': white, grey,
or black. Another should have known this. Just another reason why I
did not state a color; was specific about twisted verses non-twisted
wires.

USB cables use a A series (more square) and a B series (more
rectangular) plug. Low speed cables (without twisted pair wires) only
have a B series plug and must be attached to the USB device. Only
Full speed and High speed cables are detachable. Both must have
twisted pair signal wires.

If no twisted pair wire, then the cable will act like an antenna;
inject noise into the device. Cable must have twisted pair AND if
must have a bare 'drain' wire. No way around that fact.

If cable is not twisted pair, well, try the experiment anyway to
learn. Disconnecting the untwisted wires should not cause loss of
signal in direct contradiction to what another has posted.

Cables that violate USB standards: extension cables with both a
male and female A or B type plug. Cables with untwisted wires that
are detachable. Detachable cable without a drain wire inside. Cable
without the USB icon molded into every connector.

USB cables can exist with any color wire inside as quoted above from
a USB standard.

If cable is not twisted pair, well, try the experiment anyway to
learn. Disconnecting the two untwisted wires must not cause what
another has posted for reasons not relevant here. But be very
concerned if this cable has USB icon markings on connectors and no
twisted pair inside. That is an absolute violation for detachable
cables.


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Chris Hornbeck Chris Hornbeck is offline
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Default USB hum/noise isolation?

On 20 Mar 2007 20:26:03 -0700, "w_tom" wrote:

If no twisted pair wire, then the cable will act like an antenna;
inject noise into the device. Cable must have twisted pair AND if
must have a bare 'drain' wire. No way around that fact.


We've gotten pretty far afield, but it might be interesting,
in the general context, to note that twisting doesn't have much
effect where the dimensions are small WRT a wavelength.

The purpose of twisting is to "average" the geometries of the
twisted conductors, allowing a differential receiver to
ignore a better "average" of an imposed hum field.

Turns out that this train is on another track (and God help
the passengers) but maybe some airing of ground loop issues
will be useful generally. Unfortunately, not specifically.
(Insert frowny-face emoticon.)

All good fortune,

Chris Hornbeck
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[email protected] eklaver@souvenirmusic.net is offline
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Default USB hum/noise isolation?

On Mar 20, 2:07 pm, "Arny Krueger" wrote:
"StudioDog" wrote in message

oups.com

And does that happen with both the Behringer interface
and the Alesis used as output device?


Meindert


Yes. The noise comes through either interface as soon as
I boot Cubase.


Nothing attched to the interface but the computer?



I have the same problem. I run Reason 3.0 and Cubase SX3, an Alesis
Multimix8, and an EMU Xboard 61 USB controller. As soon as I boot up
either program-- seperately or using ReWire-- the hum starts with
nothing connected to the inputs.

Here is the interesting bit. If I play with the sample rate in Reason
the pitch of the sound changes. If I play with theASIO buffer size in
the driver (ASIO4all) the hum becomes more modulated as the buffer
size gets larger (i.e. the hum begins to pulse).

When I listen to music through the Alesis using iTunes the hum is not
there.

StudioDog, does any of this reflect your experience? This suggests a
problem with the mixer's USB data input-- maybe a bad D to A
conversion on the input stage?


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[email protected] johnlitt@gmail.com is offline
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Default USB hum/noise isolation?

On Mar 24, 8:10 am, wrote:
On Mar 20, 2:07 pm, "Arny Krueger" wrote:

"StudioDog" wrote in message


roups.com


And does that happen with both the Behringer interface
and the Alesis used as output device?


Meindert


Yes. Thenoisecomes through either interface as soon as
I boot Cubase.


Nothing attched to the interface but the computer?


I have the same problem. I run Reason 3.0 and Cubase SX3, an Alesis
Multimix8, and an EMU Xboard 61USBcontroller. As soon as I boot up
either program-- seperately or using ReWire-- the hum starts with
nothing connected to the inputs.

Here is the interesting bit. If I play with the sample rate in Reason
the pitch of the sound changes. If I play with theASIO buffer size in
the driver (ASIO4all) the hum becomes more modulated as the buffer
size gets larger (i.e. the hum begins to pulse).

When I listen to music through the Alesis using iTunes the hum is not
there.

StudioDog, does any of this reflect your experience? This suggests a
problem with the mixer'sUSBdata input-- maybe a bad D to A
conversion on the input stage?


I'd like to put up my hand at this time to say I've been experiencing
the same annoying problem with My Nehringher xenyx 1622 mixer. I get a
high pitched whine with a beeping on top. I was trying to figure out
what was going on and noticed that the mouse light was flashing at
exactly the same rate as the beeping. Is this a clue? I was hoping
this usb thing was going to cure these problems, not introduce
more......
No difference when I use my old NEC laptop. It's still there. Can't
believe these things could be pumped out with this inherent problem on
all units. Is there anyone out there who is using these usb interfaces
successfully?


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