[StudioDog]

Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise coupled with a lower frequency hum. I was able to decrease
the noise somewhat by purchasing a simple Behringer 2-in/2-out USB
audio interface instead of the Alesis built-in USB connection, but it
is still there, and passes the nois down the monitor chain from the
mixer to headphone amp (Behringer HA4700) to power amp (QSC USA370) to
montiro speakers (Behringer Truth passives).

To bugger things up even more, I periodically have interferenc ion the
recorded signal as well (bad hiss/white noise that makes the recording
take useless). The only way I can reset the system is to exit Cubase
and power off the mixer for a few seconds before repowering and
restarting Cubase. This can sometimes do the trick for the rest of the
session, sometimes I have to repeat this power-down several times per
session.

I believe the issue is a ground loop problem at the computer end of
things, probably exacerbated by the 15ft USB cable used to run the
mixer signals to my CPU in another room.

Does anyone know how to balance a USB cable? Would a firewire cable
work better? How about the ebtech HumX power plug? All my equipment is
on the same power bar -does anyone know if the HumX would sort out
all the kit on my power bar at the same time?

Any help/suggestion/suggested products would be great. Let's keep
budget (or lack thereof) in mind, too - this is a home studio, adn my
wife holds the chequebook!

Thanks.

[Richard Crowley]

"StudioDog" wrote ...
Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise

OK. So does your "high-pitched beeping/pulsing type noise" go
away when you disconnect the USB cable?

coupled with a lower frequency hum.

Does the "lower frequency hum" go away when you disconnect the
USB cable?

To bugger things up even more, I periodically have interferenc ion the
recorded signal as well (bad hiss/white noise that makes the recording
take useless). The only way I can reset the system is to exit Cubase
and power off the mixer for a few seconds before repowering and
restarting Cubase. This can sometimes do the trick for the rest of the
session, sometimes I have to repeat this power-down several times per
session.

I use a little utility called "End-It-All" to kill off all the useless MSwin
processes before attempting to use any computer for recording.
Of course, one would never turn off things like virus protection when
connected to the internet. And of couse wireless networking is among
the things that are known problems while recording.

I believe the issue is a ground loop problem at the computer end of
things, probably exacerbated by the 15ft USB cable used to run the
mixer signals to my CPU in another room.

The USB cable itself does not pick up audible hum. It is digital.

Does anyone know how to balance a USB cable?

USB is already balanced. But it isn't picking up audible hum,
so it wouldn't matter, anyway.

Would a firewire cable work better?

Firewire is electrically almost identical to USB. It is balanced in
the same way USB is.

How about the ebtech HumX power plug? All my equipment is
on the same power bar -does anyone know if the HumX would sort out
all the kit on my power bar at the same time?

Dunno. Have you done all the work to isolate exactly what
is causing the hum? Doesn't sound like it from what you
have written so far.

Any help/suggestion/suggested products would be great. Let's keep
budget (or lack thereof) in mind, too - this is a home studio, adn my
wife holds the chequebook!

Is is possible that the ground connection in the USB cable
could be contributing to a ground loop. You could always try
butchering a cable to make one that has only the D+ and D-
(balanced data lines) without the power, ground, and shield
lines connected. It would be the data equivalent of making a
balanced audio cable with "ground lift". You can find the USB
pinouts, etc online he http://en.wikipedia.org/wiki/USB
Of course, this assumes that your USB device (mixer, etc.)
is not being powered through the USB cable.

[Richard Crowley]

"Soundhaspriority" wrote ...
"Richard Crowley" wrote ...

Is is possible that the ground connection in the USB cable
could be contributing to a ground loop. You could always try
butchering a cable to make one that has only the D+ and D-
(balanced data lines) without the power, ground, and shield
lines connected. It would be the data equivalent of making a
balanced audio cable with "ground lift". You can find the USB
pinouts, etc online he http://en.wikipedia.org/wiki/USB
Of course, this assumes that your USB device (mixer, etc.)
is not being powered through the USB cable.

Dangerous if the devices are separated, as he indicates. A ground plane
differential could blow one side.

I thought the OP said they were all plugged into the same power strip.

[w_tom]

On Mar 9, 3:12 pm, "StudioDog" wrote:
Does anyone know how to balance a USB cable? Would a firewire cable
work better? How about the ebtech HumX power plug? All my equipment is
on the same power bar -does anyone know if the HumX would sort out
all the kit on my power bar at the same time?

USB signal wires are already balanced which is also why it is a
twisted pair and why each USB connecting cable cannot (should not) be
daisy chained.

Other wires in that cable are not balanced - the +5 volt power
wires.

If you don't know a USB interface at that level of detail, then you
are literally spitting in the wind. To really tear into this
problem, learn the most basics of basics - a difference between
differential and common mode noise. Currently, you don't even know
whether noise is one or the other; nor know if the noise if via USB
signal wires or USB power wires. Your experiments should start by
answering fundamental questions. Else all you can do is shotgun - try
this and try that - until something works. Often that only cures
symptoms - a temporary solution.

Noise is a hardware problem. Any magic solution on the power plug
already must be inside electronic power supplies. Software may mask
the problem. A hardware solution is necessary which requires answers
to those above questions: what type of noise and on which wires.
Provides are basic information to learn; to step through and solve
this problem.

[Michael Wozniak]

"StudioDog" wrote in message
ups.com...
Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise coupled with a lower frequency hum. I was able to decrease
the noise somewhat by purchasing a simple Behringer 2-in/2-out USB
audio interface instead of the Alesis built-in USB connection, but it
is still there, and passes the nois down the monitor chain from the
mixer to headphone amp (Behringer HA4700) to power amp (QSC USA370) to
montiro speakers (Behringer Truth passives).

To bugger things up even more, I periodically have interferenc ion the
recorded signal as well (bad hiss/white noise that makes the recording
take useless). The only way I can reset the system is to exit Cubase
and power off the mixer for a few seconds before repowering and
restarting Cubase. This can sometimes do the trick for the rest of the
session, sometimes I have to repeat this power-down several times per
session.

I believe the issue is a ground loop problem at the computer end of
things, probably exacerbated by the 15ft USB cable used to run the
mixer signals to my CPU in another room.

Does anyone know how to balance a USB cable? Would a firewire cable
work better? How about the ebtech HumX power plug? All my equipment is
on the same power bar -does anyone know if the HumX would sort out
all the kit on my power bar at the same time?

Any help/suggestion/suggested products would be great. Let's keep
budget (or lack thereof) in mind, too - this is a home studio, adn my
wife holds the chequebook!

Thanks.

Laptop or desktop? 2-prong or 3-prong AC plugs? Standard procedure - get the
problem noise started, then unplug (not just shut off) ALL components in
your system (including all that nasty behringer and alesis stuff) - *one at
a time* - and see if the problem goes away. I had a bad hum with my XP
desktop with Creamware Pulsars, which I traced to the LCD monitor (which is
powered by a 3-prong transformer brick, but sending 2 prongs to the
monitor). After putting a 3-to-2 prong adapter in line, the problem went
away.

It sounds like your problem is worse, but it's worth a try. I don't know
what the USB cable length spec is, but 15 feet sounds long to me.

Mikey Wozniak
Nova Music Productiuons
this sig is haiku

[Loren Amelang]

On 9 Mar 2007 12:12:21 -0800, "StudioDog"
wrote:

Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise coupled with a lower frequency hum. I was able to decrease
the noise somewhat by purchasing a simple Behringer 2-in/2-out USB
audio interface instead of the Alesis built-in USB connection, but it
is still there, and passes the nois down the monitor chain from the
mixer to headphone amp (Behringer HA4700) to power amp (QSC USA370) to
montiro speakers (Behringer Truth passives).

Is the noise synchronized with disk access or some other noticeable
computer function? I get noise synchronized with disk access if my
external USB drive is connected during audio work. No amount of ground
isolation seems to affect it, and I 've given up and just disconnect
it.

To bugger things up even more, I periodically have interferenc ion the
recorded signal as well (bad hiss/white noise that makes the recording
take useless). The only way I can reset the system is to exit Cubase
and power off the mixer for a few seconds before repowering and
restarting Cubase. This can sometimes do the trick for the rest of the
session, sometimes I have to repeat this power-down several times per
session.

That sounds like what my M-Audio Transit did before I cut away their
mic power feeds from the inputs. It would randomly start recording a
loud hiss, and the only solution was to power it down. The noise only
appeared if there was a ground offset between the Transit input and
the equipment connected to it, but exactly when it would start seemed
random. Once I disabled the mic power, the problem disappeared. My
suspicion is that the audio cables use much heavier wire than the USB
cables, so any ground offset ends up across the USB cable and
eventually swamps the digital signal.

Loren

[ChristopheRonald]

i have the humx ebtech plug, and i absolutely love it. kills all noise
on my laptop when it comes to that sorta stuff. everyone should own
one...

[Chevdo]

In article . com,
says...

Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise coupled with a lower frequency hum. I was able to decrease
the noise somewhat by purchasing a simple Behringer 2-in/2-out USB
audio interface instead of the Alesis built-in USB connection, but it
is still there, and passes the nois down the monitor chain from the
mixer to headphone amp (Behringer HA4700) to power amp (QSC USA370) to
montiro speakers (Behringer Truth passives).


USB audio always gives me a ground loop hum if I have any other soundcard
hooked up to the same amplifier as the USB audio output. The noise disappears
if I plug it into an amp without any other connections from my computer to that
amp. I suspect it will be very easy to look over your topology and find out
where the USB is able to loop back to your computer, but whether or not you can
disconnect that link and still run your setup the way you intend to is another
issue you might have to sort out.

[StudioDog]

On Mar 11, 2:40 am, (Chevdo) wrote:
In article . com,
says...



Hi all. I'm looking for suggestions/insight into a sticky noise
problem with my home studio.

The problem is that the USB connection between my computer (AMD 64x2
(2.0GHz) dual core running Cubase LE and Reason 3.0) and my mixer
(Alesis Multimix 8USB) is NOISY. I have a high-pitched beeping/pulsing
type noise coupled with a lower frequency hum. I was able to decrease
the noise somewhat by purchasing a simple Behringer 2-in/2-out USB
audio interface instead of the Alesis built-in USB connection, but it
is still there, and passes the nois down the monitor chain from the
mixer to headphone amp (Behringer HA4700) to power amp (QSC USA370) to
montiro speakers (Behringer Truth passives).

USB audio always gives me a ground loop hum if I have any other soundcard
hooked up to the same amplifier as the USB audio output. The noise disappears
if I plug it into an amp without any other connections from my computer to that
amp. I suspect it will be very easy to look over your topology and find out
where the USB is able to loop back to your computer, but whether or not you can
disconnect that link and still run your setup the way you intend to is another
issue you might have to sort out.

The USB audio link is the only connection between my studio setup and
the computer. I tried switching out the mixer yesterday, to no avail -
the beeping noise is coming through the USB interface (also replaced
with a new unit). My only guess at this point is that the noise is
somehow caused by the crappy wiring in my 27-yr-old house. I would
point fingers at my computer power supply. except that I get the noise
using other computers in the house too (laptop and PC tower).

Can anyone suggest a rack-mount power conditioner that also isolates
the ground? Thre only unit I have found so far that gets close is the
EBtech HumX, whihc I guess I could place between the wall outlet and
my power bar.

Thanks to everyone who has posted their replies here. I do appreciate
your input. Please, though, try to keep the discussion on a user-
friendly basis. I'm not a techie, just a guy trying o record some
tunes

[Scott Dorsey]

StudioDog wrote:

The USB audio link is the only connection between my studio setup and
the computer. I tried switching out the mixer yesterday, to no avail -
the beeping noise is coming through the USB interface (also replaced
with a new unit). My only guess at this point is that the noise is
somehow caused by the crappy wiring in my 27-yr-old house. I would
point fingers at my computer power supply. except that I get the noise
using other computers in the house too (laptop and PC tower).

If you disconnect everything but ONE audio input, does the problem
persist?

If you lift the pin 1 ground on that ONE audio input, does the problem
persist?

If you have just the interface and computer with no input plugged in,
do you have the problem?

Can anyone suggest a rack-mount power conditioner that also isolates
the ground? Thre only unit I have found so far that gets close is the
EBtech HumX, whihc I guess I could place between the wall outlet and
my power bar.

To isolate safety ground requires a real isolation transformer, which is
neither small nor cheap.

It is almost always easier to isolate signal grounds.

The next question: Does your building actually HAVE valid grounds?

Thanks to everyone who has posted their replies here. I do appreciate
your input. Please, though, try to keep the discussion on a user-
friendly basis. I'm not a techie, just a guy trying o record some
tunes

You need to take elements out of the system until the noise stops, then
you'll know where the loop is, if it's a loop, so you will know where
to break it.

If these cheap PC interfaces actually had real transformer-isolated inputs
and outputs like high-grade pro gear does, they'd cost ten times what they do.
So sometimes you need to add isolation transformers to signal lines, lift
signal grounds, and deal with the issues. Treat all inputs as if they were
really unbalanced.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[StudioDog]

On Mar 11, 1:29 pm, (Scott Dorsey) wrote:

If you disconnect everything but ONE audio input, does the problem
persist?

Yep

If you lift the pin 1 ground on that ONE audio input, does the problem
persist?

Run through my active DI, I can cut the noise dramatically, but it is
still there.

If you have just the interface and computer with no input plugged in,
do you have the problem?

Yes. Inputs seem clean; it's the outputs that are noisy.

The next question: Does your building actually HAVE valid grounds?

As far as I know. All my equipment runs into a Belkin power bar
(supposedly with RFI/EMI filters as well as surge protection), and the
Ground light on the bar indicates the presence of a ground.

You need to take elements out of the system until the noise stops, then
you'll know where the loop is, if it's a loop, so you will know where
to break it.

I have disconnected and unplugged everything but the computer and the
mixer and the noise persists. There is no noise on the built-in
Realtek HD Audio card, though. I may have to go analog to avoid the
noise. (I did instal a USB2.0 PCI card to try to isolate the USB ports
from any computer/electrical noise, but had no luck here either).

Treat all inputs as if they were really unbalanced.

Now looking at the ART DTI dual transformer isolator box. One of the
few unitsn with RCA, 1/4" and XLR in/out jacks.... no ground lift,
though.

Thanks for the plain english, Scott!

[Scott Dorsey]

StudioDog wrote:
On Mar 11, 1:29 pm, (Scott Dorsey) wrote:

If you disconnect everything but ONE audio input, does the problem
persist?

Yep

Okay, so you know it's a ground loop that can be solved by disconnecting
inputs.

If you lift the pin 1 ground on that ONE audio input, does the problem
persist?

Run through my active DI, I can cut the noise dramatically, but it is
still there.

That's not the question I asked. If you use a ground lift adaptor or
a cable with the shield telescoped at one end, does the problem persist?

If you have just the interface and computer with no input plugged in,
do you have the problem?

Yes. Inputs seem clean; it's the outputs that are noisy.

Are the outputs differentially-driven or are they cheesy "impedance
balanced" outputs?

The next question: Does your building actually HAVE valid grounds?

As far as I know. All my equipment runs into a Belkin power bar
(supposedly with RFI/EMI filters as well as surge protection), and the
Ground light on the bar indicates the presence of a ground.

Okay, that's a good sign.

You need to take elements out of the system until the noise stops, then
you'll know where the loop is, if it's a loop, so you will know where
to break it.

I have disconnected and unplugged everything but the computer and the
mixer and the noise persists.

Do you get noise on the outputs if you do not have the mixer plugged into
it? If you just plug headphones into the output with no mixer, nothing
that could POSSIBLY have a connection to ground, does the problem persist?

If you hear the problem that way, you aren't going to fix it with changing
audio stuff around. If you don't hear the problem that way, try connecting
ONE line to the console. If you still hear it, try connecting one line with
the ground lift adaptor on the console input. If you still hear it then,
it's probably transformer time.

Treat all inputs as if they were really unbalanced.

Now looking at the ART DTI dual transformer isolator box. One of the
few unitsn with RCA, 1/4" and XLR in/out jacks.... no ground lift,
though.

I would be very suspicious of any ART product containing transformers. I'd
suggest at LEAST the Ebtech if you can't afford the Jensen.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[videochas www.locoworks.com]

On Mar 11, 9:13 am, "StudioDog" wrote:
On Mar 11, 2:40 am, (Chevdo) wrote:

snip

Can anyone suggest a rack-mount power conditioner that also isolates
the ground? Thre only unit I have found so far that gets close is the
EBtech HumX, whihc I guess I could place between the wall outlet and
my power bar.

Thanks to everyone who has posted their replies here. I do appreciate
your input. Please, though, try to keep the discussion on a user-
friendly basis. I'm not a techie, just a guy trying o record some
tunes

Take a look at the line of Furman power conditioners. I use two
RP-8's. They are well made and not too expensive. And, no, I don't
own stock.

[w_tom]

On Mar 11, 2:59 pm, "StudioDog" wrote:
...
The next question: Does your building actually HAVE valid grounds?

As far as I know. All my equipment runs into a Belkin power bar
(supposedly with RFI/EMI filters as well as surge protection), and the
Ground light on the bar indicates the presence of a ground.
...

I have disconnected and unplugged everything but the computer and the
mixer and the noise persists. There is no noise on the built-in
Realtek HD Audio card, though. I may have to go analog to avoid the
noise. (I did instal a USB2.0 PCI card to try to isolate the USB ports
from any computer/electrical noise, but had no luck here either).

Does everything have three prong plugs? When you say you
disconnected everything but .. everything means even disconnecting
power cord. IOW do you put those other items on an isolated power
source such as a UPS that is only running on internal batteries? If
not, then that wire is also carrying signals - you did not disconnect
everything.

The Belkin provided only enought EMI/RFI filtering to make a claim.
Put numbers to that claim and Its filtering is zero. Also one
potential noise carrying wire through that Belkin must have no
filtering as required by human safety. Don't think of it as a magic
box. Think of it in terms or each seperate wire inside that Belkin.
Think in terms of each wire; not in terms of boxes.

Isolation - every electronic device must already contain an
isolation transformer or something equivalent. It is required for
human safety. That isolation would only address differential mode
noise. Noise can exist by coming down one wire and returning on the
other. Or noise can exist by coming down only one wire and continuing
through. Two completely different noise modes. Three AC electric
wires. Different units see one signal / noise and not the oher even
when both modes exist. Without this simple concept, then all you can
do is keep buying magic box solutions.

To get anything more than a 'try this and try that' response,
diagram every connnection. That means listing each of three wires in
the AC cable because even that may define connections for different
noise modes. That means listing which USB wires are and are not
used. USB has four wires. You need to know that.

USB is not just a signal wire. Does your mixer use power wires on
that USB; or only use balanced signal wires? To get an answer that
can target the problem, know things at that level of basic detail.
Only alternative is to keep changing things and spending money until
noise diminishes to an acceptable level.

Ground - your household wiring is 100% best. 27 year old wiring
would be same as 1 year old wiring. For this problem, irrelevant
whether a building safety ground exists. What matters is a single
point ground that you apparently established on the power strip.
Everything that connects to an entire system - everything - must get
power only via that strip. Nothing can be grounded or connected to
anything else - even touch baseboard heat . Otherwise that is another
connection that is not through the power strip. Anything else
conductive (tabletop, floor, etc). Then these also must be connected
to the Belkin safety ground and added to your diagram of wire
connections.

For useful replles, what is connected to what must be defined in
terms of every wire in every cable. For example, computer and mixer.
Computer connects to power strip. Mixer connects to power strip. USB
connects between them. Right there are mutliple wires that could be
an electrical loop - reason for noise. Question is whether a common
mode noise is using that loop. In theory, differential mode noise
would not onduct if mixer and computer only used signal wires in USB
cable. But USB cable is four wires. How do the other two wires
connect?

Above is the simplest way for layman to solve a noise problem.
Nothing posted is technically complex - requires any training.
Everything posted is at the layman level - except EMI/RFI claims from
Belkin which uses deceptive claims. Otherwise keep buying and trying
things randomly.

[StudioDog]

On Mar 11, 4:31 pm, (Scott Dorsey) wrote:
Do you get noise on the outputs if you do not have the mixer plugged into
it? If you just plug headphones into the output with no mixer, nothing
that could POSSIBLY have a connection to ground, does the problem persist?

.....sort of. My USB adapter is a Behringer UCA202 with L/R RCA INs and
OUTs, and a headphone jack. Plugging directly into the headphone
jack, I still get the noise, although very faintly. If I patch this
output to the mixer or headphone amp, however, the noise is as loud as
ever. If only I could get by with just one set of phones.....

Suggestions? Buy a better USB adapter? Firewire? Something else
entirely?

[Scott Dorsey]

StudioDog wrote:
On Mar 11, 4:31 pm, (Scott Dorsey) wrote:
Do you get noise on the outputs if you do not have the mixer plugged into
it? If you just plug headphones into the output with no mixer, nothing
that could POSSIBLY have a connection to ground, does the problem persist?

....sort of. My USB adapter is a Behringer UCA202 with L/R RCA INs and
OUTs, and a headphone jack. Plugging directly into the headphone
jack, I still get the noise, although very faintly. If I patch this
output to the mixer or headphone amp, however, the noise is as loud as
ever. If only I could get by with just one set of phones.....

If you got the noise with JUST headphones and the computer plugged in,
you know it can't be a ground loop because there is no ground in the
system other than the one on the USB cable.

Suggestions? Buy a better USB adapter? Firewire? Something else
entirely?

Or get your broken one fixed, maybe.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[w_tom]

On Mar 11, 7:42 pm, "StudioDog" wrote:
....sort of. My USB adapter is a Behringer UCA202 with L/R RCA INs and
OUTs, and a headphone jack. Plugging directly into the headphone
jack, I still get the noise, although very faintly. If I patch this
output to the mixer or headphone amp, however, the noise is as loud as
ever. If only I could get by with just one set of phones.....

Suggestions? Buy a better USB adapter? Firewire? Something else
entirely?

If you have a computer only with headphones - no other box connected
to it - and laptop only connected to AC mains. Noise is heard on
headphones. Why then would any other item - ie USB cable or another
USB adaptor- solve anything? The noise is balanced - differential
mode - exactly same as the signal. Therefore all equipment would
mix / amplify both noise and signal as if they were same. Nothing
else will solve this problem because both signal and noise are same
balance signals - therefore cannot be separated.

Meanwhile you are still shorting important facts. For example, what
kind of computer? Laptop? Desktop? Clone? Previously noted is that
every wire is important. Does the computer, for example, connect to
third prong safety ground? Some laptops, for example, don't make
that direct connection even thought the power plug has three prongs.
Number of wires in its power cable significantly changes possible
reasons for your problem.

I am assuming this is only a two wire, analog headphone - no
amplifier or other electronic controls.

This post is about a last test; unclear what is connected to what.
We don't even know if it has a two wire or three wire connection to AC
mains. But when noise mode is same as signal mode, then both will not
be separated. Solution is installed / implemented where or before the
two 'same mode' signals combine. Where does analog signal connect
that is somehow before noise and signal gets combined?

[StudioDog]

On Mar 12, 7:29 am, "w_tom" wrote:
On Mar 11, 7:42 pm, "StudioDog" wrote:

....sort of. My USB adapter is a Behringer UCA202 with L/R RCA INs and
OUTs, and a headphone jack. Plugging directly into the headphone
jack, I still get the noise, although very faintly. If I patch this
output to the mixer or headphone amp, however, the noise is as loud as
ever. If only I could get by with just one set of phones.....

Suggestions? Buy a better USB adapter? Firewire? Something else
entirely?

If you have a computer only with headphones - no other box connected
to it - and laptop only connected to AC mains. Noise is heard on
headphones. Why then would any other item - ie USB cable or another
USB adaptor- solve anything? The noise is balanced - differential
mode - exactly same as the signal. Therefore all equipment would
mix / amplify both noise and signal as if they were same. Nothing
else will solve this problem because both signal and noise are same
balance signals - therefore cannot be separated.

Meanwhile you are still shorting important facts. For example, what
kind of computer? Laptop? Desktop? Clone? Previously noted is that
every wire is important. Does the computer, for example, connect to
third prong safety ground? Some laptops, for example, don't make
that direct connection even thought the power plug has three prongs.
Number of wires in its power cable significantly changes possible
reasons for your problem.

I am assuming this is only a two wire, analog headphone - no
amplifier or other electronic controls.

This post is about a last test; unclear what is connected to what.
We don't even know if it has a two wire or three wire connection to AC
mains. But when noise mode is same as signal mode, then both will not
be separated. Solution is installed / implemented where or before the
two 'same mode' signals combine. Where does analog signal connect
that is somehow before noise and signal gets combined?

Here's my setup:

Computer - HP Pavilion with AMD 64x2 2.0GHz dual core processor, USb
2.0 PCI card installed
USB interface - Behringer UCA202 (2 in/2 out, unbalaqnced RCA in/out
jacks)
Mixer - Alesis Multimix 8USB (bought the Behringer interface when it
proved quieter than the buillt-in USB in the deck)
Headphone amp - Behringer HA4700
Monitor Amp - QSC USA370
Studio Monitors - Behringer Truth passives
Headphones - a variety of analog, 2-wire type phones for basic
listening and playback
Midi keyboard - M-Audio Keystation 39e via usb to computer

Main outputs from mixer -- inputs on usb interface via unbalanced
1/4" - RCA cables --Cubase LE

Monitor path is Cubase LE --usb interface --Tape IN on deck via
unbalanced RCA cables --Control Room outputs on mixer --head amp via
balanced TRS cables --monitor amp via balanced TRS cables -- monitor
speakers.

All mains power cords run from equipment to Belkin power bar; all are
3-prong except mixer (2 prong wall wart). All gear independently
powered (separate mains cables) except USB interface which is powered
by USB cable.

Also note that all computer cables (monitor, keyboard, mouse, usb, and
on-board sound (windows sounds only - studio record/playback routed
through usb) run on extensions to computer tower in adjacent room.

Hope this info helps.

[Philippe Lemaire \(remove oldies\)]

StudioDog wrote:
On Mar 11, 4:31 pm, (Scott Dorsey) wrote:
Do you get noise on the outputs if you do not have the mixer plugged into
it? If you just plug headphones into the output with no mixer, nothing
that could POSSIBLY have a connection to ground, does the problem persist?

....sort of. My USB adapter is a Behringer UCA202 with L/R RCA INs and
OUTs, and a headphone jack. Plugging directly into the headphone
jack, I still get the noise, although very faintly. If I patch this
output to the mixer or headphone amp, however, the noise is as loud as
ever. If only I could get by with just one set of phones.....

Suggestions? Buy a better USB adapter? Firewire? Something else
entirely?

On my laptop, I can stop the noise :

by touching one of the speaker grids
plugging the analogue out of the M-Transit to the amplifier

Otherwise an MD player connected by USB to the PC gives hum
on its own headphones...


Philippe

[Chris Hornbeck]

On 12 Mar 2007 07:17:58 -0700, "StudioDog"
wrote:

All mains power cords run from equipment to Belkin power bar;

Also note that all computer cables (monitor, keyboard, mouse, usb, and
on-board sound (windows sounds only - studio record/playback routed
through usb) run on extensions to computer tower in adjacent room.

Which is plugged into AC where perzactly?

All good fortune,

Chris Hornbeck

[StudioDog]

On Mar 12, 6:50 pm, Chris Hornbeck
wrote:
On 12 Mar 2007 07:17:58 -0700, "StudioDog"
wrote:

All mains power cords run from equipment to Belkin power bar;
Also note that all computer cables (monitor, keyboard, mouse, usb, and
on-board sound (windows sounds only - studio record/playback routed
through usb) run on extensions to computer tower in adjacent room.

Which is plugged into AC where perzactly?

Computer mains power comes back through the wall to plug into the
power bar with the rest of the kit.

[w_tom]

On Mar 13, 10:04 am, "StudioDog" wrote:
Computer mains power comes back through the wall to plug into the
power bar with the rest of the kit.

First, the system that creates noise is an HP computer, a mixer, and
only headphones - not even a headphone amplifier. HP is powered by a
how many foot of three wire extension cord to Belkin power strip? HP
also has a monitor. What is every wire that connects to the monitor?
Monitor also connects via that same extension cord. Nothing else in
the HP system has a power connection. What is that station sitting
on .. remember that may be conductive even if you don't think so?

From HP is a 15 foot USB cable to the mixer. Mixer has a metal
surface? Therefore what is mixer sitting on - electrically connected
to? Assumed is the mixer is a three prong power cord that plugs into
Belkin.

Headphone plug directly into mixer; no other connections. Noise is
heard on headphones even when that mixer control program is not
running on HP.

Is this all correct? Nothing else - amplifier or speakers - connect
to mixer. HP sound card has zero connections. No ethernet, no phone,
nothing else connects to HP. Remember, every wire in every cable must
be defined.

Fine. Get a six foot USB cable. Temporarily move the HP to the
mixer. Connect HP to mixer with six foot USB cable and then confirm
that noise still exists.

Next, with a razor blade or knive, carefully open USB cable
insulation jacket. Inside will be four wires. Two are twisted pair
Other two are untwisted. (When power is off), cut the two non-twisted
wires. Restore all connections. Discover how much noise still
exists. With only those two wires cut, what now happens.

This is not a fix. Never try to fix when still collecting data.
Earlier discussed were many noise modes. That is what we must
discover. Long before we can make a permenant solution, first define
the problem. After all this time, nothing defined the problem; which
is why zero got accomplished. Do this experiment and post back. And
do not do this experiment if anything above is not as assumed. Do not
cut the wire yet if some connection is not as in the above list.

[Chris Hornbeck]

On 13 Mar 2007 07:04:11 -0700, "StudioDog"
wrote:

Which is plugged into AC where perzactly?

Computer mains power comes back through the wall to plug into the
power bar with the rest of the kit.

Cool. Probably not strictly code, but cool.

The computer doesn't have any TV cards, networking, etc.?
And its monitor (if external) also has Edison run back to
the other room? Printers, yada, yada?

All good fortune,

Chris Hornbeck

[Meindert Sprang]

"w_tom" wrote in message
oups.com...
Next, with a razor blade or knive, carefully open USB cable
insulation jacket. Inside will be four wires. Two are twisted pair
Other two are untwisted. (When power is off), cut the two non-twisted
wires. Restore all connections. Discover how much noise still
exists. With only those two wires cut, what now happens.

DON'T DO THIS!!!!!

This is very stupid advice, since this will blow the USB port electronics
whenever there is more than 5V voltage difference between the equipment.
Ungrounded equipment with a mains filter inside will have the "ground"
floating at half the mains voltage. If such a device is connected to a
grounded one, this voltage difference will exist between these devices. If
these are the computer and the USB sound I/F connnected to a mixer, this
voltage will now be injected onto the data lines of the USB port and blow
it. I have seen serial ports go the same way.

Meindert

[[email protected]]

Have been havin this problem ever since I decided to use my laptop as
a giant sampler/keyboard sound module. Have never been able to solve
it. First I thought it was the fault of my Dell Latitude computer -
that I was unlucky enough to get a laptop that had as interfering
power supply with my Edirol UA25. But as my brother got a new Toshiba
laptop and an M-Audio Firewire audio box for it and had the same
problems I think this seems to be a common problem. I also have a
Digidesign M-Box1 and it has exactly the same problem;

When connecting the outputs to a PA/Studio mixer or a guitar amplifier
there is digital noise interference coming down the line. Plugging out
the power supply and just leaving the laptop run on battery power the
noise all but disappears.

The funny thing i know of several high profile bands using Apple
computers live in this way - either to run backing track playback from
ProTools/Cubase or as a software sampler/synth sound modules.... I
dont know if the Apples are free from this problem or they know a way
around it but its interesting. I also wonder since music stores are
selling buckets of these things shouild there not be thousands of
people around the world experiencing thiese problems? I've tried 4 PC
laptops now and various audio devices and have had no different
results. Does anyone here have a laptop with USB/Firewire audio
interface that you can connect to a PA mixer that doesn't give out
these problems?

Very interested to get to the bottom of this. Someone suggested
removing the earth from the laptop power supply but was told by a live
sound engineer that he tried this with no success.

Martin

[Scott Dorsey]

In article . com,
wrote:
Have been havin this problem ever since I decided to use my laptop as
a giant sampler/keyboard sound module. Have never been able to solve
it. First I thought it was the fault of my Dell Latitude computer -
that I was unlucky enough to get a laptop that had as interfering
power supply with my Edirol UA25. But as my brother got a new Toshiba
laptop and an M-Audio Firewire audio box for it and had the same
problems I think this seems to be a common problem. I also have a
Digidesign M-Box1 and it has exactly the same problem;

When connecting the outputs to a PA/Studio mixer or a guitar amplifier
there is digital noise interference coming down the line. Plugging out
the power supply and just leaving the laptop run on battery power the
noise all but disappears.

Yes, this is very common. Ths switching supply is spewing out huge
amounts of trash and corrupting the grounds. You'll find it causes
noise problems on equipment not even connected to the computer.

The only solution is to replace the switcher with a quiet power
supply. Odds are the switcher doesn't even meet FCC noise specs, since
most of the ones on the market don't sem to.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[w_tom]

If Meindert Spang's concern was true, then this 'his failure' would
occur often on differential mode serial connections - ie firewire.
His failure cannot happen because of how electronics is designed. And
then it cannot happen again because all electronics share the same
Belkin power strip. And it that port did blow as Meindert suggests,
then we have found currents that must not exist; may have damaged
other more expensive equipment later.

Cut the two untwisted wires only because reason for the noise (that
also could be a symptom of more serious problems) is the objective.
Those reasons result in a cure later. Cutting that wire will cause no
damage, for many reasons listed above.


On Mar 14, 2:42 am, "Meindert Sprang"
wrote:
"w_tom" wrote in message
Next, with a razor blade or knive, carefully open USB cable
insulation jacket. Inside will be four wires. Two are twisted pair
Other two are untwisted. (When power is off), cut the two non-twisted
wires. Restore all connections. Discover how much noise still
exists. With only those two wires cut, what now happens.

DON'T DO THIS!!!!!

This is very stupid advice, since this will blow the USB port electronics
whenever there is more than 5V voltage difference between the equipment.
Ungrounded equipment with a mains filter inside will have the "ground"
floating at half the mains voltage. If such a device is connected to a
grounded one, this voltage difference will exist between these devices. If
these are the computer and the USB sound I/F connnected to a mixer, this
voltage will now be injected onto the data lines of the USB port and blow
it. I have seen serial ports go the same way.

[w_tom]

On Mar 14, 8:56 am, wrote:
Have been havin this problem ever since I decided to use my laptop as
a giant sampler/keyboard sound module. Have never been able to solve
it. ...

Very interested to get to the bottom of this. Someone suggested
removing the earth from the laptop power supply but was told by a live
sound engineer that he tried this with no success.

Notice the completely different strategic approach to the problem.
Too many want to fix the problem immediately. Instead, a problem is
better solved when the only objective is learning WHY the problem
exists. Then later, we solve that problem. Trying to solve a problem
without first learning 'reason why' often results in shotgunning and
solutions that only cure symptoms.

[Meindert Sprang]

"w_tom" wrote in message
ups.com...
If Meindert Spang's concern was true, then this 'his failure' would
occur often on differential mode serial connections - ie firewire.

This has nothing to do with differential connections. First, my concern IS
true because I have seen it happen with a serial port. I had a laptop
connected to another device without ground (2 prongs). Plugging in the
serial connector blew the serial port in the laptop. I have seen it happen
with people sharing one printer on two computers with a printer switch..

His failure cannot happen because of how electronics is designed. And
then it cannot happen again because all electronics share the same
Belkin power strip.

Don't tell me how electronics is designed, that is my job (www.customware.nl
, www.shipmodul.com ) and I design for much harsher environments (marine)
than an electrically "quiet" studio or home environment.

Once again: every device has a filter in the mains, by regulations. These
filters have input capacitors between the power wires and the ground wire.
If you plug such a device in a non-grounded power outlet, the ground or case
of that device is floating at half the mains voltage because both caps act
as an AC voltage divider. If you have a second device which is grounded,
then a voltage exists between the ground of both devices. This voltage is
enough to kill a serial, USB or firewire input at the moment the connection
is made. At that moment the caps discharge though the electronics of the
port. If the connecion is already made, cutting the ground is not a big
problem since the caps have sufficient high impedance for 50/60Hz for not to
be able to build up any charge (around 300kOhm).

Plugging a USB or Firewire is no problem since these connectors are designed
to make the ground connection first, before connecting the data signals.

And it that port did blow as Meindert suggests,

I am not suggesting, I have seen it happen.

then we have found currents that must not exist; may have damaged
other more expensive equipment later.

In "the old days" you would find warnings in manuals of serial devices and
parallel printers to disconnect the mains first before plugging in the data
connections. Exactly for that reason.

The rule of thumb is: when a device has a 3 prong power plug, use a grounded
socket because a mains filter exists. I don't know about the US but here in
Europe we have 230V and when you plug a computer in an ungrounded socket and
you touch the case, you can feel a tingling sensation. If you grab the
central heating and ground yourself, you will experience a shock from the
115V voltage on the housing. you can even see arcs if you touch the housing
with a grounded wire.

Meindert

[w_tom]

On Mar 15, 3:19 am, "Meindert Sprang"
wrote:
This has nothing to do with differential connections. First, my concern IS
true because I have seen it happen with a serial port. I had a laptop
connected to another device without ground (2 prongs). Plugging in the
serial connector blew the serial port in the laptop. I have seen it happen
with people sharing one printer on two computers with a printer switch..
...

Once again: every device has a filter in the mains, by regulations. These
filters have input capacitors between the power wires and the ground wire.
If you plug such a device in a non-grounded power outlet, the ground or case
of that device is floating at half the mains voltage because both caps act
as an AC voltage divider. If you have a second device which is grounded,
then a voltage exists between the ground of both devices. This voltage is
enough to kill a serial, USB or firewire input at the moment the connection
is made. At that moment the caps discharge though the electronics of the
port. If the connecion is already made, cutting the ground is not a big
problem since the caps have sufficient high impedance for 50/60Hz for not to
be able to build up any charge (around 300kOhm).

Yes that failure can happen - iff .... First, that type filter
design cannot exist on devices without a third prong 'equipment'
ground. It would violate safety standards and create so many other
problems. If failure happens as you have described, then we have
found the problem - a box that is designed defectively.

Second, if what was described exists (creates damage), then firewire
also would be routinely destroyed.

Cut the untwisted wire on USB cable and do the test. Since both HP
computer and mixer both are safety (equipment) grounded to power
strip, then we have a third reason for why 'what Meindert Sprang
suggests' cannot (and must not) happen.

[Meindert Sprang]

"w_tom" wrote in message
oups.com...
Second, if what was described exists (creates damage), then firewire
also would be routinely destroyed.

Why? Firewire also has a ground which connects before both twisted pairs do.

Meindert

[w_tom]

On Mar 15, 6:26 pm, "Meindert Sprang"
wrote:
Second, if what was described exists (creates damage), then firewire
also would be routinely destroyed.

Why? Firewire also has a ground which connects before both twisted pairs do.

OK, only some firewire are differential mode only. But every
computer user is familiar with other serial connections that have no
ground and must suffer no damage: ie Ethernet. Again a differential
mode connection between two boxes or sometimes even between buildings
- no ground - no damage.

Provided was why damage would not occur in that experiment - three
times over.

Cut untwisted wires in a USB cable to perform the test. If damage
were to occur as Meindert suggests, then we have found a serious,
unacceptable, and maybe even human safety problem. That damage must
never occur. Solution is to also fix reason for that damage - not
cure its symptoms.

Why do we connect boxes with differential mode signals such as USB,
firewire, ethernet, etc? Because we don't want currents flowing
between those boxes - create ground loops. What is the source of
StudioDog's problem? Maybe - only maybe - ground loops. Without
facts obtained from that modified USB cable, then replies can only be
speculation.

Provided three times over - and now with the Ethernet example - are
reasons why cutting the untwisted wires must not cause any damage.

[Meindert Sprang]

"w_tom" wrote in message
ups.com...
On Mar 15, 6:26 pm, "Meindert Sprang"
wrote:
Why? Firewire also has a ground which connects before both twisted pairs
do.

OK, only some firewire are differential mode only.

No, every firewire is differential. But the ground is needed to prevent
excessive common mode voltages since firewire has no galvanic isolation.

But every
computer user is familiar with other serial connections that have no
ground and must suffer no damage: ie Ethernet. Again a differential
mode connection between two boxes or sometimes even between buildings
- no ground - no damage.

That is because ethernet is galvanically isolated with transformers
capabable of withstanding 1500V.

Provided was why damage would not occur in that experiment - three
times over.

As long as the OP can ensure that both devices at the end of the USB
connection are grounded through another path, he'll be fine. But at one
stage he also mentioned a 2 prong laptopt adapter thats why I warned.

Why do we connect boxes with differential mode signals such as USB,
firewire, ethernet, etc? Because we don't want currents flowing
between those boxes - create ground loops.

Wrong. The only interface that prevents groundloops in this case is ethernet
because of it's transformers. USB of completeley DC coupled and firewire can
be either DC coupled or AC coupled through 10nF//1MOhm. Read the standards.

And the signals are differential beacause it provides better common mode
rejection and better bandwith. Nothing to do with isolation.

What is the source of
StudioDog's problem? Maybe - only maybe - ground loops. Without
facts obtained from that modified USB cable, then replies can only be
speculation.

Provided three times over - and now with the Ethernet example - are
reasons why cutting the untwisted wires must not cause any damage.

As long as the devices have a common ground it is indeed no problem. It's
just that you keep backing this up with wrong facts and/or examples.

Meindert

[w_tom]

On Mar 16, 2:19 am, "Meindert Sprang"
wrote:
As long as the OP can ensure that both devices at the end of the USB
connection are grounded through another path, he'll be fine. But at one
stage he also mentioned a 2 prong laptopt adapter thats why I warned.

And so StudioDog noted he has everything plugged into a Belkin power
strip. IOW Meindert knew when he was posting this warning that it was
not relevant. IOW Meindert has spent post after post to obstruct the
OP in learning what has caused his noise.

Strip the insulation from a 6 foot USB cable. Conduct the test.
Ignore everything that Meindert has posted because it is not relevant
and because Meindert now acknowledges his posts were not relevant.

[Meindert Sprang]

"w_tom" wrote in message
oups.com...
On Mar 16, 2:19 am, "Meindert Sprang"
wrote:
As long as the OP can ensure that both devices at the end of the USB
connection are grounded through another path, he'll be fine. But at one
stage he also mentioned a 2 prong laptopt adapter thats why I warned.

And so StudioDog noted he has everything plugged into a Belkin power
strip. IOW Meindert knew when he was posting this warning that it was
not relevant. IOW Meindert has spent post after post to obstruct the
OP in learning what has caused his noise.

Strip the insulation from a 6 foot USB cable. Conduct the test.
Ignore everything that Meindert has posted because it is not relevant
and because Meindert now acknowledges his posts were not relevant.

Man, what is your problem? I just tried to warn against potential damage!

Meindert

[w_tom]

On Mar 16, 5:57 pm, "Meindert Sprang"
wrote:
Man, what is your problem? I just tried to warn against potential damage!

Why do you keep interrupting with irrelevant warnings? Why confuse
and scare StudioDog about damage that you now admit would not happen?
Why do you confuse StudioDog and others with posts that have no
relevance? Why do you encourage him to not test - to not learn - to
not discover his problem? Why but another post when Meindert finally
admits his warning was about something non-existent? Meindert,
demonstrated three times over were that your posts are completely
relevant. You now admit that. Why do you keep posting - and then be
such a jerk as to complain? Shame on you. Stop confusing everyone
with things irrelevant. Man, what is your problem?

StudioDog: Get that USB cable. Test it for noise. Then strip back
the insulation, cut untwisted wires, and test again. Don't let so
many irrelevant posts from Meindert scare you off. He now admits to
warning of something that did not exist. He did not even learn what
you had before posting his irrelevance.

[StudioDog]

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.

I'll post again when I have something useful to contribute.

[Harry Lavo]

"StudioDog" wrote in message
oups.com...
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.

I'll post again when I have something useful to contribute.


Do you have any Paddy's Day gigs in Holyoke, MA? We could use one that
could melt 10" of snow, so that the second largest St. Patrick's Day parade
in the country can happen tomorrow. The normal 10K road race associated
with it has already been canceled.

[w_tom]

On Mar 17, 9:12 am, "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.

[Meindert Sprang]

"w_tom" wrote in message
oups.com...
On Mar 17, 9:12 am, "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.

One last thing and then I'll shut up, I promise you.

Why is a ground loop causing hum? Becaue a closed path exists through which
current flows. This current flow produces a voltage between any of two
points in the ground loop. It has to, otherwise you would not hear it. To be
able to hear it, the voltage can be small on a single-ended connection, but
on a differential connection, the voltage must be larger because a
differential connection is quite insensitive to common mode. And a large
voltage across a ground path simply means there is quite a high common mode
current (Ohm's law).

So far, relevant to StudioDog's problem I think.

Breaking this ground loop can result in quite a high voltage across the
point where you break the loop. If that point is the ground of the USB link,
this voltage will cause a current flow into the USB port's datalines because
that is the only path that now exists. Whether this current is high enough
to destroy the USB port, I cannot say beforehand. The only question to
StudioDog is: will you take that risk?

Meindert