I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away. I tried a monster cable power supply, then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

TIA!

-emde

In article . com,
wrote:
I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away. I tried a monster cable power supply, then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

Lift the signal ground, NOT the safety ground.

If the M-Audio thing has a balanced input, use it. And lift the signal
ground on it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Hmm, the 410 does have balanced XLR inputs on the front... even though
the Triton doesn't have balanced trs outputs I should still benefit,
correct? I'll give this a shot after work. Thanks.

-emde

In article .com,
emde wrote:
Hmm, the 410 does have balanced XLR inputs on the front... even though
the Triton doesn't have balanced trs outputs I should still benefit,
correct? I'll give this a shot after work. Thanks.

You can benefit in that it will let you break the ground. Tip and ring
to pins 2 and 3, ground floats.
--scott

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

wrote:

I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away.

No surprise. This is a regular issue.

I tried a monster cable power supply,

I *seriously* hope that wasn't your own idea !

then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

Use DIs between the audio gear and the M Audio interface ? Find a better
audio interface that doesn't inject the PC's ground noise into the audio
path perhaps ? Don't expect a PC store 'advisor' to have remotely the
faintest clue about this btw !


Graham

I tried a monster cable power supply,

I *seriously* hope that wasn't your own idea !

It was step one, a guitar center sales person suggested it.


Use DIs between the audio gear and the M Audio interface ? Find a
better
audio interface that doesn't inject the PC's ground noise into the
audio
path perhaps ? Don't expect a PC store 'advisor' to have remotely the
faintest clue about this btw !


Graham


I was thinking of giving this a try if the XLR connection doesn't
resolve it.

http://www.8thstreet.com/product.asp...o_Proce ssors

-emde

emde wrote:

I tried a monster cable power supply,

I *seriously* hope that wasn't your own idea !

It was step one, a guitar center sales person suggested it.

Don't take advice from THAT guy ever again.
--scott

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

Scott Dorsey wrote:
Don't take advice from THAT guy ever again.

I am learning that most of the GC reps give lousy advice.

-emde

I have a similar problem: I'm using an Echo Indigo card in my laptop,
however, the problem also exists in the built-in sound card. If I use
headphones, NO NOISE! But if I plug an audio cable in and take it to a
mixer I get noise. This only occurs when using the AC power, not when
using the battery.

What can I do?

Skippy


wrote in news:1113932523.796793.49630
@o13g2000cwo.googlegroups.com:

I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away. I tried a monster cable power supply, then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

TIA!

-emde

On Wed, 20 Apr 2005 00:59:07 GMT, Skippy wrote:

I have a similar problem: I'm using an Echo Indigo card in my laptop,
however, the problem also exists in the built-in sound card. If I use
headphones, NO NOISE! But if I plug an audio cable in and take it to a
mixer I get noise. This only occurs when using the AC power, not when
using the battery.

What can I do?

This is a classic, textbook, for-the-record-book ground loop issue.
Or my name isn't O. Gadfly Hurtz.

PWK RIP.

Chris Hornbeck
"Hum is more than just not knowing the words." -ha

"emde" wrote ...
Scott Dorsey wrote:
Don't take advice from THAT guy ever again.

I am learning that most of the GC reps give lousy advice.

NOMINATED: Understatement of the month.

FWIW, this is one reason Walkabout's standard kit included 50' of heavy
extension cord -- to make sure we could run everything off a single
supply and thus avoid having to think about ground loops.

Well I tried using XLR cables, no help there. So I am going to try and
pick up an isolator similar to this tomorrow:

http://www.8thstreet.com/product.asp...o_Proce ssors

I'll post my results.

-emde

On Tuesday 19 April 2005 07:59 pm, Skippy thusly spake:

I have a similar problem: I'm using an Echo Indigo card in my laptop,
however, the problem also exists in the built-in sound card. If I use
headphones, NO NOISE! But if I plug an audio cable in and take it to a
mixer I get noise. This only occurs when using the AC power, not when
using the battery.

What can I do?

Skippy


Is the AC power for your laptop and the mixer running off the same power
source? If you're plugged into two separate outlets then try plugging both
the mixer and AC power into the same powerstrip to ensure they use the same
ground. (or lack thereof) Even then, that may not totally fix the problem
since most AC adapters don't have a ground pin.

-Reuben

"emde" wrote:

I was thinking of giving this a try if the XLR connection doesn't
resolve it.

http://www.8thstreet.com/product.asp...o_Proce ssors



That seems like a good idea. I wonder a little about that particular
iso box though, only because it seems too cheap. At $45, you get a box,
a whole whack of connectors and two transformers for less than half of
what one good Jensen xformer costs. It makes me wonder what it will do
to the bottom end of your synth signal, but maybe I'm just being a snob.

If you want more confidence in what you[re buying, take a peek at the
Jensen web site. They have similar boxes built with well respected
coily things.

--
"It CAN'T be too loud... some of the red lights aren't even on yet!"
- Lorin David Schultz
in the control room
making even bad news sound good

(Remove spamblock to reply)

Skippy wrote:
I have a similar problem: I'm using an Echo Indigo card in my laptop,
however, the problem also exists in the built-in sound card. If I use
headphones, NO NOISE! But if I plug an audio cable in and take it to a
mixer I get noise. This only occurs when using the AC power, not when
using the battery.

What can I do?

Break the signal grounds. There is a whole section in the FAQ on proper
grounding practice.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

emde wrote:
Well I tried using XLR cables, no help there.

Yes, but did you break the ground on the XLR like everyone suggested?

Your goal is to have one and only one ground path from each piece of
equipment to every other. Never zero paths, never two.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 19 Apr 2005 20:55:04 -0700, emde wrote:

Well I tried using XLR cables, no help there. So I am going to try and
pick up an isolator similar to this tomorrow:

http://www.8thstreet.com/product.asp...o_Proce ssors


Did you connect the cables correctly with pin 1 on the XLR isolated? If
you did then the M-Audio box must have very poor inputs.

Cheers.

James.

"emde" wrote in message
ups.com...
I am learning that most of the GC reps give lousy advice.

GC is good only when 1) you know exactly what you want already and 2) You
know what you're willing to pay for the item (i.e. you've done your homework
and make an offer on the verge of lowballing).

--
http://www.bobsavage.net

"Lorin David Schultz" wrote in message
news:NWn9e.41689$vt1.13060@edtnps90...
"emde" wrote:
That seems like a good idea. I wonder a little about that particular
iso box though, only because it seems too cheap. At $45, you get a box,
a whole whack of connectors and two transformers for less than half of
what one good Jensen xformer costs. It makes me wonder what it will do
to the bottom end of your synth signal, but maybe I'm just being a snob.

If you want more confidence in what you[re buying, take a peek at the
Jensen web site. They have similar boxes built with well respected
coily things.

Radial Engineering has some very nice products too, some of which use the
Jensen transformers.

http://www.radialeng.com/dis.htm


--
http://www.bobsavage.net

emde wrote:

Well I tried using XLR cables, no help there. So I am going to try and
pick up an isolator similar to this tomorrow:

It'd be a hell of a lot cheaper to read the rec.audio.pro FAQ and learn
something aout signal grounds and what to lift when...

www.recaudiopro.net

--
ha

At the risk of again catching hell for making the same post. Cut the ground
off the laptop and if you work pro than replace the whole plug with a two
wire.

If you want to record with a laptop and use AC power you can not use a 3
prong. You already established that.

Now you can ask the manufacturer if there is anything really being protected
on this DC device by using a 3 prong plug on a low power ac to dc converter.
I can not believe they will tell you that there is.

Rich

"Pooh Bear" wrote in message
...

wrote:

I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away.

No surprise. This is a regular issue.

I tried a monster cable power supply,

I *seriously* hope that wasn't your own idea !

then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

Use DIs between the audio gear and the M Audio interface ? Find a better
audio interface that doesn't inject the PC's ground noise into the audio
path perhaps ? Don't expect a PC store 'advisor' to have remotely the
faintest clue about this btw !


Graham

According to the RAP faq something like this should help in conjunction
with XLR cables.

http://www.hosatech.com/hosa/products/GLT-255.html

I'll pick one up on the way home from work and post my results.

Thanks everyone, this is definitely a learning experience.

-emde

Rich wrote:
At the risk of again catching hell for making the same post. Cut the ground
off the laptop and if you work pro than replace the whole plug with a two
wire.

This is stupid and illegal.

If you want to record with a laptop and use AC power you can not use a 3
prong. You already established that.

No. Break SIGNAL grounds, not SAFETY grounds. SAFETY grounds are for
SAFETY. When safety grounds are lifted, people die.

Lifting the signal ground is no more difficult than lifting the safety
ground. The only difference is you won't be creating a hazard.

Now you can ask the manufacturer if there is anything really being protected
on this DC device by using a 3 prong plug on a low power ac to dc converter.
I can not believe they will tell you that there is.

Even wall-warts can have transformer failures with major AC leakage to
ground. In the case of the laptop, that means the laptop case becomes
energized since most of those gadgets share DC ground with the line safety
ground to eliminate static electricity problems.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

emde wrote:
According to the RAP faq something like this should help in conjunction
with XLR cables.

http://www.hosatech.com/hosa/products/GLT-255.html

I'll pick one up on the way home from work and post my results.

A swiss army knife to cut the connection to pin 1 will work also.
--scott

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

Yea, but I don't want to waste an XLR cable if it doesn't work. Plus
there is a GC on the way home

So I just tried the XLR with no pin 1. The sound gets worse, even more
static. One thing I did find interesting, if I use the headphone output
of the Triton and patch it to the 410 - no noise (with pin1). This must
have something to do with how the outputlevels are on the headphone vs.
line outs?

-emde

Bob Savage wrote:
"emde" wrote in message
ups.com...
I am learning that most of the GC reps give lousy advice.

GC is good only when 1) you know exactly what you want already and
2)
You know what you're willing to pay for the item (i.e. you've done
your homework and make an offer on the verge of lowballing).

You forgot:

(3) You are buying something with a wall wart and you want to have to
make a second trip get a second wall wart because the one that came
with the product from GC is fried or missing.

The %$#! have done this to me twice!

emde wrote:
So I just tried the XLR with no pin 1. The sound gets worse, even more
static.

Static? Wait, I thought you had a buzz.

One thing I did find interesting, if I use the headphone output
of the Triton and patch it to the 410 - no noise (with pin1). This must
have something to do with how the outputlevels are on the headphone vs.
line outs?

No, it has something to do with the cable you're using.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

wrote in message
ups.com...
I have a ground loop problem that is driving me nuts. Hopefully someone
here can help me out. Here is the setup: a laptop, Korg Triton Pro
keyboard and an M-Audio Firewire 410 audio interface. When all of the
devices are plugged into power I can hear the laptops hard disk, video
refresh, etc. When I lift the ground on the laptop (3 to 2 prong
adapter from the hardware store) or use the laptop on battery power,
the noise goes away. I tried a monster cable power supply, then a
furman PL-Plus II, neither helps.

Other than continuing to use the 3 to 2 adapter and risk death from a
haphazard shock, can anyone suggest a solution?

Do you have an AC voltmeter? If so, I advise using the 3 2 prong adapter
and measuring the voltage difference between the safety ground and neutral.
If the difference is in the millivolt region, then I'd simply connect a
rectifier diode from ground to neutral, and another one in the other
direction. This 2-way diode pair will allay any safety concerns, and at the
same time prevent the flow of ground loop currents.

Norm Strong

By static (unwanted noise) I mean I can hear the hard disk access,
video refresh, etc. I am ready to buy a Digi 002. These problems must
be due to a faulty design or bad m-audio 410 unit. I don't know what
else to try. *sigh*

I've got an email in to m-audio tech supt. We will see what they say.

-emde

Rich wrote:

At the risk of again catching hell for making the same post. Cut the ground
off the laptop and if you work pro than replace the whole plug with a two
wire.

Do not do this. This is an ignorant and potentially dangerous way to do
something wrongly when there are easily implemented methods of doing it
rightly.

If you want to record with a laptop and use AC power you can not use a 3
prong. You already established that.

I have established the opposite right here, daily. Lift destination
_signal grounds_ where necessary. Do not lift _power grounds_, ever.

There's a reason all this is covered in the RAP FAQ.

www.recaudiopro.net

--
ha

Like I said, I would catch hell.
And no this is not stupid or ignorant.

But the problem he has is not really a ground loop.
The problem is rf transmission.

For the sake of argument I will change my recommendation.

Go buy a big battery.


Rich

"hank alrich" wrote in message
. ..
Rich wrote:

At the risk of again catching hell for making the same post. Cut the
ground
off the laptop and if you work pro than replace the whole plug with a two
wire.

Do not do this. This is an ignorant and potentially dangerous way to do
something wrongly when there are easily implemented methods of doing it
rightly.

If you want to record with a laptop and use AC power you can not use a 3
prong. You already established that.

I have established the opposite right here, daily. Lift destination
_signal grounds_ where necessary. Do not lift _power grounds_, ever.

There's a reason all this is covered in the RAP FAQ.

www.recaudiopro.net

--
ha

So where's Niel Muncy when you nee him?

Rich wrote:
Like I said, I would catch hell.
And no this is not stupid or ignorant.

Once you have smelled burned flesh and seen smoke coming out of someone's
hair, it gives you a lot of additional respect for electrical safety.

Les Harvey wasn't so lucky either. Keith Relfs died from a ground
lift as well, but he was admittedly doing something extra stupid.

But the problem he has is not really a ground loop.
The problem is rf transmission.

Actually, from his latest description, it sounds like it is an RF
issue. Note that ground loops are a great way to make RF problems
worse, though. And if lifting the safety ground fixes the problem
by definition it is either a ground loop or the supply in the laptop
polluting the power line ground. Needless to say, most laptops are
not exactly well-designed in this regard.

For the sake of argument I will change my recommendation.

Go buy a big battery.

That's actually not such a bad one in this case.
--scott


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

This is a common problem with laptop recording.
He is using a device designed to type letters to record audio. If you want
a good computer to record audio then buy a Sounddevices 722.

My current laptop does not have this problem because its ac supply was built
without the ground wire on the ac outlet cord. But have seen this problem a
bunch of times.

Rich

"Scott Dorsey" wrote in message
...
Rich wrote:
Like I said, I would catch hell.
And no this is not stupid or ignorant.

Once you have smelled burned flesh and seen smoke coming out of someone's
hair, it gives you a lot of additional respect for electrical safety.

Les Harvey wasn't so lucky either. Keith Relfs died from a ground
lift as well, but he was admittedly doing something extra stupid.

But the problem he has is not really a ground loop.
The problem is rf transmission.

Actually, from his latest description, it sounds like it is an RF
issue. Note that ground loops are a great way to make RF problems
worse, though. And if lifting the safety ground fixes the problem
by definition it is either a ground loop or the supply in the laptop
polluting the power line ground. Needless to say, most laptops are
not exactly well-designed in this regard.

For the sake of argument I will change my recommendation.

Go buy a big battery.

That's actually not such a bad one in this case.
--scott


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

I also tried using a desktop computer, same problem

If it happens on a desktop then I would check into an M-Audio use group to
see if there is a history with this a/d.

I am currently fighting a month long noise battle with a set of mics. But I
record quiet stuff and seeing noise bands at -80 db down with my mic pre at
+60 db is something I can not live with. I suspect most could.

Good luck.
Rich


"emde" wrote in message
ups.com...
I also tried using a desktop computer, same problem

Rich wrote:
If it happens on a desktop then I would check into an M-Audio use group to
see if there is a history with this a/d.

I am currently fighting a month long noise battle with a set of mics. But I
record quiet stuff and seeing noise bands at -80 db down with my mic pre at
+60 db is something I can not live with. I suspect most could.

You considered using some quieter and higher gain mikes?
--scott

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

I use mainly sennheiser mkh-110's, up to 8 channels of them. very low noise
and very high gain. But rf mics can have problems receiving their neighbor
mics and that is seen as this noise problem I am getting.

It becomes a long story because I have chased this so long.

Rich

"Scott Dorsey" wrote in message
...
Rich wrote:
If it happens on a desktop then I would check into an M-Audio use group to
see if there is a history with this a/d.

I am currently fighting a month long noise battle with a set of mics. But
I
record quiet stuff and seeing noise bands at -80 db down with my mic pre
at
+60 db is something I can not live with. I suspect most could.

You considered using some quieter and higher gain mikes?
--scott

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