Could anyone please offer me some constructive suggestions:

Almost a year ago, I bought an Echo Mia soundcard and installed it in
my computer. Up to now I have not got it to work properly, suggesting
that
my set-up is incorrect.

My set-up: the soundcard is installed within a new-ish Dell Dimension
PC. It is connected to my stereo via two pairs of mono leads, each
manufactured with an RCA jack on one end and a phono jack on the
other. These are plugged into a (high quality) DIN-phono adapter,
since my amplifier has five-pin DIN inputs and outputs. The amp
operates at DIN level (a lower signal level than the line level used
by
modern equipment) and is a Sugdens A48 made in 1976. The soundcard is
connected to the amplifier via the Tape input/output.

Obviously, the soundcard is not receiving the "balanced" signal for
which it is designed, but I cannot imagine how to generate a
"balanced" input to it. And the manual does indicate that it should
work with an unbalanced signal of the kind that I am supplying to it.

When connected in this way, there is a near-constant hum in my system,
at a level high enough to be distinctly irritating. When the
soundcard
outputs are connected to the amp, the hum can be heard through my
loudspeakers, whether or not the computer is turned on, or even
connected to the mains power supply. The computer is normally
connected to the same power supply as the amplifier, and so they
should
be grounded at the same level. However, unplugging the computer (so
that of course it is no longer grounded) seems to make no difference
to
the hum.

Similarly, whenever the amplifier is connected to the soundcard's
inputs the signal that it receives includes a constant hum, so that
any
recordings I make with it from my sound system are marred by the hum
that is recorded along with the music.

Please let me know if you have any suggestions for reducing or
eliminating the hum.

In article ,
david wrote:
Obviously, the soundcard is not receiving the "balanced" signal for
which it is designed, but I cannot imagine how to generate a
"balanced" input to it.

Balanced lines usually involve XLRs - you mention RCA and phono, but these
are the same thing?

And the manual does indicate that it should
work with an unbalanced signal of the kind that I am supplying to it.

With a balanced system, you normally strap the 'cold' wire to ground for
unbalanced connection.

When connected in this way, there is a near-constant hum in my system,
at a level high enough to be distinctly irritating. When the
soundcard
outputs are connected to the amp, the hum can be heard through my
loudspeakers, whether or not the computer is turned on, or even
connected to the mains power supply. The computer is normally
connected to the same power supply as the amplifier, and so they
should
be grounded at the same level. However, unplugging the computer (so
that of course it is no longer grounded) seems to make no difference
to
the hum.

If it's humming with no earth to the computer, it suggests that there's no
ground connection between it and your amp.

--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman London SW
To e-mail, change noise into sound.

On 26 Jul 2004 09:29:13 -0700, (david) wrote:

Could anyone please offer me some constructive suggestions:

Almost a year ago, I bought an Echo Mia soundcard and installed it in
my computer. Up to now I have not got it to work properly, suggesting
that
my set-up is incorrect.

My set-up: the soundcard is installed within a new-ish Dell Dimension
PC. It is connected to my stereo via two pairs of mono leads, each
manufactured with an RCA jack on one end and a phono jack on the
other. These are plugged into a (high quality) DIN-phono adapter,
since my amplifier has five-pin DIN inputs and outputs. The amp
operates at DIN level (a lower signal level than the line level used
by
modern equipment) and is a Sugdens A48 made in 1976. The soundcard is
connected to the amplifier via the Tape input/output.

Obviously, the soundcard is not receiving the "balanced" signal for
which it is designed, but I cannot imagine how to generate a
"balanced" input to it. And the manual does indicate that it should
work with an unbalanced signal of the kind that I am supplying to it.

When connected in this way, there is a near-constant hum in my system,
at a level high enough to be distinctly irritating. When the
soundcard
outputs are connected to the amp, the hum can be heard through my
loudspeakers, whether or not the computer is turned on, or even
connected to the mains power supply. The computer is normally
connected to the same power supply as the amplifier, and so they
should
be grounded at the same level. However, unplugging the computer (so
that of course it is no longer grounded) seems to make no difference
to
the hum.

Similarly, whenever the amplifier is connected to the soundcard's
inputs the signal that it receives includes a constant hum, so that
any
recordings I make with it from my sound system are marred by the hum
that is recorded along with the music.

Please let me know if you have any suggestions for reducing or
eliminating the hum.


hi
the DIN inputs on your amp are not balanced, they will be ok level
wise with the sound card. check connections
reading left to right looking from solder side of the plug,
middle pin (2) at top.

1 - R out
4 - L out
2 - ground
5 - R in
3 - L in
yes i know its odd numbering
above for the tape socket, your lead should be connected to R in, L in
and earth.
if when you have checked the wiring is correct you still have hum try
a ground loop isolation transformer a good reasonably priced unit is
maplins code VW43W http://www.maplin.co.uk/
hope this helps
regards
bob

On Tue, 27 Jul 2004 01:57:11 GMT, burbeck wrote:

hi
the DIN inputs on your amp are not balanced, they will be ok level
wise with the sound card. check connections
reading left to right looking from solder side of the plug,
middle pin (2) at top.

1 - R out
4 - L out
2 - ground
5 - R in
3 - L in
yes i know its odd numbering
above for the tape socket, your lead should be connected to R in, L in
and earth.
if when you have checked the wiring is correct you still have hum try
a ground loop isolation transformer a good reasonably priced unit is
maplins code VW43W http://www.maplin.co.uk/
hope this helps
regards
bob

hi sorry i did not realise that you have fancy card with balanced
outputs, they will need antenuating as well as isolating, they are at
+4 dbm way too much, i will send you circuit by email please advise if
you need help or get it working ok
regards
bob

"david" wrote in message
om...
: Could anyone please offer me some constructive suggestions:
:
: Almost a year ago, I bought an Echo Mia soundcard and installed it in
: my computer. Up to now I have not got it to work properly, suggesting
: that
: my set-up is incorrect.
:
snip bits I don't follow about balanced i/o
:
: Similarly, whenever the amplifier is connected to the soundcard's
: inputs the signal that it receives includes a constant hum, so that
: any
: recordings I make with it from my sound system are marred by the hum
: that is recorded along with the music.
:
: Please let me know if you have any suggestions for reducing or
: eliminating the hum.

I have exactly the same problem connecting an old Pioneer receiver to my
Audigy Platinum card. I've tried phono and DIN leads - same result. It's my
guess that I need shielded phono cables, where you ground the shield (copper
braid) at the source end and leave it open at the destination end as in:
http://www.qed.co.uk/cables/incon/qunex_2.html
which is obviously a rather expensive cable, particularly if that's not the
problem. They're quite easy to make up from Maplin's stock tho.

Rob

"burbeck" wrote in message
...
: On Tue, 27 Jul 2004 05:41:48 +0100, "Rob"
: wrote:
:
:
:
: I have exactly the same problem connecting an old Pioneer receiver to my
: Audigy Platinum card. I've tried phono and DIN leads - same result. It's
my
: guess that I need shielded phono cables, where you ground the shield
(copper
: braid) at the source end and leave it open at the destination end as in:
: http://www.qed.co.uk/cables/incon/qunex_2.html
: which is obviously a rather expensive cable, particularly if that's not
the
: problem. They're quite easy to make up from Maplin's stock tho.
:
: Rob
:
: hi rob
: i doubt that will be of any benifit to you, a ground isolating
: transformer is what you require, the maplins one is nicely priced and
: is a stereo unit i,e you only need one, and comes with phono plugs and
: sockets maplins code VW43W http://www.maplin.co.uk/
: regards
: bob
:
Many thanks Bob - may well give it a try.

Rob

In article , david
wrote:
Could anyone please offer me some constructive suggestions:

Almost a year ago, I bought an Echo Mia soundcard and installed it in my
computer. Up to now I have not got it to work properly, suggesting that
my set-up is incorrect.

My set-up: the soundcard is installed within a new-ish Dell Dimension
PC. It is connected to my stereo via two pairs of mono leads, each
manufactured with an RCA jack on one end and a phono jack on the other.
These are plugged into a (high quality) DIN-phono adapter, since my
amplifier has five-pin DIN inputs and outputs. The amp operates at DIN
level (a lower signal level than the line level used by modern
equipment) and is a Sugdens A48 made in 1976. The soundcard is
connected to the amplifier via the Tape input/output.

Obviously, the soundcard is not receiving the "balanced" signal for
which it is designed, but I cannot imagine how to generate a "balanced"
input to it. And the manual does indicate that it should work with an
unbalanced signal of the kind that I am supplying to it.

I am not yet certain that we have clearly understood the nature of the
problem you have. Hence I'm not yet sure that the response others have
given are optimised.

Afraid I don't know the sound card you are using as I don't use IBM
machines much. I assume that you are using the four coaxial leads to
connect to the tape in/out pins of the DIN socket on the Sugden.

What are the details of the 'balanced' connections on the sound card? In
particular, what are the outers (shields or braids) of the coax cables
connected to at the soundcard end of the link?

When connected in this way, there is a near-constant hum in my system,
at a level high enough to be distinctly irritating. When the soundcard
outputs are connected to the amp, the hum can be heard through my
loudspeakers, whether or not the computer is turned on, or even
connected to the mains power supply. The computer is normally
connected to the same power supply as the amplifier, and so they should
be grounded at the same level. However, unplugging the computer (so
that of course it is no longer grounded) seems to make no difference to
the hum.

Similarly, whenever the amplifier is connected to the soundcard's
inputs the signal that it receives includes a constant hum, so that any
recordings I make with it from my sound system are marred by the hum
that is recorded along with the music.

Please let me know if you have any suggestions for reducing or
eliminating the hum.

It may be as someone has suggested that you need an isolation transformer.
Although I am not yet sure of this. There may be a simpler solution.

Can you confirm that the Sugden *is* signal grounded? i.e. that the outers
of its cables are connected through to the earth pin on the Sugden's mains
plug? What I am not sure of as yet is the reason why you still hear hum
when the computer is off and disconnected from the mains. This cannot be a
loop via the earth, so sounds like lack of shielding (electrostatic) or the
signal wires acting like a magnetic loop.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On Tue, 27 Jul 2004 05:41:48 +0100, "Rob"
wrote:



I have exactly the same problem connecting an old Pioneer receiver to my
Audigy Platinum card. I've tried phono and DIN leads - same result. It's my
guess that I need shielded phono cables, where you ground the shield (copper
braid) at the source end and leave it open at the destination end as in:
http://www.qed.co.uk/cables/incon/qunex_2.html
which is obviously a rather expensive cable, particularly if that's not the
problem. They're quite easy to make up from Maplin's stock tho.

Rob

hi rob
i doubt that will be of any benifit to you, a ground isolating
transformer is what you require, the maplins one is nicely priced and
is a stereo unit i,e you only need one, and comes with phono plugs and
sockets maplins code VW43W http://www.maplin.co.uk/
regards
bob

On Tue, 27 Jul 2004 02:29:46 GMT, burbeck wrote:



hi sorry i did not realise that you have fancy card with balanced
outputs, they will need antenuating as well as isolating, they are at
+4 dbm way too much, i will send you circuit by email please advise if
you need help or get it working ok
regards
bob


posted circuit to alt.binaries.schematics.electronics
hope this helps
regards
bob

"david" wrote in message
om

Could anyone please offer me some constructive suggestions:

Almost a year ago, I bought an Echo Mia soundcard and installed it in
my computer. Up to now I have not got it to work properly, suggesting
that my set-up is incorrect.

Obviously, the soundcard is not receiving the "balanced" signal for
which it is designed,

Ironically, the Mia does not have *real, active* balanced inputs, just input
jacks that would be capable of handling the outputs from a balanced source.
It doesn't have *real, active* balanced outputs, either.

However, you could still have all of the problems you have, even with real,
active balanced inputs and outputs. For example, your most obvious problem
exists at the input to your amplifier, not at the input to the sound card.

but I cannot imagine how to generate a "balanced" input to it.

You don't need to.

And the manual does indicate that it should
work with an unbalanced signal of the kind that I am supplying to it.

The manual is telling you like it is.

First off, you've confused inputs with outputs. I read your post as saying
that the sound card makes your system hum. Problems with balanced inputs
would make your recordings hum, but you seem to be saying that anything you
playback hums, and in fact you've got a hum even where there is no playback
or recording active.

When connected in this way, there is a near-constant hum in my system,
at a level high enough to be distinctly irritating.

You've got a ground loop!

When the soundcard
outputs are connected to the amp, the hum can be heard through my
loudspeakers, whether or not the computer is turned on, or even
connected to the mains power supply.

A ground loop is due to two or more ground connections between two pieces of
equipment. The basic trick is to reduce that to one good ground.

My take is that there is something else connected to the computer that
effectively grounds it, even when disconnected from the mains. The mains
connection is probably the third or fourth or whatever ground. With the
mains disconnected, there are still two or more, one being the connection to
your ampliifer.

The computer is normally
connected to the same power supply as the amplifier, and so they should
be grounded at the same level.

But, the amplifier is also connected to the computer through the audio
wiring, so there are your 2 or more grounds.

However, unplugging the computer (so
that of course it is no longer grounded) seems to make no difference
to the hum.

That just means that there is a third and perhaps also a fourth or fifth
ground, as well.

Similarly, whenever the amplifier is connected to the soundcard's
inputs the signal that it receives includes a constant hum, so that any
recordings I make with it from my sound system are marred by the hum
that is recorded along with the music.

All things considered, that is to be expected.

Please let me know if you have any suggestions for reducing or
eliminating the hum.

Please read these documents:

Introduction:

http://www.smr-home-theatre.org/Ground-Loops/

Meat of the matter:

http://www.epanorama.net/documents/g...oop/index.html

I have recommended these two documents dozens of times, and know of no
situations where they did not fail to shed light. You may still have some
questions after you read them, but reading them will explain a lot of things
to you.