I've got a computer in one room, with line level input & output on the sound
card. I'd like to move music back & forth to my stereo (Hafler preamp) in
another room. Both rooms are on the ground floor, and I have easy access to
the basement for running wires. Assuming I'm using decent shielded cable,
and I avoid other wires which might cause noise, is 50 feet too much
distance for line level signal?

Doug Kanter wrote:

I've got a computer in one room, with line level input & output on the sound
card. I'd like to move music back & forth to my stereo (Hafler preamp) in
another room. Both rooms are on the ground floor, and I have easy access to
the basement for running wires. Assuming I'm using decent shielded cable,
and I avoid other wires which might cause noise, is 50 feet too much
distance for line level signal?

No. 50 feet is maybe pushing things a just a little bit, but the length
itself won't be a problem unless you live in a high RF environment.
However, if your computer and stereo take their AC power from different
circuits you may encounter a ground loop that will induce hum and noise.
If you do, running a balanced line and isolating the grounds should
cure that.

The most likely source of interference is those wall wart transformers
that cheap electronic devices use. Make sure you keep your cables away
from them.



//Walt

"Walt" wrote in message
...
Doug Kanter wrote:

I've got a computer in one room, with line level input & output on the
sound card. I'd like to move music back & forth to my stereo (Hafler
preamp) in another room. Both rooms are on the ground floor, and I have
easy access to the basement for running wires. Assuming I'm using decent
shielded cable, and I avoid other wires which might cause noise, is 50
feet too much distance for line level signal?

No. 50 feet is maybe pushing things a just a little bit, but the length
itself won't be a problem unless you live in a high RF environment.
However, if your computer and stereo take their AC power from different
circuits you may encounter a ground loop that will induce hum and noise.
If you do, running a balanced line and isolating the grounds should cure
that.

The most likely source of interference is those wall wart transformers
that cheap electronic devices use. Make sure you keep your cables away
from them.



//Walt


What about running the wire through metal conduit, and grounding the conduit
in some way? Would that be a waste of time, or useful?

In article , wrote:
Doug Kanter wrote:

I've got a computer in one room, with line level input & output on the sound
card. I'd like to move music back & forth to my stereo (Hafler preamp) in
another room. Both rooms are on the ground floor, and I have easy access to
the basement for running wires. Assuming I'm using decent shielded cable,
and I avoid other wires which might cause noise, is 50 feet too much
distance for line level signal?

No. 50 feet is maybe pushing things a just a little bit, but the length
itself won't be a problem unless you live in a high RF environment.
However, if your computer and stereo take their AC power from different
circuits you may encounter a ground loop that will induce hum and noise.
If you do, running a balanced line and isolating the grounds should
cure that.

The most likely source of interference is those wall wart transformers
that cheap electronic devices use. Make sure you keep your cables away
from them.



//Walt



Need a direct box of some sort. Basically a transfomer isolator to
avoid noise and hum.

greg

What about running the wire through metal conduit, and grounding the
conduit in some way? Would that be a waste of time, or useful?

A better move might be using RG-178 (?), the thin RF-grade coaxial cable,
instead of audio cable.

Doug Kanter wrote:
"Walt" wrote
Doug Kanter wrote:


is 50 feet too much distance for line level signal?

No. 50 feet is maybe pushing things a just a little bit, but the length
itself won't be a problem unless you live in a high RF environment.

What about running the wire through metal conduit, and grounding the conduit
in some way? Would that be a waste of time, or useful?

That would be overkill in the average residential dwelling. If I were
doing it, I'd just run the wires, plug it in, and see if it hums. If it
does, I'd look at other solutions like balancing the lines or lifting
grounds long before I'd even think about conduit.

Keep the cables away from fluorescent lights, TV monitors, wall warts,
AC cables and you'll probably be OK as far as induced noise. If you
don't have a ground loop problem, you're home free.

//Walt

"Doug Kanter" wrote in message
news
I've got a computer in one room, with line level input & output on the
sound card. I'd like to move music back & forth to my stereo (Hafler
preamp) in another room. Both rooms are on the ground floor, and I have
easy access to the basement for running wires. Assuming I'm using decent
shielded cable, and I avoid other wires which might cause noise, is 50
feet too much distance for line level signal?

No.

BTW, Walt is giving you pretty good advice.

Try it and see if it works.

Do try to not run your wires close to known sources of interference which I
believe it was Walt listed them for you.

A lot of whole-house audio systems are being done with unshielded wires and
balun or balanced-wiring matching transformers. But in many cases the
transformers are overkill, and can cause sound quality loses of their own.

Gregs comments about using direct boxes repersent a worthwhile work-around
if problems are encountered.

"Arny Krueger" wrote ...
"Doug Kanter" wrote ...

I've got a computer in one room, with line level input & output on the
sound card. I'd like to move music back & forth to my stereo (Hafler
preamp) in another room. Both rooms are on the ground floor, and I have
easy access to the basement for running wires. Assuming I'm using decent
shielded cable, and I avoid other wires which might cause noise, is 50
feet too much distance for line level signal?

No.

BTW, Walt is giving you pretty good advice.

Try it and see if it works.

Do try to not run your wires close to known sources of interference which
I believe it was Walt listed them for you.

A lot of whole-house audio systems are being done with unshielded wires
and balun or balanced-wiring matching transformers. But in many cases the
transformers are overkill, and can cause sound quality loses of their own.

Gregs comments about using direct boxes repersent a worthwhile work-around
if problems are encountered.

Or perhaps balancing transformers. Traditional "direct boxes" tend to
run at levels or impedances which are not appropriate for just sending
line-level signals over distances.

Richard Crowley wrote:
"Arny Krueger" wrote ...
"Doug Kanter" wrote ...

Gregs comments about using direct boxes repersent a worthwhile work-around
if problems are encountered.

Or perhaps balancing transformers. Traditional "direct boxes" tend to
run at levels or impedances which are not appropriate for just sending
line-level signals over distances.

Agreed, although DI boxen can be used in a pinch, and in some
circumstances they'll solve the problem. Those of us who are involved in
the pro audio world usually have a dozen lying around, so they tend to
get used in situations where they aren't ideal.

Transformers would not be my first choice, because they do affect the
sound if minimaly. If I were doing it "right" I'd look at using
something like one of these at each end:
http://www.henryeng.com/matchbox.html. But at over $200 each, it's
probably overkill for the OP's situation.

Anyway, there's no point in solving problems until we're sure they
exist. Wire it up unbalanced, see where you are.

//Walt

"Walt" wrote in message
...
Richard Crowley wrote:
"Arny Krueger" wrote ...
"Doug Kanter" wrote ...

Gregs comments about using direct boxes repersent a worthwhile
work-around if problems are encountered.

Or perhaps balancing transformers. Traditional "direct boxes" tend to
run at levels or impedances which are not appropriate for just sending
line-level signals over distances.

Agreed, although DI boxen can be used in a pinch, and in some
circumstances they'll solve the problem. Those of us who are involved in
the pro audio world usually have a dozen lying around, so they tend to get
used in situations where they aren't ideal.

Transformers would not be my first choice, because they do affect the
sound if minimaly. If I were doing it "right" I'd look at using something
like one of these at each end: http://www.henryeng.com/matchbox.html. But
at over $200 each, it's probably overkill for the OP's situation.

Anyway, there's no point in solving problems until we're sure they exist.
Wire it up unbalanced, see where you are.

//Walt


I'm not sure what you mean by "unbalanced", except as it applies to some of
my teenage son's friends. I'm planning on using the best audio wire I can
find (single conductor, wrapped in shield) for each channel, with the shield
attached at both ends. In other words, the same type of wire you get when
you buy a typical RCA to RCA stereo cable for connecting a CD player to a
receiver/preamp. Is this wire considered "unbalanced"?

"Doug Kanter" wrote in message
...

I'm not sure what you mean by "unbalanced", except as it applies to some
of my teenage son's friends.

"balanced" as applied to signal cables refers to a system with two signal
wires, operating with opposite polarity, and a ground.

I'm planning on using the best audio wire I can find (single conductor,
wrapped in shield) for each channel, with the shield attached at both
ends.

That would be "not balanced" or as it is commonly said: unbalanced.

In other words, the same type of wire you get when you buy a typical RCA
to RCA stereo cable for connecting a CD player to a receiver/preamp. Is
this wire considered "unbalanced"?

Short answer: yes.

But it should be fine. If it isn't, we'll clarify plan B.

In article , "Doug Kanter" wrote:

"Walt" wrote in message
...
Richard Crowley wrote:
"Arny Krueger" wrote ...
"Doug Kanter" wrote ...

Gregs comments about using direct boxes repersent a worthwhile
work-around if problems are encountered.

Or perhaps balancing transformers. Traditional "direct boxes" tend to
run at levels or impedances which are not appropriate for just sending
line-level signals over distances.

Agreed, although DI boxen can be used in a pinch, and in some
circumstances they'll solve the problem. Those of us who are involved in
the pro audio world usually have a dozen lying around, so they tend to get
used in situations where they aren't ideal.

Transformers would not be my first choice, because they do affect the
sound if minimaly. If I were doing it "right" I'd look at using something
like one of these at each end: http://www.henryeng.com/matchbox.html. But
at over $200 each, it's probably overkill for the OP's situation.

Anyway, there's no point in solving problems until we're sure they exist.
Wire it up unbalanced, see where you are.

//Walt


I'm not sure what you mean by "unbalanced", except as it applies to some of
my teenage son's friends. I'm planning on using the best audio wire I can
find (single conductor, wrapped in shield) for each channel, with the shield
attached at both ends. In other words, the same type of wire you get when
you buy a typical RCA to RCA stereo cable for connecting a CD player to a
receiver/preamp. Is this wire considered "unbalanced"?

Doug, you can have the best cable, but you can still create ground
loops traveling to another outlet and ground. Lengthy cable
runs can do this as well as short runs. The isolation transformer, DI Box,
etc,, will get rid of ground loops, and the cable can also be very different too.

greg

Doug Kanter wrote:

I'm not sure what you mean by "unbalanced", except as it applies to some of
my teenage son's friends. I'm planning on using the best audio wire I can
find (single conductor, wrapped in shield) for each channel, with the shield
attached at both ends. In other words, the same type of wire you get when
you buy a typical RCA to RCA stereo cable for connecting a CD player to a
receiver/preamp. Is this wire considered "unbalanced"?

Yes. An unbalanced line is one conductor that carries the signal. Most
consumer gear uses unbalanced interconnects.

A balanced line has two conductors, and each carries the signal with the
signal inverted on one of the conductors. At the input, the circuitry
takes the diference between the two conductors, the idea is that any
noise picked up along the way will appear equally in both conductors and
by taking the difference between the two it will be cancelled out. This
is called "common mode rejection".

Another major benefit of balanced is that connecting the shield is
optional*, so you have more flexibility in your grounding scheme -
usually you want to connect the shield at one end only. With
unbalanced, you are basically required to connect the shield at both
ends, which connects the grounds

Balanced interconnects are preferable for long runs, and in high RF
situations. Most professional gear uses balanced interconnects. I've
run balanced lines several miles. For unbalanced, you probably don't
want to go much more than 100 feet.

The Henry Engineering boxes I linked to will convert your unbalanced
outputs to balanced and back again, so you derive the benefits of
balanced.

But, as I said before, this is probably overkill for your situation.
Standard unbalanced lines should work.

I'm planning on using the best audio wire I can find...

If by "best" you mean "most expensive", please rethink. There are
people out there who will sell you cable for $1000/ft and claim that
it's the best. Avoid this stuff. It's marketed to suckers.

Personaly, I'd install some workaday pro cable like Belden 8451. This
is balanced cable, with two conductors inside a shield. That's OK, you
can just ingore the black wire and it'll work just fine for an
unbalanced signal. The advantage is that if you do run into a problem
that will be cured by a balanced signal, you won't have to run the wires
again. Installing cable is a PITA, and I like to avoid doing it twice.
My guess is that half of the recordings in your collection have had
their signal pass through a hundred feet of Belden 8451 already, so
another 50' shouldn't hurt.

Or just buy standard unbalanced audio cable. If you go this way, hook
it up before installing the wire inside the walls so you can see if you
have a hum problem. Don't buy junk cable, but don't spend a fortune either.

//Walt

"Walt" wrote in message
...
Doug Kanter wrote:

I'm not sure what you mean by "unbalanced", except as it applies to some
of my teenage son's friends. I'm planning on using the best audio wire I
can find (single conductor, wrapped in shield) for each channel, with the
shield attached at both ends. In other words, the same type of wire you
get when you buy a typical RCA to RCA stereo cable for connecting a CD
player to a receiver/preamp. Is this wire considered "unbalanced"?

Yes. An unbalanced line is one conductor that carries the signal. Most
consumer gear uses unbalanced interconnects.

A balanced line has two conductors, and each carries the signal with the
signal inverted on one of the conductors. At the input, the circuitry
takes the diference between the two conductors, the idea is that any noise
picked up along the way will appear equally in both conductors and by
taking the difference between the two it will be cancelled out. This is
called "common mode rejection".

Another major benefit of balanced is that connecting the shield is
optional*, so you have more flexibility in your grounding scheme - usually
you want to connect the shield at one end only. With unbalanced, you are
basically required to connect the shield at both ends, which connects the
grounds

Balanced interconnects are preferable for long runs, and in high RF
situations. Most professional gear uses balanced interconnects. I've run
balanced lines several miles. For unbalanced, you probably don't want to
go much more than 100 feet.

The Henry Engineering boxes I linked to will convert your unbalanced
outputs to balanced and back again, so you derive the benefits of
balanced.

But, as I said before, this is probably overkill for your situation.
Standard unbalanced lines should work.

I'm planning on using the best audio wire I can find...

If by "best" you mean "most expensive", please rethink. There are people
out there who will sell you cable for $1000/ft and claim that it's the
best. Avoid this stuff. It's marketed to suckers.

Personaly, I'd install some workaday pro cable like Belden 8451. This is
balanced cable, with two conductors inside a shield. That's OK, you can
just ingore the black wire and it'll work just fine for an unbalanced
signal. The advantage is that if you do run into a problem that will be
cured by a balanced signal, you won't have to run the wires again.
Installing cable is a PITA, and I like to avoid doing it twice. My guess
is that half of the recordings in your collection have had their signal
pass through a hundred feet of Belden 8451 already, so another 50'
shouldn't hurt.

Or just buy standard unbalanced audio cable. If you go this way, hook it
up before installing the wire inside the walls so you can see if you have
a hum problem. Don't buy junk cable, but don't spend a fortune either.

//Walt

Thanks, Walt, Arny, Greg and everyone else who responded here. I'm going
fishing for the weekend, during which I'll mull this wiring plan over.
Please stay tuned for further questions on Monday!