[Asorka]

Hi all

Simple question.
Typical line-out/phones output on digital devices (mp3 players/
computers) is stereo, istruments amplifier (eg: guitars, basses) is
mono.

If I make the link one chanell is lost. How should I do avoiding the
use of a proper mixer?
I'd like the right/left chanells to fuse together to one/mono chanell:
is that possible

I guess:
- if it's a computer I should obtain by the software interface... but
I'm using a Mac and VLC and don't know how (it will probably let me
choose just one channel)
- if it's not a computer (something with a basic UI) I should find a
cable which fisically fuse the two chanells together

Well, I hope to find some help and that you'll forgive my english :P
Thanks!

[Richard Crowley]

"Asorka" wrote ...
Simple question.
Typical line-out/phones output on digital devices (mp3 players/
computers) is stereo, istruments amplifier (eg: guitars, basses) is
mono.

If I make the link one chanell is lost. How should I do avoiding the
use of a proper mixer?
I'd like the right/left chanells to fuse together to one/mono chanell:
is that possible

I guess:
- if it's a computer I should obtain by the software interface... but
I'm using a Mac and VLC and don't know how (it will probably let me
choose just one channel)
- if it's not a computer (something with a basic UI) I should find a
cable which fisically fuse the two chanells together

Well, I hope to find some help and that you'll forgive my english :P

The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

The prefered method is to use "build-out" or "mixing" resistors
in series with each of the outputs (Left and Right). This prevents
the Left output from affecting the Right output and vice-versa.

But this scheme is not generally available pre-assembled.
Because it somewhat depends on the output impedance
of the source and the input impedance of the destination,
the value of the resistors must be selected for optimal
performance.

For casual use, using a simply "Y-adapter" is likely OK.

[AZ Nomad[_2_]]

On Mon, 19 Oct 2009 10:02:23 -0700, Richard Crowley wrote:
"Asorka" wrote ...
Simple question.
Typical line-out/phones output on digital devices (mp3 players/
computers) is stereo, istruments amplifier (eg: guitars, basses) is
mono.

If I make the link one chanell is lost. How should I do avoiding the
use of a proper mixer?
I'd like the right/left chanells to fuse together to one/mono chanell:
is that possible

I guess:
- if it's a computer I should obtain by the software interface... but
I'm using a Mac and VLC and don't know how (it will probably let me
choose just one channel)
- if it's not a computer (something with a basic UI) I should find a
cable which fisically fuse the two chanells together

Well, I hope to find some help and that you'll forgive my english :P

The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

They make mixer cables that simply use a few resistors to connect the
outputs in a passive mixer without shorting them together.

[Richard Crowley]

"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

The reason this works is that the analog outputs from most
audio equipment (consumer and professional) is NOT zero
impedance. They all have some amount of output resistance,
most typically with a simple series resistor in the output if you
look at the circuit schematics. Pro equipment typically has
~600 ohm resistors in series with the outputs, and consumer
stuff has at least 1K and likely higher.

Now it is true that SOME equipment may have very low output
impedance and will be affected by shorting to another output,
but I have personally never encountered such equipment.

I stand by my recomendation to use a simple Y-adapter and
I practice it myself. If the OP experiences "horrible distortion",
then he can make or buy a passive mixer cable/adapter with
series resistors.

They make mixer cables that simply use a few resistors to connect the
outputs in a passive mixer without shorting them together.

Fine. Provide the OP with some URLs demonstrating where he
can get these.

[Arny Krueger]

"Richard Crowley" wrote in message


Fine. Provide the OP with some URLs demonstrating where he
can get these.

Good question - I've always had to make my own.

[Don Pearce[_3_]]

On Mon, 19 Oct 2009 13:53:21 -0400, "Arny Krueger"
wrote:

"Richard Crowley" wrote in message


Fine. Provide the OP with some URLs demonstrating where he
can get these.

Good question - I've always had to make my own.


This is the kind of thing - pretty cheap, I'd say.

http://www.mediaatlantic.com/product.php/19094/0/

d

[AZ Nomad[_2_]]

On Mon, 19 Oct 2009 10:27:39 -0700, Richard Crowley wrote:
"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

If you listen using something better than $5 computer speakers, the
distortion isn't subtle.

[Richard Crowley]

"AZ Nomad" wrote ...
Richard Crowley wrote:
"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

If you listen using something better than $5 computer speakers, the
distortion isn't subtle.

Sorry. My reality doesn't correlate with your theory.
Good luck with that.

[GregS[_3_]]

In article , AZ Nomad wrote:
On Mon, 19 Oct 2009 10:27:39 -0700, Richard Crowley wrote:
"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

If you listen using something better than $5 computer speakers, the
distortion isn't subtle.

Most of the audio is not dead short. Its only the extreme left or right
stereo info thats shorted. The bass is mostly all mono.

As a general rule I insert 100 to 1 K resistors in stuff I build.
Some older op-amps were less tolerant of capacitive loads.
To get full current transfer out of a typical op-amp you need a 600
ohm resistor. An audio grade driver needs about 15 ohms. .015ma and
07 ma. respectively. I would NOT connect two headphone outputs
together.

greg

[Mr.T]

"Richard Crowley" wrote in message
...
"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

The reason this works is that the analog outputs from most
audio equipment (consumer and professional) is NOT zero
impedance. They all have some amount of output resistance,
most typically with a simple series resistor in the output if you
look at the circuit schematics. Pro equipment typically has
~600 ohm resistors in series with the outputs, and consumer
stuff has at least 1K and likely higher.

Which is perfectly true for line level outputs, but NOT necessarily for iPod
headphone outputs.


Now it is true that SOME equipment may have very low output
impedance and will be affected by shorting to another output,
but I have personally never encountered such equipment.

I don't have an iPod, but it probably comes under "such equipment".
Whether it will be affected can usually be determined by trying it :-)

MrT.

[Richard Crowley]

"Mr.T" wrote ...
"Richard Crowley" wrote ...
Now it is true that SOME equipment may have very low output
impedance and will be affected by shorting to another output,
but I have personally never encountered such equipment.

I don't have an iPod, but it probably comes under "such equipment".
Whether it will be affected can usually be determined by trying it :-)

I have NOT heard AZ's "horrible distortion" even when shorting my
iPod's L/R headphone outputs. (Both 5G Video and iPod Touch)
Perhaps we should stay away from AZ.

[Randy Yates]

"Richard Crowley" writes:

"AZ Nomad" wrote...
Richard Crowley wrote:
The simple and inexpensive method is to just use a "Y-cable"
which connects the Left and Right outputs together to form a
monaural signal combined from both. This is effective most of
the time, and with reasonable quality.

That's a terrible solution. If you mix them and the outputs don't
like being shorted together then you'll end up with horrible
distortion.

Yes that is the common theory. However, I have actually done
this many times and I have NEVER had "horrible distortion".
Sorry to hear that you have had such poor luck.

The reason this works is that the analog outputs from most
audio equipment (consumer and professional) is NOT zero
impedance. They all have some amount of output resistance,
most typically with a simple series resistor in the output if you
look at the circuit schematics. Pro equipment typically has
~600 ohm resistors in series with the outputs, and consumer
stuff has at least 1K and likely higher.

Why would they do that? They'd be derating an ideal voltage amplifier
characteristic (zero output impedance) that is desirable in such devices.
--
Randy Yates % "Though you ride on the wheels of tomorrow,
Digital Signal Labs % you still wander the fields of your
% sorrow."
http://www.digitalsignallabs.com % '21st Century Man', *Time*, ELO

[Richard Crowley]

"Randy Yates" wrote...
Why would they do that? They'd be derating an ideal voltage amplifier
characteristic (zero output impedance) that is desirable in such devices.

Zero output impedance is not necessarily desirable in the Real World(TM).
Furthermore it is more expensive to implement than some sensible finite
output impedance. For that reason it is rarely done IME.

[Dave Platt]

In article , Randy Yates wrote:

Why would they do that? They'd be derating an ideal voltage amplifier
characteristic (zero output impedance) that is desirable in such devices.

Short-circuit protection?

Ensuring that the output amplifier remains stable even in the face of
high capacitive loads (e.g. the shunt capacitance of many feet of RCA
cable or equivalent)?

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

[Arny Krueger]

"Randy Yates" wrote in message

"Richard Crowley" writes:

The reason this works is that the analog outputs from
most
audio equipment (consumer and professional) is NOT zero
impedance. They all have some amount of output
resistance,
most typically with a simple series resistor in the
output if you look at the circuit schematics. Pro
equipment typically has ~600 ohm resistors in series
with the outputs, and consumer stuff has at least 1K and
likely higher.

Agreed. The part is sometimes called a "building out" resistor. The lowest
I've seen in use might be 70-ish ohms.

Why would they do that?

Stability and reliability.

They'd be derating an ideal
voltage amplifier characteristic (zero output impedance)
that is desirable in such devices.

Simplistic theory meets real world practicality.

Consider the stability of an amplifier with an extremely low output
impedance with that of one with a higher output impedance, achieved
passivly. Note the near-universal use of output inductors on power amps.