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Asorka Asorka is offline
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Default how to force a stereo output to mono without a mixer

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!
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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"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.


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AZ Nomad[_2_] AZ Nomad[_2_] is offline
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Default how to force a stereo output to mono without a mixer

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.
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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"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.


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Arny Krueger Arny Krueger is offline
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Default how to force a stereo output to mono without a mixer

"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.




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AZ Nomad[_2_] AZ Nomad[_2_] is offline
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Default how to force a stereo output to mono without a mixer

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.
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Don Pearce[_3_] Don Pearce[_3_] is offline
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Default how to force a stereo output to mono without a mixer

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
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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"Don Pearce" wrote ...
"Arny Krueger" wrote:
"Richard Crowley" wrote ...
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/


That is the dead-short type (which "AZ nomad" seems to have
so much trouble with.) Arny and I are implying that the kind
with mixing resistors are not available as a ready-made product.


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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"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.


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David Nebenzahl David Nebenzahl is offline
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Default how to force a stereo output to mono without a mixer

On 10/19/2009 11:41 AM Richard Crowley spake thus:

"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.


Same here; I've run two line-level channels into one input where such
distortion, if present, could definitely be heard (decent quality home
stereo), and there was no such distortion.

Look at circuit diagrams for amplifiers: as Richard C. pointed out,
there is enough resistance between stages, as well as high enough
impedances, to make any problems tying the two channels together negligible.


--
Found--the gene that causes belief in genetic determinism


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Mr.T Mr.T is offline
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Default how to force a stereo output to mono without a mixer


"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.


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Randy Yates Randy Yates is offline
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Default how to force a stereo output to mono without a mixer

"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
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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"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.


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Richard Crowley Richard Crowley is offline
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Default how to force a stereo output to mono without a mixer

"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.


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Dave Platt Dave Platt is offline
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Default how to force a stereo output to mono without a mixer

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!


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Arny Krueger Arny Krueger is offline
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Default how to force a stereo output to mono without a mixer

"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.


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Arny Krueger Arny Krueger is offline
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Default how to force a stereo output to mono without a mixer

"Dave Platt" wrote in message

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)?


IME, good real world examples.

Removal of question marks recommended. Exclamation points may be
appropriate! ;-)


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GregS[_3_] GregS[_3_] is offline
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Default how to force a stereo output to mono without a mixer

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
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AZ Nomad[_2_] AZ Nomad[_2_] is offline
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Default how to force a stereo output to mono without a mixer

On Tue, 20 Oct 2009 14:12:11 GMT, GregS wrote:
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.


Yes. It isn't 100% distortion; perhaps only 3-10%.
I'd rather have the passive mixer; it's less than a buck worth of
resistors even at radio shack prices and about a half hour of cutting
and soldering to make the mixer cable.



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lambwell lambwell is offline
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Default

Hi all,
I am not sure if this is the correct place to ask this question but here it goes...
I would like to build a small mixer that has one stereo and two mic inputs and combine the three inputs and have a single stereo output.
I have already build one working model that does this with a mono output and when I tried to double the output section of the schematic for a left and a right, it doesn't work anymore.
So does anyone have a sample schematic combining stereo with mono I can take a look at to see if I can track doen my error?
My current mixer uses nothing but res, caps, pots, and transistors with a 9V battery supply.
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