Parallelling audio outputs

[bruce varley]

Hi, This must be a common question, but I can't find anything relating to
it in back postings on my machine. What's the effect of parallelling two
stereo outputs to produce one mono one, without any interposing resistance?
Can you actually break something by doing it with ordinary hifi-standard
gear? Is there any devastating effect on quality, I guess I'll hear it if
there is. TIA

 

[bruce varley]

bruce varley <bxvarley@weqstnet.com.au> wrote in message news:...

Hi, This must be a common question, but I can't find anything relating to
it in back postings on my machine. What's the effect of parallelling two
stereo outputs to produce one mono one, without any interposing
resistance?
Can you actually break something by doing it with ordinary hifi-standard
gear? Is there any devastating effect on quality, I guess I'll hear it if
there is. TIA

Line level (Ca 100mV)

 

[Pete]

chris wrote:

At the outputs, connect the -ve of Ch1 to the +ve of Ch2 then use +ve of
Ch1 and -ve of Ch2 as the speaker connection.

The -ve outputs are at ground potential, so connecting them as you
suggest shorts the output of one channel to ground, and connects the
speaker to just the other channel.

What you need to do when bridging the outputs is connect the speaker
between the two +ve outputs, and leave the -ve outputs unconnected.

Anyway, I believe the original poster was talking about line level
outputs, not speaker outputs.

Peter

 

[Simone Merrett]

Just do it.
You wont fry anything - promise.
If it for a single audio system, it will be a capacitively or inductively
coupled output, meaning DC will not go through it.... this means no high DC
currents ...no smoke.

"Poxy" <pox@poxymail.com> wrote in message
news:Fg2Uf.13417$dy4.7373@news-server.bigpond.net.au...

chris wrote:
bruce varley wrote:
bruce varley <bxvarley@weqstnet.com.au> wrote in message news:...
Hi, This must be a common question, but I can't find anything
relating to it in back postings on my machine. What's the effect of
parallelling two stereo outputs to produce one mono one, without
any interposing resistance? Can you actually break something by
doing it with ordinary hifi-standard gear? Is there any
devastating effect on quality, I guess I'll hear it if there is.
TIA

Line level (Ca 100mV)

It's called bridging - there's probably heaps of info around on it.
Some dual channel sound-reinforcement (eg Rock PA) amps have it
built-in.

I think you've grabbed the ball and gone charging off for the wrong goal
line there - the poster was asking about connecting line-level outputs
together to get a mono signal, an whether this would fry anything in the
output stage of the devices involved.

 

[Phil Allison]

"Simone Merrett"

Just do it.
You wont fry anything - promise.

** What is an anonymous promise made on usenet worth ?

If it for a single audio system, it will be a capacitively or inductively
coupled output, meaning DC will not go through it....

** Nonsense.

Many audio line outs are direct coupled to the output of an op-amp or
similar cct.

this means no high DC
currents ...no smoke.

** But also no sound or terrible sound.



........ Phil

 

[Rod]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:48bsa5Fjb4fcU1@individual.net...

"bruce varley"

Hi, This must be a common question, but I can't find anything relating
to
it in back postings on my machine. What's the effect of parallelling two
stereo outputs to produce one mono one, without any interposing
resistance?
Can you actually break something by doing it with ordinary hifi-standard
gear? Is there any devastating effect on quality, I guess I'll hear it
if
there is. TIA



** The outcome of linking L & R audio line outputs is not predictable,
since a wide variety of audio line output circuits arrangements exist in
common use.

It may work out OK .

OR

You will experience loss of level AND bass frequencies

You will experience peak clipping on loud passages.

You will experience clipping all the time.


NB:

If the signal is in exact mono - it will work fine !

Unfortunately the OP said stereo.
But Phil is right with the other answers.
The next question is why you would want to do it that way?
Just use a resistor summing network and all will be OK.

........ Phil

 

[Phil Allison]

"Rod"

NB:

If the signal is in exact mono - it will work fine !

Unfortunately the OP said stereo.

** Unfortunately you cannot read.

The programme can be mono or switched to mono.

It is the one case where current cannot flow from one output into the other.

Mentioned for completeness and to give a hint to the OP at the reasons
behind my predictions.




......... Phil

 

[bruce varley]

<snip >

If the signal is in exact mono - it will work fine !

Unfortunately the OP said stereo.
But Phil is right with the other answers.
The next question is why you would want to do it that way?

Because you can buy neat adaptors from stereo 3.5 to Mono 6.5. I never put
an ohmmeter to them, but my guess is they simply parallel the two inputs.

Thanks for the info, confirms what I thought.

Just use a resistor summing network and all will be OK.




........ Phil

 

[Phil Allison]

"Jason James"

Use a hybrid transformer. Two inputs have high rejection (typically
higher than 30db),..a common output.


** LOL.

That is what you call a forced laugh,..lol!

** Laughing at fools like you needs no forcing.

A two resistor "mixer" does the job OK

Still less than good design.

** How would a moron like you know "good design" from a dog's turd ?

OK for mikes and passive signal sources.

** You must tell us why it is not OK for the other sources.

We would all love a good belly laugh.

Or, the luxury method is two 1:1 *audio line transformers* with
secondaries wired in *series*.

Luxury? Try proper,.

** You must tell us what is "proper" and improper.

We would all love a good belly laugh.


...but still a bit spastic,..the hybrid is THE way.


** Drivel.



........ Phil