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Stereo Mini Plugs to RCA Plugs to Receiver Aux In-- Signal..

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Anonymous
April 7, 2005 11:47:57 PM

Archived from groups: rec.audio.tech (More info?)

Hello. I'm in the process of putting together a PC->Stereo System setup
for my daughter. Budget limitations confine me to using a mini stereo
system (Panasonic SCM PM39D,
http://www.jr.com/JRProductPage.process?Product=3985852), which rules
out using a digital link from her PC soundcard to the receiver (as no
mini systems, to my knowledge, offer digital input).

Ideally I would like to use a stereo mini plug adapter at the soundcard
which includes an input for computer speakers as well as branching off
into left and right RCA plugs for the stereo (see picture here, listed
as "Option 2": http://www.pcstereolink.com/stereocomputer.html).

Can any of you tell me whether this sort of adapter involves any signal
degradation compared to a normal Y-adapter? Also, I'm thinking it might
be more flexible to use an adapter that terminates in female RCAs and
then use an extended Male-to-Male RCA cable to go the rest of the way.
Since this uses an additional coupling, does it entail signal loss or
weakening?

Thx,
JG
Anonymous
April 8, 2005 3:06:46 AM

Archived from groups: rec.audio.tech (More info?)

"Jim G" wrote...
> ... mini stereo system (Panasonic SCM PM39D,
> http://www.jr.com/JRProductPage.process?Product=3985852),
>
> ...stereo mini plug adapter...(... "Option 2":
> http://www.pcstereolink.com/stereocomputer.html).
>
> Can any of you tell me whether this sort of adapter involves
> any signal degradation

Unlikely any that you would hear on your mini system.

> compared to a normal Y-adapter?

It *is* a Y-adapter. Dunno why it would be any different
than a "normal" one (whatever that is?)

> Also, I'm thinking it might be more flexible to use an
> adapter that terminates in female RCAs and then use an
> extended Male-to-Male RCA cable to go the rest of the
> way. Since this uses an additional coupling, does it entail
> signal loss or weakening?

Not unless the connectors are falling apart. 95% of the quality
of the sound is those speakers. You are worrying about 1/10
of one percent. I wouldn't even give it a second thought.

There is a small possibility that the computer sound card
won't like driving both the computer speakers AND the
input to your mini system, but even that is a <2% chance,
very unlikely in my opinion.
Anonymous
April 8, 2005 12:23:23 PM

Archived from groups: rec.audio.tech (More info?)

I would beg to differ. Maybe it's a question of "how hi" is hi-fi, but
I think you should try listening to the system with one of the output
cables disconnected from the "Y", and then connect the second output
cable to see if you can tell the difference. I can tell quite a
difference when I do this. The impedance mismatch resulting from
connecting the two output cables in parallel really drags down the
signal's amplitude and causes noticeable distortion. If you want to do
it right insert, for example, a $30.00 Behringer mixer at this point
just to isolate the amp output from the two devices that you want to
drive. Another possibility is to construct a proper terminator to
eliminate the impedance mismatch, but that will involve some signal
loss, so the little mixer seems like the way to go.
Related resources
Anonymous
April 8, 2005 8:49:49 PM

Archived from groups: rec.audio.tech (More info?)

bcrowell wrote ...
> I would beg to differ. Maybe it's a question of "how hi" is hi-fi, but
> I think you should try listening to the system with one of the output
> cables disconnected from the "Y", and then connect the second output
> cable to see if you can tell the difference. I can tell quite a
> difference when I do this. The impedance mismatch resulting from
> connecting the two output cables in parallel really drags down the
> signal's amplitude and causes noticeable distortion. If you want to do
> it right insert, for example, a $30.00 Behringer mixer at this point
> just to isolate the amp output from the two devices that you want to
> drive. Another possibility is to construct a proper terminator to
> eliminate the impedance mismatch, but that will involve some signal
> loss, so the little mixer seems like the way to go.

I got the impression the OP wanted to feed the line-level sound output
from his computer into two amplifiers, his little plastic computer speakers,
and the mini-stereo system. Since most modern audio circuits have pretty
low impedance (~1K) and most input circuits are rather high impedance
(~10K), it seems pretty unlikely that the computer output would have a
problem with these two pretty high impedance loads. This is traditionally
called "bridging".

If he is trying to combine two different outputs into a single input, then
I'd agree that a passive "Y-adapter" is likely a poor choice.
Anonymous
April 9, 2005 10:18:58 PM

Archived from groups: rec.audio.tech (More info?)

Hi, Richard. Well, once recently I tried "Y"'ing up the tape output of
my phono preamp so as to make it feed two supposedly high-impedance
devices, and when I "A-B"'d the arrangement I could hear noticeable
signal degradation.
Anonymous
April 9, 2005 11:56:41 PM

Archived from groups: rec.audio.tech (More info?)

bcrowell wrote ...
> Hi, Richard. Well, once recently I tried "Y"'ing up the
> tape output of my phono preamp so as to make it feed
> two supposedly high-impedance devices, and when I
> "A-B"'d the arrangement I could hear noticeable signal
> degradation.

There are single-case examples all over the map because
there are no hard standards for consumer equipment. OTOH,
I believe you have a better than even chance that a modern,
low-impedance source can drive several high-impedance
loads without significant side-effects.

For your "once" I can cite scores of times I have done the
same thing without any problems. But you make a good
point that you can't rely on it.
!