I would like to split the output off of one channel of my preamp, with
one side having inverted polarity so I can capture/mix an M/S
recording without using a matrix. I would make a Y-cable (XLRF -
2xTRS with one having pins 2 & 3 cross-wired). Should I be concerned
about the difference in impedance that the output of the preamp will
be seeing by splitting this way? I know that you can burn out a power
amp by not paying attention to the load that it is driving, and I am
wondering if a preamp might have the same issues. Anything else I
should be worried about if I do this?

I know only the very basics of electronics so forgive the nature of
the question, but I definitely would not want to burn out my pre by
recording a 2 or 3 hour concert this way.

locosoundman wrote:

I would like to split the output off of one channel of my preamp, with
one side having inverted polarity so I can capture/mix an M/S
recording without using a matrix. I would make a Y-cable (XLRF -
2xTRS with one having pins 2 & 3 cross-wired). Should I be concerned
about the difference in impedance that the output of the preamp will
be seeing by splitting this way? I know that you can burn out a power
amp by not paying attention to the load that it is driving, and I am
wondering if a preamp might have the same issues. Anything else I
should be worried about if I do this?

I know only the very basics of electronics so forgive the nature of
the question, but I definitely would not want to burn out my pre by
recording a 2 or 3 hour concert this way.

You won't burn anything out.

"Balanced" must at least mean impedance balanced throughout (ie, the
output and both inputs), otherwise you won't hear anything. If all are
called "balanced" by the mfgr, then this shouldn't be a problem. Then,
at minimum, you must have a balanced signal out of the preamp
(hit-or-miss, you may have that, you may not; "transformer" or "servo"
would be a balanced signal but not as cheap) OR the input the inverted
plug is connected to must have a true balanced input (much more likely).
If at least one of these conditions isn't met, you'll get no, or
reduced, signal at one or both inputs, being shorted to ground at the
inverted plug. No massive amounts of power are involved so "shorted to
ground" only means loss of signal, not destruction. Nothing like a
power amp.

Definitely, you can try it, and it will probably work fine as you
describe it. More information (what equipment?) would help predict your
likelyhood of success, but trying it out is the best way.

Now, re-reading your question, you know you can matrix the M-S tracks
AFTER everyone goes home?

In article writes:

I would like to split the output off of one channel of my preamp, with
one side having inverted polarity so I can capture/mix an M/S
recording without using a matrix.

You have to use a "matrix" no matter what, if you want to turn M-S
into a far more listenable L-R. Perhaps you mean "using a mixer rather
than a dedicated matrix box?"

I would make a Y-cable (XLRF -
2xTRS with one having pins 2 & 3 cross-wired). Should I be concerned
about the difference in impedance that the output of the preamp will
be seeing by splitting this way?

Not unless you're sending it to something really strange. Assuming
you're talking about the line inputs of a reasonably modern (say from
the last 25 years) recording or PA mixer and not some recycled
broadcast thing, that will work fine. But be sure that the mixer's
line inputs are really balanced, and the output of your preamp is
really differential. If your preamp has "impedance balanced" outputs,
pin 3 of the XLR has no signal on it, so connecting that pin to the
tip of a TRS plug going to the mixer won't work.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

"Balanced" must at least mean impedance balanced throughout (ie, the
output and both inputs), otherwise you won't hear anything. If all are
called "balanced" by the mfgr, then this shouldn't be a problem.

Nope - not correct. See my warning about this in my other post on this
subject. Today, sadly, many outputs that are labeled "balanced" are
not differential, and have no signal between one of the pins (almost
always Pin 3 or Ring) and the (ground) reference for the output.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Mike Rivers wrote:
In article writes:


"Balanced" must at least mean impedance balanced throughout (ie, the
output and both inputs), otherwise you won't hear anything. If all are
called "balanced" by the mfgr, then this shouldn't be a problem.


Nope - not correct. See my warning about this in my other post on this
subject. Today, sadly, many outputs that are labeled "balanced" are
not differential, and have no signal between one of the pins (almost
always Pin 3 or Ring) and the (ground) reference for the output.

Right, that's what I meant by "impedance balanced", but I didn't
differentiate from "differential". Thanks for clarifying.

But a single-ended output into the + input of one channel and into the -
input of the other would invert the polarity between the channels if the
*inputs* are differential, and that's fairly common. And to kill the
horse in prep for beating, only the inverted one actually needs to be
differential.

In article znr1084106410k@trad, Mike Rivers wrote:
In article writes:

"Balanced" must at least mean impedance balanced throughout (ie, the
output and both inputs), otherwise you won't hear anything. If all are
called "balanced" by the mfgr, then this shouldn't be a problem.

Nope - not correct. See my warning about this in my other post on this
subject. Today, sadly, many outputs that are labeled "balanced" are
not differential, and have no signal between one of the pins (almost
always Pin 3 or Ring) and the (ground) reference for the output.

Those outputs are about as balanced as "nutritious wonder bread" is
nutritious.

This is the difference between the materials of 20 years ago that were
written by engineers, and the materials today, which are written by
marketing droogs.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article writes:

Today, sadly, many outputs that are labeled "balanced" are
not differential, and have no signal between one of the pins (almost
always Pin 3 or Ring) and the (ground) reference for the output.

Those outputs are about as balanced as "nutritious wonder bread" is
nutritious.

Technically, all a source needs to be in order to qualify as
"balanced" is that it presents the same impedance when looking back
into it from a balanced input. It's the balanced input that does the
work.

This is the difference between the materials of 20 years ago that were
written by engineers, and the materials today, which are written by
marketing droogs.

The point I would make, and that I think you're trying to make, is
that it used to be that this was never either an issue nor an
advertising point. Today, because "balanced output" has become an
advertised feature, today's less educated user needs to be even more
educated than before.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Thanks for all the info! I am using a Sytek preamp which I believe
has a servo on the output (if that is the right way of saying it). In
other words, I do not believe that it is "impedance balanced." That
is a very interesting bit of information - thank you for enlightening
me.

Another related question - say I split the output of the mic itself
going into the pre. Would the same hold true - that there would be no
change in impedance, and so there would be little or no change in the
sonic characteristic and/or output level of the mic? I have in mind a
C414 or a Schoeps CMC6MK8.

You have to use a "matrix" no matter what, if you want to turn M-S
into a far more listenable L-R. Perhaps you mean "using a mixer rather
than a dedicated matrix box?"

Yes - sorry for my confusion - I would like to be able to get a true
picture of what I am actually capturing so that I may adjust my mic
placement if I so desire.
I would make a Y-cable (XLRF -
2xTRS with one having pins 2 & 3 cross-wired). Should I be concerned
about the difference in impedance that the output of the preamp will
be seeing by splitting this way?

Not unless you're sending it to something really strange. Assuming
you're talking about the line inputs of a reasonably modern (say from
the last 25 years) recording or PA mixer and not some recycled
broadcast thing, that will work fine. But be sure that the mixer's
line inputs are really balanced, and the output of your preamp is
really differential. If your preamp has "impedance balanced" outputs,
pin 3 of the XLR has no signal on it, so connecting that pin to the
tip of a TRS plug going to the mixer won't work.

locosoundman wrote:
Thanks for all the info! I am using a Sytek preamp which I believe
has a servo on the output (if that is the right way of saying it). In
other words, I do not believe that it is "impedance balanced." That
is a very interesting bit of information - thank you for enlightening
me.

No, the servo circuit replaces blocking capacitors and really has little
to do with whether it's properly balanced or not. Get out the meter and
find out for yourself.

Another related question - say I split the output of the mic itself
going into the pre. Would the same hold true - that there would be no
change in impedance, and so there would be little or no change in the
sonic characteristic and/or output level of the mic? I have in mind a
C414 or a Schoeps CMC6MK8.

Depends on the mike. The Schoeps won't care about impedance. A C414/TL
won't care about impedance, but a C414B/ULS will, because the transformer
on the ULS is a little touchy about loading. An SM-57 will care a huge
amount.

In general, splitting after the preamp is much easier since you have less
of a worry about noise problems with the higher signal level, and you'll find
it easier to lift grounds on the line level side. But sometimes you will
find yourself having to split mike signals for political reasons, and there
are transformer boxes that will split the signal and give proper loading
to the microphone.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article writes:

Another related question - say I split the output of the mic itself
going into the pre. Would the same hold true - that there would be no
change in impedance, and so there would be little or no change in the
sonic characteristic and/or output level of the mic? I have in mind a
C414 or a Schoeps CMC6MK8.

This is almost always the way I do it, and honeslty I don't give a
hoot whether there's any change in the sound of the mic. Who cares, as
long as it works? Actually, there is more likely to be a change in
sound when paralelling two mic preamp loads on a mic than paralleling
two mixer loads on a preamp output. It's really better not to worry
about what you might be doing to the sound, and how it might be
different if you didn't have to do what you're doing, but rather be
concerned about how it sounds when it's connected as you need it. I'd
suggest that you experiment with your own mic and preamp if this
concerns you. All it takes is a simple cable, and it's OK to have
phantom power turned on in both channels.

Yes - sorry for my confusion - I would like to be able to get a true
picture of what I am actually capturing so that I may adjust my mic
placement if I so desire.

In that case, being able to monitor in L/R stereo is essential. And
it's commendable that you actually want to hear what happens when you
change placement of the microphone.

Incidentally, in my "dream" M-S matrix box, you'd have the option of passing
the mid and side signals straight to the recorder and taking a split through
a matrix decoder so you could listen in stereo with a standard mid/side
balance, or could listen to the mid mic by itself. That's a good way to tell
that you have the mic array positioned for a well balanced pickup. and good
balance between direct and reverberant sound. It's too easy to get
distracted by that newfangled stereo stuff. g



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

In general, splitting after the preamp is much easier since you have less
of a worry about noise problems with the higher signal level, and you'll find
it easier to lift grounds on the line level side. But sometimes you will
find yourself having to split mike signals for political reasons

I understood the question about splitting the mic to be to split it
into a normal and reversed polarity channel for the purpose of M-S
decoding. If it's a matter of sharing a mic with the PA system, unless
the plan is to take direct ouptuts from the PA console for recording,
I'm all for transformer splitters. That way there are no surprises on
either side of the split - it looks like a microphone to both
customers.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo