The term is a mystery to me. Anyhow, I run straight out of a plain jane
Shure SM-58 into my little reverb unit - a Yamaha R100. The R100 accepts
only a 1/4" input, and it has a trim knob. Then, I come out of the Yamaha
unit, and go into a Mackie Powered speaker - an SRM 450. I do this as a mic
on my vocal only, while I play an acoustic piano. I employ no mixer. No
need.

My questions:

1. Do I need a low z to high z converter as I go into the Yamaha reverb
unit? Or is a simple wire converting the signal from an XLR to a TRS enough,
without changing the impedance?
2. Do I need a hi z to low z converter as I come out of the Yamaha reverb
unit and go into the Mackie? Or is a simple wire converting a TRS to XLR
enough, without changing the impedance?
3. Anyone know of a place I can learn what this **** means, rather than
trying to work with something that has zero feel for me? I am an engineer
for goodness sakes (mechanical)!
4. Does impedance refer to the output signal of a device, or its internal
resistance?

Mackie could have made it a LOT easier if they would simply have included
1/4" unbalanced inputs on their SRM 340s instead of only XLR balanced ones.

"Jimmy Lee" wrote in message
...
The term is a mystery to me. Anyhow, I run straight out of a plain jane
Shure SM-58 into my little reverb unit - a Yamaha R100. The R100 accepts
only a 1/4" input, and it has a trim knob. Then, I come out of the Yamaha
unit, and go into a Mackie Powered speaker - an SRM 450. I do this as a
mic
on my vocal only, while I play an acoustic piano. I employ no mixer. No
need.

My questions:

1. Do I need a low z to high z converter as I go into the Yamaha reverb
unit? Or is a simple wire converting the signal from an XLR to a TRS
enough,
without changing the impedance?
2. Do I need a hi z to low z converter as I come out of the Yamaha reverb
unit and go into the Mackie? Or is a simple wire converting a TRS to XLR
enough, without changing the impedance?
3. Anyone know of a place I can learn what this **** means, rather than
trying to work with something that has zero feel for me? I am an engineer
for goodness sakes (mechanical)!
4. Does impedance refer to the output signal of a device, or its internal
resistance?

Mackie could have made it a LOT easier if they would simply have included
1/4" unbalanced inputs on their SRM 340s instead of only XLR balanced
ones.
==============

Hey JL, try yer post over at alt.audio.live.pro-sound.

And have a look around, check out the Catalog on left side of page at:

http://www.musicbooksplus.com/

Cheers,

-bg-

www.thelittlecanadaheadphoneband.ca

1. Do I need a low z to high z converter as I go into the Yamaha reverb
unit? Or is a simple wire converting the signal from an XLR to a TRS enough,
without changing the impedance?

Are you getting enough signal level when you do this? If so, then you're fine.
But if not, as I suspect, you need sometihng to boost the level. It's called a
"mike preamp", and you can get them starting at about $99 for a crappy one. The
problem is not likely to be impedance, but level.

2. Do I need a hi z to low z converter as I come out of the Yamaha reverb
unit and go into the Mackie? Or is a simple wire converting a TRS to XLR
enough, without changing the impedance?

The latter should be fine, but does the Yamaha have a balanced output? If so,
you're okay; if not, make sure the Mackie will accept an unbalanced signal if
the XLR is wired right. The Mackie manual should tell you.

3. Anyone know of a place I can learn what this **** means, rather than
trying to work with something that has zero feel for me? I am an engineer
for goodness sakes (mechanical)!

Check out Mike Rivers's series on impedance in the last several issues of
"Recording". Keep in mind, though, that impedance isn't the only issue involved
in audio; level makes a difference too.

4. Does impedance refer to the output signal of a device, or its internal
resistance?

Both. A device with inputs and outputs will have an input impedance and an
output impedance. A device with only an output, like a microphone, will have
only an output impedance.

Mackie could have made it a LOT easier if they would simply have included
1/4" unbalanced inputs on their SRM 340s instead of only XLR balanced ones.

Yes, but they might have had to charge more for it (extra parts), and these
things are designed to meet a particular price point.

Peace,
Paul

In article writes:

The term is a mystery to me. Anyhow, I run straight out of a plain jane
Shure SM-58 into my little reverb unit - a Yamaha R100. The R100 accepts
only a 1/4" input, and it has a trim knob. Then, I come out of the Yamaha
unit, and go into a Mackie Powered speaker - an SRM 450. I do this as a mic
on my vocal only, while I play an acoustic piano. I employ no mixer. No
need.

My questions:

My question:

Does it work? If so, don't worry. If not, you need to learn a few
things about interfacing.

1. Do I need a low z to high z converter as I go into the Yamaha reverb
unit? Or is a simple wire converting the signal from an XLR to a TRS enough,
without changing the impedance?

Neither. If the reverb unit is designed for a microphone input (RTFM),
you need only to make the connectors fit. If it's designed for a line
level signal, you will need to boost the level of the microphone
output in order to get enough signal into the reverb unit so that it
will work properly. You can do this with a transformer (you can buy an
adapter that includes a transformer and has the proper connectors on
each end), which incidentally also changes the impedance. The reason
why it fixes this problem isn't because it changes impedance, it's
because it raises the voltage coming out of the microphone.

The usual device for accomplishing this is a microphone preamplifier,
but I can tell that you don't want to buy another box. Try the simple
solution first.


2. Do I need a hi z to low z converter as I come out of the Yamaha reverb
unit and go into the Mackie? Or is a simple wire converting a TRS to XLR
enough, without changing the impedance?

Probably not. The output of the reverb unit is almost certainly at
"line level" (assuming you have the proper level going in) and you
will need only a properly wired cable or adapter.

3. Anyone know of a place I can learn what this **** means, rather than
trying to work with something that has zero feel for me? I am an engineer
for goodness sakes (mechanical)!

I wrote a monthly series of articles in Recording Magazine between
1996 and 2000, and occaional articles since which deal with
interfacing. As far as I know, there is no book entitled something
like "Interfacing for Beginning Audio Engineers." Maybe I should write
one one of these days. You might want to look at my articles in the
August through November issues of Recording for some fundamentals.

4. Does impedance refer to the output signal of a device, or its internal
resistance?

Both, and neither. But like I say, there's a book's worth to learn, so
I'm not going to try to summarize it in a few sentences. I'll leave
that to others (who will try).

Mackie could have made it a LOT easier if they would simply have included
1/4" unbalanced inputs on their SRM 340s instead of only XLR balanced ones.

This is something that your dealer should have helped you with. If he
sold you all the stuff, he should have told you that you needed
certain cables or adapters to put it together. If you choose to do
your own system engineering (buy from here and there and just buy the
boxes), you need to determine the type of inputs and outputs and make
whatever adapters and adjustments you need. Even if a manufacturer
anticipates everyone's needs, they can't always afford to accommodate
them. It's really more typical for the speakers to be connected to the
outputs of a mixer with balanced connections. If you choose to use
them in a way that's different from the primary intent, it's up to you
to find out how.



--
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