Reply
 
Thread Tools Display Modes
  #1   Report Post  
Peter B.
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?
Please pick from well shielded quality cables.

Thanks,
Peter
  #2   Report Post  
Rob Adelman
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

The cable is not the place to be looking to color the sound. Even though
some claim different cables can sound different, the diffences would
miniscule compared to differences encountered with microphone selection,
preamp selection, and any type of processing that might be used.

-Rob

Peter B. wrote:
Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?
Please pick from well shielded quality cables.

Thanks,
Peter


  #3   Report Post  
Scott Dorsey
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Peter B. wrote:
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?
Please pick from well shielded quality cables.


With what mikes into what preamps?

Cable difference with mikes are very subtle, because mikes are designed
for fairly low impedances specifically to minimize noise pickup and
contributions of cable effects.

They also aren't always predictable because they depend so much on the
preamp.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #4   Report Post  
Scott Dorsey
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Andrew M. wrote:
What about the cables that have a silever core and very expensive? Those
are supposed to have a distictly "open" sound.


They might. By layering different metals, you can get all kinds of
semiconductor junctions that can add distortion to the sound to make
for more exaggerated top end sounds.

But these effects are also minimized on mike cables, because of the low
source and destination impedances, as well as the balancing (which tends
to null out anything common to both lines). This is why we use these
things in the pro audio world.

Effects that are very audible on cheesy home stereo gear with high-Z
unbalanced inputs will disappear with low-Z balanced connections.
Better electronics design makes cable effects much less of a worry,
which is important when you're routinely running a couple thousand
feet between mikes and preamps.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #7   Report Post  
Rob Reedijk
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Peter B. wrote:
Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?


Hosa.

Please pick from well shielded quality cables.


Oops.


Rob R.
  #9   Report Post  
Rob Adelman
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

L.o.l.!

Rob Reedijk wrote:
Peter B. wrote:

Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?



Hosa.


Please pick from well shielded quality cables.



Oops.


Rob R.


  #10   Report Post  
Rob Adelman
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.



Mike Rivers wrote:


What about the cables that have a silever core and very expensive? Those
are supposed to have a distictly "open" sound.


Yes, it's the sound of your wallet opening.



Hahaha



  #11   Report Post  
James Boyk
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

This is not an appropriate role for the cable. What are you going to do:
label this cable "Dark-sounding cable for use with Mike A and preamp 1?"
Then what happens when you grab it because it's the only remaining cable
and use it with Mike B and preamp 2? No; use the best possible cable;
and if you really want to roll off the highs, insert an
appropriate-value cap across the preamp input. For how to calculate the
value of the cap, see any handbook or textbook. However, what you mean
by "dark" may not be just rolloff of highs. It might be rather an
emphasis of a certain other range. Or it might not have to do with the
"audio" side of things at all; maybe it's a matter of the musical
instrumentation or choice of instruments.

It would seem that this issue is one on which you need to do the
homework yourself, experimenting with all these aspects--and what others
you can think of--'til you discover what you're really after.

James Boyk

  #12   Report Post  
Chris Hornbeck
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

On 1 Aug 2003 18:34:30 -0700, (Peter B.) wrote:

Say for example the mic is a Shure SM 81 with a rated output impedance
of 150 ohms. The preamp has a 13K input impedance. What kind of values
of cable capacitance would make a difference and how would I calculate
this? What other practical values should be taken into consideration
when doing this math? It might not reflect 100% what happens in the
real world but I'd like to know anyhow.


Hi Peter,

You have to expect a certain amount of good-natured flak on this
topic. Keep your powder dry and accept the teasing in the good
spirit it's meant. Of course, you already know this.

To answer your technical question: assume that the cable is a
lumped-sum capacitor and the source (in this case only) is a
pure resistor of 150 ohms. Ignore the preamp loading.

Now you have an R/C lowpass network, right out of the textbook.
At what corner frequency would you expect to hear effects? At
the corner frequency response will be 3dB down; at one octave
lower it will be 1dB down. So maybe a good first pass might
be at a corner frequency of 20KHz. Or you pick a number.

How much capacitance does it take to have a capacitive reactance
of 150 ohms at 20KHz? How many feet of your chosen wire is that?

Are there any other possible effects from wire? Of course there
are! The world is infinite and ultimately unknowable. But this
*one* you can know and measure.

Good Fortune,

Chris Hornbeck,
guyville{at}aristotle{dot}net
question Authority

  #13   Report Post  
Peter B.
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Rob Reedijk wrote in message ...
Peter B. wrote:
Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?


Hosa.

Please pick from well shielded quality cables.


Oops.


Rob R.


Ha... I actually intended that last line to be an anti Hosa clause.

It worked!

Peter
  #16   Report Post  
Peter B.
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Chris Hornbeck wrote in message . ..
On 1 Aug 2003 18:34:30 -0700, (Peter B.) wrote:

Say for example the mic is a Shure SM 81 with a rated output impedance
of 150 ohms. The preamp has a 13K input impedance. What kind of values
of cable capacitance would make a difference and how would I calculate
this? What other practical values should be taken into consideration
when doing this math? It might not reflect 100% what happens in the
real world but I'd like to know anyhow.


Hi Peter,

You have to expect a certain amount of good-natured flak on this
topic. Keep your powder dry and accept the teasing in the good
spirit it's meant. Of course, you already know this.

To answer your technical question: assume that the cable is a
lumped-sum capacitor and the source (in this case only) is a
pure resistor of 150 ohms. Ignore the preamp loading.

Now you have an R/C lowpass network, right out of the textbook.
At what corner frequency would you expect to hear effects? At
the corner frequency response will be 3dB down; at one octave
lower it will be 1dB down. So maybe a good first pass might
be at a corner frequency of 20KHz. Or you pick a number.

How much capacitance does it take to have a capacitive reactance
of 150 ohms at 20KHz? How many feet of your chosen wire is that?

Are there any other possible effects from wire? Of course there
are! The world is infinite and ultimately unknowable. But this
*one* you can know and measure.

Good Fortune,

Chris Hornbeck,
guyville{at}aristotle{dot}net
question Authority




Thanks Chris,
This was what I was looking for.

I take it all in good fun. I knew this thread would bring some fire
down on me. I haven't been around different cable types enough to
actually pick out differences like some here have. For all practical
purposes the subtle differences may not matter much at all. I kind of
wanted a little direction from people who may have experimented with
this before. I thought it might be interesting to test out two cables
of the same length and guage which have different capacitance. I guess
I should have stated this outright. It sounds like these tests would
be easier with line level signals.

I search the archives often and come across talk of cables imparting a
signature on the sound. Some of these posts are from people who have
responded to this thread. I'm glad they chimed in. I'd just like find
two opposite extremes in cables and compare them side by side with the
same listening setup for both. Kind of like first learning about EQ
and cranking boost and cut to the extreams to see what happens.
Sometimes it's easier to understand something when the scope is
broadened. Create a wide scale and the divisions become easier to see
or hear.


Peter
  #17   Report Post  
James Boyk
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

You have, I believe, a completely wrong idea about cables. Among cables
technically appropriate for a given use--doesn't have too much
capacitance, etc.--the differences may well be audible but will be
subtle; while other cables are simply not appropriate. The cable is
simply not the component via which to implement the kind of sonic
control you're talking about. Why are you insisting on doing it this way?

James Boyk

  #20   Report Post  
Arny Krueger
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

"Carey Carlan" wrote in message
. 10

"Arny Krueger" wrote in
news


"Peter B." wrote in message
m
(Scott Dorsey) wrote in message
...


Say for example the mic is a Shure SM 81 with a rated output
impedance of 150 ohms.


Source impedance to the cable.


The preamp has a 13K input impedance.


Nice, but not that relevant.


What kind of values of cable capacitance would make a difference


Big, 1/20 the size of crossover caps.


For example, 1,000 feet of 35 pF/foot cable and 150 ohms give a
corner frequency of about 30 KHz. Under ideal conditions, this HF
loss might be just barely audible, might not.

and how would I calculate this?


Corner frequency (-3 dB point) = 1/ (2*pi*R*C)

R in ohms
C in Farads

1 dB point is half the 3 dB point
0.1 dB point is about 1/6.66 the 3 dB point


What other practical values should be taken into consideration
when doing this math? It might not reflect 100% what happens in the
real world but I'd like to know anyhow.


Opps, I didn't answer this. See below.

Bottom line, mics are designed to work well with what most of us
would call long cables.


Of all the comments in this thread *this* is the one I save.


Thanks. However, I feel obliged to point out that this analysis is way too
simple and way too pat to sit as is, IMO.

If capacitance were the only relevant parameter for mic cable, the world
would probably also have no wars.

;-)

A mic cable can sound very different in actual use for a number of other
reasons. Leading my list a

(1) Pick up of electrical noise. People didn't invent highly shielded and
star-quad cable for nuttin'.

(2) Pick up of mechanical noise. When you apply mechanical stress to cables,
something electrical definitely happens to all of them, and the degree can
vary very strongly. People have sold mic cable that could act as a mic all
by itself!

A cable can also be unacceptable to a user because of its mechanical
qualities. I've had musicians ask for a different cable because the one they
had was too stiff. In this day and age there's no logical reason to argue
with someone over a stiff mic cable.

Since the part of a mic cable that is most likely to fail is the
termination, the quality of the connector and the quality of the workmanship
that attached it to the cable is highly critical. I've seen cheap cables
break after a few performances, or even be broken as delivered.




  #21   Report Post  
Peter B.
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

"Arny Krueger" wrote in message ...


What kind of values of cable capacitance would make a difference


Big, 1/20 the size of crossover caps.

For example, 1,000 feet of 35 pF/foot cable and 150 ohms give a corner
frequency of about 30 KHz. Under ideal conditions, this HF loss might be
just barely audible, might not.

and how would I calculate this?


Corner frequency (-3 dB point) = 1/ (2*pi*R*C)

R in ohms
C in Farads

1 dB point is half the 3 dB point
0.1 dB point is about 1/6.66 the 3 dB point



Thanks! This is exactly what I needed to know. It just took me a
couple tries to get to the point of my question.

Changing the output impedance to 1500 makes a big difference in this
equation.

Peter
  #22   Report Post  
Scott Dorsey
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Peter B. wrote:
Corner frequency (-3 dB point) = 1/ (2*pi*R*C)

R in ohms
C in Farads

1 dB point is half the 3 dB point
0.1 dB point is about 1/6.66 the 3 dB point



Thanks! This is exactly what I needed to know. It just took me a
couple tries to get to the point of my question.

Changing the output impedance to 1500 makes a big difference in this
equation.


Right. THAT is why cable effects are so much more significant in consumer
gear.

Note that this whole thing ignores cable inductance, or the fact that the
input and output impedances might be reactive. These make it even more
evident that the solution to cable problems is in fixing the interfaces
rather than using fancier cables.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #26   Report Post  
Justin Ulysses Morse
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

Peter,
Your Equalizer analogy would be more analagous to this cable topic if
you simply tried breathing heavily upon the boost/cut knob in both
directions, because that's about the amount of difference we're
talking about here between "good" (not defective) microphone cables.
In case you haven't done the math yet on Chris' nice description of
your "problem," you'd need about 1000 feet of some of the
highest-capacitance cable you're likely to encounter in the pro audio
world, up to about 4000 feet of the lowest-capacitance cable you're
likely to find. To save you some legwork, I'll point out that the
lowest capacitance I've found in any microphone cable is Belden 1800F,
which is about 13pF per foot. The highest will probably be a star-quad
cable, which has superior noise rejection, and a quality brand might
top out at about 50 or 60pF per foot (Belden, Canare, and Mogami all
make them).

ulysses


Peter B. wrote:

I take it all in good fun. I knew this thread would bring some fire
down on me. I haven't been around different cable types enough to
actually pick out differences like some here have. For all practical
purposes the subtle differences may not matter much at all. I kind of
wanted a little direction from people who may have experimented with
this before. I thought it might be interesting to test out two cables
of the same length and guage which have different capacitance. I guess
I should have stated this outright. It sounds like these tests would
be easier with line level signals.

I search the archives often and come across talk of cables imparting a
signature on the sound. Some of these posts are from people who have
responded to this thread. I'm glad they chimed in. I'd just like find
two opposite extremes in cables and compare them side by side with the
same listening setup for both. Kind of like first learning about EQ
and cranking boost and cut to the extreams to see what happens.
Sometimes it's easier to understand something when the scope is
broadened. Create a wide scale and the divisions become easier to see
or hear.

  #27   Report Post  
Chris Hornbeck
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.

On Mon, 04 Aug 2003 17:59:13 -0500, Chris Hornbeck
wrote:

So I propose the deciToot, to be defined as:

20 log (observed phenomenon / one mouse fart)


Unfortunately math errors have crept into this discussion
already. Mike had already clearly defined Mouse Farts as
units of power, so the correct equation should be:

10 log (observed phenomenon / one Mouse Fart)

Sorry for the confusion. Must be from all these chickens
I've been straightening lately.


Chris Hornbeck,
guyville{at}aristotle{dot}net

  #28   Report Post  
Geoff Wood
 
Posts: n/a
Default Cable coloration of audio signals in mic apps.


"Peter B." wrote in message
om...
Hello,
I'm interested in testing out different cables for running mic levels.
What cable types will give a darker rolled off character to the sound?
Please pick from well shielded quality cables.


Star-quad mic cables have higher capacitance, which may increase the
'darkenss' at frequencies above human hearing in typical lengths.

Apart from that, differences between matched microphones are likely to be
greater than anything attributable to cables. 'Competent cables' meaning
well-screened and mechanically 'sound'.

geoff


Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
rec.audio.car FAQ (Part 2/5) Ian D. Bjorhovde Car Audio 0 March 6th 04 07:54 AM
Crazy market saturation! CatalystX Car Audio 48 February 12th 04 10:18 AM
Dithering Digital Audio Karl Uppiano High End Audio 12 December 30th 03 05:12 AM
cabling explained Midlant Car Audio 8 November 14th 03 04:07 AM
science vs. pseudo-science ludovic mirabel High End Audio 91 October 3rd 03 09:56 PM


All times are GMT +1. The time now is 09:13 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"