Cables and wires

Wasn't really sure where to post this - or even if it's relevant to the board at all.  I feel like the guys on this board would have the best input about things.  So here goes. . .

I'm working on an XLR patch panel for a friend.  It's a really simple 12 Female XLR across with cable coming out of the back to plug into his mic preamps.  I have something similar that I made for myself.  On mine, I used some installation grade balanced audio cable.  For his I have a couple options and am trying to figure out how much this will matter.

I could order "West Penn" 291 cable from redco (http://www.redco.com/West-Penn-291.html) at 10cents a foot, but I already have some cable that may or may not work for it.  It's Extron E197502-7.  22AWG.  There are 2 leads as well as a foil shield and a stranded drain wire.  Physically, it seems identical to the West Penn cable I was looking at.  Problem is that I can't really find any specs on it, so i'm unsure about things like capacitance, etc.  ALSO not sure how much that would come into play at short distances (these would be about 4' runs).  I believe it was originally intended as coax cable for A/V installations.  (I got it from a buddy who worked at an A/V company) 

In the end, the West Penn 291 at Redco is cheap at 10cents a foot and it's pocket change to just get it from there.  I'd just like to learn what i'm looking for here so i'm more informed in the future.  I'd rather know how to tell if a cable would work for my intended purpose rather than just poke and hope.  It also would be great to have a use for this cable (I have at least 100') as I already have it.  It's almost certainly not going to get used as a coax.

-James

I came up blank when Googling Extron E197502-7 (with or without "Extron").  Are there other numbers on the jacket?

Bri

Brian Roth said:

I came up blank when Googling Extron E197502-7 (with or without "Extron").  Are there other numbers on the jacket?

Bri

Click to expand...

It says:

"EXTRON ELECTRONICS  ANAHEIM, CA  E197502-7 22 AWG STP PLNM/STP 22 (UL) CMP 60c  273808"

The 273808 is a length marker, though.

-James

Well, I sure can't seem to find anything for that number at extron.com....so it's a mystery!

Bri

Brian Roth said:

Well, I sure can't seem to find anything for that number at extron.com....so it's a mystery!

Bri

Click to expand...

Although I was hoping for a better answer, that one actually makes me feel better!  I have been looking for info on it for days!  (i'd like to think i'm pretty great at searching!)  Doing some more digging, it seems like this is the only Extron cable that matches what I have:

http://www.extron.com/product/product.aspx?id=audiocontrolc22&subtype=263&s=3#feature6950

There's the STP22 and STP22P  (non-plenum and plenum jackets?)  I assume mine would be Plenum (from the "PLNM/STP" on the jacket).  So, it would seem, I guess I have regular install-grade balanced cable with an outer jacket rated for open air installation.  (Assuming that is what I have)  Any reason to think this would not perform as well as the West Penn 291 in a patch panel install with short (4') cables?

And thanks for your help, Brian.  Believe it or not, you not being able to find info drove me to search through some extron custom cable PDFs until I found a match!

-James

Short cables in benign rooms: anything with enough conductors will do.

Capacitance: there's really very little choice unless the cable is strange. Teeny core wire in large shield with mostly-air (foam or bead insulation) will be somewhat lower C. Big core in small shield is higher C. But it's all log relationship, so large change in construction is small change of C.

What can go wrong? Solid-core will break on long road-trip over bad pavement. Loose-wrap shield is a little worse for shielding. Wax-plastic (Radio Shack) insulation melts-back so you get shorts when flexed. Plenum cable costs more and wastes money in non-plenum work.

I think you are over-thinking. If you can't find something cheaper than free, use the free stuff.

I'm with PRR.  Plenum rated cables are designed to be legally used in installations such as above the "drop" ceilings in office buildings.  That space above the push-up ceiling tiles is a return air pathway (plenum) for the heat and air conditioning, so you don't want the plastic insulation to melt and emit toxic smoke in case of a fire.

Nothing says not to use plenum rated cable for other purposes, like wiring within a rack.  But, plenum rated wire is often stiffer, and sometimes harder to strip.  On the plus side, the insulation won't melt as easily when soldering.

Bri

Thanks guys!  This is definitely stiff, but it will be used behind the rack and in short runs.

Case closed!

-James

Checked with search option for a thread dedicated  to info about proper cables type
tu use for audio diy and related power supply connections ,

found this thread with proper title but no much infos as help inside , overall for beginners ,

then post this , Just for ask to post some info like : type , model code , manufacturer, source links , etc..
and (if you like) personal opinion as well ,
about proper  good cable to use for connect :

-Audio signals inside the rack enclosure  or desktop box ,

-Most common internal power supply lines with 3,5V ,  5V ,  12V , 15V , 17,5V , 18V , 24V

-Good cable for phantom power 48V connection between power supply , on-off switch , and connector,

-Tubes / valves when no connected with pcb socket etc..

Also as well ,
info about cable for onnections between :
-External microphones (dynamic & active condenser) and preamp
-Line to line,  like from preamps to  AD converters or tape machine
-Keyboards and instruments to line input (console , AD converter , outboards…)
-Console to outboards
-Consoles patchbays
-Master out to active speakers or power amp if passive and from power amp to passive speaker
-Digital spdif , aes ebu , madi

-Guitars  and bass to amplifier

and other more "accidentally"not included in this post…

thanks for any post about.

Mogami/Neutric 

enuff problems in studio without having to second guess the routing system,

PRR said:

Short cables in benign rooms: anything with enough conductors will do.
...
I think you are over-thinking. If you can't find something cheaper than free, use the free stuff.

Click to expand...

Pretty much this.

scott2000 said:

I don't know if there is a meta for this topic but I'm sure it would be a nice addition.......

Click to expand...

Unfortunately no "meta" about (from that the search option give out)

and yes it will be a great help ,(another Gdy "force" point)

Overall for the inside "box" connections  part , 
like , power supply : for common used voltages and ampere , as wrote above,
and audio signal too ,

considered the level of attention reserved for specifications precision of the components / parts
(resistors 0,1% ,  capacitors , potentiometers, etc…,  type and quality ,
depending from the type of use/role ,

a bit of attention for the cables  quality , type , size , metal type (copper or alloy) , etc..
would not be necessary / appropriate ?
or it is not relevant / important ?

thanks

Sixtyniner, if I read you correctly, your making a general request for info from folks who know a lot about wire and its proper applications? 

I think CJ summarized it:

Mogami/Neutric 
enuff problems in studio without having to second guess the routing system

Click to expand...

Mogami's website has a pdf that is pretty comprehensive:
http://www.mogamicable.com/pdf/Mogami_Tech_cat2014.pdf

I ordered some W2944 http://www.mogamicable.com/category/bulk/console/  for rack stuff and other audio projects, and have not looked back since. Yes it's a bit pricey, but damn if it isn't flexible and a pleasure to work with.

boji said:

I ordered some W2944 http://www.mogamicable.com/category/bulk/console/  for rack stuff and other audio projects, and have not looked back since. Yes it's a bit pricey, but damn if it isn't flexible and a pleasure to work with.

Click to expand...

from the link:

"Served (spiral) shield provides easier cable termination and better sound quality than braided shield."

I'm sure it's fine and good to terminate. But I have to wonder about the claim that the Spiral shield "sounds better"  than a braid ???

As PRR says 4 feet is not much to worry about.  I use Mogami but love it for DB 25 cables .   

If you have a known length ,  you can measure actual cap/ft between conductors.   

Also has to do with impedance.  In a true 600 ohm circit , it doesn’t matter so much.  In a high impedance circuit like old tascam systems from 70s,  cable is audible on playback of a tape deck.  I agree that in a mic circuit with 4 feet of cable it’s nothing to worry about. 

My question is 4 feet of wire does not give much room to move a panel without stepping on cables at your feet when your rack is pushed up next to a wall.  I would think 8 feet would give more options for placement in future even if you don’t need it now.

while doing studio wiring I have seen 3 main kinds of shields. They are foil wrap, braided and spiral wrapped.  While spiral wrap is the easiest to undo so you can solder it, I can't say it sounds any better or worse then the other two. I have had it in the past exhibit being microphonic having handling noise and picking  up stray noises from outside the mic cable.

Braided shield and foil are equal as far as keeping out all the noises and doing their job but they are a little more harder to work with. Foil in particular does not wrap up and un wrap over and over before it breaks. I never found out how many times you can do that with a cable.  braided shield can wrap and unwrap as many times as needed.  but they are harder to work with thge a spiral wrap. 
As with anything there will be tradeoffs.

If I were you, I would go with redco cable. It's mogami but less $$. then get some neutirk connectors and you are done.

I was asked by a friend of a friend in a working band to assemble a patch bay. His guitar amp was mounted in a flight case and he wanted a front panel to access the jacks on the back of the amp. Easy enough. He provided all the parts,  dummy panel, "the best" quality jacks and cable. The jacks were beefy, they looked good. The cable was fat and very flexible, it looked expensive. I did not care about specs. I thought I could make it look nice by adding heat shrink. I placed some heat shrink over the first wire, and tried to solder the wire to a jack. This is when I encountered a problem. It seemed like the cable sucked the heat out of the iron before I could get the solder to melt. The heatshrink shrunk. I think this cable may have been designed for a screw terminal and not to be soldered. I did not use heatshrink. I was able to complete the job and he was very happy with it.  I don't know what brand or what kind of wire this was, does anyone know anything about this kind of wire?

what was the wire gauge? We had wire at work that solid core copper for ground stuff and boy did you really have to crank the heat on it to get it to solder up.

pucho812 said:

Braided shield and foil are equal as far as keeping out all the noises and doing their job but they are a little more harder to work with. Foil in particular does not wrap up and un wrap over and over before it breaks.

Click to expand...

But don't you have a drain wire with the foil wrap that makes it easy to terminate ?
Technically a copper braid will tend to give better rejection of rfi than an aluminium metallised foil.
But whether you experience any difference will depend on the circumstances.
A foil can give you 100% coverage as opposed to the typically quoted 95% coverage of a braid.
Best I've seen is cable with both - metallised foil with a braid over that. Only cable that got rid of noise on video from a camera in an EMC chamber during rf susceptibility testing (yeah - I know it's not audio but it's easy to see

scott2000 said:

I have that happen to me sometimes....Maybe I'm using too much heat......or the jacket material isn't as good at insulating......some (silver) solder is harder to melt too..... Usually I just have to move the shrink back enough or put a clip or something to transfer the heat.... stinks because it limits your options sometimes...


Or just try to stay out of cold....lol

Click to expand...

Same here. It can help if you have a hotter and larger solder iron tip so you can make the joint more quickly. But basically if you have to keep the heatshrink too near the joint then there'll be problems.
It is by definition heat sensitive and can shrink if the iron is simply held too near it .
May need to look at rubber / silicon sleeving to avoid.