Economy in Building Snakes

[phyl]

I want to run two snakes from the control room to the live room. Each will terminate at a wall panel in the live room and have a XLR/TS fan out in the control room.

I've researched cable, connectors, wall plates, etc, and even with drilling my own wall plates and building my own wall boxes, it's hard to compete with companies like Horizon who sell pre made snakes with breakout boxes attached.

Granted their products are meant to be used on the stage, but is there any reason they wouldn't suffice for a studio? What major differences in performance could I expect when compared against a snake I home build using good cable (mogami) and good connectors (nuetrik, swithcraft)?

[AVare]

If you use the same contstruction methods, none.

Andre

[phyl]

That's the problem.

Without opening up a manufactured snake, I have no idea what type of cable they used, how it's wired, soldered versus crimped connections, yada yada, yada...

[tmix]

I have been wondering this very thing.
I know a lot has been written about the virtues of high quality larger diameter wire.
I wonder if the typical snake cable is of sufficient quality to be used in shorter lengths such as 25 to 30 feet or so?

Tom

[AVare]

but is there any reason they wouldn't suffice for a studio?

Nnoe. Being built for stage means built for greater physical abuse.

Without opening up a manufactured snake, I have no idea what type of cable they used, how it's wired, soldered versus crimped connections, yada yada, yada...

Now you are geting into a difffernt question.

If you feel that the price is good on pemade snakes then gpwith them.

Canare, Mogami, Belden, etc all make good cable for snakes. You can use any of them.
Andre

[Aaronw]

It also depends on your setup. Often times if you buy a premade snake, you're going to have a hell of a time trying to run connectors through a wall or conduit.

If it's going to be a "Permanant Install" you'll probably want to run the cable and do your own connections. If it's a setup that will move or you'll relocate in a couple years, then go w/ a premade setup.

If you do buy Horizon, buy their "Studio Grade" wire, not the cheap stage stuff. Their studio grade is suppose to be just as good as Mogami and others, just a heck of a lot cheaper.

But there's also something to be said about doing your own cables. You can completely customize for your needs. You know the quality of your solder connections, etc. In my experience, I have found premade stuff to break down or short out more times than a custom made cable. That may not always be the case, but if something shorts out, you'll know exactly where to look on custom cables...because you've built them.

Also, speaking of custom cables, you can have the option of doing XLR's, or Elco's, or going straight to a patchbay. I don't know your setup, so I can't say for sure, your best setup.

Then again, I do tech work, so making my own cables is preferred. And often times cheaper for custom wiring.

[phyl]

Thanks guy, I'm convinced doing it myself is the way to go. The more I think about it, having custom made panels exactly where I want them and laid out the way I want them is worth the extra time and money.

[rocktavian]

I dont know the specs nor am i an expert in wiring recording studios. i am an electrician and here is my plan for my studio. I work in a lot of refineries and they use Instrument cable that can go for literally miles without any loss. now they are only operating at 1 to 5 volts or 4 to 20 milliamps so this is a pretty good piece of cable in my eyes. It comes in configurations from 1pr 16awg to 32pr 16awg. im sure it can be found any way you need it. I just borrow whats left on the reel and take it home. I have some 8pr 16awg i plan on using. all of this wire is made by Belden i believe.

My suggestion is talk to someone who works in a refinery, or large commercial plant like a car factory. and get them to give you the hook up. The flexibility of this wire is not as nice as a store bought snake but if it is gonna be in a wall it will work great. i will however suggest when you run whatever you decide on the thru your walls that you avoid running it parallel with any electrical lines(causes inductive noise). If you have to put them parallel on a wall drop just keep them at least 12" apart. hope i helped.

[Aaronw]

Phyl,

Just FYI...I may be passing through your way in about 3 1/2 weeks.

[phyl]

Aaron - Cool. Email me at scoumans@networld.com***NO SPAM*** if you want to set something up.

Just delete the no spam part of the email address.

[knightfly]

Phyl, I work in a rare metals plant as an Instrument Tech, so am aware of the various Belden cables - we don't use voltage signals because of their susceptibility to noise, but do use 4-20 ma for virtually everything that isn't wireless; a 4-20 loop has a typical design spec of 250 ohms total loop resistance, and 16 gauge wire has about 250 feet per ohm of resistance, so there's a theoretical max of about 60,000 feet of conductor possible; this is cut in half by the fact that it's LOOP resistance (out and back) and cut further by whatever devices that are in the loop and their internal resistance, but still it's good for a LONG ways.

However, for audio this isn't the main, or even a serious, consideration - it's the SOUND. Instrumentation stuff typically doesn't care about anything above a few hZ, so frequency response isn't even talked about for instrumentation; for audio, it's pretty important.

This is why (for studios) we look for lower capacitance cable, and foil (100%) shielding, and balanced lines, etc - if you run a signal high impedance for about 30 feet on typical NON-low capacitance cable, you'll cut the 10 kHz response by about 10 dB or more - boosting the treble to make up for this will also boost any other white noise; not a good plan.

The Belden "leftovers" you have are fine for odd cables, short runs, etc, but if you want best sound over longer runs with large numbers of channels, then dedicated audio snake cable of good quality will do a better job.

I've also used 27-pair Belden Datalene cable for audio with good results; the data types have really low capacitance so they don't "round off" digital pulses, but this stuff isn't cheap either; runs around $5 per foot last I looked. The stuff I used cost me $10 for almost 500 feet, scrapped after a feasibility study. The entire spool cost about $2200, but was worthless as scrap because it is mostly insulation/shield with very little copper. Right place, right time... Steve

[AVare]

If you are geting inot signifiactnt (>100') runs of mic cable, investigate the "digital" snake cables. Typically half the capacitance of regular mike cable.


Andre

[phyl]

Knightfly - I think you have me confused with Rocktavian,; he's the guy with instumentation cable scraps.

I'm looking at using either Mogami or Canare snake cable. I've seen some good looking Gepco cable for a reasonable price but no one local carries it.

Your comment about 100% foil shielding is interesting. I somehow got the impression that foil was a bad thing, but that might be because so many people seem to have a problem soldering it during the install.

As far as capacitance, what's a reasonable value per foot for quality cable?

It looks like I'll have two snakes, one ~50' and another ~10' in length. I say snake but I really mean multipair cable runs terminated at junction boxes on both ends.

Thanks for your input.

[rocktavian]

indeed i am the one that has the scraps. my runs will also be less than 50'. This appears to be the same type wire that is in my 100' storebought(carvin) snake. 8prs 16awg with individual sheilds and individual foil sheilding.

Also if you use 4 to 20ma at 250 ohms then arent you using 1 to 5 volts?
Ohms law says volts=amps x resistance

btw sorry for cluttering up your post with my problems

[knightfly]

Guys, sorry for the mixup - to cover all points -

first, foil shield isn't as durable (nor as flexible) as braided shield as a general rule, but you don't solder to the foil - this stuff all has a bare braided ground wire run OUTSIDE the foil (but in contact with the foil) for soldering. For stage use, foil isn't as durable so it's not the best thing to use. For studio use, especially fixed wiring, the foil shield has better coverage so less noise, and is MUCH easier to terminate than separating all those tiny little sheild wires out of a braid.

There is a tool, available in at least 4 sizes, that makes separating braided sheilds nearly painless, if not actually fun - it's called the Little Joe Lead Extractor. It looks like an oversized hypodermic needle, but with the "needle" part "bologna-sliced" and smooth - you strip the outer sheath, push the braid back along the cable just a little, then shove the "hypo" up over the inner insulated conductor, pull the shield back down around the barrel of the "hypo", squeeze the shield agains the barrel, and depress the plunger; the inner insulated conductor pops out between the braid right where the outer jacket stops, and "voila"...

Not sure if these are still made, I've had my set since about 1973 - just did a search and came up empty...

Also, braided shields tend to be a bit more noisy than foil in my experience; another reason to use foil for fixed studio wiring.

second, the 110 ohm (characteristic impedance) AES digital cable typically has as low as 10-12 picofarads per foot, the lowest single conductor shielded audio cable I've seen is Tascam's (belden) 400 series RCA cables, they measure typically 13 pf/foot. RG-59 coax typical cap. is around 30 pf/foot, some twisted pair belden runs as high as 50-60 pf per foot, and most audio snakes seem to run (when specs are even available) between 25-50 pf/foot.

I know this doesn't seem like much, and for LOW impedance BALANCED wiring it's NOT - but for those "semi-pro" items you don't want left out, typical input impedances run around 10k - when you do the math using RC, it works out that about 30 feet of crap cable vs. 30 feet of low-cap cable will cost you around 10 dB at 15 kHz (it's been a while since I've done the math, so don't quote me exactly; bottom line is, when you gotta turn up the treble to get back what you shouldn't have lost, it gets noisy.

rocktavian, the only time 1-5 volts is the same as 4-20 milliamps is when the loop is actually closed so there's current flow; you're right in that 20 mils thru 250 ohms is 5 volts, but audio wiring isn't 250 ohm impedance nor does it have 20 milliamps running thru it in most cases.

If you connect a 5 volt DC signal across a pair of wires, and the other end has a 250 ohm resistor across it (typical for a lot of instruments, they want a voltage input but must conform to industry standards and noise cancellation) then yes, you will have 5 volts and 20 milliamps.

But, if you hook 5 VDC up to the SAME cable and the other end goes into an input whose impedance is more like 100 k ohms, then your current isn't 20 mils anymore; it's 0.05 mils. (It could STILL be a 1-5 volt signal though) - most newer instrument inputs would be just as happy with a higher impedance, straight voltage input; but since most SOURCES implement a series resistor of their own (and measure the voltage drop across it to make sure the line's not broken) we still need to maintain the 4-20 loop impedance, hence the 250 ohm total loop resistance.

Main thing is, industrial stuff is dog-slow compared to audio gear so capacitance doesn't matter; plus, most instruments have serious filtering to block out 60 hZ (obvious reasons :=) so if you lose a few dB at 15 kHz, it's just a bonus.

HTH... Steve