mic lines/Cat5e/coax other wiring needed for single room?

[Jeff Chitouras]

i am planning wiring-in-wall needs in a 520 sq ft/48 sq meters single room recording space operating around Logic Pro 8/HD24XR. I am planning on having 5-6 wall plates loaded with Neutrik Combo XLR/1/4" connectors scattered around the room.

I understand it is wise to use 110 Ohm digital audio cable for mic lines though I already own a bit of Gepco 6 pr multicore snake cable that I wouldn't mind using (longest run is less than 60 feet/20 meters).

1. Am I making a mistake by using the (already paid for) Gepco rather than installing 110 Ohm digital audio cables?

2. Should I be adding wall plates with Cat5e/r45 jacks and/or 75 Ohm coax connectors? What is limitation using cat5e versus Cat6?

3. Given the digital realities of today's audio electronics are there other wiring I should be considering?

Thanks.

[brianrcdd]

I'll be glad to give you some facts interspersed with opinion.

1. It's alway good to have more options, and plan for the future/unknown technologies that will surely come. One way to assist in future-proofing when it comes to wiring is to run conduit to your wall boxes. You can then pull in whatever crazy cable is the next big thing (fiber optic mics?) long after the fact. Yeah, it adds to the cost. But how costly is it down the road to run new cables without a pathway established?

2. Opinion: 110 ohm digital audio cable is meant for just that - AES/EBU digital audio signals. It is overkill for analog audio, such as a normal balanced condenser or dynamic mic. I don't know of anybody that is seriously recommending it for mic line. Seriously, meaning they have verifiable, repeatable scientific data showing how it improves an audio-frequency analog signal in short length cable runs (i.e., your scenario). I would venture to say it won't hurt a thing however, except maybe your pocketbook. I would use the Gepco.

3. CAT6 vs CAT5e is an interesting subject. One reason I recommend CAT6 over 5e is the tighter specs on the cable can compensate for less-than-perfect installation practices. If either cable is installed properly, the throughput will be the same on either a 100M or 1Gig network connection. But it's rare that even the pro installers get it perfect. Ethernet's dirty little secret (but well documented) is it's ability to compensate for cable problems via retransmits. This happens more or less behind the scenes, so you don't really know it's happening, other than lowered throughput. Just because you PC says "connected at 100M" doesn't mean it's actually getting anywhere near that throughput.

A few years back there was a large price difference between CAT5 and CAT6. Today it's not that painful; I'd get the CAT6. This assumes CAT6 hardware at the ends. "Weakest link in the chain" applies here. CAT6 cable with CAT5 jacks will perform to CAT5 specs. As to whether or not you should install it at all, I just look at the increasing number of devices that are designed to be network attached or at least use network cabling.

[Jeff Chitouras]

Thanks for your time/advice. Makes sense.

Would there be increased performance of Cat5e cable if the Cat5e cable used Cat6 jacks in a 100M or 1Gig network configuration? I ask because I also have a good amount of Cat5e cable laying around (so to speak)...

[Aaronw]

Jeff,

What will be your primary use of the Cat5e/Cat6 cable?

For most purposes, you probably will not notice any major benefit unless you're running an extremely high end server w/ 10GB NIC and switches.

One of the main differences in Cat5e vs. Cat6 is the twisting in the pairs, and what it offers for RF rejection, etc.

For the short runs you're doing, the "free" cat5e cable or access to cable, will more than likely be enough for your requirements.

Unless you're planning on running some extremely high bandwidth, such as video, Servers, SANs, or other similar requirements, or have problems with some kind of interference in your area, you probably don't need it (cat6). However, with the ever changing technology, cat6 does plan for future needs if you need it and it's already there.

I just ran the first Cat6 cable at our office for our server in a new room buildout, but it hasn't been connected yet, so I haven't had the pleasure of checking out any speed performance changes. But will be happy to give results if/when they're available in the next month or two.

Aaron

[brianrcdd]

I agree with Aaron. Your environment is pretty small compared to the limits of ethernet cabling which is 100 meters (technically 200, but don't get me started). It's in the longer lengths that benefits in better cabling really show up. To prove a point to my tech staff once, I ran a network connection over two 30 foot runs of lamp cord. Worked like a champ. The point is, don't fret too much about the CAT5/6 thing for runs that are under 100 ft or so. Either will pass gigabit ethernet signal with flying colors unless you really mess up on the installation.

Technically, CAT5e cable with CAT6 jacks should perform to CAT5e specs - weakest link in the chain rule at play once again. But the actual result in a mismatched or mis-installed system is once again tied to the length of the run. That's just one of many variables in the equation. Bottom line: if you have some CAT5e cable available, install it.

[Jeff Chitouras]

Thanks so much Aaron, Brian.

Done. Installing Cat5e and coax this weekend so I cacn finally start to close up the walls.

[knightfly]

I was probably me for the recommendation for 110 ohm aes cable - for balanced, low impedance it's not necessary (mic runs) - where it can help is if you have long runs (over 10 feet) of multi-channel, high impedance, unbalanced audio - the main difference in this application is capacitance. Typical audio cables have anywhere from 30 to 100 pF/foot capacitance, where the aes cable, being optimised for high speed digital, needs to be better - typically 8-10 pF/foot.

Over the course of a signal traveling thru 30-40 feet or more from start to finish (thru patch bay, in and out of processors, etc) this extra capacitance adds up (in high impedance ONLY) to a serious treble cut - enough to cause you to crank the treble EQ by several dB in a lot of cases. I first discovered this about 20 years ago when I used 120 feet of salvaged Belden 27 pair data cable to build a snake - could not believe the treble response in that live system, I ended up re-normaling the board's EQ's to LESS than "0" by quite a bit compared to "regular" audio cables.

To me, if you need to boost treble due to line loss you're also boosting any OTHER noise that's riding on the conductors - so good cable's kinda like a "free noise reduction box".

But for mic signals, it's all a waste of time - use what you have. Any extra capacitance won't have a high resistance to help form a high cut filter, so it's a non-problem... Steve