Wiring Your Studio with Audio Over Cat5 (AES72/QTP/RJ45)

[aidanknight]

Good Morning Everyone,

First post I apologize if this has been covered in other threads, I tried searching for this exact subject but didn't find an answer.

I am working on a new studio build where I live in Western Canada. 650-750 sq ft, 2 iso rooms (100-ish sq feet each). ISO1 is a drum room with 12 channels of audio + 1-2 HP boxes (probably the Behringer P16 system), ISO2 is a piano and vocals room with 8 channels of audio + 1 HP boxes. 24 channels of audio in the MAINROOM (synths, CP70, misc mic lines, etc). Another 4 channels of audio in the tiled bathroom bc why not! Reverb! So, 48 Channels of audio total coming back to the desk/patchbay.

I would like to run the wiring over CAT5/6 cables (4 analog channels per Cat5), which I understand from many festival FOH folks are great for long cable runs. Plus the Behringer system uses RJ45 connections. Plus I can send video (maybe to a monitor with lyrics/arrangements for performers) and digital signals in general, from what I understand.

I have a few questions:

1. I want to run cabling through the floor, which allows me to avoid punching holes in my walls. What is considered best practice? PVC conduit? Or something shielded?
2. Can I run digital signals alongside analog? I will also be running power through the floor as well, so I have two places/conduits I can put cables. Power in Conduit 1, Cat5's in Conduit 2?
3. Should I install XLR boxes (like the Sound Tools WallCAT) or leave them as RJ45/Ethercon connectors and use breakout boxes (like the Sound Tools CAT Tails)?
4. My interface (Apollo 16 + 8) is only 24 channels, not 48 - Could I use a RJ45 patchbay to patch groups of 4 to my patchbay (DB25)?. For example, ISO1 XLR 1-4 + ISO1 XLR 5-8 + ISO2 XLR 1-4 > PATCHBAY 1-12.
5. What are my options to convert the RJ45/Ethercon to DB25? I've found a few computer networking parts that fit the description but I have no idea if they will work for DB25 audio wiring (probably Tascam)

Really appreciate any insights from anyone who's installed analog audio over CAT5 in their studio. Thanks for reading!

 

[Papanate]

1. I want to run cabling through the floor, which allows me to avoid punching holes in my walls. What is considered best practice? PVC conduit? Or something shielded?

PVC is best because it keeps it organized. You could also just run it minus the PVC.

2. Can I run digital signals alongside analog? I will also be running power through the floor as well, so I have two places/conduits I can put cables. Power in Conduit 1, Cat5's in Conduit 2?

Digital along side analog is fine - but they should be ran separate to keep it cleaner - power should be routed completely separate.

3. Should I install XLR boxes (like the Sound Tools WallCAT) or leave them as RJ45/Ethercon connectors and use breakout boxes (like the Sound Tools CAT Tails)?

I like the WallCAT best - but you have to use high grade shielded Cat 6 cable.

4. My interface (Apollo 16 + 8) is only 24 channels, not 48 - Could I use a RJ45 patchbay to patch groups of 4 to my patchbay (DB25)?. For example, ISO1 XLR 1-4 + ISO1 XLR 5-8 + ISO2 XLR 1-4 > PATCHBAY 1-12.

I'm not sure - let me think about that.

5. What are my options to convert the RJ45/Ethercon to DB25? I've found a few computer networking parts that fit the description but I have no idea if they will work for DB25 audio wiring (probably Tascam)

There are Audio RJ45 to DB25 cables - but I don't know how well they work.

 

[aidanknight]

Is there a reason for running the digital signals separate from the analog? Is there crosstalk or interference that happens if I run the cables together in one chase? The separation of power and audio seems like a no brainer. I will be hiring an electrician so I'm sure they will have their own opinions on wiring too

 

[rob aylestone]

The benefit of using CAT 5 is it's a simple way to get balanced audio from A to B using cheap and easily available cable. The downside is simply the need for a ground if you need to use mic level with phantom power. There are CAT 5 types that feature individual and overall screens, but the screening seems to be unimportant for normal use - the twisted pairs offering good rejection up to modest RF levels. The screened type does make wiring consistent. I've seen cases where a separate earth has been provided as a separate core.

The biggest snag comes when you need to run a non-balanced connection. Most of us have XLR to mono jack adaptors and stereo versions to let us use a standard balanced 3 circuit cable to do two unbalanced circuits - headphones out of a phone or other player, and at the other end, a cable with XLR 3 to two mono, unbalanced connectors. These cab hum like hell on a cat 5 transmission system, because it's using one of the pairs, losing hum rejection. screened cat 5 wired like ordinary cable would work. Shared separate grounding would be problematic. We even squeeze the odd synth or guitar down room to room wiring - we know we should use a DI, but sometimes we just don't.

If you use a cat 5 wiring system 100% for balanced sources only, it should work fine. Your patch panels could have XLR3, RJ45 or whatever you want. You could use break out spiders but cat 5 is not a sturdy cable system - it's mean to be installed and forgotten.

 

[aidanknight]

The benefit of using CAT 5 is it's a simple way to get balanced audio from A to B using cheap and easily available cable. The downside is simply the need for a ground if you need to use mic level with phantom power. There are CAT 5 types that feature individual and overall screens, but the screening seems to be unimportant for normal use - the twisted pairs offering good rejection up to modest RF levels. The screened type does make wiring consistent. I've seen cases where a separate earth has been provided as a separate core.

I'm a novice when it comes to wiring schematics etc: Is the ground carrying the phantom power? And the ground is shared?

The biggest snag comes when you need to run a non-balanced connection. Most of us have XLR to mono jack adaptors and stereo versions to let us use a standard balanced 3 circuit cable to do two unbalanced circuits - headphones out of a phone or other player, and at the other end, a cable with XLR 3 to two mono, unbalanced connectors. These cab hum like hell on a cat 5 transmission system, because it's using one of the pairs, losing hum rejection. screened cat 5 wired like ordinary cable would work. Shared separate grounding would be problematic. We even squeeze the odd synth or guitar down room to room wiring - we know we should use a DI, but sometimes we just don't.

I wouldn't be using any individual twisted pair to go stereo, just as balanced mic line inputs to the desk. But definitely sorting out sending, say, a guitar signal to the ISO2 room.. is something to think about. Maybe something like this? Radial SGI

If you use a cat 5 wiring system 100% for balanced sources only, it should work fine. Your patch panels could have XLR3, RJ45 or whatever you want. You could use break out spiders but cat 5 is not a sturdy cable system - it's mean to be installed and forgotten.

I think I would upgrade Cat5/6 to some of the Sound Tools cabling with Ethercon connectors for anywhere exposed. I'm just not sure it's worth having tails in the rooms when a few strategically placed panels around the room might be a more robust solution that's equally good at maintaining short XLR runs. I love neat cabling around my drums. Would love to have every XLR cable under 10ft with minimal spaghetti

 

[rob aylestone]

Is the idea to save money? Cat 5/6 is dirt cheap, so if you are pulling miles of cable into a studio I can see the advantage, but for shorter distances, one cost effective system is to buy those Chinese multicores - usually 8 screens individuals in an overall jacket - with 3 circuit jacks. I've got a few 5m ones that I simply chopped off the connectors and used the cable to go into the boxes.

Phantom power needs 3 circuits - the mic hot and cold on pins 2 and 3, ad the screen/ground on pin 1. The pins 2 and 3, connected via Cat 5 carry the audio, but the missing screen prevents phantom power working. Using a separate core, or something else can restore phantom operation. I use a bodged up adaptor so I can get 4 audio circuits out of a 4 pair cable - but I've broken them running flight cases over them and snapped one when somebody tripped. In my studios everything is real screened audio cable - separate cables or the multicore type - either bought per metre or using a chopped up ready made cable. I'm old, so I'm very comfy making cables, and mic type cable is very convenient - You can squirt almost anything down it - balanced or unbalanced audio - headphone feeds, lighting DMX, mixer inserts anything really. With adaptors, most of these will also work with cat 5 - but with unscreened cat5, some types of audio might be trouble.

I really don't know why, but I was brought up with audio cables being screened. I know this is less critical with cat 5 as the rejection is really good - better than the gentle twist in ordinary mic cables - but I still like the idea of screened cables. Price wise? that might change my mind?

 

[bouldersoundguy]

From what I've been reading, twisted pair will reject EMF well enough, but it won't necessarily reject RFI. Shielding does that, so you'd have to use STP (shielded twisted pair) CAT cable. I'm pretty sure Ethercon supports that. It should also enable phantom.

I did a CAT6 run through a studio wall recently with standard Ethernet jacks on wall plates and a pair of those breakout boxes to 4x XLR (one male, one female). I'm sending fairly strong line level signal through them and have had no interference problems.

 

[aidanknight]

Is the idea to save money? Cat 5/6 is dirt cheap, so if you are pulling miles of cable into a studio I can see the advantage, but for shorter distances, one cost effective system is to buy those Chinese multicores - usually 8 screens individuals in an overall jacket - with 3 circuit jacks. I've got a few 5m ones that I simply chopped off the connectors and used the cable to go into the boxes.

It's a bit of a combination of price and sound and space for me. I love how compact the cabling is in comparison to a snake multicore. And according to Dave Rat, the signal is better over distance than XLR (granted he's testing it up to something like 2000 meters/1.5 miles ha!). Obviously I'm not running that length of cable in my studio (40-50 ft max from ISO1 rom to desk/patchbay)

Phantom power needs 3 circuits - the mic hot and cold on pins 2 and 3, ad the screen/ground on pin 1. The pins 2 and 3, connected via Cat 5 carry the audio, but the missing screen prevents phantom power working. Using a separate core, or something else can restore phantom operation. I use a bodged up adaptor so I can get 4 audio circuits out of a 4 pair cable - but I've broken them running flight cases over them and snapped one when somebody tripped. In my studios everything is real screened audio cable - separate cables or the multicore type - either bought per metre or using a chopped up ready made cable. I'm old, so I'm very comfy making cables, and mic type cable is very convenient - You can squirt almost anything down it - balanced or unbalanced audio - headphone feeds, lighting DMX, mixer inserts anything really. With adaptors, most of these will also work with cat 5 - but with unscreened cat5, some types of audio might be trouble

I understand now. Yes, this would be a problem in my studio as I need to send phantom to some mics and definitely not others. Assuming that solutions such as the Sound Tools etherCON cable provide a common ground but +48v would be applied to all 4 channels on that cable. Definitely a con, and something to consider.

I really don't know why, but I was brought up with audio cables being screened. I know this is less critical with cat 5 as the rejection is really good - better than the gentle twist in ordinary mic cables - but I still like the idea of screened cables. Price wise? that might change my mind?

I've only ever used XLR cables myself. I'm new to patchbays, panels, and certainly to RJ45 connectors and Cat5/6 cable. This seemed like a fun opportunity to go a little bit down a rabbithole and see what's possible! Also, it's pretty nice running the HP system over the same cable type, and potentially video too. Whatever I choose, I will allow myself enough space to go with screened cables if I ever change my mind.

 

[aidanknight]

From what I've been reading, twisted pair will reject EMF well enough, but it won't necessarily reject RFI. Shielding does that, so you'd have to use STP (shielded twisted pair) CAT cable. I'm pretty sure Ethercon supports that. It should also enable phantom.

I did a CAT6 run through a studio wall recently with standard Ethernet jacks on wall plates and a pair of those breakout boxes to 4x XLR (one male, one female). I'm sending fairly strong line level signal through them and have had no interference problems.

Great to know! Other than the higher data speeds capable with Cat6.. Is there a difference between the two in terms of shielding?

 

[rob aylestone]

For years we were told about crosstalk in multi cores and running mains cable next to your multis. A kind of rules that most of us broke. Remember being told to cross mains and audio at right angles? Somebody discovered you could squirt analogue audio and video down cat 5 and we started believing real world success rather than paper negatives. We stuck DMX a dirty digital signal down our multis and discovered it worked. And when it didn’t, it was always dodgy cores that were ‘just’ working for audio.

 

[ecc83]

Just my 2 p'oth.. I have been messing with CAT cable for some years at home (got all the bits free!) and can give my personal results.

First off, for audio and data signals you want shielded cable but buy 'backbone' cable with solid pair conductors, much cheaper than 'patch' cable with stranded cores. The latest and fastest ethernet need shielded cable I think? (FTP) B'bone FTP has a drain wire and if you common up 4 XLRs at a time this works fine for phantom power (ppower is comonned in the mixer/AI afterall!)

There are 'codes' for how to run mains cables and the distances other cables need to be from them.

For 'robust' signals, headphone and modest power speakers use the very cheap CAT 5 UTP solid cable. You can use a 'pair and a half' for stereo!
I have recently moved my printer and its desktop into another room and use two VGA to RJ45 boxes to run a monitor in my living room (a 32" Sony FSTV) Works great!

Meant to add...PUT IN LOADS! The cable and conduit is cheap, go nuts.

Dave.

 

[TAE]

I love the Cat 5 / 6 direction we are going and Behringer certainly is on board...VERY Cool...

I installed phone Key systems for a while and have run a ton of cat 5 over the years. on the interior of offices and homes I can't think of a time we ran in conduit of any kind for very long distances. From the main box either up into the attic or down under a raised floor. If it went underground to some destination it would go in the grey plastic conduit used for electrical. Always in conduit on the exterior....Metal above ground, plastic underground.

 

[ecc83]

I don't know about other countries but if you have a lot of mains to wire it is much cheaper and easier to run single 'conduit' wires in plastic rather than grey 2.5mil.

Dave.

 

[aidanknight]

First off, for audio and data signals you want shielded cable but buy 'backbone' cable with solid pair conductors, much cheaper than 'patch' cable with stranded cores. The latest and fastest ethernet need shielded cable I think? (FTP) B'bone FTP has a drain wire and if you common up 4 XLRs at a time this works fine for phantom power (ppower is comonned in the mixer/AI afterall!)

Is there a link to an example of this "backbone" cable? I think I understand, but would love to see one!

There are 'codes' for how to run mains cables and the distances other cables need to be from them.

For 'robust' signals, headphone and modest power speakers use the very cheap CAT 5 UTP solid cable. You can use a 'pair and a half' for stereo!
I have recently moved my printer and its desktop into another room and use two VGA to RJ45 boxes to run a monitor in my living room (a 32" Sony FSTV) Works great!

Yes, I love the ability to run digital over the cabling. The modularity is the biggest feature to me. Still sorting out how the +48v is working (ideally I'd like it per channel) but otherwise I think the price to features ratio is excellent.

Meant to add...PUT IN LOADS! The cable and conduit is cheap, go nuts.

Absolutely. And also I will have accessible channels in the floor to fish additional wire (or space to go full XLR if Cat5/6 doesn't work out for me. Always add an extra 15-20% more cables for future expansion, I say.

 

[aidanknight]

I love the Cat 5 / 6 direction we are going and Behringer certainly is on board...VERY Cool...

I installed phone Key systems for a while and have run a ton of cat 5 over the years. on the interior of offices and homes I can't think of a time we ran in conduit of any kind for very long distances. From the main box either up into the attic or down under a raised floor. If it went underground to some destination it would go in the grey plastic conduit used for electrical. Always in conduit on the exterior....Metal above ground, plastic underground.

Really good to know. My guess is the cable needs to go in conduit anytime there's potential moisture exposure from the ground/also relieves pressure from applying directly on top of the cable? From some of the responses I've gotten, plus some more reading, shielded CAT5/6 is pretty high spec - due to it carrying ethernet. So I'm gonna assume it's pretty good with interference. I'm hoping that is also true while having a digital signal next to a 4 channel analog audio signal.

For my purposes, the plastic underground conduit would be underneath my flooring and would allow me to fish more lines through if needed, or remove lines for repair. If it doesn't need additional shielding, I think I will go with a cheap and cheerful PVC tube, probably 2" into each room.

 

[ecc83]

"Still sorting out how the +48v is working" Not really a problem? I can scrawl a schemo for you if you like?

I don't know what your mains outlets are like but here you can get 4 XLR sockets across a dual 13A faceplate for a metal back box. You can buy metal punches for XLR holes but much easier is to find a tame engineer with CNC gear!

Dave.

 

[aidanknight]

I'll try my best to read one! Am I incorrect about the 4 lines sharing +48v phantom? Can i have channel 1 with phantom to a condenser, channels 2-4 no phantom to a ribbon?

 

[ecc83]

I'll try my best to read one! Am I incorrect about the 4 lines sharing +48v phantom? Can i have channel 1 with phantom to a condenser, channels 2-4 no phantom to a ribbon?

Only if you remove the 48V at source. Or you could fit some isolating capacitors. However, ribbon mics are perfectly safe on phantom power...IF you had a really old mic worth a 5 figure sum you might avoid spook juice but even designs as old as the Coles (orig STC) 4038 are regularly connected to phantom lines at the BBC, millyons of times, for years!

I will draw you something up the morrow.

Dave.

 

[bouldersoundguy]

I'll try my best to read one! Am I incorrect about the 4 lines sharing +48v phantom? Can i have channel 1 with phantom to a condenser, channels 2-4 no phantom to a ribbon?

As long as it's separately switched at the source, it will be separate at the mics. The voltage is applied at pins 2 and 3, which are not shared between channels.

 

[ecc83]

I am sorry for the crapyness of the attached drawing, my scanner is out of use pro-tem.

The 'metal box' is the size of a UK 13 amp twin outlet faceplate. The CAT cable comes in left and 'CT' is a cable tie to the common return screen wire. I used some ~1mm solid copper wire for this and the runs up to each pin 1 makes for a solid job.

The pair colours follow the CAT outlet wiring (but see later) and I have chosen to make the solid colour 'hot' pin 2. Note I have kept Gr/GrW and Bl/Bw AS pairs whereas they are not in an RJ45 plug.

The cables 'X' are others in the conduit bundle and run thru the box but you might prefer to run each outlet as a 'spur'?

Note, the 'lug' is the XLR solder tag to the case. I have left that NOT connected to the pins 1 and I assume you will make other arrangements to ground the boxes? It might be fine to ground the boxes via the cable screen but be aware that it could be a problem.

From other's comments it seems data to audio crosstalk will not be a problem. I would however urge you to keep data grounds and audio grounds separate. This will of course depend upon the exact nature of the build but keep it in mind. Grounding systems always need lots of thought and can be a PITA.
A good way to check the system is to make a 'silent' recording and put it through an analyser such as Right Mark Analyser, it's free! That will show up very low level noises you can miss with the lugs. Helps diagnosis if you know the nature of the noise as well.

Best of..

Dave.