Audio, Video and other signals over UTP

CAT 5, 5e and 6 UTP (unshielded twisted pair) cables are the most commonly used communication wiring in building. Those wires are normally designed to carry signals like Ethernet and telephone. Those wires can be also used to carry many other signals. Some signals can be directly wires to them (with suitable adapter cables) and some signals need to adaptation to go nicely over UTP wiring. When properly used UTP wiring will have good performance because the wire is a well balanced twisted construction (for more details read Use a twist (and other popular wires) to reduce EMI/RFI and Video and audio over twisted pair wiring). You need to know how to connect different kind of signal to UTP wiring properly, because wrong kind of connection will make the UTP cable to perform poorly (unbalanced signal directly wired to UTP cable will pick up interference easily). Here are some tips how to do the connection:


Balanced line level audio (XLR or 6.3 mm TRS jack): Balanced audio signal goes nicely over twisted pair. It works normally acceptably without shielding on the wiring. Wiring idea: Wire audio + and – to one wire pair. Use another wire pair to carry signal ground from one end to another (if needed). Use for example RJ-45 pins 1+2 for audio and 7+8 for signal ground.

Unbalanced audio (RCA connectors): Use audio isolation transformers to convert signal to balanced format and back to unbalanced on other end. The output impedance of the signal source (lower the better) and the quality of transformers use affect the signal quality.

Composite video: Video baluns will do to needed signal balancing and impedance matching. There are both active and passive adapters to do this. I have been happy with (cheaper) passive models. Composite video over twisted pair is commonly used in CCTV applications.

S-video: Sepate video baluns for Y and C components works.

RGB: Separate video baluns for each vide component. Make sure that video baluns can handle the bandwidth and have identical performance. There are commercial adapters with three baluns built into one unit.

YUV component video: eparate video baluns for each vide component. Make sure that video baluns can handle the bandwidth and have identical performance. There are commercial adapters with three baluns built into one unit.

VGA: There are commercial active adapters that convert VGA signal to RJ-45 connector

HDMI: There are commercial adapters that convert HDMI signal to UTP wiring. Most converters use two RJ-45 connectors (some more expensive ones can run using one).

S/PDIF digital audio: Use video balun for conversion. The S/PDIF signal is signal levels, bandwidth requirements and impedance is pretty similar to composite video signal, so the baluns designed for video signals work well.

DMX-512 light control network: Works well. The difference between Category 5 and low capacitance 120 ohm EIA-485 cable is too small to be of any noticeable effect in DMX512 transmission and reception. Use RJ-45 pins 1+2 for data and 7+8 for signal ground.


You can find some more detailed information on this topic at Video and audio over twisted pair wiring.


  1. Q-factor says:

    Thank you for this great article!

  2. Jems Carrry says:

    Thanks for This UTP model, nice post with great information Thanks for sharing..

  3. Helotiaceae says:

    Excellent post. I was checking continuously this blog and I’m impressed!
    Very helpful info specifically the last part :) I care for such
    info a lot. I was looking for this certain info for a very long time.

    Thank you and best of luck.

  4. Tomi Engdahl says:

    Passive component extends audio signal reach over Cat 5, 5e, 6 or 6a data cables

    From Energy Transformation Systems, Inc. (ETS), the Single Channel InstaSnake is a passive component that allows a user to send audio signals over Cat5, 5e, 6 or 6a data cables. Designed to operate within those “crunch times” when one needs a quick, handy, reliable audio fix, the Single Channel InstaSnake allows bi-directional mic level, line level, analog or digital audio signals to run over UTP cable up to 1900 ft.

    InstaSnake™ Products

    The ETS InstaSnake™ Series (PA200) is a compact, lightweight, versatile passive group of components allowing you to run audio signals over a single run of Cat 5, 5e, 6 or 6a data cables. With a roll of cable, these compact units are easily transported and/or stored solving dozens of live and/or recording sound problems.

    The InstaSnake™ is a passive unit, so you do not need power. The InstaSnake™ accepts “mic” level or line level analog or digital audio and supports phantom power when using shielded Cat 5 or 6 cables. The basic units are a pair of passive units with bi-directional capability which can be input directly into analog or digital consoles.

    The ETS CINESNAKE™ Series PA210 is a compact, lightweight, versatile passive group of components allowing you to run audio signals over a single run of CAT5 or better cables.

    The CINESNAKE™ is a passive unit, so you do not need power. The CINESNAKE™ accepts “mic” level, line level, analog or digital audio and supports phantom power when the slide switch is “ON” position.

    One cable carries both audio signals simplifying the user or installer’s job. Ordinary UTP cabling may be used, however distance and quality are enhanced with cat5 or better cable.

  5. Tomi Engdahl says:

    4K Images and Pictures: What Do They Really Mean?

    So you want to upgrade to a 4K system? There are several options when it comes to the type of signal your 4K system can send to display 4K images. T

    The Definition of 4K

    Let’s start with the basics: What does “4K” really mean? There are different answers to this question, depending on the industry. The broadcast/video industry defines 4K differently than the motion picture industry. Both industries refer to their versions as 4K images, but they are slightly different.

    The motion picture/film industry has been shooting movies in digital high definition for some time now, moving away from using actual film. If you’ve been to a movie theater recently, chances are good that you watched a 2K Digital Cinema Initiatives (DCI) native resolution image, which has 2048 pixels horizontally and 1080 pixels vertically on the screen. The 4K version of this is 4096×2160 (four times the size of the 2K). On the other hand, the broadcast/video industry’s standard for 4K is four times a 1080p (1920×1080), which is 3840×2160 pixels. The majority of U.S. consumers are working with the broadcast/video industry image, where a 4K image is more precisely referred to as ultra-high definition (UHD).

    Traditionally, frame rates were 24 per second for movies to balance between film costs and creating what seemed to be a “moving picture.”

    Over the years, there has been an increased demand to display more frames per second to better capture action and sporting events. Because of this, you now have the option to double the frame rate to 60 frames per second. A frame rate of 120 is even possible.

    Traditionally, each color is represented by 8 bits of information, which equates to 256 choices per color (2 to the power of 8 choices). With all three colors making up a picture, you have over 16 million choices

    For even more options, the market now offers 10, 12 and 16 bits of information per color.

    Instead of sending three colors, luminance and chrominance red and blue (or YCrCb) are sent. Both color patterns are used for 4K images.

    A traditional TV has a brightness range of about 150 nits. The industry has developed a new TV with a standard called high dynamic range, or HDR, which offers a brightness range of 1,000 nits.

    Bandwidth requirements can be in excess of 18 Gbps. This causes a problem when it exceeds the limits of today’s systems, requiring users to make compromises. You can limit the chrominance information, which is the least perceptible part of the image – as we talked about earlier in the blog.

    You do this by having pixels share chrominance information with adjacent pixels. (If two pixels share chrominance, this is called 4:2:2 sampling; if four pixels share chrominance, it’s called 4:2:0 sampling.) This can help you reduce bandwidth requirements and make it compatible with today’s systems.

    The Future of 4K

    Remember: This is cutting-edge technology, and it’s anyone guess as to where the improvement will stop. In fact, the industry is already working on 8K.

  6. Tomi Engdahl says:

    Tuoteryhmä: LiitosjohdotAntennikaapelitTuotemerkki: Macab
    Hinta 27,00 €

    TVB-01 Liitosjohdolla saat otettua signaalin tietoliikenneverkosta johon on syötetty tv-/radiokanavia. Liitosjohto soveltuu käytettäväksi myös päinvastaisessa tilanteessa kun IP-palveluita on välitetty koaksiaaliverkossa

  7. Tomi Engdahl says:

    Long distance digital signals over RJ45
    A simple 50mmx44mm board to route differential signal (RS-485) over RJ-45

    I need to transfer a digital signal (ex: data signal to some WS2812 LEDs) over a long-distance using an inexpensive RJ-45 cable. This uses RS-485 differential signaling to make it possible and reliable. This board is designed to accept input voltage between 8V-28V, and will output 5V and 3.3V. Both output voltages, GND, along with the RO, RE, DI signals can be accessed through a 6-pin JST header.

    The two modules will be connected through a 15 meter RJ45 cable, and we’ll assume there’s a 12V power source near the MCU.

    Connect the 12V and GND from your power source to the VIN/GND pins on module 1
    Connect the 6-pin JST cable to module 1 and wire the other end to the MCU’s data pins (and power/gnd if needed), and wire RE to 5V
    Connect the RJ45 cable between the two modules
    Connect the 6-pin JST cable to module 2 and wire the LED strip to it (and wire RE to GND)

    If you need to pull more power (ex: 500mA), more than can be handled by the RJ45 cable, use thicker cables (ex: AWG 16) to transmit 12V from the power source to the VIN/GND on module 2 (the module connected to the LEDs), instead of VIN/GND on module 1. Those cables can easily be threaded along in parallel with the RJ45 cable.

  8. Tomi Engdahl says:

    Yes, this is common these days. Using an ethernet patch bay you can send 8 channels/4 pairs over each cat 5. Just don’t feed it through a switch! I’ve included a pinout.

    Couple of points – Cat5/6 has the same characteristic impedance as balanced AES, and shielding is not necessary – ethernet is not shielded.
    The TX and RX of a balanced AES stream is transformer balanced and floating.
    Cat5e or 6 is not an issue, but not for the reason you’d expect – the bandwidth of AES is a hair under 2 MHz, nowhere near the 50MHz of Cat5 or the 500MHz of Cat6. That said, AES receivers are not as good at reclocking rounded signals, so you’re better off with Cat6 in theory. However, Cat5e works very well and it’s cheap.
    If you’re sending the signals a distance you’re always better with 75ohm coax AES, but if you’re just shipping it around locally then Cat5e will work great. It’s NOT a compromise at all.

    Pinout PDF

  9. Tomi Engdahl says:

    No difference at all for almost any length of cable. Silver has a few percent better conductivity than copper, so that means that the maximum length of cable before the signal gets too weak for reliable data slicing will be a few percent longer if you use silver. This is in the hundreds of feet range.

    At 3 feet you could probably get away with almost any cable of any type.

    For AES/EBU almost any twisted pair will work better than coax, for the simple reason that AES/EBU is balanced. For SPDIF almost any coax will work better than twisted pair. Horses for courses.

  10. Tomi Engdahl says:

    I can safely say that CAT5 works fine. Bits are bits and as someone already argued before, if it sounds any different, it means you’re losing bits. If you think CAT5 is bad for AES, we would make your head spin at the Olympics, where in the past, AES was passed over 20m of unshielded CAT5 without issue and 50m of shielded CAT5 but that was way way back in the day. Not even a glitch, pop or click, carrying 48kHz/24bit.

    In recent times, we use CAT6 and out of desperation, I have had 100m runs in CAT6, carrying 192kHz/24bit and again with no issues to air at any point. I say desperation though because typically, I make it a rule to use coax cable for anything over 50m for reasons already explained by other posters here about balanced vs unbalanced cables.

    But in all honesty, if you’re going for 150ft and you want multiple balanced AES feeds in a single cable snake, I’d strongly suggest you either use multi-core AES cabling made for the task by someone reputable but not with a “Monster Cable” price tag, be it from Belden, Canare, Draka or Canford, or alternatively, if you don’t mind going unbalanced, use something like Belden 1855A or an equivalent. There are multi-core snake versions with this type of cable within as well, for neatness sake. I’d be aiming for unbalanced cables at that length, personally, unless your gear only accepts balanced connections and using transformers would be expensive and cumbersome for you.

    If you must use data cabling, I suggest you aim for shielded CAT6 and ground the shield at both ends to play it safe. While that is the general rule, where a ground loop is present, one breaks the rule by shielding the cable only at one end and while it shouldn’t work in theory, it does in practice on those rare occasions. I’ve seen it before and we’ve either had to have the equipment all plugged into the same circuit in a cabin out at a venue or we otherwise isolate the AES cable’s grounding from each other. Got to love digital voodoo.

  11. Tomi Engdahl says:

    It might boil down to what / how good Cat5 – Cat5e – Cat 6 cable you actually use. AES audio needs to see 110 ohm impedance otherwise you can have clocking problems due to signal reflection. Cat5 – Cat5e – Cat 6 is 100 ohms with a +/- 15% margin. This means that Cat cable could be 85 ohms up to 115 ohms impedance (if it’s in spec). Maybe one guy gets lucky and uses some Cat cable that’s close to 110 ohms or the gear it’s connected to isn’t as picky with impedance or reflected signal. Maybe the next guy has a different set of variables. This could account for the two completely different users experiences reported in this thread.

    Such 15% mismatches in those impedances aren’t such a big issue when you’re dealing with lengths of less than 30m, in my experience. You’d be surprised how much AES audio is transported along unshielded CAT5e or CAT6 in broadcast facilities. Thankfully not as much as the proper AES shielded twisted pair multicore cables but still a fair amount all the same and they get away with it, thanks in part to the robust nature of AES.

  12. Tomi Engdahl says:

    Theory and Practice with AES/EBU

    The AES/EBU standard for digital audio transmission, more correctly but seldom called AES3, has been with us for a while now… long enough, at least, that most of us will run into it from time to time (1983? where has the time gone?) It is quite forgiving of a little rule-bending in many respects, but still can produce surprising faults with little or no notice past a certain (alarmingly unknowable) point. Typical of digital stuff, it often works great… until it doesn’t! And that, gentle reader, is today’s subject!

    To recap, AES3 most often carries one or two channels of digital audio from A to B. Most often in radio stations, it uses shielded balanced cables and XLR connectors. There’s also an unbalanced variety, which we will touch on a little later. You’re not supposed to use normal analogue-style audio cabling, as AES3 wants 110-ohm cables (+/- 20%), and the analogue stuff, not typically specified, usually averages about 35 ohms or so. Some do get away with it, particularly if the cables are only a few feet long, but this is poor practice, and sooner or later it may bite you. Many others use CAT5 Ethernet cable, which is close enough to the standard (it’s 100-ohms +/- 15%) that it’s unlikely to ever give you grief. And let’s face it, CAT5 cable is an awful lot easier to obtain (and a lot less expensive) than AES/EBU cable. But you should make the extra effort if your application is going to need the extra physical strength, improved flexibility, or the shielding of proper AES/EBU cable.

    The reason for all this foofaraw about impedance is that the digital pulse rates are high enough (128 times the sample rate being used; typically 4-6 MHz or so; up to 26 MHz for MPX over AES) that our cables will start to show transmission line effects: impedance mismatches will result in standing waves, which are the quickest way to get into trouble with this standard. So we want to keep everything impedance-matched. That means the signal should leave the (110-ohm) equipment output, be carried on the (110-ohm) cable, and terminate at the (110-ohm) equipment input. Open hunks of line tapped onto our circuit are to be avoided at all costs. And one source feeds only one input.

    I mentioned an unbalanced AES/EBU variant above, and it’s very popular in TV installations, since it’s 75-ohms, and thus can use standard 75-ohm coaxial cable, same as video (analogue or digital). In hindsight, perhaps it would have been better for everyone if this had been the only standard. It uses a type of cabling that’s already common; impedance-matching rules are largely already understood; and cable lengths are much less of an issue. Unfortunately, every transition between balanced and unbalanced requires a 110/75-ohm balun — hardly a commonplace item!

  13. Tomi Engdahl says:

    Network Cable Math

    Most people think that the reach of Ethernet is 100 meters — at true statement for a system operating at 20°C. We usually do not discuss what limits the reach of the cable. For the discussion at hand today, I will assume that signal attenuation limits the reach of the cable. There are other factors that can limit the reach of a system, but for today we will only look at signal attenuation.

    CAT5e insertion loss (90 meter in wall and 10 meter patch cable)
    10 MHz 7.1 dB
    20 MHz 10.2 dB
    100 MHz 24 dB

    Cat 5e stranded cable table shall meet the values computed by multiplying the horizontal cable insertion loss requirement in clause by a factor of 1.2 (the de-rating factor), for all frequencies from 1 MHz to 100 MHz. The de-rating factor is to allow a 20% increase in insertion loss for stranded construction and design differences.,%20Cat6%20and%20Cat6a%20difference.pdf
    CAT 6
    100 MHz 18.6 dB
    250 MHz 31.1 dB

    CAT 6A
    100 MHz 18.6 dB
    250 MHz 29.5 dB
    500 MHz 43.8 dB

  14. Tomi Engdahl says:

    Cabling Ad Hoc Cat 5e Measurements

    Propagation delay varied from 450 to 500 nsec over different cable samples (be careful using propagation delay to measure length!)

    Delay skew less than 15 nsecover various cable samples

    Lots of Cat 5e cable performs muchbetter than specified TIA/ISO limits•Most significant channel degradations are due to connectors•Poor connectors can significantly increase internalcrosstalkand reduce return loss•TIA/ISO limits are designed for worst-case pass/fail limit bounds–Never intended as a typical channel characterization–Provide margin for test equipment imperfections and measurement noise–Use of extrapolated TIA/ISO insertion loss limits as a channel model is very pessimistic with respect to a typical Cat 5e channel•Typical Cat 5e channel insertion loss at room temperature can beapproximated by the extrapolated Cat 6 channel limit line
    Significant channel degradations can be mitigated by replacing connectors

  15. Tomi Engdahl says:


    Basically the quote you have shown was written by someone who either didn’t understand what they were talking about, or oversimplified it.

    The bandwidth of the cable is a result of the resistance of the cable and the fact that it is capacitive. These act like an R-C low pass filter limiting the bandwidth. Additionally the distributed inductance and capacitance of the cable are frequency dependent so have a more complex affect on the bandwidth.

    The “insertion loss” which is a measure of the gain of the cable is dependant on both frequency, but also on length. The longer the cable, the more lossy it is.

    Here is one example of the insertion loss of a CAT5e cable, this for a 100m length

    Here we see that at 100MHz, the loss is actually more than 20dB – a lot more than the 3dB (power gain) or 6dB (voltage gain) point that would be used to specify the bandwidth of a first order low-pass filter as the quote implies.

    Further up the Wikipedia page more accurately explains where the 100MHz figure comes from:

    The specification for category 5 cable was defined in ANSI/TIA/EIA-568-A, with clarification in TSB-95. These documents specify performance characteristics and test requirements for frequencies up to 100 MHz

    Basically, the requirements in terms of insertion loss that must be met for a cable to be classified as Cat5 are only specified up to 100MHz. Beyond this point the specifications of the cable are undefined by the standard – though manufacturers may well provide data at the higher frequencies.


    The difference between Cat5 and Cat5e is in the way the cables pairs are twisted. The twist in a Cat5e is tighter and this is done to reduce crosstalk.

    Fast ethernet (100Mbps) uses only 2 pairs (one for TX and one for RX). Gigabit ethernet uses all 4 pairs for RX and TX at the time (using echo cancellation) which makes it very sensitive to crosstalk.

  16. Tomi Engdahl says:

    Why You Need Cable Insertion Loss Margin

    In most cases, when it comes to cabling and connectivity, it’s better to play it safe instead of cutting it close. For example: You don’t want a cabling system that can barely support your current application requirements. A system that is fully capable of handling current application bandwidth needs, as well as future needs, offers more peace of mind, ensures continued productivity and reduces the need for costly upgrades later.

    The same holds true when talking about cable insertion loss margin. Insertion loss is the ratio of received to inserted signal power at the end of a cable and is dominated by the cable attenuation. Expressed in decibels (dB), insertion loss levels increase as cable temperature rises.

    Cable insertion loss margin represents the difference between the cable’s measured insertion loss and the maximum insertion loss level allowed per standards; the higher the margin, the better the cable performance. Cutting it close when it comes to cable insertion loss margin doesn’t leave much wiggle room for cable temperature levels to rise without experiencing negative impacts.

    What the Requirements Say

    The insertion loss requirement given in the standards is at 20 degrees C. If cable temperatures exceed that level, which reduces insertion loss margin, performance requirements must change to accommodate the higher temperatures – otherwise, you’re not taking full advantage of what your cabling system has to offer.

    If controlling the temperature of the environment is not an option, channel lengths must be shortened to continue to move data along the cable; otherwise, data transmission will suffer (there will be too much cable loss for successful transmission). How much the channel needs to be shortened depends on the construction and type of category cable being used: Category 5e, 6 or 6A. Reduced cable insertion loss margin will also reduce information capacity, lowering signal-to-noise ratios (which indicate the relationship between desired signals and background noise levels).

    Sufficient Insertion Loss Margin

    Sufficient cable insertion loss margin is especially crucial in Power over Ethernet (PoE) applications, as well as in digital buildings and IoT environments, where DC current is running through cable bundles along with the data, causing heat build-up if it doesn’t have a chance to dissipate into the environment.


Leave a Comment

Your email address will not be published. Required fields are marked *