Blog 24 | Quick guide to Audio Cables | Part 3



December 4, 2024 - Posted by Mash Maximus


DB25 Cables

For multi-channel digital and analog audio, DB25 cables are an essential part of any professional setup. These multi-pin cables allow you to connect interfaces, patchbays, and other gear with high-density connections.

You know what they are. Its very likely that your multi-channel interface, summing mixer, patchbay or console has them on the back. The D-sub series of connectors was introduced by Cannon in 1952. Cannon's part-numbering system uses D as the prefix for the whole series, followed by one of A, B, C, D, or E denoting the shell size, followed by the number of pins or sockets. In this case, D is the type of shell, B is the size of the shell, and 25 being the number of pins it houses = DB25. There are a few different variants of D-Sub cables but the most common one in professional audio is the DB25. Enough history, though, let's talk about applications.

DB25 connections are most commonly used on multi-channel devices. Each DB25 connector can house up to 8 balanced analog audio channels. So, if you have an audio interface that has 8 input or output channels, it would be possible to fit them all into one compact DB25 connector with each channel taking up 3 pins. Wait a minute! That makes 24 pins!! More on this later.

The efficient use of space is what has made DB25's ubiquitous in today’s professional audio manufacturing. Brands can fit more channels into smaller chassis thus adding complexity and value to their products. This is one of the reasons why modern consoles can be so much smaller than their vintage counterparts. DB25 breakout cables allow you to access up to 8 channels of analog audio and in some cases 16 channels of digital audio. Lets deal with analog signals first as this is arguably more common.
Analog DB25: As the name implies, Analog DB25 pass balanced analog audio between devices and/or sources. Eg. A Universal Audio Apollo x16 has 4 DB25 connectors on the back. 2 for input channels 1-16 and 2 for output channels 1-16. You can use a couple of DB25 to XLR-Female breakout cables to access the physical inputs and 2 DB25 to XLR-Male cables for the outputs. Similarly, if your Apollo x16 was connecting to a patchbay, you would likely want DB25 to DB25 cables instead.

Pro Audio LA also offers DB25 to wall/stage box and rack panels. These are basically the box and rack panel variants of a regular breakout cable. Breakout snakes can get messy as the channels just hang there and are prone to creating cable rat’s nests. Many of our loyal customers prefer their breakouts to be contained within a stage/wall box or a rack panel.

Digital DB25 cables. What’s so special about them? For one, they are made with physically different cable. Digital cables intended for AES/EBU and S/PDIF require cable with specific impedance values to pass signal properly. For further differentiation, Digital DB25 cables often use different pinouts. The pinout is the wiring scheme used to connect the cable to the individual pins inside of a DB25 connector. Two of the most popular pinout schemes are Tascam and Yamaha. As their names suggest, they were established and heavily utilized by each brand for their own products and thus became an industry standard that is used to this day. There are other pinouts for surround and multi-channel applications, but we won't go there today. Analog DB25 cables always use the Tascam pinout. Digital DB25's can use either the Tascam or Yamaha pinout – this can get confusing – which is why you should talk to our specialists if you have any questions. Digital DB25 breakout cables also need to have a specific connector configuration to allow for proper signal transmission. Eg. Most AES connections on AES-equipped professional audio devices use half the channels on a DB25 for Inputs and the other half for outputs; therefore a breakout snake for such a DB25 application would have 4 XLR-Female and 4 XLR-Male connectors.

Check out our collection of digital snakes HERE. Something to note about Digital DB25 cables: If you are trying to connect 2 digital units (AES/EBU to AES/EBU, for example), you will need a DB25 Crossover cable. These can be Tascam to crossover Tascam or Yamaha to crossover Yamaha. There can even be Yamaha to Tascam crossover applications! Yes, this is utterly confusing, so we encourage you to reach out to us so we can figure it out for you! It's worth noting that patchbays tend to employ Tascam pinouts, and it's common to not crossover signals when connecting to a patchbay. Our relevant products on our site contain options to configure Digital DB25's per your specific application. In some rare cases, digital devices can crossover the signals internally which as a result requires Digital DB25 cables that do not crossover. Like we said, confusing!

Digital DB25's that utilize the Yamaha pinout can have 2 pins missing, this is because they are not used. I had mentioned the missing pin on Analog DB25's earlier and before you start making fun of my math skills, please note that Pro Audio LA’s handmade Analog DB25 cables use the correct number of pins (24) – which is why you will notice a missing pin in position 13. This pin is not required and is therefore left empty. Since we hand crimp the pins on our DB25 cables using the highest-quality milspec Gold HD pins available, we choose to leave the unused pin out of our assemblies. This unused pin has no impact on audio quality as that pin would never have been connected to anything in the first place. Also, Gold-plated pins are expensive! When you have to make thousand DB25 cables, it really adds up! In general, the parts that go into our DB25 builds cost upwards of 25 times more than a solder-type DB25 which is most common in the market.

Conclusion

We appreciate that this is a lot of info about some already complex cables and while there are a lot of details that we could provide here, they may not necessarily help you get any closer to the DB25 cables you need. We provide custom-length DB25 cables to seamlessly integrate with your equipment. Whether you need 8 channels or 24, our DB25 solutions will have you covered.

No matter what type of audio cabling you require, our team at Pro Audio is here to provide the perfect solution. Contact us today to discuss your specific cabling questions and needs.