AES EBU 110 Ohm Digital Cable

The very first real-time software MP3 player was a program called WinPlay3. This program was released way back in September of 1995, back in the days of half gig hard drives. As MP3s gained popularity and began to distract computer users from glorious MIDI music, Winamp from Nullsoft was released in 1997 and by the next year, Winamp in its various iterations was downloaded over 3 million times. Several years later, the first version of iTunes was released to the public in 2001. Fast forward to today, a little over a decade later, and computer audio has become very widely accepted and many audiophiles are more likely to fire up a PC than pop open a compact disc player.

The WinPlay3 Program

Because the CD player is going the way of the dodo (obsolescence), audiophiles choose to interface their PC with a DAC (digital audio converter) in order to extract the music in the best sounding way possible. A DAC requires a digital signal be carried from the PC to the external DAC. In some cases the PC has a direct output for a digital signal from the motherboard or sound card, in other cases, a user may choose to use a USB to SPDIF converter box, such as the M2tech HiFace or Musical Fidelity V-Link to name a few.

Digital signals can be carried a few different ways, either optically or via a coaxial cable. Many enthusiasts frown upon optical cables due to perceived jitter and myriad other issues, although I have found the glass ones to be acceptable in the past. Optical cables actually isolate the ground from one device to another which can be a benefit in the case of a dirty ground at the source. The other option, a coaxial cable with a single center conductor isolated with a dielectric and a return which is typically a copper mesh over the dielectric, can be terminated with either an RCA or BNC.  In the case of the AES/EBU, there is still the copper mesh over the dielectric and there are two conductors in the center.

Standard digital coaxial cables are preferred to be rated at 75 ohms, and since BNC connectors are legitimately 75 ohms, they are preferred, but in many cases BNC connectors are not offered and an RCA will suffice. If you are lucky and your PC output and DAC both have an AES/EBU jack, then you’ll have the best possible connection between your devices. AES/EBU coax cable should be rated at 110 ohms.

AES/EBU, also known as AES3, was developed by the Audio Engineering Society (AES) and the European Broadcasting Union (EBU) way before the first software MP3 player in 1985 (although revised in ’92 and ’03) and is effectively the professional version of S/PDIF. Much more additional information regarding the AES/EBU standard, including protocols, time slots and channel status bits can be found at http://en.wikiaudio.org/AES_EBU .

Musical Fidelity V-Link 192 featuring an AES EBU connection

Now that we covered what an AES/EBU is and where it came from, I’ll go ahead and assemble a nice audiophile quality one. One of the fortunate things about the AES/EBU protocol is that is calls for a standard XLR connector, of which there are many audiophile versions floating around, I’m sure some of which use time-corrected flux capacitors and pixie dust gathered during ancient times. I’ll personally be using the DHLabs Silver Sonic XLRs, which is a strange name as the contacts are gold-plated pure OFC copper (no brass!), but they’re great connectors for the dollar, and the DHLabs Silver Sonic D-110 110ohm coax cable, which has silver plated copper conductors within a PTFE dielectric, spacers for constant impedance and a 100% coverage shield.

Silver Sonic D-110 Cable and XLRs

First on the agenda is covering the wire with some nice sleeving. I selected the Techflex brand Carbon Reflex sleeving, which is a polyethylene terepthalate material braided with 3M Ultra reflective monofilament. In simple terms, the weave reflects light and looks pretty impressive.

As noted in the photo below, there are two insulated wires (positive and negative) and a drain wire which connects to the shield for the ground. Also in the center is the Silver Sonic XLR female pieces.

Sleeved with Carbon Reflex

...and here are the Silver Sonic XLR male pieces.

Silver Sonic XLR male connector

Although not necessary, I sleeved the drain wire with Teflon like the other two conductors for uniformity.

Drain wire with Teflon sleeve

These wires are soldered in place on each of the male and female connectors. The ground wire (the drain wire in this case) is soldered to pin 1, the positive wire (red in this case) is soldered to pin 2, and the negative wire (black in this case) is soldered to pin 3. Also note that with the Silver Sonic connectors, slipping the boot over the decorative sleeving requires some patience.

XLR Pin Diagram

Once everything is soldered in place, the barrels of  the DHlabs connectors are slid over the soldered connections and the three screws over each connector are replaced. The two screws over the boot in the back back a very substantial strain relief system. Below you will see the finished digital AES EBU cable. 

Finished digital AES EBU Cable

Hope you enjoyed reading this post. If you are interested in having your own custom digital AES EBU cable (or any other cable) made, please contact Zynsonix for a quote.


The Fine Print:
The above steps detailing the building of a cable are for entertainment purposes only, and not to be performed under any circumstances. The owner of this blog and all associated parties can not / will not be held responsible if you attempt the process posted and cause physical harm to yourself, your surroundings or your property. Please keep this in mind.

Glassware Audio LV-Regulator Power Supply

Wallwarts... you know them as the little black plastic boxes that take up precious real-estate on your wall outlet or your surge protector. These little devices are generally mass produced overseas as a cheap method of converting your house's AC (alternating current) to usable DC (direct current) for whatever device they'll be powering. This process requires transformation, rectification and filtering in order to make the power worthwhile for your device. Transformation is the process of converting the voltage from 120v (in the U.S.) to whatever the device is calling for, whether it be 9V, 12V, etc. Rectification periodically reverses the direction of AC to convert it to DC, usually using diodes or vacuum tubes in some circumstances. Filtering is reducing the power ripple to produce stable power and reduce EMI (electromagnetic interference), often times making use of capacitors.

Not all power supplies are created equally. Many high-end electronics shrug off the little wallwarts and have a dedicated power supply built-in, or even in a separate chassis. Using higher quality transformers and better filtering circuits improves the quality of power entering your equipment, which will hopefully improve the listening experience if all goes according to plan. As many forum members agree, there are a number of devices that can benefit from a dedicated power supply, such as the Squeezebox, Cambridge Audio DACMagic, Wadia 170 and 171 iTransport and the Musical Fidelity X-Series and V-Series components. 

This brings us to the Glassware LV-Regulator (LV standing for Low Voltage) which can be configured for 5v, 9v or 12v DC output and makes use of a 3A low-dropout regulator (LD1085). As stated by John Broskie on the Glassware website: "The LV-Regulator uses a simple RC filter (1 ohm & 10kµF) as a pre-filter before the LDO regulator and holds bypass capacitors for all the electrolytic capacitors and a 4.7µF/400V polypropylene shunting capacitor at the output. The 1-ohm resistor is a 4W device, so the maximum current output is 2A. The RC filter before the voltage regulator unburdens the regulator from having to deal with sharp transients."

The Glassware LV-Regulator board (copyright Glassware)

This board, when combined with a suitable transformer, will make a nice power supply for low voltage devices like many mentioned above. The one being assembled in this particular post will be 9v and making use of a center-tapped Hammond transformer. Below is the initial board assembly and the Hammond 166M10 3A transformer. Because the transformer is center tapped, the board would be configured as full-wave center-tapped. 

Transformer and LV-Regulator Board

Aside from the transformer and board, a few other things will be necessary, including a chassis, IEC inlet, power outlet, umbilical power cable, pilot light, and on-off switch. The IEC inlet will be a EMI/RFI filtering type that should help further clean up the power. For the power outlet, a Neutrik Powercon connector will be used. For the chassis, I'll be using a custom 8" x 5.5" chassis from Keith (Ebay member po1019). Below is a quick initial chassis layout for the build.  

Custom 8" x 5.5" chassis with mahogany panels

Initial chassis layout

Below is a photo of the chassis after the holes were drilled and it was powdercoated a cream color. I have a nice Greenlee punch for handling the Neutrik Powercon connector (it handles the Powercon, the locking 1/4" jack and other similarly shaped panel mounted jacks). The IEC inlet has to be cut with a Dremel cutting disc which requires a bit more time and effort. I typically drill four holes in the corners, then cut between them with the cutting disc, then finally use a hand file to smooth out the cuts. All the other holes on the chassis were created with a drill press. 

The LV Regulator Chassis

Next comes the process of adding the parts and the populated circuit board to the chassis. Thankfully everything fit without issue. 

Parts added to chassis

With everything in place, the circuit could be wired up. 16 gauge silver-plated copper in PTFE was used for all wiring, aside from the pilot light which was 18 gauge. The wood side panels were then slipped in place and screwed in. 

The LV Regulator all wired up

With the wiring complete inside the unit, there will be a need to get the amps to the transport it will be powering via a cable. The cable from a power supply to the unit it is powering is typically called a "umbilical" cable. The center of this cable is a twisted pair of 18 gauge silver plated wire, one for power and one for return. This was carefully wired to a small 3 pin power connector that closely matches the Wadia 171i input. Multiple layers of heatshrink were used to ensure to possibility of a short within the plug. 

Creating an umbilical cable for the power supply

I decided to shield this cable, so some additional steps are necessary. The twisted pair was covered with Teflon tape, then a bus wire wrapped around it. This bus wire will conduct to the foil shield that will be wrapped around it. 

The foil tape is made by 3M and is a basic way to reduce EMI (electro magnetic interference). I used it rather than copper mesh to keep the cable from getting too bulky. 

3M foil tape wrap

The cable then gets another layer of teflon tape on top.

More to come...

 

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.