Removable Balanced Cable Mod for Beyerdynamic DT-1770 Headphones

I'm personally digging the newer, more upscale DT-1770 and DT-1990 from Beyerdynamic. The sound is more balanced and not quite as peaky in the upper midrange. The DT770, 880 and 990 are still incredible values though, and I'd recommend them to anyone looking to get into headphones. 

There's one glaring omission that Beyer could have done better with 1770 and 1990, and that's not using a 4-pin XLR with isolated grounds so the headphones could be run with balanced amps. For a headphone costing nearly $600 and given how little it would cost to implement is a strange business decision. Drop has actually released a version of the 1770 called the DT-177X which uses a 4 pin XLR, so I encourage anyone considering the DT-1770 to get that instead. 

3-pin XLR? That's no good!

Fortunately for Beyer fans, the existing units can be modified for balanced amplifiers. This involves removing the 3-pin XLR and much of the existing wiring and isn't very difficult. 

Below you'll see the offending 3-pin XLR which needs to be replaced. To open up the headphones, first the earpads are removed, then pry off the retaining ring using an envelope opener or similar tool. 

Under the retaining ring are the drivers. If you look carefully, there is a little indent on the outer edge of each. Using a small flathead screwdriver, you can apply some pressure to pry up the driver frame and remove it from the cups. This should all be done carefully as to not damage the drivers or the fabric on the driver frame. 

The drivers will often have a number on them. This is likely for matching purposes at the factory. In addition they will have a red dot near one of the wires. This tells you which side is positive. The wires can be trimmed and the drivers removed. Next the headband has to come off to replace the wire between the cups. There are a couple of screws to remove on the plastic brackets and you can then open up the headband and remove the wire. 

Other items that need to come off are the 3-pin mini XLR and the little strain relief pieces. The mini XLR has a plastic ring that screws it in place. There's a little bit of adhesive but it's not difficult to get off. The strain relieve pieces have a metal retaining piece, remove that and pull them out of the cup. They will need to be cleared out inside with a drill or dremel to provide clearance for thicker wire. 

Once everything is out, the replacement wire is soldered to a 4 pin mini XLR (Switchcraft or similar) and is fed through the strain relief pieces (orange circle below) through the headband and out the other side. The plastic pieces holding the headband in place have small indents where the wire enters and exits (red circle below). Inside, a zip tie should be placed right under the strain relief so the wire can't yank on the driver connection if it gets caught, and some light adhesive can be placed, then the metal retaining piece can be reinserted. 

Once everything is in place, you can insert the mini XLR back into the cavity on the bottom of the cup and screw on the stock plastic ring. Use a bit of adhesive or Loctite to ensure this does not come undone. 

Below you'll see the wire running to one of the headphone drivers. Beyerdynamic is now using small pins and a circuit board for ease of assembly. The pins are too small to solder to directly, so the wire should be soldered close to the board with a little bit of room for flexibility. Adhesive heatshrink should be used to prevent shorting. 

If you decide to try and remove the pin jacks and solder directly to the PCB, be very careful as you can damage the diaphragm wire which is quite thin. I personally do not recommend this as you'll likely find yourself buying a new set of drivers, but if you'd like to try it, godspeed. 

 

Once you have everything in place, you can reassemble the headphone. Below you'll see the modded DT1770 Pro (sans earpads, they were retained by the owner) and a spiffy new Zynsonix Ballista cable to go with them. 

I hope you enjoyed this brief tutorial and hope your mod goes well. If you'd prefer someone else have all the fun, please contact Zynsonix Audio who would be happy to handle it for you. 

Disclosure: Please remember that using a soldering iron and/or modifying headphones 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 modification posted above and cause physical harm to yourself or your surroundings. 

Balanced Audio Switchbox - Audiophile Quality

If you're an audio purist, it can be worrisome adding components in the signal path, even if it enhances convenience during your listening sessions. This is compounded even further if you are taking a delicate signal from a turntable to a phono pre. It doesn't make sense to to spend all that money on fancy interconnects if they are plugged into a switchbox with a low-quality switch, forcing the signal to travel across questionable metal contacts that may not be making a secure connection. That being said, everyone appreciates being able to change inputs and/or outputs at the turn of a knob. There's an easy solution, use the best materials available so the switchbox will be as transparent as possible.

A great client of mine, Todd, wanted a balanced switchbox that would fit conveniently on his rack and not harm the signal. Based on the sizing constraints, he chose a size that would match his Schiit Audio Mjolnir 2 headphone amplifier and fit conveniently underneath. We selected a Par-Metal 16" wide aluminum case (20-16123x) that matched the dimensions perfectly, anodized with alodine for EMI/RFI shielding, and black on the exterior.

Par Metal aluminum chassis 20-16123x

The unit would have a single pair of balanced XLR inputs, and four pair of balanced XLR outputs. I selected the Neutrik DLX series with heavy duty shielding. As Neutrik states on their page: "[the] all metal housing works in combination with a new duplex ground contact yielding the best RF protection and ground conductivity in a chassis mount XLR". Creating the holes in the back chassis panel simply requires using a ruler to plan out where the holes would be cut. Greenlee makes an excellent punch for D-size mounting dimensions. The D mount specification calls for a 23.80mm (0.9370") diameter hole, but a 15/16" hole is 0.9375" and works perfectly well. As you've likely seen in many of my other posts, I use these punches a lot. You drill a pilot hole, insert the bolt and tighten with a ratchet and you get a nice accurate punch every time.

Greenlee 15/16" Metal Punch

The XLR connectors can be inserted from the back for a clean mount. I chose to use pop-rivets to install the connectors as I like the look, however, a screw, nut and lock washer would also suffice. 

Aluminum pop-rivet

Installing the D mount XLRs on the back panel 

Below you'll note the D-mount XLRs installed. Despite being directly installed to the metal chassis, solid grounding is very important, so a bus wire is run across the chassis ground pin on each unit, and each unit is shorted to the metal surrounding the plug. You'll also note the mount for the switch has been installed a little past the halfway point on the chassis.

Bottoms up!

And here comes the fun part, wiring. I encourage labeling the chassis interior which won't be visible after completion so you don't get mixed up during the wiring process. In this case, one wafer (or level) on the switch is dedicated to the right signal (both positive and negative), and the other to the left (+ and -). At any given time, four connections are being made: L+, L-, R+, R-. The Elma switch selected is really nice quality, make before break, with Swiss movement, gold plated connectors, the works. Solid core UP-OCC in teflon wire is being used for all connections. The shaft extension rod is a general cut-to-size unit with lock-nuts and a brass fitting. 

Wiring up the Elma switch

I do like to tidy up the wiring after the fact with a few zip-ties, although this is not a necessary step. 

For a nice finishing touch, brass plates are engraved to fasten to the chassis.

 
The front art I created in Adobe Illustrator in EPS format so the engravers could use it. This was the design Todd and I collaborated on. The knob is knurled aluminum from Goldpoint and has a nice solid weight and feel. I added a bit of J.B. Weld to the connections on the shaft extension to ensure they wouldn't loosen up over time and annoy poor Todd.

Engraved brass plate

Goldpoint milled aluminum knob

And some final photos to see the finished product. The footers are EAR isolation feet.

Balanced Switchbox Front

Balanced Switchbox Back

The Fine Print:

The above steps detailing the creation of a switchbox are for entertainment purposes only are not intended to be instructional. 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.