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November 10, 2016

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.

October 4, 2016

Fostex T50RP mk III Modded Build - New Cups, Cable, the works!

If you've been following my posts you'll see I usually leave audio products alone once I get them ... kidding ;) I picked up a Fostex T50RP mk3 (or mk III, however you want to write it) so I could see the differences from the original T50RP I modded. Other than a different headband, removeable cable, and different handling of the felt behind the driver, there was no difference, so I suggest if you are already modding, go with the original as it's cheaper and you can set up the felt however you like. If you still want the mk3, You may consider purchasing across the pond, it seems like Fostex has a deal with U.S. retailers that they can't advertise below $159.99, but it averages around $130 in the UK... much more palatable as you're replacing everything anyway.

The headband is worlds better than the original model

The removable cable was a nice new feature on the mk III

I had some very nice wood cups CNC cut for me by my friend Fewzi (if you'd like his contact information, shoot me a message, we're hoping to offer at Zynsonix soon), the quality of the machining is excellent, perfect driver fit. CNC machining has really changed the way a lot of things are manufactured in a positive way, the amount of precision it offers is outstanding. Anyway, the wood cups rock. There is the cup itself, a second wood layer with a square hole that holds the driver in place, and a third plastic layer that holds the ear pads in place.

Driver frame and wood cup, ultimate precision

This picture below shows a wood ring and plastic ring for the earpads, Fewzi discovered that plastic was more durable for the earpads to stretch over (it's a tight fit). 

First the stock pads and foam are removed.

Then the driver frame is unscrewed (4 screws), and the driver unscrewed from the frame (3 screws). There is an extremely thin gasket that sandwiches between the driver and frame that needs to be handled gently. 

The drivers are snipped free and then I had to remember how to get the cups off. I didn't want to read my existing post because I enjoy discovering how things come apart and go back together. Fostex hides the screw behind a thin shroud of plastic, which I believe is sonically welded in place (micro-vibrations that fuse plastic together). It comes off with a razor, and once unscrewed, releases the clamp on the other side.

That's about the only unusual aspect of the assembly. Once everything is apart, the wood cup was fitted. There are little brass fittings included with the wood cup (the original plastic ones are too small) that allow the cup to pivot when screwed in, I found the sizing of the brass fitting and tightness of the screw makes a huge difference in the articulation. 

If anyone has heard a T50RP,  modified or otherwise, they know there is no lacking in the bass department. this is where mass damping plays an interesting part. Adding loaded sheets like Dynamat Xtreme can help curtail flabby bass and tighten things up. Adding foam with a texture can also assist with reducing reverberation / standing waves in the cup. 

The cups included 3.5mm mini inlets, which are great, but I personally like the mini XLR for headphones due to it's locking mechanism, and I could configure it the same as Audeze headphones, which you can read more about here. The driver is fastened on to the wood frame, which was a fantastic fit, with the gasket in place. Wiring up is a simple ordeal, but I wanted to ensure all the original solder was removed so I could replace the tin solder with Cardas Quadeutectic solder. The tabs are marked with a "+" and "-". Below you have a view of both sides being soldered in. 

Once the drivers are happy, the frame is lined up on the cup and it's important to ensure no stress is on the solder pads, so loose wiring is okay here. Then the earpad frames are sat on top and four screws replaced. The foam that was set aside in the first step is replaced in each cup. 

This could be no exciting rebuild without fancy pads. Fortunately there are a couple different types available from ZMF (run by Zack, cool bro), and MrSpeakers. ZMF has a number of pads available, including lambskin, cowhide, protein, and Omni. MrSpeakers offers the Alphapads which are lambskin. Lambskin seems to be the most popular headphone pad material for higher end headphones, for which I am glad, I hate velvet ;) ZMF also has a nice "pilot pad" to provide some extra cushion on the top of your head.

ZMF lambskin earpads and pilot pad

Now that we're all padded up, we have what appears to be a finished headphone, but wait...

...where's the cable you ask?! We won't have any sound if we don't have a cable. Where will we get a cable from?

Image result for gasp cartoon

Fortunately, we have the brand new Zynsonix Ballista cable here, featuring 28 strands of ultra pure ohno cast copper, 12 of which are clad with high purity silver in an alternating geometry, then each are electrically isolated with a clear coat, fed through low loss dielectric, resulting in an extremely well balanced sound with great detail retrieval... completely custom made for Zynsonix. 

There we go, now we're talking! 

I'm now going to reveal a special secret that will enhance your life forever make your cans sound better... you can get the Zynsonix Ballista configured for pretty much any headphone you have. It's the best cable I've made to date, I spared no expense, because you guys deserve it. Use the handy dandy contact link to share what you need. Also if you are interested in purchasing some great sounding cups, feel free to reach out as well. Fewzi is experimenting with some additional woods now, so there should be a variety of species to choose from. 

Anyway, that's all from me. Happy listening, building, etc. and don't be a stranger.

Disclaimer: The above steps detailing the building of a headphone are for entertainment purposes only and not intended to be used as directions. 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.

August 31, 2016

Building a Mini Audio Rack with Bamboo Cutting Boards

As you may have noticed, we are at the age of the computer audiophile, and standardized 19" components are no longer relegated to audio racks because they are typically sitting near a computer rig on a desk. I personally think that's awesome as I'm not a fan of wasted space, components should be the exact size they need to be to house the internals (at least that's my opinion). The fly in the ointment is that you may have a stack of mini components that might not sit on top of one another neatly or may need a little more space to dissipate heat.

Two companies that I've seen offer mini racks with specific dimensions to match their products, a mini rack from Parasound, and iFi Audio with their cool little iRack. Unfortunately these products only work with their specific component counterparts and are not universal.

iFi Audio iRack

So I decided the easiest way to attack this problem is to build a mini shelf from wood, and typically cutting boards are an appropriate size to sit components on. To keep the cost low while still being visually appealing, I selected the Totally Bamboo 12.5" x 8" Aruba cutting board, which were around $14 each if I recall correctly.

12.5" x 8" Aruba bamboo cutting board

To fasten the boards together, I purchased a 5/8" dowel from the hardware store. Home Depot or Lowes will typically have pine and possibly walnut or oak, which aren't a perfect match, but good enough after stain. I searched a bit for bamboo dowels, but not much luck online for the thickness needed.

First the bamboo boards needed sanding so they would accept stain evenly. NOTE: I do not vouch for the safety of whatever adhesive is used by Totally Bamboo to fasten this board together, so sand at your own risk. A reasonable person would assume it is safe as it is being used with food products, but who knows these days.

I measured a short distance from each corner and drilled 5/8" holes (and Dremeled a bit for clearance) just under 1/2" into each board. A pilot hole for a size #6 screw was drilled into the center of each hole. I then measured the component that would be on the bottom shelf to determine how long the dowels should be, added 1" and cut with a band saw. pilot holes were drilled in the center of each dowel for a #6 screw. The dowels were then inserted into the holes, 1" EAR isolation feet lined up on the other side, and a 1.5" wood screw drilled in for each.

The EAR Isolation feet are 95 cents a pop (at the time of this writing) and you can get them from PartsConnexion, or if you need a large quantity, reach directly out to EAR. I use them for nearly everything.

EAR 25mm isolation feet

After that, I lined up the holes on the other board to fit, put a small amount of wood glue in each hole and let stand upside down to dry so the glue doesn't run down the dowels. Once everything is dry, the stain/finish was applied. I used Minwax Polyshades for quickness and affordability (a 1/2 pint will run around $5). 

Minwax Polyshades - cheap and quick

After four coats, the mini rack had a nice deep glossy sheen and the dowels were pretty close in hue to the cutting boards.

Below you can see an MHDT Constantine tucked in neatly on the bottom shelf, and a Peachtree t1 SPDIF to USB converter, and Schiit Wyrd USB power isolator on the top shelf. Neat, tidy and isolated from vibration.

Hope you enjoyed this relatively simple build. I found it provides a good solution to a common problem for computer or DAP-based systems (or small headphone amplifiers).

Disclaimer: The above steps detailing the building of a mini audio rack are for entertainment purposes only and not intended to be used as directions. 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 note that some bamboo boards can contain dangerous chemicals, sand/cut at your own risk. 

July 3, 2016

Chord Mojo Headphone Amp and DAC Review

If you've been an audio enthusiast for very long, you've no doubt heard of Chord Electronics, a plucky U.K.-based audio company known not only for their great sounding devices, but wildly creative chassis designs. They're much more playful than the typical stoic aluminum rectangles we're all used to seeing stacked on shelves at the local A/V retailer (why did that become a trend in the first place? Boring!).

While you may have known Chord, you probably realized that their wares were a little pricey for the student or cost-conscious audiophile. In a shrewd business decision, Chord decided to make a device that was much more financially accessible, the Mojo. The Mojo is the Hugo's little brother, hitting the streets in 2015 and has been wildly successful, and is still pleasingly made in England.

The Mojo is a sweet little palm-able device that decodes a digital signal and acts as a headphone amp. It makes a nice companion for audio enthusiasts who are on the go with their Samsung or Apple phones listening on Tidal or whatever format their heart desires. For the record, I love Tidal, if you can get over that they only have about 80% of Spotify's library and understand the playlist game isn't too hot, the quality is surprisingly excellent and well worth the price of admission. 

For the inputs, there is a mini coaxial, full size optical, micro USB for charging, and micro USB for music input. Both the coaxial and USB inputs can accept PCM up to 32bit/768kHz and DSD up to DSD256. The optical can go up to PCM 24bit/192kHz, but no DSD. One important thing to note for Apple users, you will need an Apple Lightning to USB camera adapter to use this device. Chord didn't want to share their proprietary internal technology with Apple, which I don't blame them, but because of that you're stuck with the camera adapter and then a USB to USB micro cable too, a little unwieldy at times for portable duty, but a Chord module is supposed to be forthcoming which remedies this.

For the outputs, a somewhat surprising choice considering the glut of balanced headphone amps out there, the Mojo has two 3.5mm mini outputs, one for you and one for a friend. I'm a bit disappointed about this as 3.5mm mini connectors are known to lose their internal "springiness" over time and you end up with a static-y/spotty connection. A friend of mine here in Baltimore just learned this lesson the hard way with his $3K Astell and Kern. I'd hate to discover what the cost to replace those jacks are. I do understand Chord wanted to sell this to the largest audience possible, so it was a good business decision. I haven't opened the Mojo up yet, but it might be an easy drop in replacement, who knows. Most mini jacks tend to follow the same solder patterns. The output on these little 3.5mm minis is 35mW @ 600 Ohms, and a solid 720mW @ 8 Ohms. Output impedance is 0.075 Ohms.

You may be wondering the size, the unit is roughly 3 1/4" x 2 1/3" x 1". It has a nice weight, the weight of perceived quality, being what appears to be thickly milled aluminum, or as the Brits say, aluminium. I've lined up a number of portable amps here to give you an idea of size. AS you can see, it's a little smaller than an Altoids tin. 

One of the most pleasing things about the unit is the haptics, where you interact with the unit using three little translucent globes. The globes can be spun about, but will only respond when pressed down. They control the power, volume, and you can also use them in combination to adjust brightness level of the LEDs behind them, etc. If you're like myself, you will spin the globes around mindlessly while getting lost in the magical sound reproduction. 

So with all the boring stuff out of the way, how does it sound? That's really all that matters, right? 

You'll be pleased to know that the Chord sounds very impressive. I rarely recommend audio gear unless I feel that it's going to sound really good to most people, and I have no problem recommending the Chord Mojo. Listening on both the Audeze LCD-X and the Cardas A8 Ear Speakers, both with Zynsonix Ballista cables, the sound has a very appropriate level of detail. There's zero instance of fatigue, and has a nice warmth about it that allows it to get along with most headphones, even slightly forward ones. There is no sign of graininess, the presentation is full, but mildly restrained in the bass. Compared to the Cayin C6, another DAC/amp combo that's about 30% larger, the Chord outclassed it without much effort. 

Chord Mojo versus the Cayin C6 Amp and DAC

The C6 is more of a giver with the bass, but that's to be expected, it drains it's battery quite quickly. The sound however has more grain, a slight shrillness in the upper midrange not present with the Chord, a more compressed soundstage, and less syrupy smoothness that makes the Mojo so pleasant to listen to. Not to say the C6 is a stinker, it's quite good and much better sounding than the iPhone's headphone output, but there's a solid 10-15% increase in relative quality with the Mojo. 

The Chord Mojo with Cardas A8 and Zynsonix Ballista Cable

Should I buy a Chord Mojo? 

If you enjoy listening to music from your phone while travelling, spending $600 isn't going to agitate your significant other, and can get over the two cable adapters (with iPhone) and lack of balanced outputs, the Chord Mojo is a great purchase that you won't regret. I would encourage you to purchase a right angle Zynsonix headphone cable to reduce the stress on your 3.5mm jacks so they last longer, and you'll get better sound while you're at it. 

DIY Audio Blog does not have any affiliation with Chord Electronics Limited and did not receive any compensation and/or complementary review units for this review. 

May 19, 2016

Massdrop x Fostex TH-X00 Recable - Removable Mod

I was quite excited to head about Massdrop and Fostex teaming up to offer the TH-X00, a headphone created by the same OEM company that produced headphones for Denon (the legendary D2000, D5000 and D7000). I still to this day feel that the D2000 was the best headphone in this price range, and the D7000 is still an amazing sounding headphone compared to the latest and greatest. With this Massdrop Fostex team up, audio enthusiasts would be able to get very solid drivers that are similar to the Denons with luxurious wood cups at a very attractive price point.

An interesting phenomenon with the Denon headphones was that they were extremely receptive to a new cable (despite the stock cable being fairly decent construction). In fact the sound changed more than any other headphone I've heard, aside from the HD600, which was close (try a solid silver in teflon cable and a Cardas copper cable side by side with that one). The TH-X00s seem to follow that trend from my brief impressions (had to get them back to a client quickly).

I found the Zynsonix Xev had nice synergy with the D2000, opening up the highs and adding coherence, so that's what was used with the TH-X00s. The Xev is a silver clad copper design which has a detailed signature. It's hand braided, which you can see below, from a four wire litz braid to two twisted pairs, then sleeved with a soft black non-microphonic sleeving.

Hand braided Xev cabling

This particular headphone would have a removable/replaceable cable cable option, so whenever there is an option, I prefer to use 4 pin mini XLRs. They have a great connection, lock in place, and are used for many Audeze headphones. Since few headphone manufactures use the same connectors, we can try and standardize to some degree, so this design would not only be able to use Audeze cables, but the cable could also be used with Audeze headphones. For that to happen, the pins need to be shorted on both sides (male and female), note the small piece of bus wire connecting two pins below. You can learn more about this in a previous post.

Shorted pins for Audeze compatibility

You guys have seen me build enough cables, so we're not going to cover that, but how the wire is attached internally in the Fostex TH-X00 headphones. The pads have four plastic connectors that fasten to the cups, twisting them to the left allows them to be removed quickly and easily.

Fostex TH-X00 with removed earpad

Four screws need to be removed to remove the wood cup from the frame, then another four screws are removed to separate the driver and wood cup. 

Removing the cup from the frame

The existing cables feed in through the frame, go about an 1/8th of a turn up the cup, then enter the driver chamber. At that entrance point the cable is tied in a knot and there is a bit of epoxy/rubber cement that holds the old cable in place as a strain relief system. It's important to recreate this with the new cable to prevent damage to the soldering tabs on the driver from an inopportune yank. I personally use a special adhesive gun that creates a plastic-like joint holding the cable firmly in place. The wire is soldered to the top two pins, the red marked one being positive, the other negative. These joints should be quickly formed to avoid harming the driver and/or the thin wires leading to the diaphragm. 

Interior driver view with strain relief

While everything is taken apart, it's a good opportunity to add a bit of mass damping to the inside of the wood cup. Dynamat Xtreme, or other automotive based damping materials work here. This helps tighten up the bass. Tweaking the amount can be to preference. Since the cup is nice solid wood, only a moderate amount is necessary. Were it flimsy plastic, it would likely need a lot more. 

Dynamat Xtreme mass damping

The headphones are reassembled the same way they were taken apart. The "pigtails", or little dangling mini XLRs may look like they'd get in the way, but with the headphones on your head they are very hard to notice. Flexible joints assist with that. Removable cables are great for people who like to experiment with different cable types, lengths (portable vs. home), use one cable for multiple headphones... or who have teething pups or curious felines. The Xev is actually pretty strong against cats :)

The finished / modded Massdrop x Fostex TH-X00

If you've taken the plunge on a sweet set of Massdrop x Fostex TH-X00s and are itching for a recable, please check out Zynsonix Audio

The Fine Print:
The above steps detailing the modification and re-cabling of a headphone 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.