Cable and Mods for Sennheiser Massdrop HD6XX

Back in 2004 I purchased my first serious pair of headphones, a pair of Sennheiser HD600s. This was an introduction to a number of new concepts for me: headphones that are open, benefit from an amp, are sensitive to different cables, and are intended to be listened to at home (where you could be listening to speakers, sacrilege in some circles! haha).

In these formative days of headphone audiophilea I recall being at a meet in College Park, MD where there were a number of HD600s and HD650s. We were auditioning cables by Cardas, Stefan AudioArt and other DIY concoctions including pure silver cables. It was amazing what a difference the cable could make to the signature.

I'd long since sold my HD600s and HD650s and moved on to other headphones like Audeze, when I saw Massdrop and Sennheiser teamed up to released the HD6XX. The HD6XX is quite literally a more affordably produced HD650 (based on Inner Fidelity's measurements). I figured for $200 it would be fun to have a listen to the Sennheiser house sound once again, and see how good it could sound with a balanced amp and some tweaks.

If you're not familiar with Massdrop, it's an interesting business model where the company has a number of people commit to buy a product at a discounted price. Generally there are a certain number of buyers required to make the "drop" happen, and once it does, it can take months before you have a product in your hand. The upside is you can get some incredibly good deals so long as you're patient. Massdrop also teams up with manufactures to produce one-off products at a sizable discount, such as the Focal Elex, AKG M220 Pro, HiFiMan HE-4XX and other headphones which are a little different from what's on store shelves. The Sennheiser HD6XX is such an animal.

Looking at the HD6XX versus the HD650, you'll note the HD6XX has a dark blue headband versus silver and the screen printed "Sennheiser" on the top of the band is more subtle. I personally think the HD650 color scheme is a little easier on the eyes, but given this relatively superficial difference shaves $150+ off of the street price of the HD650s and still sounds identical, the choice is a veritable no-brainer.

The stock HD6XX

Given you're saving big bucks on the HD6XX, those dollars should go toward making them even better, right? I'll be going over a few tweaks you can do for improvements in sound, comfort, and looks.

One thing I couldn't be happier about is the trend toward calfskin earpads in the past decade. Exposed foam and velour don't feel all that great against my skin. The Sennheiser HD580, 5XX, 600, 650 and 6XX all feature velour pads, but fortunately there are companies producing replacement pads. I've found the Dekoni fenestrated pads are quite comfortable while allowing breath-ability. The pads snap in place on the frame and are quick and easy to install and uninstall.

Even with the new pads, the HD6XXs look a little dull, easily glanced over when looking at newer headphone designs with chrome and carbon fiber. I decided to reach out to Larry at Headphile to see about getting some custom wood cups. 

Talking about Headphile with some of the old-heads at HeadFi will elicit smiles and good memories. Larry's been at it for quite some time, and for a little while there, the "Darth Beyers", which were Beyerdynamic DT770 headphones modified with wood cups, were one of the most popular cans on HeadFi. Every now and then you'll see a pair pop up for sale, and if you like bass, I'd recommend you give 'em a shot. In addition, if you have the scratch, Larry is still building them with a number of wood choices... although I don't know if he's still building the deep versions (which I most favored). 

I chose Padauk (pronounced Pah-duke) wood as it's reasonably priced and has a nice reddish hue, which will pop on the dark HD6XX. Larry offers the cups open with screens or closed. The open versions sound pretty much identical to the stock screens with perhaps a tiny bit more reverb, and the closed versions have notably more reverberations (or a chamber-like effect) depending on what sort of damping is applied inside. 

The installation process is quick and painless. The screens are pressure fit on the frame, and using a spoon or similar utensil (I used an avocado knife) you can slowly pull the screen away from the frame and remove it. 

The screens can be removed easily with a spoon (or avocado knife)

The difference in color and presentation is night and day from the new wood cups and the existing stock screens. 

Headphile wood cups versus stock screens

Installation is completed on each side using a set of 4 brass wood screws. 

You will need to adjust the tension of each screw to ensure it has adequately threaded into the wood, but is not impeding on the cavity for the cable plug insert, otherwise the cable will either not insert at all or will be super tight.  

The HD650 (and HD6XX) is a warm-sounding headphone, no doubt about it. It can be a little too warm and rolled-off in the highs for some. This is where a cable comes into play. I opted to build a Zynsonix Xev cable for the HD6XX. While the most affordable in the line, it features silver-clad conductors, low-strand count and a PTFE (Teflon) dielectric, giving it a forward and detailed sound signature. It's exactly what the HD6XX needs, pushing forward the treble, resolving the bass, and giving the headphones a far more dynamic presentation. 

I wasn't sure if I would keep the HD6XX, it was more of an entertaining experiment, however with these mods the enhanced comfort and sound really make it a winner and a definite keeper. Headphone enthusiasts these days are quite lucky, as it would be very hard to reach this level of sonic performance at this price years ago. 

If you'd like a Xev cable made to your specifications (whatever length, sleeving, and termination you'd like), please reach out to Zynsonix today and take your Sennheisers to the next level. 

Zynsonix Audio, LLC does not have any relationship or financial interest in the companies mentioned in this post, including Headphile, Massdrop, Sennheiser, Inner Fidelity, Dekoni, etc. 

Four Pairs of Headphones for Any Studio Setup

This guest post is brought to you by my friends at Headphone Ninja. Anyone following the blog knows I love headphones, and Jo-Ann and company have culminated four tried-and true classics to discuss.

Studio headphones fill the market today. However, many of them are either far too expensive or far too inaccurate when it comes to meeting the referencing demands of producers and audio engineers. While everyone would love to own a pair of the sleek Sennheiser HD800s or the beautiful Japanese cherry birch wood Fostex TH 900s, we don’t all have a Hans Zimmer’s budget.

In this post we explore four of the more preferred headphones available in 2017 that are well suited to the modern day studio.


Closed-back headphones

Audio-Technica ATH-M50X

Comfort is key when it comes to long studio sessions. The generously padded earcups and adjustable headband of the ATH-MX50 provides comfort, and while the headphones do clamp down reasonably hard, they do not physically strangle the life out of your temples. They are slightly heavy at 10-ounces, but this should not be a deciding factor for those looking to use these in a studio environment.

The ATH-M50X is fitted with large 45mm proprietary drivers that deliver exceptional clarity. Some individuals who have used these thought that the bass is slightly high, but the mid frequencies are fairly well represented. The higher frequencies also appear to be slightly bright, but not to the point of fatiguing the ear. The 90-degree swivelling earcup is great for single ear monitoring and the frequency response ranges from 15 - 20,000Hz.




Sony MDR7506

Introduced back in 1991, the Sony MD7506 has remained a firm favorite amongst many looking for high quality and reliable headphones. Their durability is as decent as a pair of plastic headphones can get, with the only real issue of deterioration being the earpads on the cups, but these are replaceable. At around 8-ounces, they are light enough to not burden the wearer much.

The MDR7506’s frequency response ranges from 10 - 20,000Hz. It has revealed a solid bass response in tests, albeit slightly bumped up in the 60 -100Hz range. Mids remain fairly flat while the low treble to the high treble frequencies are quite inconsistent; the sibilance range is slightly boosted and can be slightly piercing to the more sensitive ears. The soundstage is decent for a closed-back pair of cans. They have an 63-ohm rated impedance and their low leakage is also suitable for recording purposes.

The coiled 9.8-inch cord is more than enough for studio environments and it does come with a ¼ inch adaptor. The Sony MDR7506 gives many mid-range referencing cans a run for their money.




Open-back headphones

Sennheiser HD 650

The Sennheiser HD 650 are slightly pricier, but it seems important to add these cans for those who enjoy the spacier sounds that open-back circumaural headphones offer. The suede-like fabric is a nice touch on the large, encompassing cups that house the efficient neodymium magnets.

The slightly under-emphasized low bass frequencies with the minor boost on the high bass gives the headphones a more natural sounding low end. The mid range responses are pretty much flat throughout and the treble frequencies are consistent. Their impressive frequency response coupled with the spacious sound created by the deep drivers and open-back design makes these excellent for critical listening.

Needless to say, their isolation is pretty much non-existent, making these more suited to quieter environments. They are also less suitable for recording purposes, because they do leak quite a bit of additional noise, which in turn will bleed into your microphone. 

The Sennheiser HD 650 is an excellent referencing headphone and offer an awesome frequency response, though they are less suitable for recording purposes however.

Editors Note: The 650s can sound a little dull in the treble with the stock cable in some setups. A replacement featuring silver-clad copper can bring out the highs. Check with Zynsonix for additional details.


AKG K712 PRO


The AKG K712 PRO are another great choice for mixing and mastering purposes. The design is slightly bulky, but they are purposefully built for studios, so that is completely understandable. The memory foam earcups captures the shape of your head, but they are rather large. Sound wise, they deliver a spacious and accurate audio reproduction, but the sound is a bit warmer in the upper bass. Still, it is well controlled overall. The mids are represented accurately.

Sensitive ears may find the slightly boosted (and somewhat inconsistent) higher frequencies a tad overwhelming, as they can sound harsh. The frequency response ranges from 10 - 39,800Hz in its entirety and it has a low harmonic distortion.

As a whole, the AKG K712 PRO have a natural sound and are well suited to intensive referencing sessions. The open-back design means they are more suited for mixing and mastering in studios.

Wrap up

This is by no means a comprehensive guide to selecting studio headphones, but a look at some of the more popular headphones around at the moment for any type of studio. While they may mostly be mid-range headphones, they perform well within their specific categories and are well suited for studio use.