FrankenTex: A DIY Monster!

A big thanks to Klutz Designs for the Can Cans headphone stand to display this beauty.

It's not often a pair of DIY cans comes walking in the door with its own monster branding. Not only has enthusiast 4nradio breathed life into this odd assortment of bits from previously dead or discontinued headphones, but unlike the good doctor of yore, he has fallen in love with the monster he brought to life, and given it character and personality.

Let's meet the monster.

FrankenTex by 4nradio
As with other DIY cans in for test, we'll start with the words of the builder, then I'll make a couple of listening notes and show the measurements.

4nradio's Notes - FrankenTex: it’s a JVC & Fostex headphones mashup! My DIY orthodynamic headphones is made from a JVC HA-RX900 chassis, and drivers from the popular Fostex T50rp, with JMoney aftermarket ear pads designed to fit the Denon AH-D2000. I converted the earcups to open style using a 2-1/2” drill bit and covered the opening from the inside with perforated grill material from a $2.99 bookshelf speaker (Goodwill store find).

The baffles on the JVC headphones are designed to angle the stock drivers, so I took advantage of the angle when attaching the T50rp drivers. A small piece of 1-1/2” diameter PVC tubing provides the needed clearance between the baffle and the driver. The JMoney pads provide even more driver-to-ear angling. Combined with the effect from the open earcups I feel the result is better sound staging and imaging compared to the stock Fostex T50rp.

The drivers are matched to within 0.2 ohms a low value resistor in one earcup (originally the drivers were 2.1 ohms apart). The thin cloth on the front of the T50rp drivers is removed, and the cloth at the rear is replaced with a layer of 3M Micropore tape (dyed black so it looks nicer when seen through the earcup grill). The center “cell” in the grid structure at the back of the drivers is bare so I can try various tuning ideas (currently the cell is filled with a small block of blue Scotchbrite pad).

I’ve gone through many variations of damping; currently the headphones use DynaMat Extreme on the back of the baffles, dimpled extensively with the point of a Philips screwdriver to make the surface less sound reflective. The inner sides of the earcups are lined with strips of DynaMat Extreme, covered by strips of mineral oil filled sound-absorbing vinyl (from Parts Express). Finally, my “FrankenTex” orthos have a DIY cable made from Cardas 4 x 24AWG star quad golden-ratio cable.

The best headphones I’ve owned previously have been Markl-modded Denon AH-D2000s and Sennheiser HD-595s, so my experience is limited. However, I think these DIY orthos go well beyond the audio quality I’ve heard in the Denons and Senns. They have the impactful bass and luscious midrange that T50rp based headphones can produce, along with very good sound staging that open headphones are known for.

When these orthos were still a closed cup style I found far more treble roll-off than I desired, but the conversion to open back cups did wonders for treble at the same time the imaging and sound stage was improved. I was pleased the strong bass was not affected. I’m enjoying all musical genres with FrankenTex, but I think they sound their best on blues, rock, world music, and vocals.

Tyll's Notes - FrankenTex is not nearly as hidious as it's namesake. This is a really well executed DIY project, and from the outside it would be very difficult to distinguish these cans from a pair of well built commercial headphones.

I did enjoy the sound of these headphones, though they were fairly colored. As measurements indicate, these cans have a sort of split frequency response: a fairly flat response below 600Hz, though not particularly well extended in the bass; and a region above 1kHz that's fairly well behaved. I heard the cans as having somewhat relaxed and nicely portreyed highs, a warm cozy bass, and a somewhat overly strong low-midrange/upper-bass. I tend to like a warmly tilted headphone, and I think the knee in the FR curve at 500Hz sounded like a broad peak to me.

Regardless, I did enjoy my time with these headphones, and found them to have a big, warm, and soulful character ... not unlike the fabled monster with his tender heart.

Click on graphs image to download .pdf for closer inspection.

4nradio's picture

I really appreciate your time and talent to measure & comment on "FrankenTex", my first-ever DIY headphones attempt. As I scrutinize the graphs and re-read your comments I see there's a wealth of information which I can put to good use in future efforts.

Already I'm realizing that what I thought was good bass response is really upper-bass. I'll bet the bass dropped off significantly when I drilled the cups and converted them to open style. I'm going to try removing all of the micropore tape again to see if I find any improvement.