So, now that I find myself up at 5am again, heres the process I settled on for modding the Goldring DR-100 to what has now been named the Orthodome, in line with the established Phonodome nomenclature. My aim was to use the resulting headphone with my iPod, no portable amp. So eking some strong low-end out of the drivers was more important than more pure audiophile concerns. I don't have pictures of the entire process because I only pilfered a camera off my housemate after I'd already done a lot of it. So you'll have to use your imaginations for the first half.
Disassemble them by unscrewing the driver panel, you have to remove the earpads and the earcup foams to do this. The earcup foams are held in place by double sided tape at the top and bottom and will tear easily if you are not careful. The driver is glued into place but the recess is also friction tight so its not possible to remove them by carving out the glue. You have to carefully pry them out (I used a large penknife blade). A fair bit of force is needed to get them to come out enough that they can then be more carefully taken out once they "pop".
Next you need to remove the mesh fabric like material that damps most of the earpad side of the driver mount. This stuff is a apin in the ass because its quite tough, most can be removed with a little knife and some tugging but the rest has to be scraped away.
The dartboard of rings and struts that sit in front of the dynamic driver also has to go. You can remove most of it by just snapping it out, or using a little saw would work too I guess. The resulting hole though is about 1mm too small for the SFI driver to sit inside, so using a small knife blade, I kept scraping away at the edges of the hole until it was just large enough for it to hold one of the drivers tightly after it was pushed in. Push the driver in from the earpad side so that the terminals can be bent (gently) backwards so they face into the housing.
Thusly:
We then need to seal the inside of the earcup, electrical tape does a great jorb
of this, although if you wanted you could fill those holes with epoxy if you wanted to. I've angled the drivers in my set, try angled and regular before you glue to see which you prefer.
Thusly:
Then fix the driver in place. I've used Araldite, good tough strong glue that sets nice and quickly.
Earcup damping is a disc of felt, just held gently in place by the earcup mesh.
You'll also want to reverse the earpads. This makes them thinner (brings the driver closer to the ear) and puts the plastic side against the face, this makes for a better seal than the fabric side.
So you end up with:
To remove the back grille on the headphone involves removing the spots of glue which help to affix the clips to their locks on the inside of the earcup. Once this is done the grille can be quite easily removed and put back on again even with the driver panel screwed back into place.
On the inside, another disc of felt on the back of the driver:
And then very expensive, bog roll. I was going to use cotton wool, but this does the job. 4 sheets, evenly scrunched.
Put the outer cloth on top.
And replace the grille.
I've only got a short cable on it (because it only has to reach to my jacket pocket. And this crappy telephone wire was all I had. I bored a hole in the blanking plate of the right earcup (Goldring seems to stamp all of their bits out of the same machine for both sides) and removed the mini-jack socket PCB from the left earcup for duel side entry. The cord is glued into place inside for strain relief (as you can see in the photos). You could use the existing internal wiring and continue to use the minijack socket if you wanted though.
That's about it. Not difficult although it takes a wee bit of time and a steady hand. Can't A/B to the stock DR100 of course. The DR50 has pleather earpads as standard so you wouldn't have to reverse the pads on it. The DR100 is on offer at the minute though.
-Edit-
Also (from later in the thread):
Originally Posted by Duggeh
Finally changed the cable on the Orthodome today to a "not-a-piece-of-telephone-wire-with-an-adapter". A little time consuming and I did at at 6am after a night drinking grouse and ginger yet managed to to burn myself or ruin anything.
The cable came off a set of fake PX100, and can now add to my list of differences in the real and fake PX100 an assurance that the drivers are different and not just parts of the housing and headband. But I digress form the isodynamic path...
While I was in about them I changed the damping a little, to a greater thickness of felt and some foam discs (earpads form aeroplane clip on headphones) between the felt and the loo roll that I use as housing padding. Sound has loss a little airiness at the gain of a great deal of physical tactile presence and a filling in of a midrange frequency gap just above the bass level. I would attribute the gains to the changes in damping and not he cable.
Enjoying some Mike Oldfield right now. Jolly D.
I really do like this headphone A LOT.