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New Project Idea: Combine a Ultrasone PRO 900 with grado sr-125i drivers

post #1 of 9
Thread Starter 

Hey guys, starting up a new build and i thought i would post it here

I have a pair of Ultrasone PRO 900 headphones with a busted right driver (definitely the driver being blown and not any wiring issues) I received them this way for a decent price, so i cant complain.

Originally i planned to source a new driver, but i ended up being a big issue and more trouble than i wanted to deal with. ( no warranty )

so what i have planned is to get a pair of drivers out of Grado sr-125i headphones, and transplant them.

just bought these: http://www.ebay.com/itm/Grado-Prestige-SR125i-Headband-Headphones-Black-/161005791440

i know some of you are going to flame me for this: for disassembling a new pair of grados/ saying i won't get grado sound/ soundstage might not be correct/ putting open headphones drivers into a closed headphone etc.

please don't flame. Im simply trying to have some fun and see what comes of it. not looking to replicate grado sound or pro 900 cound. I also i had to pass up using sr225i grados because i think some of you would be very upset if a ruined a pair of those haha

So im planning on using the hairdryer method tonight to remove the cups from the drivers on the grados very carefully. after this is done, I will have sr125i cups, gimbal, headband, softie pads, and 1/8 cord brand new left over if someone is interested, shoot me an offer. it will come all brand new still in the box. tried the phones for about 20 seconds today just to see if they produced sound, so everything is brand new. basically your getting everything but the drivers and the inner plastic mount that they are mounted to (not sure of its name) Maybe you have some sr60 drivers that need a new home?

also im not sure if anyone is interested in a pro 900 titanium driver. (left one still function perfectly)  maybe i can help someone out here, since they are about $75 and very hard to source. The only issue is it is glued as well as screwed to the driver mount (metal internal plate that i will be re-using) so the base of the plastic driver border may be affecting when i remove it. I am not looking for any money for this. maybe give me ten bucks to ship it out or something. Hopefully i can help someone out here.

idk what will come of this project, and how the tonal qualities of each headphone will come into play. just hoping to have some fun. Probably gonna rewire it with some silver cabling as well, since the the pro900 wiring is about as tiny and pathetic as you could have. still keeping the cables from the heaphone to the neutrik plugs tho, im assuming this is just copper.


post #2 of 9

How did it end up turning out?

post #3 of 9
Thread Starter 

i actually just finished all the soldering yesterday. i ended up switching the thin mylar wire (who puts this in a high end headphone??) for some nice silver wire, and used silver solder throughout. never used silver solder before, but it is a pain in the *****. i guess the melting point must be higher than regular lead solder, but that makes it way harder to work with since the melting process is significantly longer. managed to feed all of the wire through the same passages internally as the original thin mylar wire, with basically no modification. it was a long process, and was extremely frustrating though. if i had to do it again, i would probably wire two female 3.5mm jacks instead and use a custom cable. right now i wired it to use the original stereo port on the left earcup. im using one lead per ground and signal for each driver. if you want to run 4 wires to each side, you could not fit the cabling internally (no chance).

to remove the grado drivers, i used what many refer to as the hairdryer method, which loosens the two piece earcup glue with very little heat needed. then i marked the G and signal wires using a multimeter from the 1/4" jack. then i cut off the 4 wires from each driver. next step is so use a file to create a groove from the outside of the plastic driver housing. then i peeled away this thick plastic cylinder. finally i used a pocket knife to peel away the last inner plastic protective outer casing on the driver. this step removed the plastic grill and the cheesecloth on top of the driver. i gave it a little blow of air to remove and plastic dust from the filing process, and we were good to go.

original ultrasone drivers were removed by unscrewing the driver screws (3 from the underside of each metal driver mount plate) and then slicing the glue with a razor blade. then i positioned the new grado drivers (same mm diameter) in the EXACT original position which i market out wit a paint pen. used rubber cement to glue in place. i would avoid super glues, as they have a tendency to melt plastic, and driver diaphram was a few millimeters away. soldered everything up after i dissassembled and ran the wires internally. used silver wires and silver solder throughout. then i screwed everything back together and put on the earpads. screwed the cable in and we were ready to rock. range sounded clear and crisp. no short and no cold joints i guess. lucked out lol.

ive only listed to them for a few hours so far, and the grado drivers are unused and not burned in, but these are my impressions so far:

-  first off absolutely no tinny sound, which is what i worried about when putting a normally open driver in a closed ear cup.
- extreme high range is a little less stand out from the original titanium ultrasone drivers (less shrill to my ears, so i wouldn't say this is a bad thing. much more pleasing to the ears at high volumes than the original drivers).
- mid range is very forward, and has some real depth to to. vocals are clear and crisp. listened to some matisyahu and lossless john mayer, and it was very soothing and sounded as if he was standing 8-9 feet in front of me, if i closed my eyes.
-  the s-logic sounds just as good with the new drivers, since i positioned them in the original spot, taking my time to get it exactly the same.
- low end bass is nice, and sounds very full but not at all overpowering, which at times i felt like the pro 900s were. however if your a big hip hop, and or bassy house music type of person, you may prefer the original drivers.
- all of this testing was done with the ra-1 (AC version) grado amp, which im pretty sure is just a mid quality CMOY with some glue and a wooden enclosure. honestly, unamped, and direct from my mac pro desktop they do sound great good, but amped is a clear improvement in the mid and low ranges.
- not overly sibilant like i felt the pro 900s could be sometimes. the amp definitely improved this a little as well.

any questions let me know.


Edited by rnitch - 5/25/13 at 11:57pm
post #4 of 9

Im quite impressed that you were able to keep the Grado's from sounding tinny inside a closed headphone. When I put my hands near the cups of mine they already sound funny! Good work!

post #5 of 9
Thread Starter 

as far as the tinny side of things goes i think this is whats happening:

as everyone knows, when you put your hands over almost every grado cup, they sound very tinny and not full. it also tends to ruin the soundstage IMO. i think this is occuring because there is a very small volume of space in a sealed area behind the driver. it is constantly moving and creating a pressurized and vacuum environment behind the driver.
now with this mod, the area inside of the cup behind the driver is greatly increased over that of a grado cup. so if there was a pressurized or vacuum effect it would be lessened. not only that, but also the air has a passageway to move through the ports in the pro 900 cup, and displace itself from behind the driver to back in front of the driver, as the driver diaphram moves back and forth. so the air is not pressurized or "vacuumed", rather it is merely shifting location from in back of the driver to in front of the driver etc.

(im not acoustic audio expert so this is just a best guess)

post #6 of 9

Hello, omg do you still have that driver i'm really interested!!! i think my right driver is broken, i thought it was maybe the wire going from the left cup to the right cup trhough the headband but that's wrong as i got it rewired with dual entry mod by BTG-audio and i still have the same issue: sometimes it's perfect, sometimes i have no sound coming from the right earcup, sometimes it's lower volume, sometimes bad quality. please tell me you still have the driver!


edit: if you don't have it anymore, please tell me where i can buy it online (i'm from europe)

Edited by Sinik - 3/27/14 at 9:11am
post #7 of 9

Your driver is (most likely) fine. 

Your cable is (most likely) damaged. 

post #8 of 9
Thread Starter 

yeah man i still have it in a drawer somewhere. ill look for it this weekend. such a pain in the ass to find these things. only way i could get one was with a purchase receipt which i did not have. and ive heard you can find them online sometimes but prices r usually too high. Honestly tho, im not using it, and if it can get put to good use, i hope it helps. its free to you if you pay for shipping. im assuming shipping to europe will probably be under 20 dollars for something so small.


Edited by rnitch - 3/27/14 at 10:24am
post #9 of 9
Originally Posted by nikongod View Post

Your driver is (most likely) fine. 

Your cable is (most likely) damaged. 

ehmm are you sure? i mean did you read what i said? :D i had this issue, then i got it recabled (8 stranded silver plated copper) by brian (btg-audio.com) with a dual entry mod, and i still have the exact same problem, i doubt it can be the wire, as normally, it's the cable that is going through the headband that is powering the driver, while now it has it's own entry in the earcup... so i don't think it's possible that the cable is damaged.


edit: now the right side doesnt even work anymore...


@rnitch that's so great, yeah well ofcourse i'll pay for shipping, jsut tell me how much exactly and i'll send you through paypal! just private message me here with the price and your paypal adress :) i'm from belgium btw

Edited by Sinik - 3/27/14 at 3:19pm
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