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JVC HA-RX900 modifications, a picture tutorial. (56k, forget about it...)

post #1 of 205
Thread Starter 
Okay, I just finished doing the permanent mods on my RX900s (well, to be honest, I just finished enjoying listening to a bunch of music after finishing the mods!), and I'd like to put together a little bit of a picture guide for anyone who's interested in doing the same.

Materials:
-1/2 sheet of Dynamat
-Small amount of acoustic stuffing (like the kind found at craft stores, used to stuff dolls)

Tools:
-Knife/scissors
-Small Phillips screwdriver


Okay, here we go...


Step 1: Remove earpads

This may seem a bit tricky to anyone who's already tried it, but if you're careful, you can get them off just fine. First, tug slightly at the material (I would recommend starting at the smaller end of the taper [i.e. the opposite of what I've demonstrated in the picture], at the front of the phones), until you can see the edge of the fabric, like so:



Next, continue gently tugging at the material, until you have managed to get the whole pad off:




Step 2: Remove felt driver cover

When you get the pads off, the first thing you'll notice is the "acoustic lens", which is basically a piece of plastic with holes which covers the driver:



There are two screws on the top and bottom of the acoustic lens. Use a small Phillips screwdriver to remove these. When the acoustic lens has been removed, you can see the black felt cover that covers the driver holes, causing the recess in the midrange and treble that people have noticed with these headphones. Here begins the tricky part: with your fingernail, gently scratch at the edge of the felt until it starts to come off. Do not try to scratch the entire felt off, only the bulk of it (it will separate from the bottom layer fairly easily):



Toss the felt ring that comes off:



You will be left with a thin layer of felt which is glued onto the driver housing. In theory, you could try to cut out the rest of the felt, to get that extra nth level of detail (you can see that I already tried to do this with one hole before rethinking that move), but I would recommend leaving it on to help protect the driver from hair and dust:



Screw the acoustic lens back on.


Step 3: Dynamat the cup

There are three screws that hold together the two halves of the cup, and they can only be reached with a small Phillips screwdriver. Once the halves are separated, be very careful when you pull them apart! The signal wire is extremely thin, and will break easily:



You can see from the next picture that one of the main issues that I've tried to address with these mods is the problem with resonance of the large cup made of thin plastic:



This is where you will first use the Dynamat. Cut out two circles with a 2 1/2" diameter (one for each cup):



Pull off the backing of the Dynamat to reveal the sticky face, and place this circle in the inside of the cup, pressing firmly all around to make sure all of the air is out (this is especially important with Dynamat Extreme):




Step 4 (optional): Dynamat the ring of the cup

Given that the Dynamat will add weight to the headphones, this next step could be optional, or partially completed. Cut out small strips of Dynamat that are 1/2" wide, and place them around the side of the cup:




Step 5: Dynamat the back of the driver magnet

I had some extra pieces of Dynamat Extreme lying around, so I decided to use it for this next step. The size of the back of the driver magnet is a little larger than a penny:



Cut out a small circle of Dynamat of this size, making sure to cut a small notch on one side, which will allow for the hole in the back of the magnet to remain uncovered:



Place it on the back of the magnet, pressing firmly over the entire surface:




Step 6 (optional): Dynamat the back of the driver-side cup

Again, due to weight, this step can be omitted or partially completed. The basic idea is to damp more of the resonant thin plastic, in order to further clear up the midrange. Cut small strips of Dynamat, and place them where you wish:



Make sure to leave two areas uncovered, however. The first section is the part with the three holes that are covered with felt. These allow for air flow, and free movement of the driver, and I'm fairly certain that covering them would have detrimental effects to the sound. The second section is the part of the outer ring of the cup that lines up with the notch at the top. If this is covered, the two halves will not fit correctly when you try to put the cup back together (I learned this the hard way, as you can see by comparing the last pic with this next one):




Step 7: Acoustic stuffing

Add a thin layer of acoustic stuffing into the cup before you put the two halves back together. As markl noted in his D5000 mod post (where I originally got the idea for these mods... thanks, markl!), it is important to only put a thin layer of stuffing in the cup, since putting too much in will kill the bass response. You can tune this to your personal preference:




Step 8: Put the headphones back together

All you have left to do at this point is put the two halves of the cup back together, being careful not to tug on the thin wire. As far as putting the pads back on is concerned, I would recommend doing this very carefully, as it will be easier to rip the pads while putting them on than while taking them off. Once all of the material is back in the groove, twist the pad back and forth a few times to let the material slip into place.


That's it! Now kick back and enjoy the new sound, and be amazed at what $60 phones, a few bucks in material, and about a 30-40 minutes of your time can sound like!

As far as the sound goes, I'm fully convinced that no headphone can be found that can compete with these modded RX900s anywhere near their price. To be honest, in many ways, I prefer them over both my Alessandro MS-1s and my Beyerdynamic DT-880s... which obviously says a lot. They give a naturalness to acoustic guitar and acoustic bass that the other two simply can't touch. Also, the bass impact, even at very low volume, is fantastic. I've never heard bass punch come through at low level listening like this before. If you've tried these headphones, and were disappointed with their overwhelming, uncontrolled bass and recessed midrange, I'm sure that you will be pleasantly surprised at how drastically these simple modifications can change the stock sound!

Note on Dynamat: not knowing the difference between Dynamat Original and Dynamat Extreme, I ordered the Original for this project in order to save money. I find now that the advantage of the Original is that it has a rubber face, which will do a better job at absorbing sound, and not reflecting it back to the driver/ear (Extreme has a foil face). The disadvantage, however, is that it seems to be heavier than the Extreme.

Note on weight: the first thing you will notice when you put your modified RX900s on is the added weight. This is why I've left some of the steps as optional. I believe that performing them in the way that I have will help the overall sound, but I'm not convinced that it's the best thing to do. They are fairly heavy, and may make your neck sore after extended use. My plan is to give them a few days, and if I find that they are, indeed, too heavy, I will open them back up and remove every other strip from Steps 4 and 6.
post #2 of 205
So we need to buy Fiberloft and Dynamat Original? What size/area/amount of these would you say to purchase?

Also, would you use only Dynamat Extreme for the magnet mod or is the Original ok?
post #3 of 205
Thread Starter 
Quote:
Originally Posted by Alai View Post
So we need to buy Fiberloft and Dynamat Original? What size/area/amount of these would you say to purchase?

Also, would you use only Dynamat Extreme for the magnet mod or is the Original ok?
You're only going to need a little bit, so you can get by with the smallest they offer, which is a pack of 2 door sheets (which will still be way too much!). You can get it on Amazon. Extreme for $16, Original for $9.50. Order some more stuff to get your total above $25, and your shipping is free.

I'd imagine that the Original would be fine for the magnet. And as far as the back of the cup is concerned, I'm really not sure which would be best. It seems that you would want the frequencies to be absorbed as much as possible to recreate spacial cues accurately (which these headphones do extremely well). If that's true, the Original would be better. If you want the frequencies to be reflected, the Extreme would be better. I'm just not certain about the theory behind this (I'd imagine that absorption would be better, though, if I had to guess).


Edit: not "door sheets", but "speaker kits"
post #4 of 205
Thread Starter 
Quick update: these phones are way too heavy to be worn for an extended period of time, so I opened them back up, and removed all of the extra pieces of Dynamat, except for those in the inner ring (closest to the driver) in Step 6.

The phones are much lighter now, and I can't tell any difference in the sound. I would now recommend only putting Dynamat on the magnet, inside cup surface (Step 3), and inner ring of Step 6 (could still be optional, though, I'd imagine).
post #5 of 205
Next step.. you should get them woodied, with an optional grill (like those darths). I hope to be brave enough to do this someday, thanks for the review.
post #6 of 205
Thread Starter 
Quote:
Originally Posted by goober-george View Post
Next step.. you should get them woodied, with an optional grill (like those darths). I hope to be brave enough to do this someday, thanks for the review.
Nah. That would take the fun out of knowing how little I paid for this great sound!
post #7 of 205
Hi Toppop,

Really good instructions and very easy to follow, thanks very much.

My question, will I improve the sound quality by much if just go as far as step 2? Does removing that felt ring you threw out open up the headphones at all? Or do you have to go the whole way and put on the dynamat?
post #8 of 205
Quote:
Originally Posted by melmac View Post
Hi Toppop,

Really good instructions and very easy to follow, thanks very much.

My question, will I improve the sound quality by much if just go as far as step 2? Does removing that felt ring you threw out open up the headphones at all? Or do you have to go the whole way and put on the dynamat?
Removing the felt ring will improve the mids and highs. Try adding a small piece of foam. Sounds are improved and more balanced/
post #9 of 205
Thread Starter 
Quote:
Originally Posted by melmac View Post
Hi Toppop,

Really good instructions and very easy to follow, thanks very much.

My question, will I improve the sound quality by much if just go as far as step 2? Does removing that felt ring you threw out open up the headphones at all? Or do you have to go the whole way and put on the dynamat?
Like jaudio said, try adding foam. I first tried it with adding two piece of double sided foam tape to the cup, and, although it didn't take the modded phones all the way there, the improvement was definitely worth it. Still add the stuffing, though, if you want to tame the bass more.
post #10 of 205
Wow, nice picture tutorial. I purchased the 700's a couple weeks back and I think they're an amazing value, but I could always use nicer sound. I'm not a big DIY guy, but with all those pics, I just might be able to do this.

Thanks and good luck to all who are doing the mod.

Edit- Received a PM, thanks so much.
post #11 of 205
First post

Been a long time reader of head-fi but never got round to joining. Made my first purchase of some Etymotic hf2 IEMs thanks to this place and have loved every minute of them.

Got to say superb tutorial TopPop. My old man is sending my RX900s over from the US to the UK in the next week or so and I will definitely be attempting this.

Can I ask why you think JVC would put such a thick piece of felt under the acoustic lens in the first place?

I'd also be interested in any leftover Dynamat as it is extortionately priced here in the UK. Would need it posting to Atlanta, GA if possible. Drop me a PM if you're feeling kind. Would pay for it of course.
post #12 of 205
Ok I removed just the top layer of the felt ring, don't have any foam or dynamat here. Is the foam/dynamat essential?
post #13 of 205
Quote:
Originally Posted by melmac View Post
Ok I removed just the top layer of the felt ring, don't have any foam or dynamat here. Is the foam/dynamat essential?
Not to get some improvement in the high and mid frequencies. Cotton balls may help tame some of the bass. I have yet to add the foam to my 900's; I added foam to the 700's now I'm comparing the two. I can say that the midbass is cleaner with the foam in the 700’s.
post #14 of 205
Thread Starter 
Quote:
Originally Posted by iaTa View Post
Got to say superb tutorial TopPop. My old man is sending my RX900s over from the US to the UK in the next week or so and I will definitely be attempting this.
Thanks for the kind words! I'm glad it's helping people out!

Quote:
Originally Posted by iaTa View Post
Can I ask why you think JVC would put such a thick piece of felt under the acoustic lens in the first place?
If I had to guess, I'd say it's because JVC figured the general public would associate bass quantity with overall sound quality. The added felt ring really brings the bass out, but it muddies up everything something awful.
post #15 of 205
Thread Starter 
Quote:
Originally Posted by melmac View Post
Ok I removed just the top layer of the felt ring, don't have any foam or dynamat here. Is the foam/dynamat essential?
Many people may have double sided foam tape laying around, or can at least get it for much cheaper than Dynamat. It got me part way there, but not as effective as the Dynamat.

If you're finding that the bass is still overpowering, you should go the craft store to get some stuffing, or just go to a thrift store and get a small stuffed animal or doll for, like, a dollar or something, and use a small bit of the stuffing to line the cups.
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Head-Fi.org › Forums › Equipment Forums › Headphones (full-size) › JVC HA-RX900 modifications, a picture tutorial. (56k, forget about it...)