Just listened to some Fostex T50RPs today... WOW!
Nov 29, 2011 at 3:40 AM Post #5,146 of 11,345
I think I might have found the sound I'm looking for, or at least something close to it. I was previously using the updated version of the RP2 mods with the 840 pads, sometimes referred to as RP2i.
 
I'm no basshead, but I do like perhaps a bit more bass and warmth in my sound than most would call completely neutral. Why? I have a 12" subwoofer in my car and a nice 8" one for my stereo setup, so I'm used to plenty of sub-bass and punch. Headphones have a difficult time replicating that, and even if they measure out neutral with good bass extension, it's usually just not the same. For example, I found the stock D2000 to be slightly bloated and boomy, but I found the HD598 to be slightly bass-light. Somewhere in between there is a sweet spot for me, but probably closer to the D2000 than the HD598. I also just happen to prefer a bit of warmth in my sound. I like the life and fullness it brings to the sound. 
 
I also don't like how many headphones seem to artificially brighten the sound. I specifically use silk-domed tweeters in my car and home stereo setups because they are smoother sounding than, say, aluminum tweeters. Some might consider them to be lacking in detail, but my ears say otherwise. It's a lot like the exaggerated sharpness on most TVs you buy. When sharpness is set where it's actually supposed to be, the picture might seem less clear at first. Once you adjust to it, you realize that you're seeing the details as they are without any artificial sharpening. That's what a lot of headphones sound like to my ears. I also seem to be sensitive to brightness and sibilance.
 
How did the 840 RP2i mods work out for me? Really well, actually. I was just wishing I could get a bit more bass response out of them. I wanted some extra warmth, heft, dynamics, and lushness in my sound. And while it was completely listenable and enjoyable, I found the treble perhaps too bright at times. The key changes I made were removing the stuffing from the back of the 840 pads and getting rid of the reflex dot (duct tape, in my case) from the the back of the driver. In fact, the back of the driver had nothing covering it. No felt, no tape, just naked. With 6 regular sized cotton balls teased and stuffed in the cans, they sound fine naked (to my ears).
 
I found that I did not like how the stuffed 840 pads sounded. The stuffed pads did seem to add some favorable aspects to the sound in the mids, soundstage, and imaging, but they also seemed to reduce the bass warmth. I did some A/B comparisons, and sure enough, the sound was much more lush and full without anything raising up the back of the earpads. In some ways, they seem more 2D now, but I found the soundstage and imaging to be more than adequate. I mean, I'm used to bookshelf speakers and a dedicated subwoofer...Headphones are almost always disappointing in that area in comparison.
 
Removing the duct tape from the back center of the driver also brought out the bass a bit more and helped smooth out the treble into something quite detailed without much in the way of excessive brightness. I had to close up the vents a bit more to compensate for the extra bloat it brought to the upper bass and lower mids.
 
While they seem to extend deeper, have more bass, and have smoother treble than before, they still aren't perfect sounding. At times, the bass does ever so slightly unruly and bloated for my tastes, and the mids might not be perfect in all ways. Hard to say, because my ears aren't perfect either. I am hearing more sub-bass though, and I do like that. Overall, I'm really digging them, but I'll probably end up messing with them again for fun. All I know is that a perfectly neutral, analytical sound is not completely what I'm looking for. It's a mixture of neutrality and my own personal tastes.
 
Anyway, just to make things simple, here's a complete list of my mods. Perhaps someone will find these helpful:
 
1. Silverstone acoustic foam completely lining the cups (cut neatly, no draping, maximizing volume)
2. Felt removed from cup vents, covered all but the bottom slit in Silverstone acoustic foam. Leave that bottom vent slit open (covering it in cotton, step 3, is recommended)!
3. Filled the cups with 6 regular sized cotton balls (medical grade from CVS, if it matters). I completely teased these apart before stuffing the cups. It needs to be uniform, and it needs to cover everything, including the center post (which is covered in acoustic foam) and vent area.
4. Plasticine in the back of the driver baffle
5. Silverstone acoustic foam covering most of the plasticine
6. Nothing on the back of the drivers. No felt (stock or otherwise), no reflex dots. Nothing.
7. Felt removed from the ear-side baffle (keep protective mesh in front of driver), and just one layer of Silverstone acoustic foam covering the entire ear-side baffle. Leave openings for the screw holes, EQ hole, and, obviously, the driver.
8. 840 earpads. No stuffing in the backs or anything like that.
9. Cover the 3 vents you closed off inside with duct tape or electrical tape on the outside of the cups. For the bottom, open vent, cover about 75% of that with your tape. You can tweak that to your liking. In fact, you might want to consider placing acoustic foam on the inside of the cups to cover up as much of the bottom vent as you like.
 
 
Nov 29, 2011 at 6:44 AM Post #5,147 of 11,345
Question for you guys: are you not dynamatting the vents?  In place of electrical tape I simply dynamatted over the bottom 3 vents (figured it was the same as closing them with tape but now I'm second guessing myself).  
 
Bass is a bit low in quantity and I'm using the RP2 mods on LCD-2 pads.  Will try to completely open up the top slot and see how it works.
 
Nov 29, 2011 at 10:13 AM Post #5,149 of 11,345
 
I can second the setup wdahm519 suggested a few pages back. It was so so with my O2 pads so I didnt recommend it but it is excellent with the fa-003 pads which are similar to the 840 so I am strongly recommending it now, this is for those of you who are ok with taking off stock felts from the driver. Really enjoying this setup! the detail is best yet and they are fairly flat. 
 
M
 
- SilverStone Acoustic Foam in the back plane of the cup, not along the side walls of the cup or around the edges, also the center post has no foam on it either
- Stock bass port felt, leave it alone and fully open (the details in sound really come in when its fully open I noticed quite obviously)
- Driver felt removed and replaced with one layer of 3M Transpore tape, and another layer on top of that only covering the center three rectangles (a strip covering three rectangles)
- Slightly less than 1/2 of one "triple sized" cotton ball ("Triple Sized" from Kroger brand), extremely teased out and thin, placed gently in back of driver and not covering the bass port
- Plasticine mass loading the baffles all around, including an angled wall built between the baffle and the plastic surrounding the driver.  Plasticine also in the holes on the plastic surrounding the baffle
- Plasticine also along the outer seal of the cup for... seal.
- FatMat (can use Dynamat) on the ear side of the baffle
- Unreflective very very thin felt covering the reflective side of the FatMat
- Shure 840 Pads with a half a cotton ball hot dog rolled up on the rear underneath the pads
 
Nov 29, 2011 at 10:34 AM Post #5,150 of 11,345
So basically the pads is what make the difference in your mods?
 
Quote:
So I finally found some time to get my 2nd modded pair done.  I didn't really do a step-by-step test to see the effects as life is just full of real things to do, and leisure time on hobby is just getting more and more limted.
 
My 1st set has the following mods:
- Dynamat on cups
- Paxmate on Dynamat
- Plastacine around baffles
- Stock felt over bass port removed, covered with nashua tape with one slot cut opened
- Sony SA5K pads, with acoustic foam stuffed at the back of the driver
- grooved, thin (must be 0.5mm), rubber feet as reflex dot in the middle of each driver.
 
My 2nd set has the following mods:
- Dynamat on cups
- Silverstone acoustic foam on Dynamat
- Plastacine around baffles
- Stock felt over bass port removed, covered with electric tape with one slot cut opened
- Shure 840 pads, with three levels of silverstone acoustic foam (one donut all around, then a half donut at the back half, then a quarter donut at the back end to create an angled fit)
- Felt, 2mm think feet as reflex dot in the middle of each driver.
 
I used monster cable (the studio replacement cables), ALO Rx MKII, iPod 4G.
 
The result is that my mod number one is crisper, cleaner if you will.  It sounds more analytical, not because of more detail, but more because of the lesser bass.  The bass is enough for me personally, but I can see it being an issue with some people.  The soundstage and instrument separation seems to be better.  I would imagine this set would be better for things like Jazz, classic rock, classical.
 
My 2nd set sounds funner, more engaging.  The bass is most definitely more powerful and impactful, though it could be too much and slightly boomy.  There is still a lot of detail.  I would imagine this could be better for hip hop, dance, pop, alternative rock (though the last one is a maybe ...).
 
Too bad I am not going to keep the 2nd set, as I am going to give it to my brother as a Christmas present.  Perhaps I should make a 3rd set identifcal to the 2nd set.



 
 
Nov 29, 2011 at 1:30 PM Post #5,156 of 11,345
Those be sold matey
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Nov 29, 2011 at 2:42 PM Post #5,157 of 11,345
got quick question. when i took my fostex apart i believe on the female 1/8 connector i saw 4 wires tied to. that means there is 2 ground/negative wires,basically meaning the connector itself is balanced but possibly the cable itself it comes with isn't(only a 3-core 1/4'' jack). i would take mine apart again to conform it but i already stripped 2 screws cause i did not know how weak the plastic screw holes were and i replaced them with bit bigger machine screws,so if anyone else plan on opening them up again if they can let me know. if so i can see it being replaced with a mini female 4-pin XLR connector then in the near future maybe.
 
Nov 29, 2011 at 3:15 PM Post #5,158 of 11,345
Google's know's everything... 
biggrin.gif
 look only three cables from the connector.
 

 
Quote:
got quick question. when i took my fostex apart i believe on the female 1/8 connector i saw 4 wires tied to. that means there is 2 ground/negative wires,basically meaning the connector itself is balanced but possibly the cable itself it comes with isn't(only a 3-core 1/4'' jack). i would take mine apart again to conform it but i already stripped 2 screws cause i did not know how weak the plastic screw holes were and i replaced them with bit bigger machine screws,so if anyone else plan on opening them up again if they can let me know. if so i can see it being replaced with a mini female 4-pin XLR connector then in the near future maybe.



 
 
Nov 29, 2011 at 5:54 PM Post #5,159 of 11,345
i should of used google first. my bad.thanks anyways for letting me know. i just thought for sec i saw 2 ground wires instead of 1. must of mistaking it cause the 2 wires are white so i must saw those at quick glance when i was stuffing them. don't know why it had me thinking though.
 
Nov 29, 2011 at 5:54 PM Post #5,160 of 11,345


Quote:
RE my previous post - I have since tried 1X transpore, 1.5X transpore, 2X transpore and 3X transpore and all of these had issues with midrange peaks, most notable upper midrange sibilance which is not an issue with nothing on the back of the driver.  
 
1X - lest sibilant, too loose bass
1.5X can't recall exactly but wasn;t happy
2X - overdamped - sounds plasticky and sibilant
3X - ridiculously overdamped
 
I might try replacing the stock driver backing to see if that turns out to perform well.  No backing sounds quite balanced but a little vague in the imaging, maybe a little resonant.
 
Any suggestions re driver backing?  Just to note cup is fully damped with felt, baffle damped with plasteciene.


Try cotton.  No backing with paxmate causes a peak at 1K with almost any pads I measured.  5-6 small/regular cotton balls will fix that.  
 
I'm assuming you have some acoustic foam in the cups, but if not, cotton is not sufficient.
 
 
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