[stjj89]

Looks like there will be a head-fier bringing a stock TH900 to the SF meet to compare with my modded TH900. I am really looking forward to an extended comparison of the two, both plugged into my HP-A8!

 

[stjj89]

Impressions from briefly comparing my modded TH900 with a stock one at a noisy head-fi meet. TH900 > HP-A8 > iPod classic on digital dock.

Mods give more bass extension. This was very clear on Hans Zimmer's "Why So Serious" where the modded TH900 was able to render an entire level of deep subbass that the stock ones could not.

The mods brought the mids forward significantly. This was the other extremely obvious difference. This actually made it hard to listen to both cans at the exact same volume for some songs since I would have to turn up the volume for the stock TH900 to get the mids where I want them, then turn it down when I switched to the modded pair so the mids wouldn't hurt my ears.

Stock TH900 sounds darker. This is definitely because of the recessed mids and slightly boomier bass. That being said, I was surprised at how much I enjoyed the stock sound on this setup.

The mods' effects on clarity and detail were not extremely obvious. I previously thought that my mods really took the TH900 a notch in terms of detail retrieval and treble clarity, but this was not immediately obvious to me when swapping between the two cans. It might just have been the noisy venue that made it harder to pick out these differences, but it felt like I could pick out each of the same ambient cues on both cans.

I miss the comfort of the stock pads. One thing that struck me as I was wearing the stock TH900 was how nice it was that the pads were thick enough to keep my ears from touching the drivers. My ears are on the big side, so comfort is a slight sacrifice I've had to make for the benefits these mods bring. The ear issue isn't terrible, but it definitely causes me to readjust the headphones after prolonged wear.

That's about it! I would have liked to spend even more time comparing the two cans, but I didn't want to inconvenience the fellow head-fier who so kindly brought his TH900 along to the meet. He told me that he definitely liked the modded TH900 more, so hurray for that! Another head-fier (also my roommate) was also quite impressed by the modded TH900, and told me that it was a good listen without any noticeable flaws.

 

[yuanathan]

Thanks stjj89, this is probably the only direct comparison between a modded n stock th900 that I've read, albeit in a non ideal condition.

What are the total mods that you have on yours?

Modded earpads, Lawton lvl1 + ??

Just want to have an idea what is it giving the differences you stated.

 

[stjj89]

Thanks stjj89, this is probably the only direct comparison between a modded n stock th900 that I've read, albeit in a non ideal condition.

What are the total mods that you have on yours?

Modded earpads, Lawton lvl1 + ??

Just want to have an idea what is it giving the differences you stated.

 
Glad I could help. I basically did the entire mod described by the OP, and I added the driver rear plate dampening rings from the Lawton Level 1 kit (parts C, D, E, and F in the pictures here).
 
In a previous post, I broke down what I felt each mod did to the TH900:
 

   
I just realized that I missed this part of your question. From doing the two stages of the mod incrementally, this is my impression of how each part of the mod affects the sound of the TH900:
 
Earpad mod

1. Brings mids forward, making the headphone sound more balanced and neutral
2. Vocals more engaging and easier to follow
3. Some increase in treble sparkle and clarity (possibly because of the removed grill cloth)
4. Not much change in bass, but it is less (over)emphasized because the mids are now more in line 

 
Felt Cup Dampers + Felt damper rings

1. Bass bloom/bloat eliminated--bass is tighter and extends deeper, while still having the same impact and slam
2. More detail and refinement (not 100% sure about this one since I didn't do before/after comparisons, but that was the feeling I got)

 
I feel like the earpad mod makes a bigger difference, but the improvement to the bass from the felt mods are a big win in my book, and definitely make it worth doing. The earpad mods fixed the most glaring flaw of the TH900 in my books (slightly recessed mids), and the felt mods fixed its second biggest problem (the boomy bass), and took the refinement of the sound a step further.
 
I will report back on the Lawton ring dampers soon. I might even do a little printout of the mods (w/ pictures) to bring to the head-fi meet in case anyone there is curious about them
 

 
I will add to this by saying that the Lawton ring dampers reduced the treble shrillness, which de-emphasized the treble a little more but made it sound a little more natural. The overall effect of this is that the can sounds just a little darker. You lose a little treble sparkle, but no longer is there that slightly artificial, metallic edge to the treble. Consequently, you get a little more bass and mids from the reduction in treble, which slightly thickened the sound for me in a way I found pleasant.
 
Overall, I am very pleased with what the mods did to my TH900. They are basically sort of a closed version of my (modded) HE-560s in that they are very airy, just slightly warmer than neutral, and excel at all genres of music. My HE-560 still does string instruments better, and has slightly punchier bass on my home setup, but the TH900 actually sounds airier, and has more bass quantity, which is very satisfying on electronic and hip-hop music.
 
P.S. if anyone is seriously considering performing these mods and is figuring out how to get the materials, PM me about the leftover materials I have and we could works something out.

 

[stjj89]

Random update: I just tried swapping a pair of stock pads back on my TH900 just to see how they sound. The slightly recessed mids are back, but less recessed than I remember them being. The treble feels sharp and harsh though. Note that I am using a different DAC/Amp for this comparison (I usually use my work setup).
 
My theory is that the dense, high stock pads create more backward reflections between the driver and the ear, which cause the treble to sound more shrill. The greater distance between the ear and the driver probably causes that "cave effect" i.e. recessed mids.
 
In other news, I am experimenting with attaching a very thin circular sheet of organza to the earbad baffle using double-sided tape. This will act as a replacement dust-filter for the earpads. I used the same material for my HE-560 grill mod, and had good results (barely any effect on SQ). I will report back with results after some testing.

 

[stjj89]

I just got my hands on a stock TH900 and am working on some detailed comparisons with my modded TH900. One thing that strikes me again is how much more comfortable the tall, dense stock pads are for my relatively big ears. I'm thinking of trying to tweak the mod to raise the earpads a bit more for better comfort.
 
zolkis, playitloud, have either of you tried higher carbon pads, and if so, what sonic differences should I expect to hear?

 

[Afghan Vet]

I know whose those are! I'm very excited about this mod. It was interesting.....at a local meet last weekend, a few of the guys were standing around talking about some of the TOTL headphones......when the TH900's came up.......all those......they have really recessed mids, right? And the bass is really bloated and boomy, right?
 
So it is interesting that folks who have never heard them can tell you exactly what they are known to sound like.
 
It will be interesting to go to meets where they may be surprised by the sound versus their supposition.
 
I'm also toying with the idea of recabling.....either the entire cable (Moon Audio Silver Dragon) or mid-way down so I can go balanced to my amp.

 

[playitloud]

  I just got my hands on a stock TH900 and am working on some detailed comparisons with my modded TH900. One thing that strikes me again is how much more comfortable the tall, dense stock pads are for my relatively big ears. I'm thinking of trying to tweak the mod to raise the earpads a bit more for better comfort.
 
zolkis, playitloud, have either of you tried higher carbon pads, and if so, what sonic differences should I expect to hear?

 
You can increase the height to about 15mm in the back, and 10mm in the front. You lose a bit in timbre of instruments, detail, and focus. But you gain some extra openness. If you increase the height too much, the mids will become more recessed and you get a bit of hollowness. 

 

[zolkis]

Quote:

   
You can increase the height to about 15mm in the back, and 10mm in the front. You lose a bit in timbre of instruments, detail, and focus. But you gain some extra openness. If you increase the height too much, the mids will become more recessed and you get a bit of hollowness. 

 
My experience too, and I wanted the opposite effect of midrange recess and hollowness.
I didn't like the sound with high pads, and that applies with nearly every headphone I tried, except the Stax 009 which was less sensitive to pads. The 007 in turn is the most sensitive headphone in that regards that I know of, followed by the TH900. The modded TH900 is still comfortable for me, but it seems I am lucky.
 
I shortly tried higher pads without the cups, i.e. an open back TH900, and it was better than with the closed cup, but I specifically wanted a closed headphone which sounds good. The modded TH900 is quite good for that.
 
There was an open-back mod of the Denon D7000, and I think it may work well with the TH900 as well.
http://www.head-fi.org/t/569094/open-back-mod-for-denon-d2000-5000-7000-fr-measurements-available-updated-11-1-2011

 

[stjj89]

Thanks for the input on the pad height. Turns out it was the filter screen that I installed which was causing the discomfort as it reduced the amount of space in the pads. Removing this screen solved the comfort problem!
 
So I just finished performing the mods for @Afghan Vet, and noticed that the new carbon pads that I did for him sound a little bassier and less open than mine. I'm pretty sure I cut the pads to the same measurements, and I used the exact same sheet of carbon foam for this. My suspicion is that the more you use, compress, and toy with the pads, the more it "sheds" carbon (i.e. notice the black specks of carbon it loses when you rub or press against the foam) and that decreases the density of the foam, resulting in more space, more air, and consequently, less bass. If I am correct, I imagine these bassier pads will eventually get airier as I agitate them more. zolkis, playitloud, have either of you had this experience?
 
Also, I'm wondering if the carbon pads shedding carbon bits is an issue at all for the exposed driver enclosure. I haven't really had issues with the drivers getting dirtied by the carbon foam, but I can imagine that some of these might make it in there. Is this something to be concerned about at all?

 

[playitloud]

To be honest, I have no idea. I bought 25mm thick carbon foam, and out of that thickness I make 1 earpad of about 12mm maximum height. Hence, it should be possible to get two out of them, but I did not have the right tools to do that correctly. Hence, making earpads was a lot of work, and I lost a lot of those carbon bits while making them. In the end, my earpads did not contain a lot of carbon bits if any. And I have not tried to fill them with those bits.
 
If there is too much bass, try the 71/48 wool dampers. I use them nowadays, bass is less, but midrange more expressive. I listen a lot to opera and late romantic and 20th century classical music. Generally these compositions are quite 'dense', less bass opens them up quite a bit. I like it..... But be aware, on my equipement I liked the Sennheiser HD800 also a lot,  but I needed a closed headphone....
 
The modded Fostex TH900 scales well with better equipment, probably because you hear more into the midrange. I can clearly hear the difference between different rectfier tubes and interconnect cables. The standard TH-900 is less sensitive to those changes IMO. Curious how Afghan Vet likes the mods...

 

[zolkis]

  So I just finished performing the mods for @Afghan Vet, and noticed that the new carbon pads that I did for him sound a little bassier and less open than mine. I'm pretty sure I cut the pads to the same measurements, and I used the exact same sheet of carbon foam for this. My suspicion is that the more you use, compress, and toy with the pads, the more it "sheds" carbon (i.e. notice the black specks of carbon it loses when you rub or press against the foam) and that decreases the density of the foam, resulting in more space, more air, and consequently, less bass. If I am correct, I imagine these bassier pads will eventually get airier as I agitate them more. zolkis, playitloud, have either of you had this experience?

 
One reason for bassier output might be smaller internal diameter, or higher pads, or different density.
The internal diameter should not be too big, otherwise it will sound too hollow. I think where we ended up with @playitloud was pretty much the optimum for any height and density.
The pads height has a minimum recommended value around 10 mm, otherwise it becomes quite uncomfortable, but in general the lower the better (in the case of the TH900).
The density of the foam is definitely a factor, but in my experience it mainly comes from construction, and not that much from how much is it filled with activated carbon particles, though also that is important. I have shaken them pretty well before using, so they don't leak much carbon dust any more, and the ones which stayed more black than the other types after cleaning actually sounded better. The optimal seems to be light density of foam with small carbon particles well bond to the structure. The more loose, the better, and then you can increase the pad height, because what seems to matter, as @playitloud said once, is the total mass of stuffing/damping inside the ear pads.
 

 
Also, I'm wondering if the carbon pads shedding carbon bits is an issue at all for the exposed driver enclosure. I haven't really had issues with the drivers getting dirtied by the carbon foam, but I can imagine that some of these might make it in there. Is this something to be concerned about at all?

 
Even if you get the drivers dirty wouldn't make much of an audible difference. Anyway I think there is not much chance for particles coming out of the pressure-sealed leather pads, if not through the original sewing. For any case, I have well shaken, but not washed the carbon foam before using. My drivers are still clean, after many months of active use.

 

[Afghan Vet]

  To be honest, I have no idea. I bought 25mm thick carbon foam, and out of that thickness I make 1 earpad of about 12mm maximum height. Hence, it should be possible to get two out of them, but I did not have the right tools to do that correctly. Hence, making earpads was a lot of work, and I lost a lot of those carbon bits while making them. In the end, my earpads did not contain a lot of carbon bits if any. And I have not tried to fill them with those bits.
 
If there is too much bass, try the 71/48 wool dampers. I use them nowadays, bass is less, but midrange more expressive. I listen a lot to opera and late romantic and 20th century classical music. Generally these compositions are quite 'dense', less bass opens them up quite a bit. I like it..... But be aware, on my equipment I liked the Sennheiser HD800 also a lot,  but I needed a closed headphone....
 
The modded Fostex TH900 scales well with better equipment, probably because you hear more into the midrange. I can clearly hear the difference between different rectfier tubes and interconnect cables. The standard TH-900 is less sensitive to those changes IMO. Curious how Afghan Vet likes the mods...

I'll let you know soon They should be arriving today, and I plan to spend a considerable time with them tomorrow. I've also scheduled to get together with a couple guys locally. One has a pair of un-modded 900's and a Unison Research amp that has 2 single ended outputs - pretty easy to do direct A/B comparison. I'll also be taking my AURALiC Aries/Vega/Taurus so I can hear both cans on my set up. 
 
The other guy that I'm meeting up with at that same time is a fella who listened to the Fostex on my rig at a recent meet. It was meet conditions (guys yapping away pretty loudly close by), and he has pretty established preferences with headphone sound. But I'm looking forward (I think) to getting his overall impressions of the Fostex in better listening conditions and the difference between the modded and un-modded pairs. Here are his impressions after the meet.
 

Although it was a mini meetup, I have had a surprisingly good experience----this is the first time from head-fi systems I have heard sound effects that are in many respects resembling the hi-fi sounds from truly high end speaker systems I heard previously (obviously, lacking those immersive 3-D surrounding effects). My current head-fi systems cannot produce such sound due to weaknesses in various components.
 
I have been mostly impressed by Jason's Auralic system driving either HD-800 (with cable upgrade from Shane) or my slightly modded HE-6. Overall, I would rate HD-800 as a more or less better audiophile pair of phones than HE-6. It is no surprise that the soundstage and details were great from the former as I have read many times about these attributes. To my delight, the mids (vocals) are not recessed at all, good news for users like me who listen to songs or watching TV/movies frequently. Tonality and texture of the sound are rich and enjoyable. Bass is adequate to my taste. The only thing that concerned me was the trebles. With the Auralic system, the trebles had that hi-fi sound signature but often times were too sharp or reaching clipping points.
 
In comparison, my HE-6 behaved very well with the Auralics in the trebles. Being a muscular sound type of headphone, the HE-6 exceeded in strength and control, but lacked some rich details and subtleties (aided by that large soundstage) readily conveyed by the HD-800. I have to say, the Taurus drove the HE-6 exceedingly well. I had never heard my HE-6 sounding so good from my modest systems. If the HD-800 can be modded for better trebles or match better with some DAC/amp systems, I would love to get one (not to deny I am not tempted right now). 
 
To my ears, the TH900 was not in the same league as HD-800 and HE-6. Besides the V-shape sound masking the mids, there is a clear sense of unnaturalness with respect to the soundstage. Perhaps limited by the closed back design, I felt the peripheral soundstage was abruptly intercepted and distorted as there was a dome-like spherical wall blocking the expansion of the soundstage. Or like those distortions seen in pictures from a lens without proper corrections with edges/corners. I do not remember the Alpha Prime had such gross distortions with soundstage, but I had never used the AP with highly capable systems such as the Auralics. This is just my first listen to the TH900. So my impressions could well be severely unreliable. But I clearly did not perceive such effects with either HD-800 or HE-6.
 
I also listened to Howlin's Grado RS1i briefly. Unlike any other headphones I have listened to, the RS1i still did Guitar and rock songs with some distinct magic flavor. Too bad I had to sell mine mostly due to the issues with trebles.
 
Thanks to Shane for letting me try the HD-800 with several systems and have a good time. This is my first proper audition of these mighty HPs. Thanks to Jason for offering me the opportunity to have a taste of the great system he has.

 

[zolkis]

  I'll let you know soon They should be arriving today, and I plan to spend a considerable time with them tomorrow. I've also scheduled to get together with a couple guys locally. One has a pair of un-modded 900's and a Unison Research amp that has 2 single ended outputs - pretty easy to do direct A/B comparison. I'll also be taking my AURALiC Aries/Vega/Taurus so I can hear both cans on my set up. 
 
(...)
 
To my ears, the TH900 was not in the same league as HD-800 and HE-6. Besides the V-shape sound masking the mids, there is a clear sense of unnaturalness with respect to the soundstage. Perhaps limited by the closed back design, I felt the peripheral soundstage was abruptly intercepted and distorted as there was a dome-like spherical wall blocking the expansion of the soundstage.

 
I think that my modded TH900 does not have the soundstage limitation, at least not to this extent.
It's true that my modded Stax 007 has better stage, and so does the HD800, and perhaps even the HE-6, albeit that is a close call, and I agree that even the modded TH900 may not be as good/neutral/revealing as the HD800 and HE-6 when they are properly driven, but:
- I don't feel like having a distorting wall; when sounds seem coming from a far distance with the 007, they do so with the TH900 as well, albeit closer. The carbon foam pad filling helps a lot with soundstage. If you care more about sound stage than mids, you can try using the original dampers (the grey foam ring around the drivers) rather than the felt dampers. The felt dampers can overdamp easily, and every cutout will likely sound different anyway, it's so sensitive to minor and micro-variations, and then every felt sounds different, even from the same felt sheet when cut from different parts of the sheet.
- the main strength of the TH900 is still that it is a closed design, and that's exactly what I need most in it in the office, or when watching late night movies at high volume
- it works wonderfully with portable DAC's, and while it does scale with good amps, I get most of the goods right at the start of the range, from a Resonessence Herus, or even a Sony Z3 phone
- the modded TH900 is fun, and for me much more fun, with better stage, mids, bass and treble than the non-modded TH900 .
 
However, when in the evening I put on the 007 (not so much the 009 nowadays), I melt away.
So that's the context, and I have made peace that after a year of tweaking, I have seemingly reached the "good-enough" limits of the TH900, and it is what it is and no more .
I will notify this forum when I find a better closed headphone for the above purpose (the LCD-XC is not, at least for me, although I did not try to tweak that one).

 

[playitloud]

  I don't feel like having a distorting wall; when sounds seem coming from a far distance with the 007, they do so with the TH900 as well, albeit closer. The carbon foam pad filling helps a lot with soundstage. If you care more about sound stage than mids, you can try using the original dampers (the grey foam ring around the drivers) rather than the felt dampers. The felt dampers can overdamp easily, and every cutout will likely sound different anyway, it's so sensitive to minor and micro-variations, and then every felt sounds different, even from the same felt sheet when cut from different parts of the sheet.

 That is a very important point of Zolkis. Basically, the 73/48 dimensions of the white wool dampers is a good allround performer. However, you can still fine tune your wool damper according to your preferences and/or equipment. Leave the inside as is, or maybe very slightly reduce its thickness a bit around the inside edge. But by no means increase the inner diameter to more than 48mm.
 
The outside of the damper is another story.Here you have more possibilities to tune the sound. If you have too much bass or want a bit 'more open' sound, which is a bit of a consequence of less bass IMO, you can reduce the thickness around the outer edge of the damper. If that does not work enough, you can reduce its size to a minimum of 71mm. I gained some extra midrage detail and expressiveness.The damper will not fit perfectly, too small. I have solved that with two very small pieces of doubled sided scotch-tape. But be aware I have a tube speaker amp, and tube dac, which tend to sound relatively dark.