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Just listened to some Fostex T50RPs today... WOW! - Page 304

post #4546 of 10678
Quote:
Originally Posted by leeperry View Post


So the O2 earpads don't really have recessed mids after all? You make peremptory statements, show us measurements then say that all those earpads are highly dependent on the cups damping...I'd like to try the O2(especially the improved MK2 black version) but g*ddamn, I'm not paying $155 for recessed mids, however comfy they could be [:enrage]

 

 

I have always said any mod is a system whose interacting parts are extremely tightly coupled in their effects.  I can make a crappy sounding O2 system with sucked out mids if I used in on a setup tuned to 5000 pads, or make the 5000 pads sound gutless by sticking them on an O2.  The effects tend to be relative, though, in a sense like equalizers.  So if the O2 pad has a "U" shape on a system tuned to an 840 pad then taking an 840 pad and sticking it on a system tuned for O2 pad probably yields a upside-down "U" when all things are equal (usually).

 

It seems a lot of people are missing this point, and applying mods that have been built with one set of pads in mind then saying "that mod has thin bass" when the pad they chose wasn't aligned to the tuning (I'm not saying you, leeperry, at all, just a general comment).  I only say this so people understand that when trying to implement a mod; if you don't do 100% of something suggested in a mod your results could vary HUGELY; from "wow" to "ewww".  The difference in pads, port tuning and driver backing are all huge, and changing one can affect everything.  

 

I could go so far as to say that the pads are second only to eliminating resonances within the cup, to the extent they actually could be the main reason one choses a given mod.   


Edited by mrspeakers - 11/5/11 at 6:16pm
post #4547 of 10678
Quote:
Originally Posted by rawrster View Post

Can anyone point  me to the link of the BMF#6? I tried a search and it didn't get to it so I must have missed it and I don't exactly want to search page by page..


See posts 4471 and 4513. There are some earlier posts with pictures but these posts sum it up.
post #4548 of 10678


 

Quote:
Originally Posted by takili View Post

   New to the party and getting back into DIY audio after a very long break, Hi to everyone! I have I think been very fortunate to discover this forum and this thread in particular!

   Having now aquired the relevant beasty's and spent some time breaking in and getting a feel for the unmodded sound, (and I must say being very impressed with how these sound in their raw state), I have done a couple of the very basic mods and yes, WOW, again!

   As I first started reading the thread from the last page I soon realised that in order to get up to speed I would need some background info, so went back to page one, hence I have started with blue tack and felt. Whilst reading forward, I also worked backwards in order that I could see where the present state of the art is up to. In consequence I have some old ideas and some new ideas incorporated into my first efforts.

T50RP-mods-01.jpg

The port is currently about 85-90% closed with duct tape.

The reflex dot definitely helps the base extension for me.

T50RP-mods-02.jpg

 

Adding a roll of cotton at the rear of the stock pads to move my ears away from the drivers helped reduce harshness in the HF. So many thanks to all for the above suggestions.

   Impressions after listening to the above is that I have been able to significantly improve over stock. Bass is extended, more punchy and clearer, Mids are more detailed and less muddy, presence and separation is more defined and HF is smoother. That's from listening to a mixture of Folk, Rock, Pop and Jazz.

   My source unfortunately is in no way doing these justice, consisting of a mere Sony Playstation and the speaker out from a pair of Bose media speakers:) Even so, I am impressed with what I am hearing at present. An SSMH amp is on the building board and a Shigiaclone is in the wings. I am looking forward to the improvements...

   Next on the list is to try and dampen the cup resonance more and to move on from the Blutac to Newplast modelling clay in the Baffle channels. Was it Dogwan who was wondering about the purpose of these channels? My own opinion, (Engineering background!) is that the webs that you see help stiffen the baffle. It's easier to mould thinner plastic I would think. I am looking forward to finding out how it went with the spray on absorber.

Regards to all

   


Are you sure about the reflex dot? I think it help's the high frequency BT the bass??

 

 

post #4549 of 10678

Quote:

Originally Posted by mrspeakers View Post

Always hard to go by a frequency response test.   I listened to these and they were acoustically very flat.  


No, I completely agree with you. I'm just saying, from a pure FR measurement standpoint (with Tyll's specific method in mind), they didn't measure out perfectly. I have no doubts that they sound fantastic to the human ear. Measurements can't capture everything, and I'm aware of this.

 

 

post #4550 of 10678
Quote:
Originally Posted by mrspeakers View Post


Always hard to go by a frequency response test.   I listened to these and they were acoustically very flat.  

 

Note that Tyll uses a test measurement head and then applies a transform to map what is measured in the ear to roughly what it would look like outside the ear (hope I got that right Tyll).  My setup skips that, as I don't try to measure from within the ear, simply what arrives at the ear.  There are reasons why Tyll's might be more accurate, but I've not personally felt I really am swayed it's a lot better...  Which probably means I don't understand it.  

 


"You" (not you specifically) also have to know how to read an FR plot even with the transfer function calibration he uses.  Ideal is not a flat line, the way LFF's measured was close to ideal similar to the LCD-2 with a flat line from bass to midrange, a dip in the upper mids, then a small peak, then a few more minor ups and downs.  The peak does look a bit bigger than ideal though and the line is wobbly in the midrange to bass (but maybe close enough as to not be audible...).  As for the channel imbalance, Purrin picked that up in his test too, so I don't think it's Tyll's measuring equipment.  I wonder if it might be the big black cable connector box inside the left earcup.  It bugs me that they aren't symmetrical. 

 

post #4551 of 10678

Last 3-4 pages are somewhat hard to understand and to get the proper picture.. I believe we would all benefit from being more systematic and joining thoughts and efforts. I don't have the T50 yet and haven't done real mods, so I'm really not on par with most of you, yet I can try to think up something. We should write not only the our modding, but also the reasons behind them, I think.

 

I'll try to write some of my thoughts:

There now seem to be the two prevalent mods: Rastapants 2i (they're described at page 285, I believe) and BMF 6v(2/3). They are more similar than different, but there is a difference in approach to damping the driver itself. What they do both is what I'd call the preparation. Damping the driver is what I'd call tuning.

 

I have one point of view on preparation. IMHO, the result of preparation would be an "correct" sound - with minimum of reflections, distortion, re-emitted sound, etc. Clean, fast, detailed, etc. Tonal balance could be skewed, but tonal balance is a result, not a cause. Then, tuning should result in an even tonal balance.

 

What would that preparation be? Mass loading cups with dynamat, mass loading baffles with plasticine/putty AND also loading baffles on the earside as well. Covering all that with paxmate - both the cup and baffle from both sides. Also covering inner side of earpads so there would be even less reflection. IMHO, that is why velour earpads are said to have better soundstage - they don't reflect. Some people said that such a configuration sounds bland, but IMHO it's a result of skewed tonal balance and should be corrected later with tuning.

Note: in optics, there is reflection when light passes boundary between substances with different refractive indices. The less the difference, the less reflection. It applies to sound as well. To minimise reflection, one should use a several-layer system to deflect and absorb the sound waves. Something very diffuse and light near driver, then something denser, and so on and so on. The organic dried sponges seem to be a good choice for the near-driver layer. Then, teased cotton balls. Then, paxmate, then, dynamat and then the cups. There also may be a denser layer of cotton between paxmate and dynamat, depends on the density. Making cotton ball stuffing with different density across its thickness is also a good idea - more teased near driver, denser near paxmate.

 

The second stage of preparation would be elimination of uncontrolled variables. RP2 do some of that elimination by lining rim of the baffle with plasticine. Other uncontrolled variables are leaks from under earpads and leaks between head and earpad. First kind of leak is not hard to address - stock-like glued-on pads should be properly glued on, and with flapped pads, one might put something viscous under the flaps, but I don't think it is necessary. On the second kind of leak, leather earpads have little leak, and gel earpads have even less leak - the more isolation, the less leak. Sub-bass requires proper seal.

 

 

Now, there comes tuning. I see three things to tune: driver damping on front and rear, ports on cup, and ports on baffle. Again, tuning should first result in "proper", fast and detailed sound, and then it should be tuned further to get proper tonal balance. Bad thing, without measurements, we can't be sure what really each measure does. Seems that closing cup ports results in damping resonances and perhaps shifting them lower. However, it comes at expense of compressing bass frequencies, as air has nowhere to move.

Baffle ports seem to be overlooked. They also play role in bass, and subbass, as they leak air between front and rear. Covering them overdamps the driver and reduces bass, while having them open results in roll-off at subbass, albeit having more of the other bass frequencies. I think, they should be controlled - not by opening or closing them completely, but by changing their resistance - covering them, for example, with felt which passes air through but restricts the flow somewhat.

 

Now, the driver damping itself.. it is the most questionable area, and I don't have expertise with it. I only have some thoughts on reflex dots and bass rings. Reflex dots shouldn't really reflect a lot of sound when placed right on the driver, but they surely add damping that way - they are solid and don't pass air. So high-excursion bass waves get damped, and they-re mainly bass, so there's less bass and hence, more treble - as everything is relative. Still, I don't think anythink rigid and reflective is good. So instead of reflex dot, I'd use a damper dot, if there would be any need to boost treble.

Bass rings, I think, should be the last thing to implement, exactly to tune the tonal balance. I would implement one on the front, to further reduce phase shift in highs - it may reduce percieved amount of highs, but make responce more extended due to less parasitic sounds. And of course it should indeed boost the bass (relatively).

 

Thanks you you read it all. Maybe my thoughts would be at least somewhat useful for all of you.

post #4552 of 10678

Sorry, my question is not really relate to this topic but i want to ask about the famous blu-tack mod for many closed headphone like A900, HD280. Instead of blu-tack can i use pax mate? I think that would better absorb sound wave.

post #4553 of 10678
Quote:
Originally Posted by proid View Post

Sorry, my question is not really relate to this topic but i want to ask about the famous blu-tack mod for many closed headphone like A900, HD280. Instead of blu-tack can i use pax mate? I think that would better absorb sound wave.


They are used for different purposes. Blu-tack mass loads the housing and reduces secondary radiation of sound from the housing. Paxmate absorbs sound waves and reduces reflection, virtually enlarging cup volume.

post #4554 of 10678

Whilst there are two main mods going around here, I think you're right in saying they're essentially addressing the same problems using very similar techniques. I personally want to keep things as reversible as possible, so I've not gone down the transpore route, and I've ended up with a set of mods someway between the two - I'm sure there are many more 'quieter' posters with various mix-and-match versions of the two.

 

As for varying material reflection coefficients, I've already twigged that this might be important. The good news is your theory seems to be, in my setup at least, marginally better than just using cotton wool. There's a sketch of my setup at the end of this post (many apologies for my lack of drawing talent). Omitted from the sketch is the ring of paxmate under the pads to raise them up (just around the edge - not all the way out into the centre where the driver is), and the thin layer of plasticine I have on the inside of the cups, below the paxmate. Yes, I'm too cheap to buy dynamat. 

 

I'd be very interested to see how well the organic sponge does. The 'cheap sofa sponge' I have on my sketch was lifted from university, and I don't really know what it is, but I certainly felt it gave a sense of openness to the sound. Held up to the light, it's very uniform and transparent. How much better is it than just cotton? Err, I'll leave you guys to make your own decision on that. And finally, thanks for all the help I got a few pages back - in the end, the biggest problem I had was with the paxmate on the ear-side of the baffle. Removing it, leaving only the ring under the pads, gave some good results.


 

4-nov-2011.jpg

Quote:
Originally Posted by Nevod View Post

 

I'll try to write some of my thoughts:

There now seem to be the two prevalent mods: Rastapants 2i (they're described at page 285, I believe) and BMF 6v(2/3). They are more similar than different, but there is a difference in approach to damping the driver itself. What they do both is what I'd call the preparation. Damping the driver is what I'd call tuning.

 

 

Note: in optics, there is reflection when light passes boundary between substances with different refractive indices. The less the difference, the less reflection. It applies to sound as well. To minimise reflection, one should use a several-layer system to deflect and absorb the sound waves. Something very diffuse and light near driver, then something denser, and so on and so on. The organic dried sponges seem to be a good choice for the near-driver layer. Then, teased cotton balls. Then, paxmate, then, dynamat and then the cups. There also may be a denser layer of cotton between paxmate and dynamat, depends on the density. Making cotton ball stuffing with different density across its thickness is also a good idea - more teased near driver, denser near paxmate.

 

 



 

post #4555 of 10678

Arleus,

 

Your drawing is actually pretty descriptive.

 

About the sponges, while I think one posted in http://www.head-fi.org/t/452404/just-listened-to-some-fostex-t50rps-today-wow/4410#post_7864126 may not be very good, the one in http://www.head-fi.org/t/452404/just-listened-to-some-fostex-t50rps-today-wow/4410#post_7864064 is probably optimal as the first layer of cup filling.

 

Btw, what is the difference you've got when you removed paxmate from around the driver on earside? What was the sound like before that removal?

post #4556 of 10678

Looks great! beerchug.gif

 

If this config suits you, that's all that matters.  Could you describe the SQ, bass/treble extension, midrange clarity, etc. compared to stock?

 

BTW, very cool graphics. What software did you use to make your "drawing?"

 

Quote:
Originally Posted by Arleus View Post

Whilst there are two main mods going around here, I think you're right in saying they're essentially addressing the same problems using very similar techniques. I personally want to keep things as reversible as possible, so I've not gone down the transpore route, and I've ended up with a set of mods someway between the two - I'm sure there are many more 'quieter' posters with various mix-and-match versions of the two.

 

As for varying material reflection coefficients, I've already twigged that this might be important. The good news is your theory seems to be, in my setup at least, marginally better than just using cotton wool. There's a sketch of my setup at the end of this post (many apologies for my lack of drawing talent). Omitted from the sketch is the ring of paxmate under the pads to raise them up (just around the edge - not all the way out into the centre where the driver is), and the thin layer of plasticine I have on the inside of the cups, below the paxmate. Yes, I'm too cheap to buy dynamat. 

 

I'd be very interested to see how well the organic sponge does. The 'cheap sofa sponge' I have on my sketch was lifted from university, and I don't really know what it is, but I certainly felt it gave a sense of openness to the sound. Held up to the light, it's very uniform and transparent. How much better is it than just cotton? Err, I'll leave you guys to make your own decision on that. And finally, thanks for all the help I got a few pages back - in the end, the biggest problem I had was with the paxmate on the ear-side of the baffle. Removing it, leaving only the ring under the pads, gave some good results.


 

4-nov-2011.jpg



 



 

post #4557 of 10678
Quote:
Originally Posted by Twinster View Post


 


Are you sure about the reflex dot? I think it help's the high frequency BT the bass??

 

 

 

Aside from reflecting some treble a reflex dot actually does damp the driver a little. Try putting one on a setup that's borderline overdamped and it'll push it over the edge.

To me these get smoother sounding the more you damp them, with less peaks, including midbass, so that might explain the change to the bass.
 

Quote:
Originally Posted by rhythmdevils View Post

As for the channel imbalance, Purrin picked that up in his test too, so I don't think it's Tyll's measuring equipment.  I wonder if it might be the big black cable connector box inside the left earcup.  It bugs me that they aren't symmetrical. 

 


Yeah must be what it is, every T50rp has a pretty similar channel imbalance. Think I'm going to go the lazy route and just glue something binding post sized in the other side.

post #4558 of 10678
Quote:
Originally Posted by Nevod View Post

Now, the driver damping itself.. it is the most questionable area, and I don't have expertise with it. I only have some thoughts on reflex dots and bass rings. Reflex dots shouldn't really reflect a lot of sound when placed right on the driver, but they surely add damping that way - they are solid and don't pass air. So high-excursion bass waves get damped, and they-re mainly bass, so there's less bass and hence, more treble - as everything is relative. Still, I don't think anythink rigid and reflective is good. So instead of reflex dot, I'd use a damper dot, if there would be any need to boost treble.


Good post!

 

That's a good point. I noticed that a plastic dot made things brighter than a cloth one of the same size. I thought it was reflecting more, maybe it was just letting less air through.

 

post #4559 of 10678


FYI regarding channel imbalance. I did experienced it and it turned out I had screw the driver baffle up side down (putting the venting hole down) on one side. As soon I re-installed it properly the sound was back to normal being balanced.

Quote:
Originally Posted by 200poundsofamp View Post

 

Aside from reflecting some treble a reflex dot actually does damp the driver a little. Try putting one on a setup that's borderline overdamped and it'll push it over the edge.

To me these get smoother sounding the more you damp them, with less peaks, including midbass, so that might explain the change to the bass.
 


Yeah must be what it is, every T50rp has a pretty similar channel imbalance. Think I'm going to go the lazy route and just glue something binding post sized in the other side.



 

post #4560 of 10678

Hm, so I was looking at the measurements for the Thunderpants and LFF's Paradox mods at innerfidelity, and I noticed that the efficiency of these mods is FAR lower than stock.  I wonder what that means...?

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