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Just listened to some Fostex T50RPs today... WOW! - Page 339

post #5071 of 10599
Quote:
Originally Posted by ardilla View Post

What is the difference in function between Paxmate and Dynamat? I see Rastapants use Paxmate only, while BMP use both Paxmate and Dynamat..

 

 

FWIW...IME...My 2 cents...etc...

 

I've only been at this for 4 months so I'm still a novice and could definitely be wrong. The sound engineers among us can correct any of my misperceptions and errors. That said, this is what I think about these various materials:

 

Paxmate Plus, Silverstone, and AcoustiPack Lite are open-cell materials used for acoustically dampening the cups and baffles. They absorb unpleasant reflections and reduce standing waves. AcoustiPack Lite is the only one of the three that has a constrained layer, so it is also useful for mechanically dampening cup and baffle vibration/resonance from the drivers. Adding fiberfill, cotton, wool, etc., loosely placed inside the cup actually increases the perceived size of the cups and may improve soundstage and airiness.  Reflex dots of tape, plastic, felt, rubber, etc. may be added to the back side of the drivers if there is a need to boost euphonic treble reflections to your ears and seem to reduce bass and/or tighten the bass.

 

Dynamat, FatMat, and B-Quiet are butyl-based materials with an aluminum (?) constrained layer used for mechanical dampening. They are designed to convert mechanical vibrations into heat, thereby removing an unwanted source of resonance that would otherwise mess with the SQ. They are intended for application on the external surface, surrounding the drivers, not inside the cups. Nevertheless, some here on headfi have reported good results with installing these materials inside the cups and even on the outside of the cups. If you decide to use these products on the ear side of the baffles as I have done, you must remove the ear side dust cover felt from around the drivers, down to bare plastic. This is the only way these products will work as designed. You also should cover the constrained layer with self-adhesive felt to nullify reflections from the aluminum.

 

Both products help to clean up the sound quality by removing resonances and reflections from the stock T50RP's so their sound quality goodness can be heard. I find the combination of Paxmate, cotton, tungsten putty (or plasticine), and Dynamat work well together, in the proper configuration, by tightening and extending the bass, clarifying the midrange, and extending the treble.

 

Paxmate, or similar, placed in the cup outer ring provides a better seal with the baffle and may further reduce mechanical resonances.

 

As always, YMMV.

 

 

post #5072 of 10599

Slick Stuff, guys!  I'm gonna have to make a set of these ear pad lifters and build me a dummy box tomorrow.

 

Thanks!
 

Quote:
Originally Posted by HDMan View Post


 

 

I just used some old ordinary foam for now, need to get some more proper acoustic stuff from Jaycar, but you get the idea anyway.

 

Pic_1126_010.jpg

 

Pic_1126_011.jpg

 

Pic_1126_012.jpg

 

 

It's good if you can find a food container that is the same size in diameter as the outside of the pads.



 



Quote:
Originally Posted by Arleus View Post

So, I took a page from Twinster's book (you cunning fox, Twinster), and built a budget measurement rig from a cheapo SPL meter I got from amazon (probably too cheap - it's not great, and I'll go into why a little later). I was lazy though, and instead of mounting it in a box, I just duct taped a CD to the aperture, and covered the CD in paxmate. I've been measuring a couple of mods, and some of my other headphones over the past few evenings, and I thought I'd share, in case anyone's interested.

 

Forty test tones were produced in MATLAB, logarithmically spaced between 20Hz and 20kHz (code in the spoiler section below - in the interests in openess, I'm going to post my code in case anyone wants to use it to generate tones in Octave or MATLAB. I know nobody will, but I feel better posting it anyway). I played each tone in turn, with the 485Hz tone set to 90dB, and recorded the SPL measured on the meter, set to 'slow' speed, and C weighting. I then switched sides and went through the same process for the other cup.

 

 

Warning: Spoiler! (Click to show)

 

 

% Initialisation
close all;
clear all;
clc;

 

% Variables
Fs = 44100;     % Sample rate in Hz
maxt = 10;       % Maximum length of the tone in seconds
notones = 40;  % Number of tones
amp = 0.9;       % Amplitude of the tone

 

% Generate frequency vector
f = logspace(log10(20), log10(20000), notones);

 

% Generate time vector
t = [0:1/Fs:maxt];

 

% Loop through each frequency
for n = 1:length(f)
    y = amp*sin(2*pi*f(n).*t);
   
   
    if f(n) < 100
        name = ['000' num2str(f(n)) '_tone.wav'];
    elseif f(n) < 1000
        name = ['00' num2str(f(n)) '_tone.wav'];
    elseif f(n) < 10000
        name = ['0' num2str(f(n)) '_tone.wav'];
    else
        name = [num2str(f(n)) '_tone.wav'];  
    end
       
       
    wavwrite(y, Fs, name);
end

 

 

 

After this point, I 'correct' the data by setting 485Hz to zero, and removing the C weighting curve - this is one of the dodgiest bits I do, and if someone would like to tell me that I'm wrong to do so, please let me know. It is my understanding, however, that the meter will 'artificially' reduce the dB value at low and high frequencies to account for human hearing at those ranges. I wanted the raw numbers, not the weighted ones. I got the formula for the weighting curve from Wikipedia, and subtracted it from the recorded numbers.

 

I then put a cubic spline through the points (using MATLAB's spline function, upsampling by a factor of 10) to interpolate between the rather coarse 40 frequencies I recorded. My SPL meter does have an analogue output on it, so in future I might see if I can chav (read: steal) an oscilloscope, work out how the devil it works, and record a continuous sine sweep so I don't have such a coarse set of data points... but if I'm going that far, I might as well get a better meter too.

 

Then it's just a case of plotting. For reference, here are my results for my K702 and RS1i to give you some idea of how my graphs look. It's generally not a good idea to compare frequency responses from one person's measurement equipment to another person's results... especially if the equipment is home brew.

 

K702.png

RS1i.png

 

These look, I have to say, surprisingly good I think. Okay, so first thing to note - I don't think you can trust my results below 50Hz or so. All of the headphones I've measured show a very similar slope of roll-off below 50Hz, and I suspect that's the meter that's at fault (considering I've 'corrected' for the C-weighting). Compared to Tyll's results for the RS1, the RS1i looks incredibly flat through most of the midrange, and I don't see any 100Hz bump that he has for the older model headphone. At this point, I don't know if it's really there and I can't detect it, or if the RS1i doesn't have one. Upper midrange looks like classic Grado to me though, so that gives me some confidence. That channel imbalance at 2k? I didn't realise I had one, but it looks pretty big to me - I did double check it.

 

The K702 response again looks pretty reasonable, though a slightly different shape to Tyll's. Maybe I could chalk it up to the HRTF he uses, and my complete lack of one, but frankly it's probably because I bought cheap equipment and built it from gaffa tape and dreams.

 

Given those two results as a baseline, what do the T50RPs look like that I've modded? Well, I have to admit at this point that I don't have a stock pair to measure, so take these results with an ever growing pinch of salt.

 

 

 

Mod 1:

Plasticine on back and walls of cup (I'm too cheap for dynamat), paxmate covering it all, including the centre screw post. Stock bass port felt in place, 3 slots covered by electrical tape. A square of floppy craft felt, maybe 2mm thick, resting on the back of the cup (not glued in place). Stock white fabric on the cup side of the driver square, 3 sausages of tungsten putty (18g per cup) surrounding 3 sides of the driver housing. Plasticine in the seal between the baffle and the cup. On the ear side, the felt over the driver has been removed, and a paxmate lifter added under the rear-side of the pads (no other paxmate or putty on this side). Shure 840 pads with the centre foam removed.

 

T50RP_mod_1.png

 

Holy channel imbalance Batman! I would describe the sound as a bit confused, quite dark, somewhat congested in the upper bass / low midrange. The 1k resonance that's been plaguing my builds is also clearly visible, and quite annoying on certain songs, especially some female vocals that hit this note. At least the sound is fairly open, and the midrange, though imbalanced and a bit bumpy, has that amazing liquid quality that I can only assume is what everyone raves about when they talk about orthos (I don't own any other orthos). To my ears, the bass lacks extension - remember that you can't trust my graphs down there though.

 

 

 

Mod 2:

No plasticine in the cups. Paxmate on the bottom of the cups. Bass port felt removed entirely, and the ports left uncovered by paxmate on the inside of the cup. On the outside, electrical tape covers 3 slots. Half of a UK sized cotton ball in each cup, teased into a square the size of the bottom of the cup. The same tungsten putty surrounds the driver housing as in Mod 1, still got the plasticine seal between the baffle and the cup. Ear-side is identical.

 

T50RP_mod_2.png

 

Oh man, much much better. Firstly, I sorted the channel imbalance - that makes a big difference to the cohesiveness of the sound, I think. The mods have also really smoothed over the midrange, making it  fairly flat now. The sound is tighter, significantly faster too, partly due to there being less mid-bass bloat, and partly due to the lifted high frequency response (this one is only down at -10dB at 5kHz, whereas Mod 1 was down at -20dB. There's a dip immediately after 5k on this mod, but it doesn't go lower than Mod 1 does).  I've not noticed a sibilance problem with the 8k peak yet, but I think I'm fairly tolerant to sibilance compared to some people on these forums. The bass sounds to be better extended too - if I play my test tones, I would say things are pretty good down to about 30Hz, then take a bit of a dive after that, but nevermind.

 

 

 

In conclusion, I'm pretty happy with Mod 2 (most of the ideas for which came from bmf of course). If I do any more mods, I'll make sure to measure them, and if I think the mod is worth something, I'll post my measurements here. Whilst I would love to take a systematic approach, and measure each mod individually, I frankly don't have the time to be able to do this, plus I doubt that the mods are linear, in that if you stick two mods together, I doubt that the results will simply be the same as the sum of the individual parts, if that makes sense. If anyone else is toying with the idea, I encourage you to go and get your own SPL meter and give it a go - it's easy, and it seems to work surprisingly well. Was a great idea Twinster!



 

post #5073 of 10599

Owner requested I post this here...so here goes....

 

The Paradox Gamers Edition....

 

DSC_0006.jpg

post #5074 of 10599

Got my O2!  Initial: Very pleased with the T50RPs + O2 combination.

post #5075 of 10599
Quote:
Originally Posted by sphinxvc View Post

Got my O2!  Initial: Very pleased with the T50RPs + O2 combination.



Awesome!

post #5076 of 10599
i noticed earlier playing test tones on audacity that 100hz was bit uneven in the right side,so i opened it up added couple more cotton balls and closed it back up and now each driver is perfectly matched just about. these have great extension. extended down to 20hz very well with a good rumble and extended all way up to 20khz no sweat. i can still hear 20khz when i got my hearing checked out perfectly on both ears and these reach the 20khz extension like a champ,even though i found it extremely annoying when i was testing high frequencies on these due to i'm pretty sensitive to high and upper air frequencies.
Edited by RexAeterna - 11/25/11 at 7:18pm
post #5077 of 10599
Hey guys, i was thinking of picking up one of these next week, but before I do.
Is it possible I can change the pads to velour??
also is there any mods to make these even better
post #5078 of 10599

I put clay, dynamat & acoustic foam on the L side, and am now listening to half-modded, half-stock T50s.  The effect is subtle, but there is definitely less ringing/reverb/feedback (not sure what it's called) from the left side.  It results in a blacker, less fatiguing background.  

post #5079 of 10599
Quote:
Originally Posted by LFF View Post

Owner requested I post this here...so here goes....

 

The Paradox Gamers Edition....

 



So that is how a paradox will look, the paradox is quite interesting :D

 

edit: i can estimate how the non-gamer edition will look


Edited by abhinit90 - 11/25/11 at 10:06pm
post #5080 of 10599
Quote:
Originally Posted by abhinit90 View Post



So that is how a paradox will look, the paradox is quite interesting :D

 

edit: i can estimate how the non-gamer edition will look


LOL!

 

Mine looks like this:

 

P1010422p.jpg

 

P1010428p.jpg

 

post #5081 of 10599
Quote:
Originally Posted by LFF View Post



LOL!

Mine looks like this:

350x263px-LL-1779c23d_P1010422p.jpeg

350x263px-LL-a97f7846_P1010428p.jpeg

looks better when worn and kinda like ear muffs. what is that covering the outside?

EDIT: didn't know photos were this big. sorry,cause i do not know how to resize pictures.
Edited by RexAeterna - 11/25/11 at 11:48pm
post #5082 of 10599
Quote:
Originally Posted by RexAeterna View Post


looks better when worn and kinda like ear muffs. what is that covering the outside?
EDIT: didn't know photos were this big. sorry,cause i do not know how to resize pictures.


Pretty sure it's a sock?

 

What kind of pads are they, if I may ask?

post #5083 of 10599
Originally Posted by DaBomb77766 View Post

What kind of pads are they, if I may ask?


FA-003 leather pads.. only the finest in Russian comfort.

post #5084 of 10599

L/R balance issue seems to have comeback, really starting to annoy me, anybody here can say they don't have this problem? If not, how and what mods did you do.

 

They may become redundant soon, inexchange for LCD2. Pity though, because they really do have great drivers, just a bad design otherwise.

 

Something I noticed which I will try next, the screw holes on the left cup are worn and the baffle doesn't screw down tight like the right side, looks like its in need of some metal nuts on the inside instead of plastic screw holes, I mean to say, plastic screw holes,it's going to be a nightmare eventually.

post #5085 of 10599
If your source has a mono option, send identical signals to both channels. Then mute one side compared with the other side. This might be a useful alternative for those without a stock comparison set.

Quote:
Originally Posted by sphinxvc View Post

I put clay, dynamat & acoustic foam on the L side, and am now listening to half-modded, half-stock T50s.  The effect is subtle, but there is definitely less ringing/reverb/feedback (not sure what it's called) from the left side.  It results in a blacker, less fatiguing background.  

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