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Just listened to some Fostex T50RPs today... WOW! - Page 306

post #4576 of 10873

*** Edited** Just saw someone already point this out ***

 

This "acoustic Bass Lens" information is from the Sony MDR-F1 headphone.
 

Quote:
Originally Posted by rhythmdevils View Post



I think he's referring to "Bass Lens".  Fostex used the idea in their original T50 or at least in their OEM version for NAD, in which they have a ring/donut of felt on the ear side of the driver covering only the outside portion with a hole in the middle.  Here's a nice picture that's been posted a few times in the ortho thread.  I find that it can also work to remove peaks in certain areas of the upper midrange and treble without reducing perceived detail (I find covering the whole front of the driver can cause a reduction of perceived fine detail)

 

30caa662_mdrf1p2.gif

 

 



 


Edited by Twinster - 11/6/11 at 5:19pm
post #4577 of 10873
Quote:
Originally Posted by bluemonkeyflyer View Post

This is one of the most interesting posts I've read - thank you!

 

The topic of variable layering of least dense materials closest to the driver to most dense materials at the internal cup surface for reducing reflections has been discussed on this forum, but not in as much detail as you described in your post.  Dynamat and other materials have been tried on the internal cup surface and covered with less dense materials including open cell acoustic foam, cotton, fiberglass, etc., with consequent reduction of cup volume that may affect the sound. Several people, myself included, have tried Dynamat in the cups with a covering of Paxmate or similar acoustic foam. I did not hear any difference compared to Paxmate, alone. I don't remember if anyone else posted their impressions with this configuration. Armaegis pointed out that Dynamat may add mass loading to the cup if placed on the internal cup surface but would not result in reducing reflections because its constrained layer is not against the cup surface and is essentially mounted backwards from its intended design. (Armaegis: correct me if I am mistaken about what you said.) This got me to thinking about how to better (?) make use of Dynamat.  On BMF 5 and 6 mod configurations, I removed the dust cover and its adhesive residue from the ear side of the baffle surrounding the driver. Next, I placed Dynamat on the exposed plastic surface surrounding the drivers. To diminish reflections from the metallic-looking Dynamat constrained layer, I covered it with self-adhesive felt. 

 

After reading your post, I am now going to place AcoustiPack Lite in the cup bottoms (not the sides) to take advantage of its constrained layer (most dense layer the greatest distance from the back of the drivers). Next, on top of the AcoustiPack I am going to add 1 layer of Paxmate (not the sides) to take advantage of its (I presume) less dense and greater quantity of open cell foam in closer proximity to the back of the drivers. Everything else in my "Less Is More" and "Transpore 1.5" mods will remain the same, as described in post 4513 a few pages back, including 1/2 of one medium cotton ball loosely teased and placed between the Paxmate and the back of the driver - the least dense material closest to the back of the driver.

 

BTW, would you describe "bass rings?"



Well, dynamat is not for fighting reflection, but for fighting secondary sound emission from cups. Indeed, as it reduces cup volume, it can actually produce worse result than just using more Paxmate layers to absorb the sound. There is really somewhat too little space in these cups. I've been thinking about someday using monolithic wooden bowls and dishes as cup and baffle respectively to get new, larger, betted damped cups and then using all the stuff described here. But that is not going to happen soon.

 

The bass rings are indeed what rhytmdevils said, bass lens.


 

Quote:
Originally Posted by rhythmdevils View Post

BMF, I'm really surprised that you'd hear more bass with more of these vents open.  Kind of goes against all the conventional wisdom about it.  But we could be mistaken, or the T50rp could somehow be different, so keep exploring!  Maybe the key is a small hole, or where it is placed so close to the driver. 


IMHO that just undampened the driver and increased throw. Probably there is less sub-bass now, the question is how more "sub" it is. If the rolloff is  below 10 Hz, I don't see a problem. However, underdamping may result in sloppy and boomy sound..

 

post #4578 of 10873

quick question. I'm sure I could ask this in some other thread but oh well. Is plasticine the only type of clay I should use for the inside of the baffle on the T50RP? Or will any similar modeling clay work?

post #4579 of 10873
Quote:
Originally Posted by marioman94 View Post

quick question. I'm sure I could ask this in some other thread but oh well. Is plasticine the only type of clay I should use for the inside of the baffle on the T50RP? Or will any similar modeling clay work?



I used Sculpey with good results.  Just so long as it doesn't air dry it should be fine.

 

Anyway, after using these for awhile, I'm really missing the comfort of my 595s...I just can't wear these for longer than an hour before having to give my ears a break.

post #4580 of 10873

Just as long as it's one that doesn't dry out, it should be fine.

post #4581 of 10873
Quote:
Originally Posted by DaBomb77766 View Post



I used Sculpey with good results.  Just so long as it doesn't air dry it should be fine.

 

Anyway, after using these for awhile, I'm really missing the comfort of my 595s...I just can't wear these for longer than an hour before having to give my ears a break.



Is that with the stock pads? I'm planning on getting SRH840 pads at some point.

post #4582 of 10873
Quote:
Originally Posted by DaBomb77766 View Post



I used Sculpey with good results.  Just so long as it doesn't air dry it should be fine.

 

Anyway, after using these for awhile, I'm really missing the comfort of my 595s...I just can't wear these for longer than an hour before having to give my ears a break.



Make sure you do the simple headband mod. For me it made wearing these headphone more comfortable.

post #4583 of 10873
Quote:
Originally Posted by Raguvian View Post



Is that with the stock pads? I'm planning on getting SRH840 pads at some point.



Yeah, the 840 pads are on order right now, should hopefully be here later in the week.


 

Quote:
Originally Posted by snakeeater69 View Post



Make sure you do the simple headband mod. For me it made wearing these headphone more comfortable.



Yup, I did that, though it's a bit sloppy right now.  Definitely makes it more comfortable but it doesn't fix the earpads.  Pretty damn uncomfortable...they're too shallow and my ear rubs up against the side/back.  Stuffing tissues in the back of the earpads does help significantly, but the earpads themselves are just too hard to mold to my head properly...hopefully the 840 pads are at least a little softer?

post #4584 of 10873
Quote:
Originally Posted by DaBomb77766 View Post

Yup, I did that, though it's a bit sloppy right now.  Definitely makes it more comfortable but it doesn't fix the earpads.  Pretty damn uncomfortable...they're too shallow and my ear rubs up against the side/back.  Stuffing tissues in the back of the earpads does help significantly, but the earpads themselves are just too hard to mold to my head properly...hopefully the 840 pads are at least a little softer?


The 840 pads will be softer but what is even better is if you sandwich the T50RP pads with 840 pads.

 

post #4585 of 10873
Quote:
Originally Posted by snakeeater69 View Post


The 840 pads will be softer but what is even better is if you sandwich the T50RP pads with 840 pads.

 



Probably gonna have to do some serious modding of the earpads to make that happen.  I've never really sewn anything before. :P

post #4586 of 10873

Sorry guys, ran out of time this weekend and didn't get a chance to try making and measuring a BMF mod.  It'll thus be two weeks, maybe more.  Just too busy at the moment...

 

Cheers....

post #4587 of 10873

Quote:

Originally Posted by DaBomb77766 View Post

I used Sculpey with good results.  Just so long as it doesn't air dry it should be fine.

 

Anyway, after using these for awhile, I'm really missing the comfort of my 595s...I just can't wear these for longer than an hour before having to give my ears a break.


I have some super sculpey on hand; would that work?  

 

Sculpey tends to become rock hard in colder environments over time, the 2 lbs. of clay I have sitting in my closet are probably rock hard by now -- would this be a problem?

 

post #4588 of 10873


Holy cow this thread moves fast at weekends.

 

Quote:

Originally Posted by Nevod View Post

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?



I had a big 1k resonance problem when I had the paxmate earside. I know it sounds unlikely, but removing that paxmate seemed to magic the problem away - I can offer no expanation as to why that happened. 

 

And for some reason, Opera on Ubuntu won't let me write below the next quote, so I'll reply to it here. BMF, I wouldn't say that my mods are perfect yet. The sound to me is pretty close to what I had before when I built a pseudo RP2i. The mids are nice and lush and warm, the bass is fast, but it's definitely missing a smidgen right down at the sub-bass region, which probably means mrspeakers is achieving something I'm not yet. Highs are slightly rolled off compared to my other (arguably bright) headphones, but it's quite pleasant. The main thing the foam and cotton combo changed for me was the sense of openness. And once I'd killed that 1k resonance by removing the earside paxmate (nope, still no idea), I became quite pleased with the overall sound. There is still perhaps a slight... confusion to the sound occasionally though - I suspect it might be due to the channel imbalance I have in the upper mids, combined with the roll-off on the highs that I'm not too used to. I don't think I'm the only person on here fighting similar channel balance problems though. 

 

Oh, and the sketch was quickly knocked up in Photoshop (CS2) on a Wacom. Maybe when I actually think I've 'finished' with the T50 mods and get them 'perfect', I'll put some time into drawing up a diagram properly. I suspect that's a long way off yet.



Quote:
Originally Posted by bluemonkeyflyer View Post

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?"

 



 



 

post #4589 of 10873
Quote:
Originally Posted by rhythmdevils View Post


"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. 

 


This.  Every time I pulled mine apart, that connector box kept looking at me to tell me that even if I got another T50RP and transplanted the second connector box equipped cup...it might be volumetrically matched...but not visually.

 

post #4590 of 10873
Quote:
Originally Posted by SP Wild View Post


This.  Every time I pulled mine apart, that connector box kept looking at me to tell me that even if I got another T50RP and transplanted the second connector box equipped cup...it might be volumetrically matched...but not visually.

 


 

That would be an easy way to get a single ended re-cable and a balanced pair....

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