Fostex T50RP Incremental Mods and Measurements

[bluemonkeyflyer]

  The Alcantaras are extremely comfortable, I use them on my HE-4. I'll have to give them a try on the T50RP at some point.

Does the foam feel any different compared to 840 pads?  The perforations look pretty large. Based on a series of experiments to ventilate the 840 pads, bass rolls off pretty steeply from 200 Hz with just 6, 6mm cuts in the outside of the pad walls. I wonder what you and others who've tried Alcantara pads on modified T50RPs think about the bass? Did you have to compensate elsewhere to bring the bass up?
 
Has anyone tried bluecell replacement pads? They're likely from China. They make pads for most popular headphones. The 840 pads from bluecell cost $7 at Amazon.

 

[Thujone]

Well, I haven't tried them on the T50RP yet but they don't cause any sort of bass roll-off on the HE-4 (objectively). Subjectively the bass is better than the stock HFM velours, probably due to closer driver distance (they are really squishy).

 

[bluemonkeyflyer]

Here are dimensions for "Wave Guides" for T50RP and LCD2 v1.
 
T50/40/20RP Magnet Layout as shown:
 

Ear Side
 

Ear Side under Flash shows copper tracings
 

T50RP Magnet and Radical Russian Roulette Modified Frame
 
 

LCD2 v1 Rear Side
Six, 5  mm x 44 mm Magnets under Stators.
Add 5 mm to Left and Right verticals for Frames.
 
 

LCD2 v1 Ear Side has Thin Felt overlaying Thick Felt Damping
Six, 5 mm x 44 mm Magnets under Stators.
Add 5 mm to Left and Right verticals for Frames.

 

[hemipowered007]

This is my current mods. I opened them back up to double side tape the small card stock squares over the drive. Also to "seal" one of two custom bass ports, I used just the black tar type side of dynamat rolled into a ball and pressed into bass port hole. I also put akasa squares over the other bass port on each cup. Before with the 2 holes per cup, it was way to bassy. I would cover one hole each per cup and it would be better but still a little uncontrolled. If I covered all 4 it was anemic. But if I barely opened 2 of 4 it was near perfect. So now, I hope when I out them together its what I hope, if too anemic I'll poke holes in the akasa. Really really looking forward to all this "fazor" experimenting also. So far I'm happy with how these were while covering the bass ports but there is always a desire for better!

 

[hemipowered007]

Sorry for the crappy cell phone pics by the way.
Almost forgot, this is all with alpha pads. Also I did the ear side mod of akasa cutout exactly like bmfs above photos.

 

[bluemonkeyflyer]

Nice!
 
Looking forward to impressions and any details of what did and did not work for you.
 
Alpha Pads are very comfortable and well made.
 
 
Quote:

This is my current mods. I opened them back up to double side tape the small card stock squares over the drive. Also to "seal" one of two custom bass ports, I used just the black tar type side of dynamat rolled into a ball and pressed into bass port hole. I also put akasa squares over the other bass port on each cup. Before with the 2 holes per cup, it was way to bassy. I would cover one hole each per cup and it would be better but still a little uncontrolled. If I covered all 4 it was anemic. But if I barely opened 2 of 4 it was near perfect. So now, I hope when I out them together its what I hope, if too anemic I'll poke holes in the akasa. Really really looking forward to all this "fazor" experimenting also. So far I'm happy with how these were while covering the bass ports but there is always a desire for better!

 
 

Sorry for the crappy cell phone pics by the way.
Almost forgot, this is all with alpha pads. Also I did the ear side mod of akasa cutout exactly like bmfs above photos.

 

[ZGLISZCZ]

 

 

 
 
Hi Keith, 
 
I will try to export it for 3d print tomorrow ( I didn't 3d print anything yet), I think I finished modeling... frame is bit bigger will need to be cut if it wont fit screws. Can you take look on my private message and confirm sizes of top and bottom hole? For Fostex I dont think it will work if it will be at the top of dampening paper.  Cheers,

 

[hemipowered007]

I'm getting excited about this new adventure you guys are going on! This is awesome to watch/read right now.

 

[bluemonkeyflyer]

This looks great, Grzegorz!  I'm not certain of the "pitch" compared to the LCD2 v1 magnet width of 5 mm. Maybe 5 mm high, maybe a bit more...or less?
 
I loaned my LCD2's to my friend, again. I'll ask him to bring them to me tomorrow and I'll measure the smaller and wider areas at the top and bottom. I may be wrong, but I figured wave guides on the 6 main magnets would be enough; maybe not. I'll send them to you, though. 
 
RE:T50RP Wave Guides
 
The T50RP rear side (sides with the white damping material) probably can do without wave guides unless someone wants to remove the damping and start from scratch. I have two ear side wave guide designs in mind. What do you think?
 
BMF
 

Design One
 

Design Two
 

This confirms the layout of the magnets.
 
 
Quote:

 
 

 

 
 
Hi Keith, 
 
I will try to export it for 3d print tomorrow ( I didn't 3d print anything yet), I think I finished modeling... frame is bit bigger will need to be cut if it wont fit screws. Can you take look on my private message and confirm sizes of top and bottom hole? For Fostex I dont think it will work if it will be at the top of dampening paper.  Cheers,

 

[nick n]

any thoughts on using that guide with the ridges completely extending  to the rears in an open backed shell? Like slots with the only exit being the rear mesh. Wonder what that would do. Damping materials would have to be oput in I guess

 

[bluemonkeyflyer]

  any thoughts on using that guide with the ridges completely extending  to the rears in an open backed shell? Like slots with the only exit being the rear mesh. Wonder what that would do. Damping materials would have to be oput in I guess

 
Only that that is a Regal Idea worthy of testing!

 

[ZGLISZCZ]

 

Hi,
I think it won’t work well on top of tXXrp paper dampening but might work on ear side. Although because of plastic crate (which also doesn’t have smooth profile) there is not much space there. It might be better to make wave guides from small wood pieces with right profile. I believe it should be less than 30min work. I will actually try something like that on the ear side on my Monolith.
 
I started modeling custom headphones enclosure with driver enclosure (ear side part) integrated with baffle. That should make it more sturdy and give more options for earside wave guides design. But it will mean opening drivers and transplanting magnets, diaphragm and rear side of driver enclosure to new baffle. Should be fine but there are lot of work to do I will tell more when I will have more to show. Just hope printing wont cost fortune...
 
ah and by the way "fazors" I made have profile about 5x5mm maybe a bit higher, they just look like that from side view because frame obstruct view on their profile.

 

[bluemonkeyflyer]

  Hi,
I think it won’t work well on top of tXXrp paper dampening but might work on ear side. Although because of plastic crate (which also doesn’t have smooth profile) there is not much space there. It might be better to make wave guides from small wood pieces with right profile. I believe it should be less than 30min work. I will actually try something like that on the ear side on my Monolith.
 
I started modeling custom headphones enclosure with driver enclosure (ear side part) integrated with baffle. That should make it more sturdy and give more options for earside wave guides design. But it will mean opening drivers and transplanting magnets, diaphragm and rear side of driver enclosure to new baffle. Should be fine but there are lot of work to do I will tell more when I will have more to show. Just hope printing wont cost fortune...
 
ah and by the way "fazors" I made have profile about 5x5mm maybe a bit higher, they just look like that from side view because frame obstruct view on their profile.

Grzegorz,
 
I agree with you about putting wave guides on the T50RP rear side unless the paper damping material is sacrificed. I have a couple of sets without the damping paper that I can try rear wave guides on.
 
I think 3D printed wave guides on the ear side, however, are feasible if the ultra thin dust cover is cut removed. The design with 7 wave guides may be too much but I think the one with 4 wave guides could work. It would be fun and informative to try both if they can be modeled and 3D printed. 
 
I've used wire cutters to snip off the plastic grid "ladder rungs" that run horizontally, 90 degrees to the magnet length. Doing so leaves the 2 vertical plastic "ladder uprights" in place and does not significantly diminish the capsule integrity/strength.  Removing the horizontal "ladder rungs" should "open it up" and provide the 2 vertical columns of holes (Left side and Right side) running parallel with the magnet orientation more freedom to exit the driver capsule and react to the wave guides. I'll add a photo to show what I mean, later. Like this:
 

 
 
Your idea of fashioning wooden wave guides is worth trying. I think it will be difficult to make them all the same.
 
If you have the time and inclination, I'd love to see both the 4 and the 7 wave guide designs modeled in 3D
 
I will post the other dimensions for LCD v1, later today.
 
Thanks so much for sharing your New ideas and designs!

 

[Lohb]

  Grzegorz,
 
I agree with you about putting wave guides on the T50RP rear side unless the paper damping material is sacrificed. I have a couple of sets without the damping paper that I can try rear wave guides on.
 
I think 3D printed wave guides on the ear side, however, are feasible if the ultra thin dust cover is cut removed. The design with 7 wave guides may be too much but I think the one with 4 wave guides could work. It would be fun and informative to try both if they can be modeled and 3D printed. 
 
I've used wire cutters to snip off the plastic grid "ladder rungs" that run horizontally, 90 degrees to the magnet length. Doing so leaves the 2 vertical plastic "ladder uprights" in place and does not significantly diminish the capsule integrity/strength.  Removing the horizontal "ladder rungs" should "open it up" and provide the 2 vertical columns of holes (Left side and Right side) running parallel with the magnet orientation more freedom to exit the driver capsule and react to the wave guides. I'll add a photo to show what I mean, later. Like this:
 

 
 
Your idea of fashioning wooden wave guides is worth trying. I think it will be difficult to make them all the same.
 
If you have the time and inclination, I'd love to see both the 4 and the 7 wave guide designs modeled in 3D
 
I will post the other dimensions for LCD v1, later today.
 
Thanks so much for sharing your New ideas and designs!

The feedback from people with long 2.1's brain burn-in was the separation/soundstage got wider, but the bass lost its magic on the F iteration though it does not show so much on objective measuring graphs.....
I'm guessing there will need to be bass enhancement internal materials/tuning to off-set this with this DIY Fazzorr.

 

[bluemonkeyflyer]

 
The feedback from people with long 2.1's brain burn-in was the separation/soundstage got wider, but the bass lost its magic on the F iteration though it does not show so much on objective measuring graphs.....
I'm guessing there will need to be bass enhancement internal materials/tuning to off-set this with this DIY Fazzorr.

 
Thanks for this information.
 
I wonder if there is another variable that might be responsible for the impression that the bass quality/quantity is changed when uisng the Fazor? Some additional variables to consider include a thinner diaphragm, different rear side damping materials and their configuration, higher impedance, different magnets (strength and layout), and diaphragm tensioning.
 
It will be interesting to test for this effect with T50RP.