Fostex T50RP Incremental Mods and Measurements
Nov 20, 2014 at 3:02 AM Post #1,396 of 2,832
Great work
beerchug.gif

 
Nov 20, 2014 at 7:42 AM Post #1,397 of 2,832
  Hi Guys,
 
Bit late but I did wave guide for LCD2's without fazors:wink: it will need to be glued as I wasn't sure what is the size between edge of opening and nut. I'm not sure if its not too thin but should be fine, if not I can change frame to more thicker. I'm attaching the screen with cross-section of one of the guide (it also shows exact sizes in millimeters).

 
 
If anyone would like to get .OBJ file or see preview of the waveguides then go to this link: https://sketchfab.com/models/2ad2680119914de69ab8fb7dfeaedd28#share
 
Also please keep in mind that I checked everything and it all seems fine but I never really did and 3d print so would be nice if someone will first test if its printing nicely to avoid any surprises. tXXrp wave guides will be soon. If someone would like to have .STL file then please pm me.

 
Looks great!
 
The bottom space is 1.5 mm and the top space is 1.9 mm between the edge of the slotted openings and the nuts. 
 
Many thanks
 
Nov 20, 2014 at 8:04 AM Post #1,398 of 2,832
Hi Keith and thanks,
 
I will take look at them after work and quickly fix it if there will be differences in sizes, I was just guessing them based on your fhoto. By the way 3d print should be quite cheap as it have small volume. when you will commit OBJ file to any 3d printing place please make sure that bounding box size are same as on image in my previous post.
 
Nov 20, 2014 at 8:18 AM Post #1,399 of 2,832
  Hi Keith and thanks,
 
I will take look at them after work and quickly fix it if there will be differences in sizes, I was just guessing them based on your fhoto. By the way 3d print should be quite cheap as it have small volume. when you will commit OBJ file to any 3d printing place please make sure that bounding box size are same as on image in my previous post.

ZGLISZCZ,
 
By "bounding box size," do you mean the outer dimensions of the wave guide (L x W) at X and Y? I assume Z=Height...is "56" 5.6mm from the the base of the box to the top of wave guides?
 
I downloaded the .OBJ file. If you tweak it, I'll download the new file once you post it. What software program do you recommend for opening the .OBJ file?
 
Beautiful work...Thank you!
 
Edit: O.K., now I understand the dimensions are: X:77mm, Y:3.8mm, Z:56mm ...But, you may tweak it a bit to acommodate the 1.4mm and 1.9mm gaps between the nuts and edges of the upper and lower slots. 
 
Nov 20, 2014 at 10:18 AM Post #1,400 of 2,832
  ZGLISZCZ,
 
By "bounding box size," do you mean the outer dimensions of the wave guide (L x W) at X and Y? I assume Z=Height...is "56" 5.6mm from the the base of the box to the top of wave guides?
 
I downloaded the .OBJ file. If you tweak it, I'll download the new file once you post it. What software program do you recommend for opening the .OBJ file?
 
Beautiful work...Thank you!

Hi Keith,
 
whole element is laying flat in 3d space as it has to be like that for easy 3d print. If you will take look on image from my post (the one with sizes, your photo on left and zoomed in profile of one of the guide) then whole model is laying like this. bottom is the flat side. so height is 3.8mm almost ( height is the thin line in the middle of zoomed in guide profile. and other sizes are 76.7mm (basically 77mm) and 56mm (44mm plus 2x6mm frame) you can open it in Blender or any other 3d software (but blender is free) although I decimated the model to make it more 3d print friendly. I will send you file before the subdivide and one with basic shapes from which I started modeling just please send me your email address in pm. .OBJ file I shared should have set up sizes for 3d print but I would suggest to ask someone who will print it if he can check those sizes just in case. Please let me know if you have any other questions
 
Nov 20, 2014 at 3:40 PM Post #1,401 of 2,832
BMF's writeup mentions removing the ear-side dust cover then adding a Dynamat/felt ring. However, the image shows a photo w/ the dust cover still intact. Later in the other modifications somebody posted a Paxmate ring and showed the dust cover removed. Some have said the dust cover has no acoustic impact. I chose to remove mine because A) I accidentally smeared some Newplast residue on the dust cover and it _might_ have affected sound and B) the raw plastic might just be a better surface for the Dynamat to adhere to. Removing the dust cover is a painful process involving 30-45 minutes of careful scraping so take that into consideration.
 
I cut my template, measuring 40mm on each edge of the driver, cut the Dynamat, cut Creatology adhesive felt, bonded it all together and slapped it onto the baffle. For now, my baffle ports are open, though it is hard to see in the finished product. Here are my two photos, clearly showing the template, the lack of dust cover, and the finished product (slightly ragged, much to my dismay).
 

 

 
As to the sound? Got me. The sound seems very open at this point, though I don't know this particular mod caused it or helped it. Some of the finest details are heard, again I don't know if this mod helped. The frequencies seem all very balanced and well represented, but I would still like to bring in more low end. They are incredibly lifelike, with good instrument tone, sparkle, all that stuff, they just do not represent the fun of hiphop. I feel compelled to turn them up a bit too far to be really immersed.
 
A few weeks back, BMF posted "random thoughts on damping". I think I am ready for that phase. I do not have any Paxmate ladders, balsa structure, multiple fill materials, or even played with bass ports or baffle ports so I'm going to focus there next to try and bring in the low end. Somehow my Lawton L2 Denons make my jaw drop every time I put them on and I'd like something closer to them.
 
Nov 20, 2014 at 7:41 PM Post #1,402 of 2,832
  BMF's writeup mentions removing the ear-side dust cover then adding a Dynamat/felt ring. However, the image shows a photo w/ the dust cover still intact. Later in the other modifications somebody posted a Paxmate ring and showed the dust cover removed. Some have said the dust cover has no acoustic impact. I chose to remove mine because A) I accidentally smeared some Newplast residue on the dust cover and it _might_ have affected sound and B) the raw plastic might just be a better surface for the Dynamat to adhere to. Removing the dust cover is a painful process involving 30-45 minutes of careful scraping so take that into consideration.
 
I cut my template, measuring 40mm on each edge of the driver, cut the Dynamat, cut Creatology adhesive felt, bonded it all together and slapped it onto the baffle. For now, my baffle ports are open, though it is hard to see in the finished product. Here are my two photos, clearly showing the template, the lack of dust cover, and the finished product (slightly ragged, much to my dismay).
 

 

 
As to the sound? Got me. The sound seems very open at this point, though I don't know this particular mod caused it or helped it. Some of the finest details are heard, again I don't know if this mod helped. The frequencies seem all very balanced and well represented, but I would still like to bring in more low end. They are incredibly lifelike, with good instrument tone, sparkle, all that stuff, they just do not represent the fun of hiphop. I feel compelled to turn them up a bit too far to be really immersed.
 
A few weeks back, BMF posted "random thoughts on damping". I think I am ready for that phase. I do not have any Paxmate ladders, balsa structure, multiple fill materials, or even played with bass ports or baffle ports so I'm going to focus there next to try and bring in the low end. Somehow my Lawton L2 Denons make my jaw drop every time I put them on and I'd like something closer to them.

 
Nice work! 
 
Removing the dust cover from around the ear side of the driver may help Dynamat work as designed. It's easy to remove the dust cover if you have a Dremel with a barrel sanding attachment.
 
Covering the ear side of the baffle with felt or Paxmate (over Dynamat, or not) helps reduce ear side reflections. 
 
For more bass, try removing the stiff felt from the inside of the cup vents. If too bassy, you could try covering 1 of 4 cup vent slots with felt or tape... then 2 of 4, and so on until you dial it in.
 
You can also modify the baffle vent to make it smaller or close it off, entirely.
 
Nov 21, 2014 at 10:23 PM Post #1,403 of 2,832
Yesterday I realized the 1x3mm bass port was actually to reduce bass, not add bass. Upon this realization I removed all masking tape from the cup vents. This helped present the really low bass, but bass was not on par with the rest of the frequencies.
 
Today I spent a few hours grinding out the last couple tedious bits. A few things together really bolstered the low-end. My Fostexes are fun now :D
 
I started by tearing everything apart and looking over my jack and wire passthoughs for gaps. I sealed everything again with more liquid gasket.
Since it is all the rage, I grabbed my small screwdriver and added a bunch of stars to the Newplast.
I then scrutinized the Silverstone in the cup bottoms and the adhesive felt in the cup middles, removed 3 of the 4 Silverstone strips and all of the adhesive felt, and reinstalled with slightly more edge to edge coverage.
I then applied 28 3x18mm Silverstone strips over the existing Silverstone in the cup bottoms to create ladders. I used 7 on each side of the cup except for the jack side, which used 6.
I was using CVS sterile cotton balls in my previous build but wanted to switch to rolled cotton and fiberglass. The CVS sterile rolled cotton does not separate nearly as well as the RiteAid cotton photos, but I managed to approximate 15 layers in an uncompressed 2x6x7cm format.
The JM fiberglass I found was an odd sandy blond color and mostly uniform save for a few small clumps. After removing the clumps I gathered enough layers for a compressed 1x6x7cm batting.
 
I buttoned it all up with the screws this time and had a listen. I didn't get a chance to listen to much reference material yet, but the kickdrums are much improved. Scanning through some dance songs, hip hop songs, and other low frequency stuff, I found them all a LOT better. Wow! I blew the incremental mods and measurements part with this last round, but the bass is there and it is really low!
 
My next step is to put in some more hours on some familiar songs and likely A/B the Fostex with the Denons. I would still like to build a measuring rig and actually scrutinize the weight of the materials, but I'm optimistic that most of the way there.
 
 

 
 



 
Nov 22, 2014 at 1:57 AM Post #1,404 of 2,832
  Yesterday I realized the 1x3mm bass port was actually to reduce bass, not add bass. Upon this realization I removed all masking tape from the cup vents. This helped present the really low bass, but bass was not on par with the rest of the frequencies.
 
Today I spent a few hours grinding out the last couple tedious bits. A few things together really bolstered the low-end. My Fostexes are fun now :D
 
I started by tearing everything apart and looking over my jack and wire passthoughs for gaps. I sealed everything again with more liquid gasket.
Since it is all the rage, I grabbed my small screwdriver and added a bunch of stars to the Newplast.
I then scrutinized the Silverstone in the cup bottoms and the adhesive felt in the cup middles, removed 3 of the 4 Silverstone strips and all of the adhesive felt, and reinstalled with slightly more edge to edge coverage.
I then applied 28 3x18mm Silverstone strips over the existing Silverstone in the cup bottoms to create ladders. I used 7 on each side of the cup except for the jack side, which used 6.
I was using CVS sterile cotton balls in my previous build but wanted to switch to rolled cotton and fiberglass. The CVS sterile rolled cotton does not separate nearly as well as the RiteAid cotton photos, but I managed to approximate 15 layers in an uncompressed 2x6x7cm format.
The JM fiberglass I found was an odd sandy blond color and mostly uniform save for a few small clumps. After removing the clumps I gathered enough layers for a compressed 1x6x7cm batting.
 
I buttoned it all up with the screws this time and had a listen. I didn't get a chance to listen to much reference material yet, but the kickdrums are much improved. Scanning through some dance songs, hip hop songs, and other low frequency stuff, I found them all a LOT better. Wow! I blew the incremental mods and measurements part with this last round, but the bass is there and it is really low!
 
My next step is to put in some more hours on some familiar songs and likely A/B the Fostex with the Denons. I would still like to build a measuring rig and actually scrutinize the weight of the materials, but I'm optimistic that most of the way there.
 
 

 
I agree on the statement to some extent. Bass vents, if I remember, are there to increase air compliance. Meaning the air moves more freely in the cup, allowing easier driver movement which usually means more bass. If your cup is packed with dense cotton or thick wool, like I think I see BOTH in those photos, that can block air from moving freely. Hence why you maybe experience low bass levels, as most generally don't pack their cups that densely (I think anyways, don't quote me on that, I am by FAR no expert.... heh, that's what BMF is for :wink: ) Heh I'm glad you realized what they were for!  
 
  That being said, I have a similar mod to yours, ladder foam, newplast but only just a single layer of rolled cotton, But the bass vents are completely open. I would definitely agree with most in saying this is too much most times, but the lower and lower you turn your volume, the less and less bass you end up perceiving. I like listening at lower volumes so this is great for me.
  I also game, and I think T50RPs make PERFECT gaming sets (whole other side rant for another day why I think they are so great), I like movies as well, and I like just the smallest touch bit more bass anyways, in indescribability perfect for me.
 
Anyways got off topic from my actual point. I digress. I never seem to find anyone here in my town who knows enough about cans so I can brag to them, got to get my happy rants out somewhere.....
 
Nov 24, 2014 at 7:01 PM Post #1,406 of 2,832
   
I agree on the statement to some extent. Bass vents, if I remember, are there to increase air compliance. Meaning the air moves more freely in the cup, allowing easier driver movement which usually means more bass. If your cup is packed with dense cotton or thick wool, like I think I see BOTH in those photos, that can block air from moving freely. Hence why you maybe experience low bass levels, as most generally don't pack their cups that densely (I think anyways, don't quote me on that, I am by FAR no expert.... heh, that's what BMF is for :wink: ) Heh I'm glad you realized what they were for!  
 
  That being said, I have a similar mod to yours, ladder foam, newplast but only just a single layer of rolled cotton, But the bass vents are completely open. I would definitely agree with most in saying this is too much most times, but the lower and lower you turn your volume, the less and less bass you end up perceiving. I like listening at lower volumes so this is great for me.
  I also game, and I think T50RPs make PERFECT gaming sets (whole other side rant for another day why I think they are so great), I like movies as well, and I like just the smallest touch bit more bass anyways, in indescribability perfect for me.
 
Anyways got off topic from my actual point. I digress. I never seem to find anyone here in my town who knows enough about cans so I can brag to them, got to get my happy rants out somewhere.....

 
 
I'm no expert, either!
 
From my experiments, when the driver is depressurized by more venting, which allows for greater diaphragm excursion, you get more bass.
 
Nov 24, 2014 at 10:24 PM Post #1,407 of 2,832
Hmm, seems the forums are glitching, I can see you posted BMF, but the link seems to think there's a separate reality
 
 
EDIT: Might have been a local issue, seems after I posted this everything magically fixed itself.
 
 
And heh, well more expert then the average poster :wink:
 
But yes, less work compressing air, the easier the movement the more it moves on those big bass movements? Seems like it makes sense.
 
Considering how isobaric suspension speakers work, 2 cones connected by a completely sealed tube. Helps keeps things in control, but unfortunately doesn't help much in the volume departments. I could explain why it works, but its not on topic
 
 
BUT that being said, moving onto a new idea,
 
what about isobaric cans? As a general rule a isobaric type system acts like it would if it was a single driver in twice the cabinet size, and in theory twice as clean sounding (or 50% ish depending on what you read). Although it takes twice the power for no gain in volume (twice the amount of drivers of course) Great in car sound systems (or even little model trains) for sub-woofers when power isn't an issue but space is. Maybe the same thing with headphones? I feel that thin ortho drivers could work amazingly with this set up. Although they would weigh a TON.
 
Nov 25, 2014 at 2:59 PM Post #1,408 of 2,832
After adding akasa over my 2 bass ports per cups(remember customized cups w 2 3/16 holes at top of cups and all others bondoed) then poking tiny holes in each, ive got my bass just right. Nowhere near bass-head levels. And unless you crazy folks come up with these new cups, or baffle mods, or fazors, im done with this set. Now, i want to find a cheap t20/40/50 and start this open mod in the next year. Its gotta be possible, question is, can this driver get anywhere near my he4? Itd be real cool.
 
Nov 26, 2014 at 4:16 PM Post #1,409 of 2,832
Hey BMF, what do you think about naked drivers and cutting the cups up a little to make them open? I was thinking about trying it but I don't want to wreck a pair of cups doing it and it sounding bad.
That's what I meant, making simple full open wood enclosures with enough space to dampen IF necessary. I wish I had time to try it. Wouldn't be pretty but I could make cups pretty easily for these I think.

Voilà, presenting my open T50RPs T500RP- style...
Wood - Karelian Birch, Pads:HM5 Velours
 
Measurements:

 

Now I am wondering what the T500RPs will measure like ...
By the way, these sound great.
 

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