Just listened to some Fostex T50RPs today... WOW!

[200poundsofamp]

Has anyone measured a T50rp with a reflex dot before? Because uh,

T20v2 with reflex dot
T50rp without

Different driver, but still. That just looks too weird.

Probably why the clarity on the V2 didn't seem as good! Strange thing is it doesn't sound that bad, you'd think they'd be ridiculously harsh.

 

[Twinster]

It's getting serious guys! Here's my new design. A test tone reader based on my old Radio Shack sound level meter from the HT days I'm testing using various frequency tone to fine out the peak & lows. I'm doing one side at the time and that also make me realized that they were not equal 

.
To be followed....
 



 
So far this is the reading of my T50rp. (Pretty draft graph. It's getting late) 
 

 

[rhythmdevils]

^ That is the very definition of Ghetto Fabulous.  When I look up the term on urban dictionary I want to see those pictures next to the sooped up Grama car. 

 
Quote:

Probably why the clarity on the V2 didn't seem as good! Strange thing is it doesn't sound that bad, you'd think they'd be ridiculously harsh.

I thought the T20v2 was incredibly harsh, that graph correlated pretty well with what I heard.  I did think they managed it in an ortho-ish way, there was level of smoothness, but the upper midrange was harsh IMO.  I'm really sensitive to it though, most people think the T20v2 is smooth as they are still less harsh than most electro(ie typical)dynamics.  But I didn't use Akasa foam in them so that could be why my T50rp sounds smoother. 
 

 

[bluemonkeyflyer]

Brilliant!  Now, that is "thinking outside the box!"   

 
I've got the same SPL meter. What's your method and link to the tone generator you used? It would be fun to try. 
 
Did you test them stock for a baseline before modding?  If not, I still have 4 stock sets and could duplicate your methods and procedure, take the average, and have a rough estimated baseline.
 
Homemade Science...gotta love it.  'course we could spend countless hours agonizing over the color of cardboard box, type of foam, whether to counterbalance the box or not, brand of batteries, weighting and speed settings, and so on and on and on....LOL
 
Quote:

It's getting serious guys! Here's my new design. A test tone reader based on my old Radio Shack sound level meter from the HT days I'm testing using various frequency tone to fine out the peak & lows. I'm doing one side at the time and that also make me realized that they were not equal 

.
To be followed....
 



 
So far this is the reading of my T50rp. (Pretty draft graph. It's getting late) 
 

 

 

[MDR30]

Quote:

Has anyone measured a T50rp with a reflex dot before? Because uh,

T20v2 with reflex dot
T50rp without

Different driver, but still. That just looks too weird.

Probably why the clarity on the V2 didn't seem as good! Strange thing is it doesn't sound that bad, you'd think they'd be ridiculously harsh.

The T50RP has its own built-in reflex dot (don't know about the T20v2), the cover of the head-assembly joint, so there shouldn't be much of a difference.

 

[symphonic]

Hey guys, I'm late to the party on this, but my T50RPs arrived yesterday with some Beyer gel pads. Mod time!.
 
I have a little Panasonic WM61 mic capsule that can fit in my ear for measurements with Room EQ Wizard. I've already looked a little at the freq response. I'm considering making a convertible open/closed headphone with different damping schemes. (Or interchangeable cups at least, to avoid buying lots of T50RPs.) So I've looked a little at the measurements with no cup attached, but WITH the ear pad. The bass is certainly diminished, but I didn't see that huge of a difference over stock otherwise.
 
Besides 4nradio, everything seems to have given up on an open back design. Is it really not possible? What if I'm willing to sacrifice bass completely and let a subwoofer handle that. HRTF measurements that were made with a closed ear canal work best with headphones that approximate best free air, so an open design might be best for using my own measured HRTFs with movies. 
 
To the other guys with measuring gear - can you have a look at the open back (baffle + earpad) configuration as well, and let me know what you see?

 

[Arleus]

I'm still hoping to get some cups made (3D printed) over the next few months. I'll go with an open design - probably something that looks vaguely like the HE500 cups with a large flat grille that I can later cover if I decide that open just won't work. I'll definitely keep you guys updated if I get this project rolling, but I wouldn't hold your breath waiting for me to do that. It might be one of those things that never actually gets going (I do, afterall, have many other things to be getting on with).
 
@Twinster: does that SPL meter give you the option to set the weighting, and if so, what did you pick?

 

[Twinster]

Hey BMF. I would be glad to share my process with you.
 
I'm using the tone generator from this link  http://www.ronelmm.com/tones/. I've set the meter to C weighting & fast or slow speed doesn't matter because the tone is steady for 10 sec.
I have set the volume on my amplifier a bit over my normal listening level so it average around 90 DB. I did the test twice for each tone for Left & Right side.
I didn't test my T50rp stock (They have been altered about 5 times already) but would like to see the graphs you come up with.
 
What 's wrong with my fashionably white cardboard? I can add color on it or stick Leopard fabric if you like 

. For your interest I've used two blank clear plastic disk from a CD Stack for both side and covered them with Paxmate to provide a good seal and block the reflection. It work very well and provide a good solid platform to install the headphone on.

 
Quote:

Brilliant!  Now, that is "thinking outside the box!"   

 
I've got the same SPL meter. What's your method and link to the tone generator you used? It would be fun to try. 
 
Did you test them stock for a baseline before modding?  If not, I still have 4 stock sets and could duplicate your methods and procedure, take the average, and have a rough estimated baseline.
 
Homemade Science...gotta love it.  'course we could spend countless hours agonizing over the color of cardboard box, type of foam, whether to counterbalance the box or not, brand of batteries, weighting and speed settings, and so on and on and on....LOL
 


 

 

 

[bluemonkeyflyer]

Twinster,
 
Many thanks for the reply!  
 
I made a headphone adapter for my RadioShack SPL meter several months ago like the one you made. I never thought about using it with test tones the way you have; great idea to play with and compare to what you hear as you mod and tweak.
 
So, you set the amplifier volume at 90 dB measured by your SPL meter for any particular song and kept it at that setting for all tones?  I don't  know if this makes any sense and would work or not but, did you choose a benchmark frequency, i.e. maybe 1KHz, set the amp volume to 90 dB and keep it there for all other test tones?
 
Why does the disk on the non-measured side need Paxmate?
 
Surely you will agree that a white box is best for white noise and a pink box is a "must" for pink noise. You're going to whole 'nother dimension with Leopard fabric!
 
Quote:

Hey BMF. I would be glad to share my process with you.
 
I'm using the tone generator from this link  http://www.ronelmm.com/tones/. I've set the meter to C weighting & fast or slow speed doesn't matter because the tone is steady for 10 sec.
I have set the volume on my amplifier a bit over my normal listening level so it average around 90 DB. I did the test twice for each tone for Left & Right side.
I didn't test my T50rp stock (They have been altered about 5 times already) but would like to see the graphs you come up with.
 
What 's wrong with my fashionably white cardboard? I can add color on it or stick Leopard fabric if you like 

. For your interest I've used two blank clear plastic disk from a CD Stack for both side and covered them with Paxmate to provide a good seal and block the reflection. It work very well and provide a good solid platform to install the headphone on.

 


 

 

 

[bluemonkeyflyer]

Arleus,
 
3D printed cups? How? Where?
 
Quote:

I'm still hoping to get some cups made (3D printed) over the next few months. I'll go with an open design - probably something that looks vaguely like the HE500 cups with a large flat grille that I can later cover if I decide that open just won't work. I'll definitely keep you guys updated if I get this project rolling, but I wouldn't hold your breath waiting for me to do that. It might be one of those things that never actually gets going (I do, afterall, have many other things to be getting on with).
 
@Twinster: does that SPL meter give you the option to set the weighting, and if so, what did you pick?

 

 

[Twinster]

To be honest I didn't put a lot of thinking on the volume level & frequency setting. Like I said I just set the volume to a level and kept it on same level for the entire frequency sweep test. A benchmark frequency make sense. I'll do some research tonight on the process but if anyone want to recommend a process by no mean do. I'm not trying to compete with Tyll's here 

 this was just a tool to help me fine tune my T50rp.
 
Cheers!
Quote:

Twinster,
 
Many thanks for the reply!  
 
I made a headphone adapter for my RadioShack SPL meter several months ago like the one you made. I never thought about using it with test tones the way you have; great idea to play with and compare to what you hear as you mod and tweak.
 
So, you set the amplifier volume at 90 dB measured by your SPL meter for any particular song and kept it at that setting for all tones?  I don't  know if this makes any sense and would work or not but, did you choose a benchmark frequency, i.e. maybe 1KHz, set the amp volume to 90 dB and keep it there for all other test tones?
 
Why does the disk on the non-measured side need Paxmate?
 
Surely you will agree that a white box is best for white noise and a pink box is a "must" for pink noise. You're going to whole 'nother dimension with Leopard fabric!
 


 

 

 

[Arleus]

About a year ago, we got some optical grids (for focussed Schlieren - don't ask, was a total waste of time) 3D printed by an online company - Shapeways - we uploaded a CAD model of the part, and they printed it and posted it directly to us. The grids were quite small parts, about 50x70x5mm, and were quite cheap. I won't have a very good idea of how much a pair of cups will cost until I draft up the parts in CAD and submit them for a quote unfortunately, but if it's not horrible, I might make the investment FOR SCIENCE!
 
Quick note to those who don't know what 3D printing is: also known as rapid prototyping, a machine takes a computer model of an object, and builds it up out of a polymer, layer by layer. This means that you can make very intricate and detailed parts that you wouldn't normally be able to do by milling down a solid block. You could, for example, make a swiss-cheese with holes in it, which milling wouldn't be able to do. I thought this would be a good method of making cups, because it would allow for the mounting for an angled driver to be made quite easily. 
 
Quote:

Arleus,
 
3D printed cups? How? Where?
 


 

 

 

[sphinxvc]

^ I would be interested in a group buy if they were available at an agreeable price.

 

[bluemonkeyflyer]

Nice!
 
Yes, this is an amazing process. I saw a demonstration of Discovery or some other program. They scanned a crescent wrench and built one fully intact with functional adjusting mechanism. I just assumed the cost would be sky high. I wonder what the cost would be for a pair of something, say, 100x90x30mm?  Check out youtube.
 
The custom angle by CAD design is a good idea. Is this something you plan to share, or sell?
 
What about graphics?
 
Quote:

About a year ago, we got some optical grids (for focussed Schlieren - don't ask, was a total waste of time) 3D printed by an online company - Shapeways - we uploaded a CAD model of the part, and they printed it and posted it directly to us. The grids were quite small parts, about 50x70x5mm, and were quite cheap. I won't have a very good idea of how much a pair of cups will cost until I draft up the parts in CAD and submit them for a quote unfortunately, but if it's not horrible, I might make the investment FOR SCIENCE!
 
Quick note to those who don't know what 3D printing is: also known as rapid prototyping, a machine takes a computer model of an object, and builds it up out of a polymer, layer by layer. This means that you can make very intricate and detailed parts that you wouldn't normally be able to do by milling down a solid block. You could, for example, make a swiss-cheese with holes in it, which milling wouldn't be able to do. I thought this would be a good method of making cups, because it would allow for the mounting for an angled driver to be made quite easily. 
 


 

 

 

[bluemonkeyflyer]

The 1KHz resonance problem has been brought up many times on this forum. I am interested in hearing from any of you good people willing to describe your best example of this problem.
 
Please describe:
 
1. Your audio chain
2. Name of artist/song and time markers where it occurs
3. Measured or estimated SPL where you most easily notice it
 
Many thanks, in advance.