[bluemonkeyflyer]

Wow, those look incredible!

Beautiful.

How's the sound? Curious how you damped them.

 

[MuZo2]

Nice, are the measurements with amp?

 

[GREQ]

 

I'd be interested in the 'incremental' steps taken to reach this point. 

 

[stratocaster]

Beautiful.

How's the sound? Curious how you damped them.

 
They sound full and punchy, just a tiny little bit on the warm side, smooth, nicely balanced and mids are clear. They have to be damped tightly, really not much different from closed T50RPs. Having a measurement rig available (calibrated microphone, Steinberg UR22 audio interface plus Schiit Vali or Leckerton UH-6S.MII amp)   does help immensely to go down the right route step by step. Being 'open' they have improved clarity and soundstage. There is absolutely no 'closed-in' feeling.  The treble has to be brought down just a bit for my personal preference, so I use a thin layer of felt/foam in front of the driver to bring the highs in line with the rest. Definitely my best set of T50RPs.

 

[SeEnCreaTive]

Wow those look fantastic. I think those are the first open t50rps I've seen. I've been dying for a pair. Great work

 

[c61746961]

Is there any venting/porting on the baffle?

 

[hemipowered007]

Well, guess I need some more tools for Xmas.

 

[stratocaster]

Is there any venting/porting on the baffle?

No, it's a solid wood baffle without any port whatsoever. Just one other thing: pads are HM5 velour pads. I had the best results with these, (p)leather did not work.

 

[c61746961]

Thanks, strato, great work as always.

 

[bluemonkeyflyer]

They sound full and punchy, just a tiny little bit on the warm side, smooth, nicely balanced and mids are clear. They have to be damped tightly, really not much different from closed T50RPs. Having a measurement rig available (calibrated microphone, Steinberg UR22 audio interface plus Schiit Vali or Leckerton UH-6S.MII amp)   does help immensely to go down the right route step by step. Being 'open' they have improved clarity and soundstage. There is absolutely no 'closed-in' feeling.  The treble has to be brought down just a bit for my personal preference, so I use a thin layer of felt/foam in front of the driver to bring the highs in line with the rest. Definitely my best set of T50RPs.

No, it's a solid wood baffle without any port whatsoever. Just one other thing: pads are HM5 velour pads. I had the best results with these, (p)leather did not work.

Thanks for the details. Very interesting.

Is your internal cup volume greater than stock T50RP's?

Here's a *wild guess.* Transplanted T50RP capsules in an open back design require cups with greater volume than stock to accommodate the extra damping needed to control boomy bass and midrange bloat. The side effect is hot treble that needs toning down with foam (or felt, etc). There is still too much bass so velour pads are needed to further tune the bass. All the extra damping reduces efficiency so greater amplification is required. Fostex circumvented all this in the TH500RP with no rear side damping and a fully open back by modifying the baffle, tweaking the traces (and magnetic flux??), changing the pad construction and size, and adding what looks like a felt damping ring between the baffle and pad for fine tuning.

 

[stratocaster]

Thanks for the details. Very interesting.

Is your internal cup volume greater than stock T50RP's?

Here's a *wild guess.* Transplanted T50RP capsules in an open back design require cups with greater volume than stock to accommodate the extra damping needed to control boomy bass and midrange bloat. The side effect is hot treble that needs toning down with foam (or felt, etc). There is still too much bass so velour pads are needed to further tune the bass. All the extra damping reduces efficiency so greater amplification is required. Fostex circumvented all this in the TH500RP with no rear side damping and a fully open back by modifying the baffle, tweaking the traces (and magnetic flux??), changing the pad construction and size, and adding what looks like a felt damping ring between the baffle and pad for fine tuning.

 
There is greater cup volume, but that is not really essential (at least in my view). I am waiting for T500RP measurements to pop up. Then we'll 'see' how they perform 'measurewise'. I am sceptical about the magic trace tweaking. One thing is for sure: pads make a huge difference. I am onto something at the moment, but it is too early to post any details. Early measurements are very promising. Funny, but you mentioned what I am experimenting on in your post

 

[bluemonkeyflyer]

There is greater cup volume, but that is not really essential (at least in my view). I am waiting for T500RP measurements to pop up. Then we'll 'see' how they perform 'measurewise'. I am sceptical about the magic trace tweaking. One thing is for sure: pads make a huge difference. I am onto something at the moment, but it is too early to post any details. Early measurements are very promising. Funny, but you mentioned what I am experimenting on in your post

Here's another guess. Relative to your "damping stack" configuration in your modified T50RP, your damping stack and configuration in your wooden-transplant modification is thicker, probably fills the cup chamber, and may apply more pressure against the back of the drivers.

Pads do make a huge difference...type of foam and density, porosity, type of covering, vented or not,distance from ear, pad chamber internal volume, and seal.

Your current experiments...Hmmm...pad venting with holes and/or felt spacer and baffle venting are my best guesses. TH500R has what appears to be 3 Large, controlled baffle vents that should modulate bass:treble.

Last year, or maybe it was closer to two years ago, I did experiments opening the three faux baffle ports at the other three corners of the drivers, using a 1/16 inch drill from the rear side. Effect? Less bass. Then I closed all four. Effect? More bass. So, finally I modified the single baffle port with tape and tried punching a small hole with a pin, then made it a little larger, and larger still, using a toothpick. Effect? Another tuning variable in our modification toolbox. It's posted in Post 1 of this thread.

I look forward to hearing about your results. Thanks for sharing.

 

[stratocaster]

Here is a little treat ... T50RP Open V2. Not bad, eh?
 

 

[bluemonkeyflyer]

Here is a little treat ... T50RP Open V2. Not bad, eh?

Nice!

Measurements can save a lot of time, as you said. I like ARTA graphics much better than REW but REW is powerful and feature-rich,easier to navigate, and free. That said, I bought ARTA and FuzzMeasure. It would be helpful to see some of your measurements of stock headphones to better appreciate this graph.

Thanks!

 

[stratocaster]

My 2 sets of 'stock' T50RPs ceased to exist 2 years ago! Since then I have been modding them, first in the stock cups, later on in (closed) wood cups. Now I am going open with them. I would have to buy new T50RPs to measure and post 'stock' results  but since they are rather expensive here in Europe (>€130) I won't be able to do that for that purpose. When I am ready and certain of the repeatability of my results, I will be able to post measurements 'before and after' the new mods ...