[JadeEast]

It looks like there have been some attempts to optimize the acoustic transparency of some drivers in the past, I'm thinking the PMB "Swiss Cheese" driver in the PMB-100, while in others (Audio Technica) the micro acoustics seems to be pretty much ignored. We do know that changing the back-wave of the driver changes the response, that's some proof as to the effect of changing the way the holes diffraction works.
 
In the past, I made some attempts to control the front wave by making a pac-man shaped felt for the front of the driver. Hifiman used a similar but much less budget approach on one of their models. There's allot going on inside the cup-driver-ear cavity and the reflections off the ear back at the driver probably (speculation on my part) as much of an influence as the original sound off the driver. It's a good question.
 

 

[NuBreed]

Hi There, anyone know, something aboyt these? 
 

 
looks like ortho phones for me/ but can not find a bit info about them, 

 

[cifani090]

Quote:

Hi There, anyone know, something aboyt these? 
 
looks like ortho phones for me/ but can not find a bit info about them, 

Do you know what they are called? They do look like Ortho's because of their thickness, do they have a transformer?
 

 

[wualta]

Quote:

Hi There, anyone know, something aboyt these? 
 
looks like ortho phones for me/ but can not find a bit info about them, 

http://20cheaddatebase.web.fc2.com/VICTOR/HP-660.html
 
They're regular dynamics. "High Velocity" is a term makers used for 'phones that were basically copies of the Sennheiser HD 414. JVC's term for ortho was "Dynaflat".
 

 

[plin]

Quote:

So, obviously, ortho headphones can't possibly behave the way they do. Yet, oblivious to theory, they nevertheless measurably.. ..do. The logical conclusion: the theory needs modification. I think the key word here is significant. 
 
But as I said, there are many on this thread who, like you, remain skeptical, and there are regular calls for stronger magnets to get more bass, etc. I invite those folks to provide an explanation that will satisfy plin.

Of course I am not grasping something here, that's why I am asking 

. 
The reason I am asking is because I haven't really understand if high damping factor (low amplifier output resistance) is necessary for orthos. Some say that it isn't. Some say that it is.
My amplifier (CEntrance DACmini) has 10 Ohm output impedance. I can opt for a manufacturer's mod that will make it 1 Ohm, but it will cost me considerably. Do you thing it will be wise for driving orthos? (I am thinking some Fostex, and maybe - if my wallet permits, HE-500 or even LCD-2). 

 

[NuBreed]

 
according to some russian webpage, they are electrodynamic headphones
 
 
 
 
        
 
 
Shame, if they were orthos, i'd buy them for  nice price/   they're really good lookin' phones for me
 
 
 
PS: Tell me what is the price range fot Yamaha YH100 in v.good cond, recabled with some nice cable from STAX OMEGA and a 6,3 jack?   more than 100$ ?

 

[tyre]

 
Quote:

Yes, welcome back! Hope you can hang around, since I seem to recall there were a few questions about, guess what, the T50v1 we wanted to ask you while you were gone..  ...though I believe a ninja tracked you down.
I know what to say about that T50v0 auction: worst auction photos ever. Tyre, they need your photo skills. I'm guessing you're going to hate the Pro 30s, but let us know how it goes with them when they arrive.

 
Hey wualta, good to see you again as well. Yep, I remember, I still need to do a T50 review. I had hoped to pick up one of those new-fangled T50RP's everyone's talking about for a side by side comparison, but they seem to be out of stock everywhere. And also, the generational gap between the two is so extreme that I doubt a comparison would be meaningful.
 
My picture taking abilities are average at best, especially with my ancient point-and-shoot, but thanks for the support. Regarding the Pro 30, you might be surprised, I've actually come around somewhat on my opinion of orthos. I've been listening to my T10's a lot and they can be quite fun to use.

 

[Armaegis]

Tyll at InnerFidelity has graphs up for a stock T50rp. It's quite remarkable to see how much can be changed through modding. 

 

[wualta]

Quote:

Originally Posted by tyre /img/forum/go_quote.gif

 I had hoped to pick up one of those new-fangled T50RP's for a side by side comparison, but they seem to be out of stock everywhere. And also, the generational gap between the two is so extreme that I doubt a comparison would be meaningful.
 
My picture taking abilities are average at best, especially with my ancient point-and-shoot, but thanks for the support. Regarding the Pro 30, you might be surprised, I've actually come around somewhat on my opinion of orthos. I've been listening to my T10's a lot and they can be quite fun to use.

Yes, I see that all the dealers are out of stock again. I didn't do it this time, honest. And you're right, the 'phones are fundamentally different in every way but operating principle. They've come a long way, and the mods have brought out as much performance as Fostex built in, which is quite an achievement. But people are smart-- I see they're moving on the T40RP mk ii now. I'm anxious to see what comes of that.
 
Photography of products is a specialized field, but some people have a knack for it. It consists mostly in knowing what not to photograph, and of course you can not-photograph just about anything with even the ancientest point-n-squirt. I've used your shots many times to show people what a given 'phone looks like.
 
Let us know how you like the Pro 30. I believe it was the second-cheapest Ortho on the US market when Radio Shack put it on sale. Ah, the old days.
 
 

 

[200poundsofamp]

Quote:

Tyll at InnerFidelity has graphs up for a stock T50rp. It's quite remarkable to see how much can be changed through modding. 

 
Makes me wonder if I'm missing something with mine. Still hearing a lot of similarities, only the modded they're cleaner sounding - the notches at 1 and 3khz, treble rolloff at 16khz, dark upper mids. Guess Thunderpants still have some secret sauce.
 
The channel imbalance is interesting too, the left side with the mounting post for the cable seems to be bassier and peak earlier in the treble for both pairs.

 

[Armaegis]

Updated my transplant thread with some more pics: http://www.head-fi.org/t/569510/ortho-transplant-orthosex-sfi-into-akg-k240-sextett-lp-in-progress
 
I still have to wire it up.
 
I'm open to any suggestions for damping. Right now all I have is some nylons surrounding the driver. There is no room to put anything behind the driver because it needs some clearance to fit the wires through (I suppose I could put two halves of something between the driver and bracket if I really needed to). I also can't put anything directly behind the bracket as that mounts directly to the rear cup. So essentially that leaves the ring where I currently have pantyhose liner, and the small cup ring area behind the driver. The rear cup is open, with a stock paper filter covering the vents. 

 

[Armaegis]

Is there any compiled info about how different materials affects different frequencies? I know if's half art and science, but I'm just looking for some generalities like "dense wool improves bass, hard felt reflects treble" or something like that.

 

[micmacmo]

I Googled "coefficient of sound absorption" and found several tables that distinguished between frequencies. You might be able to refine the search to include specific materials.

 

[Armaegis]

Notes to self:
http://www.acousticalsurfaces.com/acoustic_IOI/101_13.htm
http://www.sae.edu/reference_material/pages/Coefficient%20Chart.htm
http://whitefiles.org/b1_s/1_free_guides/fg1mt/pgs/h13g.htm

 

[rhythmdevils]

It occurred to me yesterday that differences in damping schemes have a much bigger effect than any difference in amping.  I prefer certain damping schemes out of my ipod so much more than certain other damping schemes with the same phone out of a nice headphone amp and source.  And I bet the measurements would back this up, with bigger changes between dampings than between amps.