[shlightly]

Sony MDR-V150 match TDS-5M perfectly. Ebay it! =)

 

[gurubhai]

^Thanks but I would prefer something with better quality pleather.

 

[kalbee]

ATH-SJ5 fits well too, but thicker than the HP1 pads. Opening a little bigger too.

btw, HP50A spotted! Whoever wants to go for it

 

[nick n]

nvm oops

 

[hello im sean]

hey guys.. i'm just getting into the wonderful world of ortho's! considering getting a pair of Hifiman HE-400's BUT i'd also like to try my hand at making a pair.  Quick question though, does anybody know, roughly even, the spacing between the magnets and diaphragm on the average pair of ortho's?  Either that or the amount of magnetic force required on the diaphragm to run them but i think getting the spacing would be easier

Im sure i'll go through a lot of trial and error with this but im determined.. Planning on using mylar (1.4 micorns?) for the diaphragm, as for the wire... maybe capacitor foil?

 

[MDR30]

 
PMB trio. Left and right modded, centre's next one up for surgery. Will turn this closed can into a fully open one once I find  a nice, black acoustically transparent metal grid. Any suggestions?

 

[khbaur330162]

hello im sean: Hello again!
 
The capacitor foil in mind is a polymer dielectric with Aluminum cladding. You don't need both a 1.4um PET film and capacitor foil. If you're planning to make your circuit via strips of a conductive material adhered to your film (think Aluminum leaf or voice coil wire) I'm picturing something that'd be extremely laborious. Those speaker guys can get away with this more easily because of the sheer size of the design and fact that they don't want too high of an impedance anyway. A headphone driver is much smaller so even to arrive at 8ohms like they aim to you'll have to increase your "trace length" by making each trace thinner and copying the serpentine design seen on some of these vintage ortho's. See here. Can you imagine trying to glue voice coil wire into a design even half as complicated as that? It'd be "easier" in my mind to use capacitor foil and chemically etch your artwork into the Aluminum using a photoresist as an etch mask. 
 
Magnetic force isn't that important, just try to get the flux evenly distributed and perfectly parallel with your circuit. The Wharfedale's use really weak magnets and like lots of electrical current to make up for it. You can, as many people before you have, get away with weakish ceramic ferrite if cost is an issue. Might be difficult finding them in the dimensions you want, though, which leaves flexible magnets which have a pretty low MGOe rating which then makes me question heat dissipation on that 1.4um film. Could just be me not having much knowledge about the subject, and I'm sure you could overcome all doubt with a thicker conductor, but then impedance becomes a topic for debate.
 
Spacing between .5 and 1.5mm sounds about ideal to me depending on magnet strength, diaphragm size and diaphragm material. The shorter the excursion of your diaphragm (usually the smaller it is the shorter its excursion will be) the closer you can place the magnets to it without foul play between the two. Unless using flexible magnets efficiency shouldn't be too huge of an issue so neither will the magnet spacing, although the closer you can get the magnets, obviously the higher the magnetic force will be and the easier they'll be to amplify, etc.

 

[Nevod]

To anybody who has used orthos with both flat and pleated diaphragms: Do you find pleated ones produce punchier bass, other things being more or less equal?

 

[wualta]

I second KHB's suggestions/recommendations.
 
Nevod: "punchy" bass means getting the diaphragm under control, preferably so that it's critically damped or has the same response without mechanical damping, and the ease with which one can do that determines which 'phones achieve the elevated state of Punchy. Which is to say, I've heard near-tactile bass, or the plausible illusion of it, from the YH-100 and the Pro 30 and the T20v2, so it's a matter of how quickly/simply and with the fewest bad side effects a given 'phone's design lets you get control, and we know some are far easier to manipulate than others. I don't think one type of construction is necessarily inherently better than the other.
 
In this regard, Tyll's impulse response measurements are useful. I'd like to see orthos get the drop on the expensive dynamics in their response to "step" inputs someday. They're already closing in. I think it will take asymmetrical diaphragms and little extra weights on the diaphragm to achieve this. We'll see. Maybe one method of construction will get there first, and then you'll really have your answer.

 

[Nevod]

wualta ,
There aren't any new ones with pleated diaphragms IIRC, though mods I believe indeed can reach there.
 
I know about damping, that's why I written about all things being equal.. My guess is that pleated diaphragms experience less 'doming' and thus may be punchier in the end. They also have lower fundamental resonance frequency, if I'm not mistaken, although that'd depend on particular design.
 
As for step responces, I've thought orthos are already ahead, I should really check the measurements properly. Besides, not everything is in the driver itself, and orthos seem to drag behind in cup/earpad construction for the most part, in my opinion. Asymmetric and stiffer diaphragms would help, I think that as well, but not only them. In one of the patents linked to several pages before, an method of taming low-frequency resonances of ortho diaphragms was proposed, based on an irregularly perforated stators. One could emulate that on most orthos out there, though Fostex, Yamaha and SFI ones would be easier, by covering driver stator holes selectively. Probably what I'd do one day to my Fostex.  

 

[wualta]

You're correct in recalling that there are no new orthos being made with pleated, or otherwise self-supporting, diaphragms, an idea I think has merit and should be explored. All things being equal-- and they never are-- a pleated diaphragm weighs more, so at least has the potential to have a lower fundamental frequency (and lower efficiency/sensitivity). It also introduces a few new variables that must be controlled in production. One advantage of the pleated style that I can see is that the compliance of the diaphragm is independent of the thickness/stiffness/distribution of the voice coil. It also frees up the material choice for the diaphragm.
 
Anyway, if you do try some of those patent ideas in your Fostex, you know where to share them!

 

[Nevod]

To me, the main advantage of pleated ones is much lesser tension, which too reduces fundamental frequency. I actually think that the best way would be an suspended diaphragm - an stiff flat one suspended by a narrow soft pleated contour. I've already written it somewhere there though.

And there are even two places to write about that.

 

[khbaur330162]

Quote:

You're correct in recalling that there are no new orthos being made with pleated, or otherwise self-supporting, diaphragms, an idea I think has merit and should be explored....

The T50RP has those diamond shaped, non-driven traces either embedded in the diaphragm, or on the underside. Think of it as low mass pleating? You spoke of adding "little extra weights" to the diaphragm which seems rather similar to this. I was thinking about possibly trying it in the form of a double clad, double etched foil, the to-be-driven circuit etched onto one side and some other structurally supporting design etched on the other whether it's simply dots that get smaller with more open area as they get further from the center point, some kind of asymmetrical pentagon shape(s) to hopefully act similarly to the different sized and oddly spaced holes you see in the ECR stators (and Nevod's patent), or a combination of the two. A hurricane-shaped spiral might also work. If we understood how the pentagon shape killed resonances perhaps we could situate the hurricane design so that it dumped into the optimum vertex or edge's midpoint of the diaphragm, but I like the other idea more.
 
 
Edit: Btw, that Aluminized tweeter foil ER Audio carries looks oddly similar to the First Aid emergency blanket I have. The Aluminum is slightly see through when held up to the light. Although it measure 4-5ohms/inch as a fully coated sheet (I have no MM to compare the blanket), capacitor foil seems like the best route, atm. I guess I'll try to etch it and see what happens. The only other cheap source I can think of for Aluminized PET would be those shiny metallic decorative balloons. Coincidentally there's a balloon supplier very near where I live that makes their own film and prints custom designs, but I haven't heard back from them. I guess asking them whether or not they knew the micron measurements of the Aluminum and PET substrate scared them away. Sorta doubt it'd be what we're looking for anyway. :/

 

[nick n]

A brief question that may or may not have a brief answer.
 
         Regarding pads and the placing of tiny holes ( however many) in the backside of the pad that faces the baffle of a given headphone. What can one epect to see as a result from adding a couple tiny holes in the pads there? Should it help keep the pads from resonating/vibrating ?
     The crappy Superlux pleather pads had I think two tiny holes in them , and I have seen it before just can't recall where else, maybe on vintage junk.  I assume that the material plays a huge part, especially crappy pleathers, curious if a leather would need it, any idea how it can be determined if this is needed other than charts and ridiculous nitpicky trials?
 
Basically has anyone done this, what made you do it, and how many holes of what size did you use, what was the original material like?
 
I'd never move to a velour for orthos, possibly only the HiFiman ones as I think they may still have a bottom layer of pleather rather than fabric, am I right?

 

[wualta]

"Somebody's asking suspiciously pertinent questions about our product! Unplug the phone and pretend we're all dead!"
Now, why can I see this as entirely plausible? I don't know. I must be mad.
 
Fostex has put extra non-active VC traces on their diaphragms. The T30 is a good example. I always assumed it was to keep the diaphragm from becoming stiffer in one direction or area than the others. As for the weights, as I recall Strathearn resorted to all sorts of tricks to kill resonances on their driver, which was meant to be the top 8 octaves of a speaker. They'd find the node of a standing wave and poke some fiberglass at it, or stick bits of stuff to vibrate out of phase with a resonance they were trying to kill. This was described in Martin Colloms' book High Performance Loudspeakers. You can break up standing waves by making the diaphragm asymmetrical or giving it a roughed-up or blurred edge profile. Sony picked the first strategy and made their ECR diaphragm a scalene pentagon. There are other strategies available to the designer. The goal is to have perfect impulse response. Orthos are good, but I'd like to see them reach the point where they simply follow the impulse spike up and then down with very little extraneous motion, because the achievement would spur research generally, but also because I want to hear what such a headphone would sound like.