[wualta]

 
Quote:

Actually, quite a few people in this thread have noticed that the drivers do not look terribly difficult to build.....

It's true that you could probably get sound with simple magnets and hand-drawn voice coils, but the sensitivity would be low, and for the magnetic flux to be even over the whole diaphragm (which is after all the point of the exercise), not only must the magnets' strengths match, but the gap must be even (ie, the magnets must be parallel), and the faces of the magnets on each side must lie in a single plane. In the case of disc magnets, that means machining or grinding the faces. Yamaha machined; not sure what Fostex did. Maybe they were able to mold their ferrites precisely so they didn't need machining. In any case, getting an even distribution of flux over the voice coil is paramount. Focusing it so that it's as intense as possible is another trick. The principle is simple, but the details get devilish. Not unlike the case with loudspeakers, planar or otherwise. But I still hope someone glues a bunch of bar magnets to a slotted steel disk and has at it some day. Someone whose family is from, oh, say, Sri Lanka.

Quote:

 

... and talking about SFI drivers... it would be nice to have all descriptions of sfiphones attempts in a separate thread. I tried to collect all the data about it on this thread and it is close to impossible even rummaging the thread in every possible way, Of course any other alternative way is suitable, like somebody having had collected all the data in all these years and willing to share his/her effort. Wualta what do you think about it? 

I like the term "SFIphones". You knew I would. Well, you can use the Ludo search engine to get the telling results of Smeggy's Smeggipucks (my name for 'em), the dead-simplest-possible DIY enclosure for the SFI drivers. No worries about backwave, which you'd have if you went for the open-back ideal-- see GrandZechs' results above for a further demonstration of this. Here's your chance to break new ground and get measurements, something we couldn't do back then. So yes, I think you should start a spinoff thread and don't look back. Study the theory of the Puck enclosure, yes, but take off from there. 

Quote:

Does anyone perchance have a frequency response chart of the T40v1? I didn't think to write down my thoughts on the original FR before I transplanted them into my PS500.

Ah. We need to convince someone (preferably several someones) with a lovingly-modded T40v1 to send his 'phone to Tyll and his lab... which if I recall correctly is built into a van so as to be mobile, correct?
Well, maybe not, but it should be. A van disguised as an ice cream truck. But that's an idea for another time.
 
Quote:

I think it will be interesting to hear some more comparisons between the two impedances.  I know that all of this was done years ago, but those of us who are new to these drivers need a chance to figure this stuff out as well.

Yes, I agree. With the possibility of getting measurements the whole DIY picture changes. We were tuning strictly by ear, which is fine as far as it goes, but it's like using a rubber meterstick-- you can't be sure that what someone said about their results will translate to your headphone. And you don't want to be too much influenced by all the opinions, which didn't always line up the way we expected anyway. Start fresh. Many of the oldsters are still around and can kibitz.

Quote:

On my first attempt I have made some very bassy cans. They will shake the Stantons cups nicely. I tried a car audio method of a sealed baffle and stuffed the cup tightly with poly fill.

Not just car audio-- most home speakers using sealed enclosures use a similar technique. Fiberglass blankets are probably still superior to polyester fiberfill (shortened to poly fill, thus the confusion for our UK friends), but polyester fiber stuffing is far safer and easier to handle. The trick is to get enough of it in the enclosure to make a difference, and it sounds like you succeeded.
 
Quote:

Originally Posted by Antistase /img/forum/go_quote.gif
GrandZechs, poly fill over here is the think you use to fill wall cracks. Surely it is not what you mean. What it is exactly? Pictures of the inside?

You'll laugh at what we call "polyfill" over here: spackle.  It's just as funny in USian as it is in English. Sometimes tradesmen simply call it mud. Polycell in the UK sell a product called Polyfilla. Which I enjoy just knowing it exists.
 
 

 

[wualta]

Tyll, could you post a link to the description of your headphone-evaluatin' setup? No, wait, got it right here. Everybody take a peek. Are there more photos of the hardware?

 

[ontherivet]

Just to clear up a bit of confusion...the cans were submitted by me for measuring, but were most definitely not constructed by me. If you follow this and other threads you will notice the workmanship of these cans and it should be quite clear who in fact made them. If he says OK I'll come back and edit this post to note who created these masterpieces. EDIT: These are official Thunderpants from Smeggy himself as if that would come as a surprise.
 
They are truly great cans, supported by Tyll's raw data, so I'm not surprised by the results and only wish I could approach such a standard of work!
 
- Don
 
Quote:

Wanted you guys to know that I've completed my first measurements of DIY ortho's of Teejay and ontherivet's T50RP modded cans.
 
ontherrivet's cans measured spectacularly well, I think you guys are really onto something here. Nice work.
 
You can click the images for .pdf
 
ontherivet

 
Teejaay

 
I'd like to continue to measure DIY cans for you guys to help you out with some objective data as feedback for you on-going work.  I had a great time listening to these headphone and would love to do more of it. I am going to start a separate section on InnerFidelity's measurement download page for DIY headphones so you can find them more easily.
 
Please PM me and I'll be glad to measure them.
 
Also, to help make it even more worth your while to send them off, I'm running a contest. Not really supposed to put up links, but I'm sure you can find it.

 

 

[Armaegis]

I'm curious to see the response of a headphone in three states: plain driver held in open space, regular enclosure, modded/damped enclosure.
 
Quote:

Ah. We need to convince someone (preferably several someones) with a lovingly-modded T40v1 to send his 'phone to Tyll and his lab... which if I recall correctly is built into a van so as to be mobile, correct?
Well, maybe not, but it should be. A van disguised as an ice cream truck. But that's an idea for another time.

So now we can drive around in a mysterious unmarked van luring audiophiles inside...
 

 

[wualta]

...Like the Misfits of Science... But yes, I think it should play a rinky-dink tune over and over, like the Mister Softee tune.
 
I also like your idea of switching enclosures/mods on-the-fly, as it were, while the measurement proceeds, to see what the effects are.

 

[smeggy]

I might send my T40V1 or whatever pants. They sound pretty nice, especially given their age. I imagine they'd also measure reasonably well.
 
Thanks for the service Tyll!

 

[dBel84]

I would be interested to see how they compare / measure against the T20v1 or T10 ..dB

 

[GrandZechs]

Quote:

 
Not just car audio-- most home speakers using sealed enclosures use a similar technique. Fiberglass blankets are probably still superior to polyester fiberfill (shortened to poly fill, thus the confusion for our UK friends), but polyester fiber stuffing is far safer and easier to handle. The trick is to get enough of it in the enclosure to make a difference, and it sounds like you succeeded.
 
 
 

 
I guess I succeeded, lol. I wish I had a better Hi-Fi word base to describe what im hearing, They are nice for a first go but still lacking something.

 

[Tyll Hertsens]

Quote:

I might send my T40V1 or whatever pants. They sound pretty nice, especially given their age. I imagine they'd also measure reasonably well.
 
Thanks for the service Tyll!

I bow to your greatness.
 
Please don't exterminate me.
 
 
(I may get out of this with my life yet.)
 
 

 

[sulvaat]

Question for you guys; 
 
I made what I consider to be a pretty decent DIY SFI ortho (120ohm) cans from those ATH-RE70's I linked a page or so back. They sound as good or better than most of my cans and am really satisfied however, they distort at just below my "rocking out" volume. Just a little louder than average I guess. Is this because my amp isn't strong enough or is it a housing issue perhaps?
 
I tried running it from an iBasso D12, Xonar ST (highest gain) and my receiver. They all distort but see below for details:
 
The iBasso distorts at high gain around 80% volume.
The Xonar XT distorts at high gain around 55% volume
The receiver distorts at about 90%
 
Distortion occurs right above my average listening volume, none of my other dynamic headphones do that.
 
Any ideas on how to fix? If it's a power issue would a 32v 2500mW iBasso PB2 work?

 

[Armaegis]

So I've been fiddling a bit more with my T40v1/Phiaton transplant (link). I sealed up all the vents and gave the angled drivers a more tunneled line to the ear. Bass improved, midrange smoothed out, but I lost a bit of soundstage.
 
Overall sound is quite flat, a defined if somewhat polite bass, slightly forward mids, tamed highs. Almost no resonance to the bass end, which I find odd as almost every other closed can has some of that rumble to it. The highs are also not shrill in the slightest, of which I am pleasantly surprised as I am very sensitive to high frequencies, but I'm not sure if the lack of resonance is the reason for this apparent high end smoothness.

 

[rhythmdevils]

Tyll, that's really awesome!  Thanks so much, this is going to be cool! 

 
It's already interesting to see how differently the same drivers measured in a different enclosure, not just FR but the square wave response changing so radically as well.  Those are the only two I know how to read, but I'll have to figure the rest out for this. 

 

[gurubhai]

+1

 
Tyll, have you measured the stock fostex T50RP. I couldn't find them on your site.

 

[Tyll Hertsens]

Quote:

+1

 
Tyll, have you measured the stock fostex T50RP. I couldn't find them on your site.

No ... not yet. But I did email Fostex to see if they'd send me some, and ontherivet mentioned he has a pair stock and a pair damped that he would send up, so we'll have some soon.
 

 

[Antistase]

And more... after few days pushing a representative selection of my music collection through my ID1 I would say now that I'm considering the possibility of defending the actual shape of them with all my wit and strength. Those are the first pair of cans that can challenge my Tannoy Red Monitor 15".
Now it is time to build a tube amplifier around them.
 
DL1 drivers construction tolerances... Wualta, I'm not sure if you had a close look at them. You will lough loud at the standard. Cheap as it can get, all lousy and bendable plastic. There is nothing precise there.  Heck! I opened one of them simplk cutting molded plastic rivets and closed it back again gluing the lid! And the cans as comfortable as a velvet sofa. Simply the design is right and simple in first place. Best example of great engineering.
Now... why LCD2 are so expensive and heavy then?!
 
For a pair of SFIphones I really would prefer a closed schema as I want to use it at the office. But i tired ludo's search engine. The references to sfi are too many and only few are related to specific construction and results. It is close to impossible, for example, to build a full list of fosterphones used with opinion about their impact.
 
About the polyfill stuff, it is not available over here but I ordered some cashemire long fiber wool. Stay tune...
 
A
 

 
Quote:

 
It's true that you could probably get sound with simple magnets and hand-drawn voice coils, but the sensitivity would be low, and for the magnetic flux to be even over the whole diaphragm (which is after all the point of the exercise), not only must the magnets' strengths match, but the gap must be even (ie, the magnets must be parallel), and the faces of the magnets on each side must lie in a single plane. In the case of disc magnets, that means machining or grinding the faces. Yamaha machined; not sure what Fostex did. Maybe they were able to mold their ferrites precisely so they didn't need machining. In any case, getting an even distribution of flux over the voice coil is paramount. Focusing it so that it's as intense as possible is another trick. The principle is simple, but the details get devilish. Not unlike the case with loudspeakers, planar or otherwise. But I still hope someone glues a bunch of bar magnets to a slotted steel disk and has at it some day. Someone whose family is from, oh, say, Sri Lanka.

I like the term "SFIphones". You knew I would. Well, you can use the Ludo search engine to get the old data, including the telling results of Smeggy's Smeggipucks (my name for 'em), the dead-simplest-possible DIY enclosure for the SFI drivers. No worries about backwave, which you'd have if you went for the open-back ideal-- see GrandZechs' results above for a further demonstration of this. Then you can Google for post-August 2010 results, but most of the SFI experiments were done before that. Here's your chance to break new ground and get measurements, something we couldn't do back then. So yes, I think you should start a spinoff thread and don't look back. Study the theory of the Puck enclosure, yes, but take off from there.
 
Not just car audio-- most home speakers using sealed enclosures use a similar technique. Fiberglass blankets are probably still superior to polyester fiberfill (shortened to poly fill, thus the confusion for our UK friends), but polyester fiber stuffing is far safer and easier to handle. The trick is to get enough of it in the enclosure to make a difference, and it sounds like you succeeded.