[ericj]

Quote:

Originally Posted by wualta /img/forum/go_quote.gif Eh? Aren't the highs on the Maiors up to snuff? If you crave higher highs, try a reflex disc. I think isos are not quite up to 'stat quality, but with some TLC they can reach almost as high and be just as smooth if not smoother. Just my assertion, and my ears aren't what they used to be, but still...

I am unfairly comparing the Maior highs with the K145 highs, and Stax electret highs (what on earth to call my Stax Frankenphones? Are they technically an SR-30 Pro?).

I may try a reflex disc anyway, though.

 

[AudioCats]

I would think the Yamaha patterns would have expired already, it has been so many years.....The Fostex zigzag is probably still guarded though.

Wualta, how did you know that T20RP is a MKI? because of the leather handband?

I think I should keep my penny bucket and wait for a HP/YH-1.....

 

[Lazarus Short]

Hello all! I'm way late getting into this thread, but I saw the word "Orthodynamic" and had to look, owning as I do, a Yamaha YH-1. I found it at an estate sale, in the basement, on a bench in a back corner, and broken at that. "One dollar?" they said. I fixed the broken headband with parts from a broken Signet, and gave it some listening. I decided, as I did with so many other 'phones [including the Senn 600], that it did not come anywhere close [well...the 600 was close] to my vintage Stax. I lost interest, but now that I see how the driver works, I am interested again. It needs recabling anyway, and I don't have much investment to lose.

What would anyone suggest that I do to mod it, specifically?? Thanks in advance.

Laz

 

[ericj]

Quote:

Originally Posted by AudioCats /img/forum/go_quote.gif I would think the Yamaha patterns would have expired already, it has been so many years.....The Fostex zigzag is probably still guarded though.

"Whole surface driven speaker" Fostex 5003610 - 1988

http://www.google.com/patents?id=DDwkAAAAEBAJ

Just by way of example.

 

[wualta]

Quote:

Originally Posted by Lazarus Short What would anyone suggest that I do to mod it, specifically?? Thanks in advance.

Surprisingly little, actually. (All photos by Joop Nijenhuis.)

1) Cut out two discs of cheap acrylic (aka "craft") felt, one 55mm, the other 52mm. This is the stuff that's less than a dollar from the fabric store.

Scroll down to the bottom of the page and refer to the last row of photos on Refurbish Yamaha HP-1 headphone to get an idea of what you'll see when you lift the baffle off. The driver is the ferrite magnet sandwich, the big discy thing with the holes. The baffle is the lid of the cup, with a big hole in it to let the sound from the driver come out. Take a deep breath, here we go:

2) Lay the cup you're going to work on on its back. If you don't have it in this position, the driver will fall right out when you unscrew the baffle.

As you can see in the photo below, holding the baffle to the cup there are five little selftapping screws under each earpad. Don't peel off the whole earpad, just refer to the photo below and peel back the earpad just enough to get to the screws. You may find the screws covered by a thin black layer of double-sided sticky tape. Don't let this stop you.

You'll notice that Yamaha didn't put the screws where you'd expect to find them. The two that are close together are at the exact bottom, where the cable goes in. Straight up from there is "north". Yes, Yamaha was being perverse-- all the other screws are rotated about 15 degrees clockwise for no good reason.

2) Loosen the screws in a star pattern, as if you were removing a wheel from your car. The screws are very short, no pun intended, so watch out. A magnetized screwdriver helps here. Carefully lift the baffle off. Brush off or wash the nylon mesh. Resist the urge to bleach it.

You'll notice that the driver is surrounded by several black felt strips. We don't want to disturb them, so don't pull or lift the driver out of the cup; rather...

3) gently tilt the driver and the orange foam disc behind it just enough to slip the 52mm felt disc onto the bottom of the cup. This is tricky, since the black felt strips are not held in place in any way except by the driver and the foam. Let the foam disc drop back; it will help hold the felt strips in place.

Then, behind the driver, above the foam, slip in the 55mm felt disc. Align it with the driver, then let the felt drop back onto the foam. If you want electrostatic-like highs, stick a square of sticky tape to the back of the driver itself. Position it between the center and the top. Make sure the 55mm felt disc and the foam disc are lined up directly behind the driver when you...

4) ...let the driver fall gently back down. Make sure this didn't disturb the felt strips. They should surround the driver evenly. Tamp them down so that they rest on the bottom of the cup.

5) Grab the baffle, and, noting that it only goes back on one way, skootch it around on the face of the driver to make sure the driver is centered. Then, while squeezing the baffle and the cup tightly together, close up the cup, again using a star pattern.


That's it. With the YH-1, I find bass boost is often necessary, but when it comes up, it's of extraordinary quality.

Once again, thanks to Joop for taking a very useful and clear set of photos.

Keep in mind that this is just a demo, a proof-of-concept, not intended to represent the state of the modding art. It will sound good, maybe good enough to keep, but there are other things that can be done. Good luck and above all, have fun.

.

 

[ericj]

To elaborate on the "Star pattern" - the baffle can crack at the bottom where the cable enters, so the screws on either side of the cable should be the first out and the last in.

 

[wualta]

Quote:

Originally Posted by ericj To elaborate on the "Star pattern" - the baffle can crack at the bottom where the cable enters...

Wow, have you had trouble with that?

Thanks for the patent link, by the way. That's good Googlin'. There's stuff in there by Daniel von Recklinghausen, Philips, Fostex of course, lots of delicious goodies all wrapped up in dense inedible lawyerly boilerplate.

.

 

[ericj]

Quote:

Originally Posted by wualta /img/forum/go_quote.gif Wow, have you had trouble with that?

My 1st pair of YH-2's arrived with a hairline crack in the part of the baffle that provides strain-relief on the cable. The first time i opened them, I went for those screws last for some reason, and ended up having to superglue the baffles back together at that point. I'm more careful now.

Quote:

Thanks for the patent link, by the way. That's good Googlin'. There's stuff in there by Daniel von Recklinghausen, Philips, Fostex of course, lots of delicious goodies all wrapped up in dense inedible lawyerly boilerplate.

Yeah, it's pretty interesting. I found a few other relevant patents, including one owned by Audio Arts that's the spitting image of setmenu's ribbon - 3873784.

Couldn't find any Yamaha planar-related patents. Found that a little odd.

3898598 has a nice diagram of what looks like a T30, filed in 1974.

Edit: And isn't it a shame that AKG never put this one into production? http://www.google.com/patents?vid=USPAT4278852

 

[Sonar]

Some photos my Electronica TDS-5 was issued in the former Soviet Union. New pads. Has kept for a collection.

 

[wualta]

Quote:

Originally Posted by Sonar Some photos my Electronica TDS-5 was issued in the former Soviet Union. New pads. Has kept for a collection.

Amazing! What can you tell us about Electronica (or would Elektronika be a better transliteration)? Where were they located? Do they still exist? Were there any other models of this type of headphone?

Interestingly, my set (serial # 443572) doesn't have the CCCP logo on it, and the style of the lettering is different. Interesting.

And what's the difference, if any, between the TDS-5 and the TDS-5M?

What was the TDS-6 like?

.

 

[wualta]

Quote:

Originally Posted by AudioCats Wualta, how did you know that T20RP is a MKI? because of the leather handband?

Here's a quickie tutorial on the sometimes-confusing Fostex history. With that, you should be able to positively ID the version of T20 or T40 you're looking at or reading about.

For those who cant stick reading yet another of my longwinded whimsical rants at any price, here it is in a nutshell, with a proposed nomenclature that I think would help straighten things out:


CHRONOLOGY:

There were three T20s:

1) the old (the flat, circular, slightly dished "Mickey Mouse" earpad style-- call it T20v1 for "version one"-- made from '77 to '86. See Tyre's photos in post 15)

2) the middle (says "T20" on the 'phone itself)-- T20v2. Made from '87 to 2006. Confusingly, the box it comes in says "T20RP". Basically a mechanically upgraded T20. Identical-looking driver.

3) the new (says "T20RP" with "mk II" just below it)-- we could call it "T20v3", and you'll see that in some older posts, but it's really a completely different headphone inside, and sounds it. 35mm square driver. Currently in production.

See the photos below.


There were only two T40s. Since there was no T40 in the original 1978 lineup, there's only the middle, circa 1990, one-- (T40v1) and the new one, labeled "mk II" (T40v2). They look very much like the corresponding T20s.


There were only two T50s in the NA market: the original from 1978 to 1980, and the T50v2 from 1980, which has a single headband instead of the split, pivoting headband, but which is otherwise identical in appearance and specs but [most likely] not in sound, and which lasted maybe until 1985. The T50RP, from 2002, is really a different headphone entirely, and it too comes in two versions. Between the T50v2 and the T50RP there was... as far we know... nothing. Nothing branded Fostex, anyway. We've discovered that Fostex OEM'd the T50v2 design out to other audio companies: NAD sold one version (possibly two) and an obscure company called Maior sold another. Lafayette Radio sold yet a third. We call those "T50v2 clones" because they look exactly like the photos of the Fostex T50v2 except of course for the name printed on them. We've also discovered that Fostex shopped the basic T50 design around the world well before its go at the NA market, starting around 1975, and used different tuning schemes depending on which market and who was selling it for them.


In the case of the ones up for auction, since we couldn't see the cups, it was the circularity of the earpads that was the giveaway. The "Mk II" versions have oval earpads and cups.

It will be interesting to hear how different the Mickey Mouse T20 (T20v1 is so much shorter) sounds compared to the T20v2, which I should be able to lay my hands on tomorrow morning, thanks to tyre. The former was damped only by a wad of soft gooshy foam; the latter has a nonwoven damper disc held down by a slug of stiffish foam. This differs from the T40, which has the same damper disc but it's held against the driver by only a drop of glue and the clamp that holds the driver together. Odd. That would mean that the damper could flap around somewhat. Not quite ideal.

 

[wualta]

Poor T50RP-- it don't get no respeck.

So I figured what the hey, maybe it's not hopeless, maybe it's overdamped or something, so I'm working on it. Here's what the driver looks like on its baffle:

The driver is square, about 35mm on a side. The 38mm diameter Pro 30 driver actually has slightly less surface area, but I'm assuming that at max excursion the driver will form a dome shape, which is the case of the T50RP would be a circle inscribed inside the square, making the square driver effectively smaller. Either way, what the T50RP driver has that the others don't is neodymium magnets. If the diaphragm isn't completely overtensioned, there might be a way around the no-bass problem. Maybe. Who knows. If it is overtensioned, it's beyond my help. But I thought I'd give it a try. I started by removing the damping film, which looks and feels like paper stretched tight over the driver's back vents. Preliminary tests tell me I've got bass but with a very honky upper midrange, also that the T50RP cup, advertised as "closed", is actually vented, with a damper film over the vent. This thing doesn't look at all like any of the earlier iso drivers. More futzing to come.
UPDATE: More futzing indeed! Faithful Fostex fan Smeggy eventually took the T50RP driver to fame, with Stax earpads and custom wood cups, as the heart of his Thunderpants (aka "TP") transplant.

 

[ericj]

You know, it kinda looks like the diagram in that patent i dug up.

g'luck!

 

[AudioCats]

looks like that T50RP diaphragm trace is thicker than the old T40's?

 

[wualta]

All the voice coil traces in isos are surprisingly thick. I don't know how thick the copper traces on the T50RP are, though I don't think they're any thicker than the aluminum on a Yamaha driver. I could be wrong. I've peeled off the damping film/paper (it's glued on under tension-- difficult to remove it without destroying it) and will put up photos of the driver tonight. You can't see the magnets, since they sit under a corrugated steel pole piece. The construction looks very much like the Monsoon/Sonigistix planar computer speakers in miniature (click on the little diagram to see the contruction in detail). Oh heck, here's the actual diagram, probably derived from a patent drawing, enhanced a bit:

In actual production Monsoon models, the holes were enlarged and then connected to become slots, and on the back there was a nice dense damping pad. But you'll see in the closeup of the T50RP driver that we're dealing with pinholes. Well, a little bit larger than that, but still purty dang small. Scandalous? getting there.

In the upper right corner of the driver you'll see a tiny wad of yello-tack. This covers a tiny hole that leads directly into the earcup, possibly to equalize pressure when the 'phones are first put on.

.