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Orthodynamic Roundup - Page 891

post #13351 of 19952
2/12/10 at 8:37pm
Quote:
Originally Posted by DefectiveAudioComponent View Post
Although the AKAI ASE-40 is called linear drive dynamic, it looks a lot like the Victor D-30, and the specification is really similar too. It's similar to the Otto E-1000 as well, come to think of it, and has the same magnet hole pattern as in the picture on the japanese site.

AKAI ASE-40-J
VICTOR HP-D30
OTTO E-1000
Interesting theory...
I was kinnda buying it. But then I looked and saw J-Wiki was updated again.
From what I can gather it seems the D-30 was the bottom of the line and had a curious thing about it....it was only "single-driven". ie it did not have the typical magnet on both sides configuration. It was a development of a prototype Victor made in 1974.#
Unless ofc the Akai are like this too

It seems we are missing a whole tree-line of rich ortho heritage in the Victors.
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Yamaha Stereo Headphones
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Fostex T50RP Closed Ear Stereo Headphones
post #13352 of 19952
2/13/10 at 7:16am
Quote:
Originally Posted by BoilermakerFan View Post
Just awesome!

And a trip to a JoAnn Fabric Superstore yielded 6 types of different felts that are about the same thickness as the unobtanium Oz felt.

Wish me luck guys! Because if I find "it", I can buy yards of it for $10/yard or less.
my pray is sssssssssssooooo for you
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post #13353 of 19952
2/13/10 at 12:07pm
Quote:
Originally Posted by Kabeer View Post
Interesting theory...
I was kinnda buying it. But then I looked and saw J-Wiki was updated again.
From what I can gather it seems the D-30 was the bottom of the line and had a curious thing about it....it was only "single-driven". ie it did not have the typical magnet on both sides configuration. It was a development of a prototype Victor made in 1974.#
Unless ofc the Akai are like this too

It seems we are missing a whole tree-line of rich ortho heritage in the Victors.
I think it is just awful when the facts ruin my fine theory


There is a mechanical problem with the PMB-80. It sometimes gets silent, and needs a lot of power to sound again. I think it gets mechanically stuck.
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post #13354 of 19952
2/13/10 at 1:07pm
What is the sound of one magnet clapping?
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post #13355 of 19952
2/13/10 at 1:54pm
Quote:
Originally Posted by JadeEast View Post
What is the sound of one magnet clapping?
Just wanted to throw this in as food for thought...

Whether or not a planar diaphragm is driven in a "bipolar" or "uni-polar" fashion may not be as important as we think.

In the good old days of relatively weak magnets, having them on both sides of the diaphragm was critical to provide a uniformly strong & linear magnetic field against which the current flowing through the traces on the diaphragm could react.

Today's magnets can be strong enough to provide a larger, more linear magnetic field in a uni-polar design than the bipolar designs of yesteryear.
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post #13356 of 19952
2/13/10 at 1:55pm
Quote:
Originally Posted by JadeEast View Post
What is the sound of one magnet clapping?
Well if it's an electromagnet or the diaphragm changes charge, it sounds like a slap or perhaps a tick, or thwack, or pop, or... but probably not a clapping sound.
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post #13357 of 19952
2/13/10 at 2:38pm
Thread Starter 
Quote:
Originally Posted by JadeEast View Post
What is the sound of one magnet clapping?
Hey, that's my line!

Quote:
Originally Posted by kwkarth
Today's magnets can be strong enough to provide a larger, more linear magnetic field in a uni-polar design than the bipolar designs of yesteryear.
Getting magnetic flux spread out so it's uniform in area and depth is tricky. If the diaphragm is big enough, yes, it won't matter, because it won't have to move far to produce bass-- but how much bass is enough is the question. The designer would have to box clever to keep maximize bass in the earcup. We know how that story goes.

From a point source, magnetic flux drops off by the cube of the distance rather than the square, so if I were the designer, it's not a problem I'd want to have to deal with unless there was a compelling reason. The problem is independent of the strength of the magnets, but I agree that it could be easier to reach the goal with smaller, stronger magnets. The limiting factor usually is the customer's willingness to put up with a heavy headphone.

An advantage of the single-ended 'phone is that the structure need not be so heavy to be stiff enough to hold the repelling magnets in place (I'm thinking of the LCD-2/HE-5/T50 type of contruction).

Magneplanar speakers have done it the single-ended way for years, but the surface area is pretty huge.

Anyone have an already-disassembled ortho driver that could be driven without one of the magnets?
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post #13358 of 19952
2/13/10 at 2:43pm
Quote:
Originally Posted by wualta View Post
Anyone have an already-disassembled ortho driver that could be driven without one of the magnets?
I guess with the "clamped" drivers its possible. although we'd need to find a way of holding the diaphragm down. I wouldnt like to use glue as a permanant thing.

Also it should free up a lot of treble since youd get a whole radiating surface pushing sound at your ears without obtrusive magnets. (could be good with the bassy yamahas like yh-100/HP50 too)
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post #13359 of 19952
2/13/10 at 2:53pm
Quote:
Originally Posted by wualta View Post
Hey, that's my line!


Getting magnetic flux spread out so it's uniform in area and depth is tricky. If the diaphragm is big enough, yes, it won't matter, because it won't have to move far to produce bass-- but how much bass is enough is the question. The designer would have to box clever to keep maximize bass in the earcup. We know how that story goes.

From a point source, magnetic flux drops off by the cube of the distance rather than the square, so if I were the designer, it's not a problem I'd want to have to deal with unless there was a compelling reason. The problem is independent of the strength of the magnets, but I agree that it could be easier to reach the goal with smaller, stronger magnets. The limiting factor usually is the customer's willingness to put up with a heavy headphone.

An advantage of the single-ended 'phone is that the structure need not be so heavy to be stiff enough to hold the repelling magnets in place (I'm thinking of the LCD-2/HE-5/T50 type of contruction).

Magneplanar speakers have done it the single-ended way for years, but the surface area is pretty huge.

Anyone have an already-disassembled ortho driver that could be driven without one of the magnets?
LOL! That was funny Walt.

A disassembled ortho? I have a few, but you alluded to the inherent problem, a single magnet isn't strong enough, plus I suspect the efficiency will go to hell and the driver will be slow, even slower than a good dynamic. Going to take a lot of power to slow the diaphragm when it's moving away from the magnet, then revers the charge and build enough to attract it again. Then how do you keep it spaced so it doesn't smack the magnet? Yeah, I could make spacer rings of various thickness from aluminum or SS, but if I went through that much trouble, why not just make my own driver from scratch. I have a concept, kind of an offshoot idea that Kabeer and Don gave me, but I have WAY too many other project in queue first.
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post #13360 of 19952
2/13/10 at 3:27pm
Quote:
Originally Posted by wualta View Post
Hey, that's my line!
Sorry I just saw it laying around and grabbed it without checking the label.
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post #13361 of 19952
2/13/10 at 4:12pm
I have done a little reading about the unipolar concept since seeing this thread over at DIYA . I could see it working but with the caveats noted by BMF. The simplest way to test the theory would be PMB / Yamaha style driver but at the same time feel that the unipolar design is better suited to a tensioned driver like the fostex. I have a hard time seeing the advantages over a bipolar design. You still have to deal with similar cancellation and interference ..dB

ps Hi Kwkarth, being lured into the ortho world at last - make us some ortho iems and we'll all be happy
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post #13362 of 19952
2/13/10 at 4:22pm
I am trying the one magnet out right now with my t20 and it is working fine. Takes more power but needs less damping.

I actually think it is fine with only the stock foam(no felt at all) inside with the front magnet taken out.

I only did the right driver so I'll take some pics in a min when I do it to the left driver.

Edit: Gotta let my camera charge for 10 mins or so before i can do it.

Ok so got it done now. I just used the outside of some felt rings to take the space of the magnets. Seems to be working great. Just needs more power now but thats not a problem with this amp. Also I don't recommend doing this unless you have one hell of an amp. After listening to a few songs, there is treble similar to when I had it damped by 2 felt discs + the foam. The felt took some of the midrange away though. Now the midrange is right back up there.
LL
LL
LL
LL
LL
LL
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LL
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post #13363 of 19952
2/13/10 at 10:34pm
Thread Starter 
Quote:
Originally Posted by JadeEast View Post
Sorry I just saw it laying around and grabbed it without checking the label.
Actually, now that I look at the label, it says dBel84!


Quote:
Originally Posted by Pyriel0 View Post
I am trying the one magnet out right now with my t20 and it is working fine. Takes more power but needs less damping...
Great experiment! thanks for doing that. Did you notice any increased distortion in the bass that you couldn't attribute to amp distress?
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post #13364 of 19952
2/13/10 at 10:55pm
Quote:
Originally Posted by wualta View Post
Actually, now that I look at the label, it says dBel84!
I would never have challenged the master , however it did ring familiar ..dB
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post #13365 of 19952
2/14/10 at 3:39am
Wualta i can't contribute anything to an amp because I ran them off the F1 before and after. (it has huge amp output for headphones lol)

Sorry I was drunk last night when I posted this and didn't really understand the question. I don't hear any distortion in the bass with only one magnet. I listen to "#41" on Dave Matthew's Crash album and "Would" from Alice in Chains Dirt album + a few fast songs, like "Six" by All That Remains or "Deathmask Divine" by Black Dahlia, with double bass just to make sure it doesn't blend the bass kicks together to compare and contrast with headphone stuff.

Everything is sounding good to me. I wonder how much current these suck up now though lol. I leave the lavry on the same level all the time and just use the foobar2000 volume control on the computer. These take the same signal level(or pretty close at least, about 4db difference on the pc to my ears) as the K1000 does now.
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Gear mentioned in this thread:

Yamaha Stereo Headphones
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