[kinsale]

Hi all,

I got my first Ortho today. A YHD-2 from Sachu. I must say I am really impressed. It is a very involving sound. Bass is amazing. My other phone right now is the Koss ESP950. I hate to say it but I am enjoying these yamahas a lot more right now.
I know these are the smaller of the Orthos. Would something like the new Fostex phones have a similar sound as they are Orthos too??
Ian

 

[sachu]

Quote:

Originally Posted by kinsale /img/forum/go_quote.gif Hi all, I got my first Ortho today. A YHD-2 from Sachu. I must say I am really impressed. It is a very involving sound. Bass is amazing. My other phone right now is the Koss ESP950. I hate to say it but I am enjoying these yamahas a lot more right now. I know these are the smaller of the Orthos. Would something like the new Fostex phones have a similar sound as they are Orthos too?? Ian

Haha..am glad you like them man.

They are quite special despite being baby yamaha orthos.
Once you delve more and more into orthos you will understand why my ESP950 is up for sale.
Btw, those YHD-2s are stock..I liked them the way they were sounding so didn't go about messing with it.
They are also the comfiest of the yamahas believe it or not

 

[sachu]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif Well the "sony" is most likely an HP50 type driver - same impedance and build. The driver membrane in the previous series was the sony. I flushed this beastie out of the sony when i washed it in ethanol. seems it must have spent some time in there and dribbled acid everywhere as there were approx 100 small etched holes - as a result, not my best repair to date.

Damn..talk about crapping out the driver

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif Drivers after their alcohol bath Drivers re-assembled and measuring close to where they should. ..dB

and thanks to the zen master's magic healing touch there is moar orthogoodness to go about in this world

 

[wualta]

Quote:

Originally Posted by kinsale Would something like the new Fostex phones have a similar sound as they are Orthos too??

The driver in the YHD series is mechanically similar to (though smaller than) the driver in the Middle Period (~1986--2006) T20 and T40 Fostex headphones, but the Fosteces have earpads and mostly-closed cups, and as we've found out in our long, long orthojourney, cups and pads can make a huge difference. So yes, there's a similarity in character under the skin, but the skin makes a difference, because that's what meets your hearing apparatus.


Quote:

Originally Posted by sachu my ESP950 is up for sale.

Heretical apostasiac! Of course, even I would have to admit it's hard carrying around the 950 and its amp box and its C-cell battery box.

By the way, thanks to Don B. for the photos of the naked Yamadiaphragm. I've added it to post 6 of the thread. Finally, after all these years of having to show a PMB diaphragm...

 

[DefectiveAudioComponent]

Quote:

Originally Posted by wualta /img/forum/go_quote.gif By the way, thanks to Don B. for the photos of the naked Yamadiaphragm. I've added it to post 6 of the thread. Finally, after all these years of having to show a PMB diaphragm...

Speaking of that, aren't they extremely similar? Same thin traces between thicker circles that also look just about identical. Strange that Yamaha and PMB came up with exactly the same design...

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif

 

[mypasswordis]

What's also weird is how the traces don't look symmetric. Wouldn't the parts of the diaphragm with thicker traces cause weird modes with nodes and antinodes or something?

 

[iQEM]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif Well the "sony" is most likely an HP50 type driver - same impedance and build. The driver membrane in the previous series was the sony. I flushed this beastie out of the sony when i washed it in ethanol. seems it must have spent some time in there and dribbled acid everywhere as there were approx 100 small etched holes - as a result, not my best repair to date. Drivers after their alcohol bath Drivers re-assembled and measuring close to where they should. ..dB

oohh my, so that's caused the other DR11 driver dead ? a dead bug inside ? wow...

Quote:

Originally Posted by sachu /img/forum/go_quote.gif Damn..talk about crapping out the driver and thanks to the zen master's magic healing touch there is moar orthogoodness to go about in this world

agreed, he such a genious+generous man...
reviving an YH100 & "DR11" or should i say HP50 driver in just a finger snap...being very thankful for what Don had done...

 

[wualta]

Yes, dead bugs are the prime cause of nodes and antinodes in headphones that resemble beehives and/or wasp's nests.

MPI, I know a string player worries about nodey things (and the more obsessive submit their instruments to holographic interferometry and apply starquad varnish to counteract), and it's true that any nonuniformity on a planar diaphragm is always trying to start something with its neighbors, but in this case, the 'phragm is thick and stiff enough that it really doesn't matter. My opinion, of course.

Good thinking, though, because if we were talking about flat, unsupported parts of speaker cabinets, or really really badly designed headphone cups, or a badly tensioned diaphragm or a diaphragm with bad reflections from the clamped perimeter, it would be a real worry.

.

 

[mypasswordis]

Thanks, that makes a lot of sense. I wouldn't try anything like that with my instrument unless it started sounding terrible for no apparent reason, and the problem couldn't otherwise be resolved, but could see myself experimenting with something of smaller scale, like headphone diaphragms. Nonetheless, talking about acoustics and how things work is always interesting, and your expertise in the matter sure helps.

 

[JadeEast]

Thinking about the receiver as headphone amp "thing". I was reading a bit that Nelson Pass wrote about his current source amps and in it he said.

Quote:

"Most of the examples we will examine do not require true current source amplifiers, only amplifiers of quite high output impedances. Most of these cases will be happy with an output impedance of approximately 47 ohms or so and prefer 47 ohms loaded in parallel with the output of a current source. That being the case, you can build a Thevenin Equivalent of such a current source by placing a large resistor (here later referred to as R0) in series with the output of a high wattage voltage source amplifier and get similar results."

Does the tendency to drive headphone outputs through a resistor from the power amp section act like a transconductance amplifier?

 

[iQEM]

so, who's the one that won that T20v2 on listing ? i'm so close, but being sniped on 0 sec...

oohh well, let's continue to another listing...shall we ?

 

[mypasswordis]

It seems his idea is that efficient full-range drivers require less damping factor to achieve full bass response. In the case of orthos, although the impedance is already much higher than that of the speaker outs of a receiver, they are quite inefficient and in my experience pretty prone to bass-bloat. Well, the vintage ones are, at least. Not only that, his idea of 47 ohms in parallel with a current source (Thevenin equivalent being 47 ohms in series with a voltage source) applies to 4 or 8 ohm impedance speakers... in other words, the impedance must be much higher than the transducer's. And of course, most of the output power ends up dissipated in the resistor instead of going to the headphones, so you're going to need to start with a powerful receiver and then be pretty wasteful.

I might be totally wrong about this.

 

[dBel84]

Quote:

Originally Posted by JadeEast /img/forum/go_quote.gif Thinking about the receiver as headphone amp "thing". I was reading a bit that Nelson Pass wrote about his current source amps and in it he said. Does the tendency to drive headphone outputs through a resistor from the power amp section act like a transconductance amplifier?

Transconductance amps have been popular with the planars - First Watt and EHHA being the 2 examples that spring to mind in our HF world. I scanned that article and I think it relates to the property of the planar drivers acting as purely resistive elements. Thus a constant requiring less or no damping factor.

Placing a resistor in parallel with an amp - much like we do when we add adapters to power amps to drive headphones, stabilizes the resistance that the amplifier sees and must to some extent smooth it's subsequent response. I really have no theory to back this up , so perhaps someone who has done the math can step in. As for a resistor in series - I don't see this being similar to a transconductance amplifier , merely adding in attenuation in the signal path.

..dB

 

[mypasswordis]

^ If you add "enough" resistance in series the speaker load isn't really seen by the amp and so it pretty much functions as a current source. An ideal current source has infinite output impedance while an ideal voltage source has 0 output impedance, but I guess close enough is close enough. Also, ideally, damping factor is calculated purely resistively, and not by inductance or capacitance.

Placing a resistor in parallel with the headphones is a current divider.

Edit: And if the headphones have any capacitance, I guess it would also be an LP filter.

 

[cetoole]

I got to hear the LCD2 yesterday at the NYC meet. I was actually a bit disappointed, finding it on the muddy and congested side. I did end up agreeing to buy the HE-5 there. Really loving that headphone.

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif Transconductance amps have been popular with the planars - First Watt and EHHA being the 2 examples that spring to mind in our HF world. I scanned that article and I think it relates to the property of the planar drivers acting as purely resistive elements. Thus a constant requiring less or no damping factor. ..dB

Just looking at the schematic for the EHHA, it doesnt appear to be a transconductance amplifier to me. Infact, output impedance looks to be pretty low, high biased complimentary emitter-followers, with global NFB to boot. Just a high power discrete opamp with tube front end, and probably lower than normal OLG, right?


Quote:

Originally Posted by mypasswordis /img/forum/go_quote.gif It seems his idea is that efficient full-range drivers require less damping factor to achieve full bass response. In the case of orthos, although the impedance is already much higher than that of the speaker outs of a receiver, they are quite inefficient and in my experience pretty prone to bass-bloat. Well, the vintage ones are, at least. Not only that, his idea of 47 ohms in parallel with a current source (Thevenin equivalent being 47 ohms in series with a voltage source) applies to 4 or 8 ohm impedance speakers... in other words, the impedance must be much higher than the transducer's. And of course, most of the output power ends up dissipated in the resistor instead of going to the headphones, so you're going to need to start with a powerful receiver and then be pretty wasteful. I might be totally wrong about this.

This is my understanding too. Something like a Firstwatt F1, with an ~80ohm output impedance, looks like a current source to 8ohm speakers, but would just look like a lousy voltage source to most of our headphones. You would need a higher output impedance to get the same effect in the headphone world. Makes me wonder though, my current favorite headphone amp is a triode strapped E810F parafeed connected to a 15:1 electra-print OPT, which gives about 4ohm output impedance+the DCR of the OPT secondary (about 3ohm for mine). If I were to pentode connect it instead, I would be looking at an rp of ~42kohm instead of ~1kohm, for an amplifier output impedance of about 186ohm+transformer secondary DCR, making it approximate a current source amplifier for most headphone loads. Could be interesting to try, though it just sounds too good for me to really want to mess with it right now.