[MRC001]

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

--My above post was probably 100% wrong. After reading these two articles I have a much better understanding.
 

 
Nah, you're on the right track. If you run the numbers you'll see why Audeze's recommendation of 1 W is about 10x higher than you really need. This is explained in detail in prior posts so I won't repeat it here. The LCD-2 is efficient and easy to drive. The most important thing in an amp for the LCD-2 is quality, not output power.

 
Incidentally, I needed a second headphone amp for my LCD-2 and HD-580s for a second system. So I have a Meier Corda Jazz on the way ... will report back how it compares against the Headroom Maxed Out Home that I'm using now (which I like a lot and am keeping).

 

[sludgeogre]

  So first of all the lcd2's are 50ohms.

I have the newest version, and from the spec sheet on the website it says:

1. Impedance: 70 ohms, purely resistive

So, yeah. I understand that the sound quality has nothing to do with the power it puts out, but I'm just curious as to how that is affecting my LCD-2. I'm totally in love with the sound as it is right now, so I'm not really concerned, just curious.

 

[PinkLed]

   
Nah, you're on the right track. If you run the numbers you'll see why Audeze's recommendation of 1 W is about 10x higher than you really need. This is explained in detail in prior posts so I won't repeat it here. The LCD-2 is efficient and easy to drive. The most important thing in an amp for the LCD-2 is quality, not output power.
 
Incidentally, I needed a second headphone amp for my LCD-2 and HD-580s for a second system. So I have a Meier Corda Jazz on the way ... will report back how it compares against the Headroom Maxed Out Home that I'm using now (which I like a lot and am keeping).

MRC001 can you site the pages that this is explained? I am very curious to learn more. Thanks!

 

[MRC001]

If the impedance increased from 50 to 70 ohms, all else equal (assuming voltage sensitivity didn't change), the LCD-2 is now even more efficient than it was before, drawing less current and power at the same voltage and sound level. The old sensitivity was 0.225 Vrms for 90 dB SPL. Is the new sensitivity the same?

 

[sludgeogre]

They only list efficiency on the spec sheet, not sensitivity, so I'm not sure. Audeze has said that the newest revision is much more efficient. Somehow the Fazor is supposed to help that, but I think they just dialed back the requirements a bit because the Fazor added so much. It certainly is a lot easier to drive than many people claim.
 
Thanks for the clarifications, everyone. I've been reading this thread a lot more, back to the previous posts that were referenced, and it has cleared up a lot of confusion for me. Thanks.

 

[jodgey4]

The latest revision is stated to be 70 ohms and 94 dB/ 1 mW. Under the 'old' Rev. 2 at 50 ohms and 90 dB/ 1 mW, it took about one watt to reach 120 dB, which is a number usually chosen as being the highest amount of dB overhead you might need. Now, to reach 120 dB with the Fazor tech, it's just about half of that. It takes twice the wattage to get 3 more dB, so 94 dB/mW - 90 dB/mW (new-old) = 4 dB ~= a little less than half the power needed. And yet, Audeze keeps their 1-4 W recommendation, even though a similar ratio for the 2.2f should be 0.5 - 2 Watts.
Tyll, I want your article to clear everything up!

 
 
EDIT:: I misspoke on the voltage at 120 dB, wasn't thinking clearly.

 

[MRC001]

  The latest revision is stated to be 70 ohms and 94 dB/ 1 mW. Under the 'old' Rev. 2 at 50 ohms and 90 dB/ 1 mW,

If that's true, and my sensitivity spec of 0.225 Vrms for 90 dB for the old LCD-2 is correct, then the new LCD-2 is both more sensitive and more efficient.
Obviously, 4 dB more efficient - the same power plays 4 dB louder.
How about sensitivity:
1 mW @ 94 dB into 70 ohms is about 3.8 mA of current and 0.266 Vrms.
94 to 90 dB is 4 dB less voltage which is 63.1%: .266 * .631 = 0.168 Vrms.
So the new LCD-2 sensitivity is 0.168 V @ 90 dB.
The old LCD-2 sensitivity was 0.225 V @ 90 dB.
The difference is 20*log(.225/.168) = 2.54 dB more sensitive.
 
So at the same volume knob setting:
The new LCD-2 is about 2.5 dB louder and draws (4 - 2.5) = 1.5 dB less power.
So now Audeze's recommendation of 1 W power is even more ridiculous than it was before. To their credit, it's just a very conservative estimate and they publish their methodology so anyone can adjust the numbers to fit their own situation.

 

[Argo Duck]

MRC explained it not many pages back in this very thread IIRC. It's well worth reading.

MRC001 can you site the pages that this is explained? I am very curious to learn more. Thanks!

 

[Argo Duck]

Look forward to this comparison. Jan Meier does good stuff. I have his flagship amp the Classic and one of his DACs, both somewhat under-rated on headfi IMHO.

The Classic is a great match with the LCD3F - better (from memory) than with my LCD2.1

I have a Meier Corda Jazz on the way ... will report back how it compares against the Headroom Maxed Out Home that I'm using now (which I like a lot and am keeping).

 

[MRC001]

  I have the newest version, and from the spec sheet on the website it says:

1. Impedance: 70 ohms, purely resistive

So, yeah. I understand that the sound quality has nothing to do with the power it puts out, but I'm just curious as to how that is affecting my LCD-2. I'm totally in love with the sound as it is right now, so I'm not really concerned, just curious.

This could explain something. I bought my LCD-2 about a month or so ago. Its voltage sensitivity is almost the same as the HD-600 that I compared it with. But I noticed it played significantly louder at the same volume setting despite the spec saying otherwise. Perhaps I got one of these new ones that has higher sensitivity and efficiency. I should put a multimeter on it and measure impedance - see if it's closer to 50 or to 70 ohms.
 
Yep, looks I got the new ones - they measure 68 ohms on my multimeter. That's at DC, but ortho impedance is not frequency dependent. Funny because when I first reviewed them a month ago I expected their sensitivity to be the same as the HD-600, because that was the previous spec that Audeze had on their site at the time. I subjectively estimated them to be 2-3 dB louder despite the spec - looks like I was right.

 

[Zashoomin]

  Does the source output impedance play a factor here? 

As a rule of thumb you want about 8x lower output impedance of the headphone from the output.  I think.  If I remember correctly. 
 

  I have the newest version, and from the spec sheet on the website it says:

1. Impedance: 70 ohms, purely resistive

So, yeah. I understand that the sound quality has nothing to do with the power it puts out, but I'm just curious as to how that is affecting my LCD-2. I'm totally in love with the sound as it is right now, so I'm not really concerned, just curious.

Ya I just checked and you are correct.  I stand corrected.   Interested that they upped the impedance on the headphones.  On a side note, they also increased the impedance of the LCD3's to 110ohms...or maybe it was that all along and I was just hollucinating. 

 
Hey if you like how it sounds don't let anyone ever tell you otherwise.  Unfortunately for me I always want something more or better 

.  

 

[Argo Duck]

^ You're right about the LCD3; previously ~45 ohms. Or else we're sharing a collective delusion

IIRC (from contributions by various EEs around these parts) the 8x rule of thumb isn't applicable with purely resistive loads like orthos. FWIW - I'm no EE.

 

[jodgey4]

^ You're right about the LCD3; previously ~45 ohms. Or else we're sharing a collective delusion

IIRC (from contributions by various EEs around these parts) the 8x rule of thumb isn't applicable with purely resistive loads like orthos. FWIW - I'm no EE.

Supposedly true, but when members try their orthos on OTL amps like the BHC or otherwise, you don't get good results, even before the sound starts to clip.

 

[Argo Duck]

^ Agreed. My orthos definitely sound much better on my transformered than my OTL amp. Is Zout all there is to it though? IDK - just asking...

 

[Zashoomin]

The reason that the OTL amps don't work well with orthos is because they don't have enough current to drive the drivers.  Tubes deliver a high amount of voltage but not much current.  That is why you need an output transformer to increase the current and lower the voltage.  But with higher impedance headphones, you don't need that much current so the high voltage is plenty to power them.   That is how I understand it anyway.  I don't think it has anything to do with the output impedance...then again it might as well.