Audeze LCD-4

[x RELIC x]

Just in case we haven't confused you enough yet... one other important thing...

The output impedance of the amplifier and the impedance of the headphones have to be matched well too. The ideal amplifier output impedance is zero ohms, in this case, all the power gets delivered to the headphone and the headphone can be any impedance. Most solid state amps have less than one ohm amplifier output impedance, so it can be regarded close enough ideal and ignored. If the amplifier output impedance was 15 ohms, then with the 4z, 50% of amplifier power would get wasted as heat in the amplifier output impedance and never reach the 4z. As the amplifier output impedance gets larger compared to the headphone impedance, this situation gets worse. If the amplifier output impedance was 100 ohms, the 4z could be a total no go but this could still sound the best thing ever on the 4. Generally, tube amps can have 10's to 100's of ohms amplifier output impedance, they will possibly favor the 4 rather than the 4z. So, in some cases, the whole thing can work backwards.

Best just to listen and maybe there will be some special synergy happening!

Just like the Zreview of the Utopia.... he was using an amp with 164 Ohm output impedance with the 80 Ohm (@1kHz) Utopia and he thinks they are soft and mushy headphones. For the record I don’t usually watch his reviews.

Agreed, it’s always best to listen for one’s self and with your own gear if possible!

 

[commtrd]

Great discussion on the topic of load impedances vs supply output capability. I was having a hard time mentally grasping relative efficiency compared to load impedance and then relating all that to what loads are most favorable for both solid state and tube amps. Sounds like safe to say that most solid state amps are better at providing current draw type loads, and tube amps would be better suited to more voltage requisite type loads (higher input impedance et al)?
Next question: What is it about a certain type or variance in the same type driver(s) that yields a higher or lower efficiency? Just the construction elements of the driver? I had thought that a low-ohm input load would also equate to a more efficient load, but that evidently is not really the case.
Sorry for all the questions but wanted to understand this stuff better to aid in component selection in the future. Thanks guys!

 

[mlxx]

On a very simplistic level....
For planars, the impedance of the coil will determine the impedance (mainly all resistive) of the hp. The impedance itself won't determine the efficiency directly I don't think.
LCD3 at 110 ohms has better efficiency than both 4z and 4.
But, thinner coil equals higher impedance (also depends on type of material used in the coil etc.).
Thinner diaphragm as a whole means it could be lighter, means harder to push air, means less efficient.
Fazors and others tricks affects efficiency too.

Edit: oh.. better magnets, better efficiency.

 

[x RELIC x]

Next question: What is it about a certain type or variance in the same type driver(s) that yields a higher or lower efficiency? Just the construction elements of the driver? I had thought that a low-ohm input load would also equate to a more efficient load, but that evidently is not really the case.
Sorry for all the questions but wanted to understand this stuff better to aid in component selection in the future. Thanks guys!

In simple terms... For planar drivers it's the membrane mass, traces on the membrane, tension, and the magnets (strength and magnetic field shape). Measure how much power it takes to get them moving to produce a certain SPL... Efficiency.

For planar headphones the traces on the planar membrane will be a large influence on the impedance. The smaller the trace width, or longer trace length, the more resistance to the electrical flow. The larger the trace width, or shorter trace length, the lower the resistance to the electrical flow. The shape of the metal traces on the membrane will influence the length and therefor influence the resistance. The designer will have to make choices on the width, length, and shape of the traces and how they relate to the magnetic field to move the membrane to achieve their goal. It all depends on the designer. It's similar to an exposure triangle for cameras. Efficiency, resistance, and distortion are interrelated. Of course, I'm sure Audeze could explain it better but that's the very basics of it, as I understand it.

 

[mlxx]

Just like the Zreview of the Utopia.... he was using an amp with 164 Ohm output impedance with the 80 Ohm (@1kHz) Utopia and he thinks they are soft and mushy headphones. For the record I don’t usually watch his reviews.

I can imagine everyone spit their coffee out.
He did love the Elex also at 80ohms though... weird.
He didn't like the LCD4 either, he is funny at least.

 

[Zurakx]

You guys are going nuts over impedance

In other news im in the middle of ordering my LCD-4s. Just waiting for an email back about how to give them my money. Cant wait to post the picture(s) of them here. Ill finally be able to retire from buying headphone stuff for at least a year.

 

[commtrd]

For a whole year?!?

 

[gtbrown50]

A YEAR! That's funny.......

 

[mlxx]

No wonder all the LCD's have awesome bass, they are like little subs.

 

[pippen99]

Little Subs!

​

 

[mlxx]

A 12 inch little sub.
Can't see it on the LCD4. Newer drivers sometimes have some paper stuff on top.

 

[johnzz4]

No wonder all the LCD's have awesome bass, they are like little subs.

Cool video... I feel badly for those LCD2s though.

 

[x RELIC x]

That is correct assuming amps operated the same at 15 and 200 ohms which they don't.
The Dave can run speakers but not the LCD4. It will run out of current for low impedance and run out voltage for high impedance before getting to power needed.

True regarding operation at different impedance for different amps, but the DAVE has 0.5A Current (500mA), more than most headphone amps. I wasn’t speaking about the DAVE but just clarifying in general the power requirements. Plus, I disagree with running out of Voltage. The numbers tell a different story, depending on listening levels of course.

Umm.. at what impedance?
That is the point.

Good question, I may ask the designer.

Just to follow up with some information regarding our earlier discussion, below is the reply I received in a PM from Rob:

"For Dave - at 15 ohms it will be voltage limited to 6.8v RMS. That's 3W of power! 200 ohms is 231 mW at 1%.

Below 15 ohms the 0.5A RMS current limit comes in, hence why 8 ohms is only 2.1W. The LCD-4 will go to 111 dB SPL. I think that's enough SPL!"

So no, the DAVE won’t run out of Current at low Ohms and will be just fine for the efficient LCD4z. For the LCD-4 the 111dB he quotes is pretty much what I calculated earlier. If someone doesn’t like the DAVE with the LCD-4 it isn’t technically a lack of power (as is common for people to perpetuate) but personal preference/synergy (nothing wrong with that) unless listening at stupid loud levels, or the source material is incredibly quiet. I don’t mean to come off as defensive regarding DAVE, but rather just trying to inform with actual numbers.

 

[mlxx]

Just to follow up with some information regarding our earlier discussion, below is the reply I received in a PM from Rob:

"For Dave - at 15 ohms it will be voltage limited to 6.8v RMS. That's 3W of power! 200 ohms is 231 mW at 1%.

Below 15 ohms the 0.5A RMS current limit comes in, hence why 8 ohms is only 2.1W. The LCD-4 will go to 111 dB SPL. I think that's enough SPL!"

So no, the DAVE won’t run out of Current at low Ohms and will be just fine for the efficient LCD4z. For the LCD-4 the 111dB he quotes is pretty much what I calculated earlier. If someone doesn’t like the DAVE with the LCD-4 it isn’t technically a lack of power (as is common for people to perpetuate) but a personal preference unless listening at stupid loud levels, or the source material is incredibly quiet. I don’t mean to come off as defensive regarding DAVE, but rather just trying to inform with actual numbers.

I am not picking on the Dave here, because this happens with every amp, all have limitations. Run out probably wasn't the best term to use, limited probably is better (as Rob used). When I said it will run out, I was speaking in general terms, not for the 4z or the 4 or anything else as I have no idea when this will happen for specific gear, but at some impedance level it will happen since we don't have an endless supply of voltage and current. I was trying to make the point that amplifier power performance varies with impedance and why this is so, as I am sure you know but just so as to answer the original question. To clear things up a bit, Dave's limits are 0.5A max current at some impedance level and 6.8V max volts at some impedance level. If the gear works happily within these limits, then no problems in terms power, especially as the Dave has almost zero output impedance. At say 200 ohms, Dave is limited to 231mW, at that point the voltage will probably start to clip as we cannot supply anymore, and the distortion will go up very very quickly. Note, that if you needed 112dB SPL, it will run out and never get there or it will with lots of distortion. A different amp might be able to produce 1231mW at 200 ohms, it has a different limit but still limited. At 15 ohms it does 3W, so power varies greatly with impedance for amps. Regardless what impedance you choose it will always be limited, not enough volts or current can be supplied at some point (not relating it to any specific gear). I think I and some others were arguing in terms of how the gear was affected and you were arguing in terms of purely SPL requirements, that is where the confusion arose I think. Reading the original question again now, I believe it was in fact about SPL as you answered it. BTW, nice to have Rob around to answer all the questions.

Dave is a very interesting case though, it is probably the best DAC and amp out there, seems to have enough power, but just doesn't rise to the level of even of some way less qualified gear with the LCD4 (for me anyway). With my LCD3, the Dave was one of the best I have heard, it was just a little bit too dark but otherwise great. It didn't have any of the issues like I hear with the LCD4. What I hear with LCD4 does sound to me like its a power issue yet the CMA800R I use now has about the exact same amount of power yet sounds fantastic. So I can't explain it, maybe just that synergy thing again. I do hear a lot of others complain about the same thing and it is fixable by adding an external amp, yes it adds a flavor but things come alive. The TT2 may give some further clues. I got to listen to the TT2 but no LCD4 around just a HD820. Sadly it was easily out classed by the Dave for me so I am looking forward to the Dave replacement one day. I will try to test the TT2 with the 4 at some point though because who knows in this audio game, I hear if you put a brick on top it sounds better.

 

[commtrd]

Well for the sake of discussion only, and assuming arguably the top two [affordable range] amps being GSX Mk2 / Violectric V281 both of which provide excellent SQ and beyond adequate power to drive basically any HP but specifically LCD4.
IMHO it really gets down to the dac as the final arbiter of just how good a system can or will sound. To me it seems like too much emphasis is placed on the amplifier when the the dac is really where the rubber meets the road IMHO.