I'll highlight and label the portions which I will respond to below, for clarity:
Quote:
A) I am annoyed some of your comments have been directed at me as a person. Comments like, "have you ever actually heard it" or, "your desire to sell more expensive amps." You're insinuating ideas about my knowledge (assuming I have none) and my motives (that I am on HeadFi to sell things).
B) To that point: I have never once told anyone to spend more money. I am not trying to get someone to buy a more expensive amp. My words above are very plain to see: I never told the OP or anyone else on HeadFi that the solution to their problems is to spend more.
What I absolutely have done - no more and no less - is to ask them to spend differently.
For example, in this case, I have not said "do not buy the Mojo; buy the 3x more expensive Hugo." Or anything like that. I have said, "a desktop amp will be better than a battery-powered amp." Nothing about the relative costs about either component - only the product type.
C) By the same token, I have very carefully not endorsed the Deckard outright, but have implied, based on the principles of system-building, that an amp of the Deckard's category (mains-powered) would likely be a superior match to at least one of the OP’s two headphones. In a statistical probability kind of way, since in audio there are no guarantees. I do not sell the Deckard, which, for all intents and purposes in the context of the current purchase decision, costs about as much as the Mojo, anyways. If you follow my words to their logical conclusion, it would appear I prefer the category of the Deckard to the category of the Mojo. By making a recommendation for a product I do not sell, I am most obviously making a dispassionate recommendation.
So please, do not suggest I am trying to sell a more expensive amp.
*But, since you bring it up*
One of my agendas by participating on HeadFi is to get people to stop overspending on headphones. So many people go crazy on flagship IEMs, magnetic planars, or whatever FOTM top headphone is out there, and then plug them into their iPhones' headphone jacks because the iPhone somehow is "good enough." (Not always the iPhone, literally, but very frequently a source that does not meet the performance parameters of a particular headphone.)
D) Not only are individual members building systems this way, but an unfortunate number of other members even encourage the mentality that the headphone is the thing to buy, and the source that powers them only needs to be just so adequate.
No wonder we're all on the upgrade path merry-go-round: none of our systems have been optimized to achieve the performance of any one component in them.
To the first group of people, I am trying to provide guidance. To the second group of people, I am trying to provide a counter-balance by publicly presenting an alternative.
E) When I speak on HeadFi, I want to suggest that budgets should be firm, not ever-ballooning. I believe HeadFi is full of too many spend-happy addicts who would rather upgrade their headphones than buy, for example, a better mattress or better food and therefore better health. And also, I try to suggest that within any given budget, the strategy needs to be system-oriented. Not FOTM headphone-based, with scant attention paid to the source electronics. The audio chain, from start to finish, needs to be treated with consistent quality at all points.
Why? Because I have heard the difference between systems built on a budget split evenly versus on a budget heavy on one end. And I have met many experienced audiophiles who still fall for the appeal of sexier speakers and headphones.
(They call that a mullet system - short and tidy up front, long and out of control on the back. Another analogy is the girl with all looks and no personality - impressive at first glance, but tragically disappointing for the long-term, because she has no solid foundation by which to animate the attractive exterior.)
To reiterate: if you’re trying to cross a river, I’m trying to tell you the safest place to cross it. I am not the boatman charging you for passage. I am an experienced local who knows the intricacies of this river. And I am advising in good faith.
To the main part of the argument, which is technical in nature:
Surprisingly, that is not how a volume control works. Not, at least, in the majority of circumstances - because the way a volume control works in the majority of circumstances is actually the opposite.
F) What happens - in a majority of circuits - is exactly that the amplifier produces FULL SIGNAL. All the time. Without exception. With 100% strength in 100% of circumstances. But, through what we call “volume control,” you have signal attenuation. That is, burning off the full-level signal to the amplitude that produces the volume you want to hear. Volume controls have resistors that destroy and distort the full-level signal to make it comfortable for listening.
(Yes, in addition to the passive attenuation of the signal, many volume controls do also have a high-distortion, positive gain that takes over and boosts the signal when the volume knob is above certain levels. But the positive gain also powers the noise floor of the source/rest of the circuit, which is why we avoid positive gain volume controls, or at least the level on the volume where active gain kicks in. And of course, an entire preamplifier or headamp itself might be passive, or it might be active and provide gain in some stages in the circuit, where its volume control as a part of that circuit might or might not independently be passive or active. The possibilities are endless.)
I’m glad you mentioned Class A amps. Class A amps are the pinnacle implementation of a whole circuit made to be fully-on, all of the time. Whether there is audio signal or not. Everything is fired up and operating at full bore – minus whatever the volume control took away in the first place. But even in AB or D amps, the pipes are fully open - it's the number of electrons they are passing that gets cut short ahead of them.
And it is this destruction and distortion that audio companies try so hard to minimize, with all manner of exotic parts and innovative implementations. It is well-known that one of the most excruciating pieces for a company to engineer and then successfully manufacture is, in fact, the volume control.
G) So no, your pleasant little picture that "all a volume control does is make use of the first 150mW of a 3W amp" does not describe what happens at all. The volume control is far from some kind of ideal conduit in a compromised circuit, as you have implied. The volume control is a force for destruction in a system for signal augmentation. What it does is take a 2V input that exists no matter what and crushes it to within an inch of its life.
And this is why the source - in front of the volume control, and everything else as well - is actually the single most important component in the system. 1) It extracts as much information from the original media as possible, 2) It, and its power, must push through the rest of the circuit as much of that information as possible, even through such torturous stages as volume controls. What companies are trying to do when they engineer a volume control is provide that function while doing their hardest to avoid damaging the signal input from the source. Meaning, their utmost priority is protecting the source.
The major exception to this is with digital volume controls. In that case, yes, the original signal has an amplitude based on the volume you set at the source. And, if you've spent any productive time on HeadFi or in other audio outlets, you’ll be well-aware of the problems of bit-decimation inherent in this technique. So let's not try to encourage volume controls that rely on bit-decimation. (Again, I qualify this argument as true only in principle - any one given implementation may provide superior results in the context of the rest of a component's design.)
Therefore, one of the many things more power gives you is greater ability to push through the devastating path of a volume control. Volume componentry does not give sound, give power: it takes it away.
Headroom is another benefit, yes.
H) And, another, as I said above, is control – not volume, but power over the driver. These are physical masses, with inertia, that have to move real distances, pushing against real air, anywhere from 20 times a second (or less) to over 20,000 times each and every second (or more!). It takes real muscle to make that happen, even at quiet volumes. Again – this is not loudness. In fact, stopping a driver quickly is expressly about quietness. Am I still speaking romantically? Sure, so to see what a multifaceted thing audio power really is, see my next point, and notice the recurrence of certain variables in different formulae.
Which brings me to the complaint that car analogies do not apply to audio. Surprisingly, audio is described by physics, and physics is described by mathematics:
Mechanical physics:
Speed (m/s) = Acceleration (m/s/s) x Time (s)
Force (N) = Mass (g) x Acceleration (m/s/s)
Power (w) = Force (N) x Speed (m/s)
Work (j) = Power (w) x Time (s)
Electromagnetic physics:
Coulomb (c) = Current (a) x Time (s)
Voltage (v) = Resistance (ohms) x Current (a)
Power (w) = Voltage (v) x Current (a)
Work (j) = Power (w) x Time (s)
Compare the final two formulas. Work (measured in joules, BTUs, calories, and so on) is a product of both mechanical force AND electrical current. We observe this in audio when the electrical signal reaches the driver and becomes a mechanical force, and the electrons charge a magnet and that magnet moves a diaphragm and that diaphragm moves air.
It’s true there’s more going on in the conversion of mechanical to electrical energy (that is, not only are there a million ways to derive these definitions mathematically, but even when the mathematical concepts line up, the physical concepts do not). But, they do add up to at least one common thing, in this case: the quantitative measurement of power. We might think of cars using horsepower and audio electronics using watts, but they are indeed the same. Many cars use internal combustion engines, you say. I also happen to know of a few cars, and other modes of transportation, based on electric motors. How can cars use either combustion or electric motors – or even both at the same time? Because energy is energy. At some point, there is a conversion between electrical, mechanical, and thermal, but it is all still energy.
1 horsepower = 746 watts, in case you didn’t know.
So yes, I can break things down into analogies to help people understand abstract concepts in terms of concepts that are familiar and concrete. Car power relates to audio power. And a Mojo can be viewed as a motorcycle engine, while an LCD-3 can be viewed as a giant luxury saloon.
J) As I very explicitly stated in my earlier post, the Mojo would certainly work with less-sensitive cans, which may or may not include the LCD-Xs, and is less likely to include the 3s. As long as you are not overdriving the electronics and frying them, yes, the circuit works. Why you are asserting that I said the opposite, I am not sure. I did not say the Mojo is a bad product, and I will not say it; I have no reason. As far as specs go, since you asked, its THD is impeccable. But do take the time to compare its output to the Deckard, or to a Burson, a Bryston, a larger Schiit, the new Simaudio 430… and on and on. Notice how well-loved those products are, and notice how much power they have. Nobody is blasting their headphones with these amps at 140dB K) – but the power they produce is, through the filter of the volume control, making more music.
L) My example of IEMs was not that it would work “only” with IEMs, but to suggest, with a concrete example, that battery-powered devices pair better with more-sensitive transducers. Full-sized or in-ear-sized, there are plenty of headphones that are more sensitive and that would work better with the Mojo than the LCD-3s. There’s also the idea that you could use it with a dedicated headphone amp (Chord is very proud of the Mojo’s line-level function), with a full stereo or powered speakers – they have sufficient amplification on their own that the Mojo would work wonders as a DAC.
M) The reason Audeze developed the Xs alongside of the 2s and 3s is to give their flavor of sound on systems that do not have as much power. It’s also why Beyerdynamic developed the T5ps alongside the T1s. Both companies are conceding that a lighter load will work better with a smaller-powered amplifier. The Xs and T5ps might be made with something just like the Mojo in mind. And I’m sure they understand that an even lighter load will mate ideally with an amp that has even less power. Meanwhile, harder transducers pair better with more powerful electronics. The 3s and T1s are meant to be used with bigger amps. There is no controversy in this, not anywhere in the world, except from you.
Ready for a different analogy? Yes, I could use a fork to eat soup. But I would not get all the soup. I would be better using a spoon. In no way am I claiming that spoons are better than forks. Nor am I claiming that spoons are worth more money. Forks and spoons both have their uses.
And so, for the millionth time: an ultra-compact, ultra-portable amp will react with a heavier load, yes, but not ideally, while an oversized, completely stationary amp is more likely to produce a closer-to-ideal reaction with the same load. This is simply the way of things.
It is what I said at the very beginning, and it is what I will continue to say about matching headphones to amps. All caveats about a listener’s personal preferences reserved.
A) don't take the question "have you heard it?" personally. I was legitimiately asking if you had heard it. I am not sure why you took that so personally, almost no salesperson would try out every combination of gear. Especially with every product. In fact very few people have heard the Mojo, which is a new product, with the LCDX, which is also a new product. I was only lucky enough to hear it because we recently had a meet and I just happened to try that exact combination.
B) I mentioned the money and selling because that is the context
you mentioned it. IE selling an amp that cost nearly as much as the headphone as being something you advise. If you had never mentioned price, I'd have never mentioned price.
C) see, this is exactly why I was asking earlier if you had heard the combinations, that caused you such great offense. Because it's often difficult to tell from people's comments if they had heard the combination, or if they were just making guesses informed to greater or lesser extents. Again, it's not that I think people can't opine on whether or not they've heard the setups they're trying out, but I do ask "have you heard this?" to clarify. From your original statements, I had certainly though you'd heard the Deckard with the LCDX, but was very uncertain if you had heard the Mojo. Turns out you haven't heard the Deckard.
D) with objective measurements, headphones very obviously make the biggest difference. Especially todays more modern, more efficient headphones. The upgrade from a Grado SR60 to a HiFiMan Edition X, for example, will be much bigger, yes, even with an iPhone, than the difference between, say a iPhone and a T2. So, I think this is where our fundamental disagreement lies. My belief is that you should find the headphone you like, then find components that compliment it. The headphone is
BY FAR the most important aspect of the system, and an upgrade there will far outweigh upgrading your amp.
E) I agree that people need to have a real idea of their budget and spend responsibly. It stupefies me when I see comments like "aw man,I have to drop out because I don't get paid until Friday." Yes, many people like that are addicted to the surge that new gear gives them. However, I do disagree that the entire system is equally important. I disagree with that emphatically. The difference between a world class DAC and a budget DAC is not even remotely in the same ballpark as the difference between a world class headphone and a budget headphone. In fact I definitely disagree with your assessment that systems should be built from the source out. I believe you should start with the headphone, then find an amp that works well with your headphone, then see how much you have to spend on a DAC, and your music is whatever your music is.
F) Yes, I am aware that the amp doesn't "power down". What I was saying earlier is that through volume control, the headphone itself doesn't receive the full amount of power in the amp. A 4 watt amp powering a LCDX to 85 dB is only sending about 100mW through the output. the other 3.9 watts are being "destroyed" within the amp. But the headphone doesn't know or care that the amp originally had 4 watts of power, it simply only knows what hits the cable, after volume attenuation, ie 100mW. At that point, as far as the headphone is concerned, the amp is a 100mW amp, not a 4W amp.
G) I agree with what you say happens, I totally, emphatically disagree with your interpretation of what it then means. You take the fact that volume control is an inherently destructive act, with potential for signal distortions, and then view that as showing the need for more power. To me (and most electrical engineers I have talked to about it) this is exactly backwards. This is in fact a reason why you want
just enough power for your headphones to drive them to your hgihest listening levels, just short of clipping at max peak SPL, with just a bit of headroom thrown in. Because any power that isn't being used has to be destroyed, as you said. A signal that is the proper power to start with is less attenuated, and thus purer. Now, in practice, with a well made amp this isn't as big of a deal, because their volume controls are fairly close to perfect circuits. But as you note, they never quite get there. This is why most amps have a "sweet spot" on the volume control, and it is usually near full power but before its active signal boost (if it has one, which, like you noted raises noise and potential for clipping and other distortions). This is why using an incredibly high powered amp on an incredibly efficient headphone is
actually a bad thing. Because it forces the amp to create all that power and then destroy it in the volume control stage. Instead the amp that is just slightly higher powered than you need gets to stroll right through volume control with little to no attenuation as a much purer signal. Again, I don't want to overstate the importance of this, because most volume controls are good at doing this on well built amps. However, the take away is the
exact opposite of what you stated. Having extreme amounts more power than are needed is not a good thing, and it can, in fact, be bad.
This is why I always advise people to do the following:1) get their headphone that they like the sound of. 2) find their peak loudest listening level that they enjoy (hopefully this isn't higher than 85 or 90dB for safety reasons, but I try to let people be dangerous if they want). 3) Add 20dB (30dB if you listen to a lot of classical) for transient peaks. 4) Add 5dB for a bit of headroom to help assure no clipping 5) find an amp whose output impedance is 1/10 of their headphone's impedance and whose power will drive their headphone to that number we found dB wise earlier. For example, out of my HE400i I typically listen at 80dB, add 30 dB for transient peaks, add 5 dB for headroom. I get to 115 dB. Its impedance is around 50 ohms (unfortunately HiFiMan seems to have this number wrong, based on measurements by independent sites, but planars are also wonky on how their impedance measures anyway, so who knows, but I trust Tyll's readings). So, I need an amp that will at least get me to 115 dB at 50 ohms, with an output impedance lower than 5 ohms (but lower is always better there, IMHO). Surprisingly, this comes out to only needing around 500 mW. And, unsurprisingly, I've found that amps way more powerful than that actually sound worse. Typically it's fine up to about 2 watts, but 4 watt amps put you so low on the volume control that they actually sound worse. And there's no appreciable benefit to more power for me from 500 mW to 2 watts, if anything the inverse.
H) yes, this is correct, however, again, that power you are talking about, it's attenuated by the volume control, before it reaches the output stage to the headphone. The headphone can't call up the amp and say "hey, I'm gonna need more power than you're sending, because this is more dynamic!" Your headphone only receives the power it's being sent. If you have a 4 watt amp into a LCDX, nd listening at reasonable levels, again, the headphone doesn't know that 4 watts are available. It knows that the amount being sent through the output is 100mW, give or take. The 4 watt amp isn't going to more powerfully power through than the 500 mW amp, if they both have their outputs attenuated (ie volume control) to 100 mW. As far as the headphone is concerned they have the exact same amount of power, the amount that is coming out of the output.
I) It's not that electricity and power formulas work differently, yes, they're fundamentally the same formulas, it's that internal combustion engines and headphone amplifiers work differently. Like you noted, in a headphone amp, the "engine" is making all the power all the time, and then applies brakes as needed. In an internal combustion engine, this is not happening, as it's being fed less gas when less power is needed. A car with the throttle barely pressed produces less horsepower than it does wide open (and in fact horsepower of a car varies throughout the engine's RPM cycle as well).
J) your literal quote was "The EL-8s and LCD-Xs are Audeze's easier-to-drive headphones, and still I would not expect the Mojo to be sufficient for them." Now, somehow, you are saying that what you meant was just "of course the mojo is very good for easier to drive headphones like the LCDX, but not the LCD3." How is your earlier statement at all consistent with what you're saying now?!
K) "making more music"? What does that even mean?
L) Being battery powered is irrelevant, so long as it can produce enough power to drive the headphones to the needed levels. In fact the Mojo actually outputs more power than many wall wart powered desktop amps.
M) LOL, this is the exact opposite of what I've said, and the exact opposite of what you've said. What I objected to was when you said that the Mojo "would not be sufficient for [the LCDx and EL8]." What I've said the entire time is that you don't need more power than you need, and that in fact, if anything, extra power is a bad thing. The entirety of the quote I objected to was you saying that the Mojo is insufficient for the EL8 and LCDX (and other similar full sized yet efficient headphones).
