Questions Regarding Headphone Amplification

[Me x3]

I am rather new to this hobby and I am confused about somethings regarding headphone amplification. I am not sure if some of these questions have been answered so even pointing me to another thread would be extremely helpful. Thank you guys so much in advance!

1. What does the "watts" as a measurement of "power" in headphone amplification mean? I've heard many people talking power and how much watts per channel an amplifier has but what does it mean? For example, in Audeze's website, they say that LCD-X, for instance, is best driven by power between 1W and 4 W. What does it mean?

2. In sight of answers to the first question, why does balanced output have more "power" than single-ended? I research a bit about balanced and it doesn't seem to me that the rationale behind it would result in more power. So why do amplifier specs say that balanced have more output power? (one example would be Schiit Jot as indicated in their website).

3. What is the difference in driving dynamic and planar magnetic headphones? People say planar needs "power"(kind of going back to the first question), but why is "power" a more important part when ampllifying a planar? On the other hand, what is the things I should consider if I am picking an amplifier for my dynamic headphones?

4. From what I know, the output impedance of the amplifier should match the impedance of the headphone in the case of a dynamic driver; and OTL tube amp usually doesn't work well with planars. But when I am picking an amplifier for my dynamic and planar magnetic headphones, what else should I take note of?

I know they are long questions and probably take long times to write answers but I greatly appreciate any help form you guys!

1.a. Watt is a unit of Power, it's a way to quantify the rate of energy transfer from the amp to the headphone.
1.b. Feed the LCD-X with 1W to 4W and you'll damage your hearing and likely damage the LCD-X too.

2. I think this is not that simple to answer, mainly because not all amps with balanced outputs have the same topology.

3. There's no difference in the big scheme of things. Different headphones have different requirements and that applies when comparing a planar with a different planar, a planar with a dynamic, or a dynamic with other dynamic. Most simplifications such as "planar need more power" are not correct. On a side note, it can be said that planars are less affected by damping factor relative to most dynamics. That's because most planars have flat impedance (same impedance for all frequencies) and thus high output impedance on the amplifier won't colour the sound as much as with dynamics.

4.a. As an orientation rule the output impedance of the amplifier should be at least 8 times lower than the impedance of the dynamic headphone if you want to hear the headphone the way it was intended. Otherwise the sound will be coloured. Higher output impedance, higher deviation from the headphone's original response.
4.b. Most planars are low impedance (high sensitivity or low sensitivity)
For those with high sensitivity you might not want an OTL since they tend to be noisier than solidstate amps.
For those with low sensitivity you need and amp that's capable of suppling good amounts of current and most OTL amps can't do that.

 

[RRod]

Granted, the chart below is just a rough guideline, and the headphones will use more power when there is heavy bass and so on.

Is that peak SPL, because I wouldn't call 100dBSPL RMS 'moderate'.

 

[Music Alchemist]

Is that peak SPL, because I wouldn't call 100dBSPL RMS 'moderate'.

I didn't design the chart. It's from here: http://www.digizoid.com/headphones-power.html

 

[Enrico00]

In-depth info here:
https://en.wikipedia.org/wiki/Damping_factor
https://www.innerfidelity.com/conte...-250-ohm-and-dt-880-600-ohm-headphones-page-2
https://www.innerfidelity.com/content/musings-headphone-amplifier-output-impedance



As recommended before, just make sure the output impedance of the amp is at least eight times lower than the impedance of your headphones. (Most amps have an output impedance of under 1 ohm anyway.) Planar magnetics tend to have a near-flat impedance curve, so they are less affected by all this.

Why never calcoulate headphone's cable impedence?!

 

[Music Alchemist]

Why never calcoulate headphone's cable impedence?!

You'll have to get an answer from cable manufacturers for that one.

 

[Dulalala]

Why never calcoulate headphone's cable impedence?!

You're supposed to include the cable's impedance when calculating the damping factor, thing is, headphone's cable are short, meaning that the resistance of the cable itself is generally low enough that we can ignore it.

 

[Enrico00]

You're supposed to include the cable's impedance when calculating the damping factor, thing is, headphone's cable are short, meaning that the resistance of the cable itself is generally low enough that we can ignore it.

I meant that these calculations are made taking into account the power output from the amplifier and the impedance / sensitivity of the headphones (or I'm wrong?)

But if I change the cable between the amplifier and the headphones, this data will change.

it's just my observation by non-expert

 

[Dulalala]

I meant that these calculations are made taking into account the power output from the amplifier and the impedance / sensitivity of the headphones (or I'm wrong?)

But if I change the cable between the amplifier and the headphones, this data will change.

it's just my observation by non-expert

Yeah, the data will change, but as I said above, the resistance of a headphone cable is generally small enough that you can ignore it. That minute change isn't going to significantly impact the calculations.

 

[Enrico00]

Yeah, the data will change, but as I said above, the resistance of a headphone cable is generally small enough that you can ignore it. That minute change isn't going to significantly impact the calculations.

thanks!!!

 

[Dulalala]

Is that peak SPL, because I wouldn't call 100dBSPL RMS 'moderate'.

It calculates the power required to reach 100 dB SPL at 1 kHz only, so it's not the RMS value.

 

[RRod]

It calculates the power required to reach 100 dB SPL at 1 kHz only, so it's not the RMS value.

If we're testing a 1kHz tone and the peaks are 100dB SPL, then the RMS is about 97dB SPL, which is still not moderate, especially for a 1kHz tone . Just to be clear I'm not asking if it's peak or RMS *power*, but rather how they are quantifying loudness.

 

[Dulalala]

If we're testing a 1kHz tone and the peaks are 100dB SPL, then the RMS is about 97dB SPL, which is still not moderate, especially for a 1kHz tone . Just to be clear I'm not asking if it's peak or RMS *power*, but rather how they are quantifying loudness.

Ah I see what you mean. I never really realized they used 100 dB as "moderate", I personally use 100 dB because it leaves enough headroom for dynamic range, impedance swing, etc. Granted, they also said 85 dB is safe, but I honestly don't even listen to music that loud.

I suppose it could be the peak value of what is considered safe? Assuming 15 dB DR, if the 85 dB was the peak, then the average value could be around ~77-ish dB?

But then again, it could also be this...
"The daily recommended safe volume level of any sound is below 85 dB for a maximum duration of eight hours."
This could be where the safe value came from.

But honestly, I'm just as baffled as you.

 

[Music Alchemist]

Just to be clear I'm not asking if it's peak or RMS *power*, but rather how they are quantifying loudness.

I agree that the site owner should reconsider the labels. I only used it for the chart because it involved less effort than a resource I used to use. For what it's worth, I posted a loudness chart on the first page that mentions hearing damage from prolonged exposure occurring at 80-90 dB and hearing loss from repeated exposure occurring at 110 dB.

 

[ProtegeManiac]

I meant that these calculations are made taking into account the power output from the amplifier and the impedance / sensitivity of the headphones (or I'm wrong?)

But if I change the cable between the amplifier and the headphones, this data will change.

It will change but not enough to drastically alter how much power makes it to the drivers. It has about as much effect as swapping out an Iridium spark plug for a four-core Iridium spark plug. Any changes anyone observes when they go with the four core plugs after a tune up aren't isolating the effects of having done the tune up in the first place, like having old, filthy spark plugs getting replaced by a new one.

 

[Dr. Hugo]

Except that information on their website is an absolute lie. See my post and chart above. I drove the LCD-X from a Chord Mojo (which can output up to 600 mW at 32 ohms, albeit a bit more at 20 ohms) and did not even come close to pushing its limits. You're not likely to use even 20 mW with the LCD-X.

I calculated approximately how loud the headphones would get if you actually sent 1,000 mW and 4,000 mW (the listed figures on Audeze's site) into them: 133 and 139 dB. That's loud enough to cause extreme hearing damage.

Please pardon for one more question, if my planar (not dynamic) headphones reach listening level before the amplifier is at 2 o'clock, does that mean my planar is already well-driven and more power under the same "cleaniness" or distortion level wouldn't help (although cleaner power might)? In other words, my current amplifier drives my planar well enough for listening level, does that mean it has enough power and, if I ever want to upgrade the amp, I need to look for something with cleaner power instead of more power? Thanks.