[tinamou62]

Hi everyone,

I got into headphones because I love music and now am getting more and more interested in the electrical engineering behind our fancy hats. I recently got the Audeze LCD2C, and also have a pair of Sennheiser HD800S that I pair with an objective2 / Massdrop CTH.

I have read online (on Audeze's website) that the LCD2C's "recommended" power is 1-4W. With that being said, the sensitivity is 101db/mW - so wouldn't 1W be ear-blastingly loud? Meanwhile, the Sennheiser HD800S manual says that the max sustained power input should be 500mW.

I have a few questions - again, I apologize for how novice this must all sound. I consulted a lot of guides/videos/articles but still am having trouble piecing this all together.

1) Would a single amplifier be able to safely power the HD800S (< 500mW) but also power the LCD2C (1-4W)?

2) If the LCD2C sensitivity is 101db/mW, do you even need 1-4W of power? Again, that would be insanely loud right? I've seen online to calculate power you use an equation P = 10([desired db]-sensitivity/10).

2a) Would more power affect the acoustics in any way? So even if they CAN be powered by a low-power amp, would it matter to get a more powerful amp?

3) Do my CTH (1W at 50ohms) and Obj2 (613mW at 32ohms and 355mW at 150ohms) power these two headphones well enough, or should I look for a more powerful amp?

Thank you so much for your help.

Cheers!

 

[castleofargh]

1) Would a single amplifier be able to safely power the HD800S (< 500mW) but also power the LCD2C (1-4W)?

sure. because the 1-4W power suggestion is meaningless crap. they post that same stuff in the specs for all their headphones no matter how much difference there is in sensitivity and impedance. it's pretty much telling you get a powerfull amp so that you won't come crying when you realize that some planars are hard to drive. just disregard and instead rely on impedance and sensitivity at 1khz.

2) If the LCD2C sensitivity is 101db/mW, do you even need 1-4W of power? Again, that would be insanely loud right? I've seen online to calculate power you use an equation P = 10([desired db]-sensitivity/10).

same as above. you got the correct idea from the start.
but your equation isn't right. to estimate power you need the impedance somewhere. P=U²/R there are plenty of online calculators and hopefully they all give the same results ^_^. with my little excel file for 101dB@1mw and 70ohm I get 25mW to reach 115dBSPL.

2a) Would more power affect the acoustics in any way? So even if they CAN be powered by a low-power amp, would it matter to get a more powerful amp?

the specs for an amplifier is the max power into a given load. not how much power will be used and sent into the headphone at any volume setting. in this case you'd apparently have very loud music with 25mW, so having a very powerfull amp with huge gain will mostly mean that you will have to turn down the volume knob a lot to get your desired listening level.
there are always some arguments that more power is better. be it because of ignorance and fear of not getting enough, or because the user expects powerful amp in general to have better parts, you even find people who say that they sound better because if they can do high frequencies with high voltage swings, it means the amp has very good transient response. and in some far fetched logic that isn't completely false, but not really correct either and of course there is no clear experiment demonstrating that better transient response beyond what allows to reconstruct the audible range is having any sort of audible impact on music.
I honestly don't know statistically how often a more powerful amp is better, but I suspect that there is a strong bias toward bigger numbers and bigger prices that lead many people to assume that such variables correlate fidelity. except that they don't, amateur audio products have an aggravating lack of correlation between prices and objective fidelity.
personally I certainly wouldn't purchase too weak an amplifier, but I also avoid amps that are over the top compared to the needs of my headphone. my rational on this being that too much gain often means higher noise level, and sometimes hard to use volume knob, because we end up struggling within a 5°angle where above is too loud and below too quiet, instead of having an amplifier with more adequate gain settings where the volume knob is more likely to offer a more comfortable range of positions. also on many volume knobs, the lowest part is likely to exhibit higher channel imbalance(although that entirely depends on the type of volume system). so all that to me isn't encouraging me to look for amps with 1.21gigawatts. I'm of the group of audiophiles thinking that there very much is such a thing as too much power. now that's just my opinion. I have no hard evidence one way or the other and most likely good designs are good, bad designs are bad and the rest is bad oversimplification ^_^.

3) Do my CTH (1W at 50ohms) and Obj2 (613mW at 32ohms and 355mW at 150ohms) power these two headphones well enough, or should I look for a more powerful amp?

the hd800S is clearly the harder to drive headphone here. I have no idea about the CTH, I couldn't find specs into other loads, which would be a red flag for me and my hyperskepticism, but maybe I just suck at googling stuff.
on the O2 depending on the gain options you have, the hd800 might on occasion fail to be loud enough? you'd need about 4.5V to reach a max of 115dBSPL and the lowest gain values won't give that. but I'd expect typical listening condition to work just fine unless your typical listening conditions are listening super loud.
again, you'll have no trouble finding people telling you that you're wasting good headphones on crap amplifiers, and most of them will bring up power as the one fit all answer for stuff they don't understand. power is probably not the problem and if other amps do sound better(objectively or subjectively), that's most likely not the actual reason why on those headphones.
now can another amp measure better or sound subjectively better than the O2? sure! there are many amplifiers with very good measurements, as for subjective preference, well that's subjective and why someone will prefer something to something else, only he knows, and often even he doesn't. so I won't make any claim on the subjective side of things .
if you can try other gears, you should(it's part of the fun in this hobby). find meetings or audiophiles in your area and bet them to come see you or to invite you to try their gears with a friendly invite, some alcohol or just the opportunity to try your 2 headphones as after all they're good stuff that any audiophile who didn't yet try them would surely love to try. then when you've had more experience with more gears, you're better armed to make your own decisions.

 

[tinamou62]

sure. because the 1-4W power suggestion is meaningless crap. they post that same stuff in the specs for all their headphones no matter how much difference there is in sensitivity and impedance. it's pretty much telling you get a powerfull amp so that you won't come crying when you realize that some planars are hard to drive. just disregard and instead rely on impedance and sensitivity at 1khz.

same as above. you got the correct idea from the start.
but your equation isn't right. to estimate power you need the impedance somewhere. P=U²/R there are plenty of online calculators and hopefully they all give the same results ^_^. with my little excel file for 101dB@1mw and 70ohm I get 25mW to reach 115dBSPL.


the specs for an amplifier is the max power into a given load. not how much power will be used and sent into the headphone at any volume setting. in this case you'd apparently have very loud music with 25mW, so having a very powerfull amp with huge gain will mostly mean that you will have to turn down the volume knob a lot to get your desired listening level.
there are always some arguments that more power is better. be it because of ignorance and fear of not getting enough, or because the user expects powerful amp in general to have better parts, you even find people who say that they sound better because if they can do high frequencies with high voltage swings, it means the amp has very good transient response. and in some far fetched logic that isn't completely false, but not really correct either and of course there is no clear experiment demonstrating that better transient response beyond what allows to reconstruct the audible range is having any sort of audible impact on music.
I honestly don't know statistically how often a more powerful amp is better, but I suspect that there is a strong bias toward bigger numbers and bigger prices that lead many people to assume that such variables correlate fidelity. except that they don't, amateur audio products have an aggravating lack of correlation between prices and objective fidelity.
personally I certainly wouldn't purchase too weak an amplifier, but I also avoid amps that are over the top compared to the needs of my headphone. my rational on this being that too much gain often means higher noise level, and sometimes hard to use volume knob, because we end up struggling within a 5°angle where above is too loud and below too quiet, instead of having an amplifier with more adequate gain settings where the volume knob is more likely to offer a more comfortable range of positions. also on many volume knobs, the lowest part is likely to exhibit higher channel imbalance(although that entirely depends on the type of volume system). so all that to me isn't encouraging me to look for amps with 1.21gigawatts. I'm of the group of audiophiles thinking that there very much is such a thing as too much power. now that's just my opinion. I have no hard evidence one way or the other and most likely good designs are good, bad designs are bad and the rest is bad oversimplification ^_^.



the hd800S is clearly the harder to drive headphone here. I have no idea about the CTH, I couldn't find specs into other loads, which would be a red flag for me and my hyperskepticism, but maybe I just suck at googling stuff.
on the O2 depending on the gain options you have, the hd800 might on occasion fail to be loud enough? you'd need about 4.5V to reach a max of 115dBSPL and the lowest gain values won't give that. but I'd expect typical listening condition to work just fine unless your typical listening conditions are listening super loud.
again, you'll have no trouble finding people telling you that you're wasting good headphones on crap amplifiers, and most of them will bring up power as the one fit all answer for stuff they don't understand. power is probably not the problem and if other amps do sound better(objectively or subjectively), that's most likely not the actual reason why on those headphones.
now can another amp measure better or sound subjectively better than the O2? sure! there are many amplifiers with very good measurements, as for subjective preference, well that's subjective and why someone will prefer something to something else, only he knows, and often even he doesn't. so I won't make any claim on the subjective side of things .
if you can try other gears, you should(it's part of the fun in this hobby). find meetings or audiophiles in your area and bet them to come see you or to invite you to try their gears with a friendly invite, some alcohol or just the opportunity to try your 2 headphones as after all they're good stuff that any audiophile who didn't yet try them would surely love to try. then when you've had more experience with more gears, you're better armed to make your own decisions.

sure. because the 1-4W power suggestion is meaningless crap. they post that same stuff in the specs for all their headphones no matter how much difference there is in sensitivity and impedance. it's pretty much telling you get a powerfull amp so that you won't come crying when you realize that some planars are hard to drive. just disregard and instead rely on impedance and sensitivity at 1khz.

same as above. you got the correct idea from the start.
but your equation isn't right. to estimate power you need the impedance somewhere. P=U²/R there are plenty of online calculators and hopefully they all give the same results ^_^. with my little excel file for 101dB@1mw and 70ohm I get 25mW to reach 115dBSPL.


the specs for an amplifier is the max power into a given load. not how much power will be used and sent into the headphone at any volume setting. in this case you'd apparently have very loud music with 25mW, so having a very powerfull amp with huge gain will mostly mean that you will have to turn down the volume knob a lot to get your desired listening level.
there are always some arguments that more power is better. be it because of ignorance and fear of not getting enough, or because the user expects powerful amp in general to have better parts, you even find people who say that they sound better because if they can do high frequencies with high voltage swings, it means the amp has very good transient response. and in some far fetched logic that isn't completely false, but not really correct either and of course there is no clear experiment demonstrating that better transient response beyond what allows to reconstruct the audible range is having any sort of audible impact on music.
I honestly don't know statistically how often a more powerful amp is better, but I suspect that there is a strong bias toward bigger numbers and bigger prices that lead many people to assume that such variables correlate fidelity. except that they don't, amateur audio products have an aggravating lack of correlation between prices and objective fidelity.
personally I certainly wouldn't purchase too weak an amplifier, but I also avoid amps that are over the top compared to the needs of my headphone. my rational on this being that too much gain often means higher noise level, and sometimes hard to use volume knob, because we end up struggling within a 5°angle where above is too loud and below too quiet, instead of having an amplifier with more adequate gain settings where the volume knob is more likely to offer a more comfortable range of positions. also on many volume knobs, the lowest part is likely to exhibit higher channel imbalance(although that entirely depends on the type of volume system). so all that to me isn't encouraging me to look for amps with 1.21gigawatts. I'm of the group of audiophiles thinking that there very much is such a thing as too much power. now that's just my opinion. I have no hard evidence one way or the other and most likely good designs are good, bad designs are bad and the rest is bad oversimplification ^_^.



the hd800S is clearly the harder to drive headphone here. I have no idea about the CTH, I couldn't find specs into other loads, which would be a red flag for me and my hyperskepticism, but maybe I just suck at googling stuff.
on the O2 depending on the gain options you have, the hd800 might on occasion fail to be loud enough? you'd need about 4.5V to reach a max of 115dBSPL and the lowest gain values won't give that. but I'd expect typical listening condition to work just fine unless your typical listening conditions are listening super loud.
again, you'll have no trouble finding people telling you that you're wasting good headphones on crap amplifiers, and most of them will bring up power as the one fit all answer for stuff they don't understand. power is probably not the problem and if other amps do sound better(objectively or subjectively), that's most likely not the actual reason why on those headphones.
now can another amp measure better or sound subjectively better than the O2? sure! there are many amplifiers with very good measurements, as for subjective preference, well that's subjective and why someone will prefer something to something else, only he knows, and often even he doesn't. so I won't make any claim on the subjective side of things .
if you can try other gears, you should(it's part of the fun in this hobby). find meetings or audiophiles in your area and bet them to come see you or to invite you to try their gears with a friendly invite, some alcohol or just the opportunity to try your 2 headphones as after all they're good stuff that any audiophile who didn't yet try them would surely love to try. then when you've had more experience with more gears, you're better armed to make your own decisions.

Wow! Thank you so much for your informed and excellent reply.

1) I figured - 1W of power would produce extremely high listening levels. No clue why that's still to this day up on the site, as 101db is already plenty loud and that's at 1mW

2) I think I gave the equation for voltage. I found it here: https://linustechtips.com/main/topic/221772-calculating-audeze-lcd-2s-power-requirement-vs-o2/

3) I completely agree with you on many of your points here and the next one - I think we can get so caught up in numbers and measurements we forget it's not electronicophile, it's audiophile, and at the end of the day what sounds good is what sounds good. I didn't think at all my headphones weren't loud enough, in fact on my obj2 the volume knob is barely 1/4 of the way turned with my LCD2's running - so it SHOULD? produce enough power. It seems then, if there is enough power, the sound signature is just that of the amplifier - nothing to do with power provided there is a minimum.

I really do need to try new gear. But it's tough and I'm scared of bringing my headphones out of my house. They're really precious to me. Maybe one of these days.

Thank you very much for your answers. It was a great read and I enjoyed learning more. Have a fantastic 2019!

 

[ProtegeManiac]

I have read online (on Audeze's website) that the LCD2C's "recommended" power is 1-4W. With that being said, the sensitivity is 101db/mW - so wouldn't 1W be ear-blastingly loud? Meanwhile, the Sennheiser HD800S manual says that the max sustained power input should be 500mW.
---
2) If the LCD2C sensitivity is 101db/mW, do you even need 1-4W of power? Again, that would be insanely loud right? I've seen online to calculate power you use an equation P = 10([desired db]-sensitivity/10).

I always assumed that discrepancy means they're puling the same kind of switcheroo that other headphone manufacturers do and switch around xxxdB/1V with th xxdB/1mW. If you converted 101dB/1V to xx/1mW, it comes out along the lines of 92dB/1mW. You'd need around 700mW for that as a rough guesstimate of how much power you will ever need with a fair bit of overestimation over realistic use (gain of course is not yet accounted for but then you'd have to be using something like a 1.2V iPod feeding an amp with +4dB gain or lower).

1) Would a single amplifier be able to safely power the HD800S (< 500mW) but also power the LCD2C (1-4W)?

Burson Conductor, AudioGD NFB-28, Violectric V281...

2a) Would more power affect the acoustics in any way? So even if they CAN be powered by a low-power amp, would it matter to get a more powerful amp?

3) Do my CTH (1W at 50ohms) and Obj2 (613mW at 32ohms and 355mW at 150ohms) power these two headphones well enough, or should I look for a more powerful amp?

Thank you so much for your help.

Cheers!

Think of it in terms of PC games. Minimum is i3 and GTX 750Ti, recommended can be i7 and GTX 970. Minimum means "crouching in grass will not render you blocked by grass" and recommended means "choose between rendering grass really well with very low 1% lows/bad frame time peaks and smooth 60fps." Doesn't always hurt to get a 9900K with a cooler and motherboard that will help it run at 5.0ghz and a GTX 2080Ti (assuming you don't have to starve yourself).

With amps as much as you can't easily quantify it the difference is kind of similar - minimum is "sure you can get loud enough but does it sound good at high volumes or why would you only listen at very low volumes" while Recommended runs the gamut between "HAVE A LOT OF POWER HEADROOM!!! FOUR WATTS M**********R!!!!" and "buy something expensive with deliberate euphonic distortion." Somewhere in the middle of that but closer to the first is "If you have a headphone that needs XXmW (or a speakers that needs XXWatts depending on how far you'll sit), a Class A amp with XXmW-50mW output will not sound all that different if from a Class A/B amp with 4XXmW that you might not get into Class B mode at the realistic output level you'll actually use it at."

3) Do my CTH (1W at 50ohms) and Obj2 (613mW at 32ohms and 355mW at 150ohms) power these two headphones well enough, or should I look for a more powerful amp?

I'd just use the CTH on both headphones.

 

[PaganDL]

@ProtegeManiac,

Agree with you on the using CTH for both headohones.

 

[castleofargh]

Wow! Thank you so much for your informed and excellent reply.

1) I figured - 1W of power would produce extremely high listening levels. No clue why that's still to this day up on the site, as 101db is already plenty loud and that's at 1mW

2) I think I gave the equation for voltage. I found it here: https://linustechtips.com/main/topic/221772-calculating-audeze-lcd-2s-power-requirement-vs-o2/

3) I completely agree with you on many of your points here and the next one - I think we can get so caught up in numbers and measurements we forget it's not electronicophile, it's audiophile, and at the end of the day what sounds good is what sounds good. I didn't think at all my headphones weren't loud enough, in fact on my obj2 the volume knob is barely 1/4 of the way turned with my LCD2's running - so it SHOULD? produce enough power. It seems then, if there is enough power, the sound signature is just that of the amplifier - nothing to do with power provided there is a minimum.

I really do need to try new gear. But it's tough and I'm scared of bringing my headphones out of my house. They're really precious to me. Maybe one of these days.

Thank you very much for your answers. It was a great read and I enjoyed learning more. Have a fantastic 2019!

for 2) the formula just seemed wrong and was. but the formula in the link leaves dB and mW as only units and works fine. it's just 10 "to the power of" the rest(if that's how we say it in English?) instead of simply multiplied like you posted.

 

[tomb]

If you go back and look at Audeze's website, they quote the sensitivity at Drum Reference Point (DRP). "Drum" is the simulated position of the human ear drum in the testing bust (head). Most headphones' sensitivity is measured at the headphone's output point, somewhere inside the can, or otherwise known as the Ear Reference Point (ERP). DRP tends to be about 10dB higher than ERP. This sort of makes sense if you imagine that the ear and canal "focus" the sound stream into the eardrum. All those sound waves are distributed along a much smaller surface area, meaning the sound pressure is automatically higher for the same headphone output. DRP tends to register about 10dB higher than ERP. So, you can take that Audeze sensitivity of 101 and say that it's really 91dB/mW, not a really very high efficiency … at all.

Factor in the fact that every 3dB needs a doubling in power, and citing that sensitivity at the DRP means the headphone needs over 8 times the power than a headphone of 101dB measured at the ERP.

 

[castleofargh]

If you go back and look at Audeze's website, they quote the sensitivity at Drum Reference Point (DRP). "Drum" is the simulated position of the human ear drum in the testing bust (head). Most headphones' sensitivity is measured at the headphone's output point, somewhere inside the can, or otherwise known as the Ear Reference Point (ERP). DRP tends to be about 10dB higher than ERP. This sort of makes sense if you imagine that the ear and canal "focus" the sound stream into the eardrum. All those sound waves are distributed along a much smaller surface area, meaning the sound pressure is automatically higher for the same headphone output. DRP tends to register about 10dB higher than ERP. So, you can take that Audeze sensitivity of 101 and say that it's really 91dB/mW, not a really very high efficiency … at all.

Factor in the fact that every 3dB needs a doubling in power, and citing that sensitivity at the DRP means the headphone needs over 8 times the power than a headphone of 101dB measured at the ERP.

that's just Audeze obfuscating things.
from some old ITU doc:

Also if the measured value of receiving sensitivity/frequency characteristics refers to the eardrum, it must be converted to a value of SJE that refers to ERP

I usually don't mind that because measurements at 1khz don't change all that much between reference points(at least if I remember correctly). but we could probably lower the specs by maybe 2 or 3dB just to be cautious(nothing that will change how even an O2 can handle that, even 10dB wouldn't be a power problem with a 2V DAC and that headphone).
at this point I feel tempted to wonder if Audeze actually measures the output at 1khz? it would be weird not to, but how they present their data is plenty weird already IMO.

 

[ProtegeManiac]

@ProtegeManiac,

Agree with you on the using CTH for both headohones.

Yeah it's got enough power. Not gonna be my first choice to recommend but OP already has it.

this point I feel tempted to wonder if Audeze actually measures the output at 1khz? it would be weird not to, but how they present their data is plenty weird already IMO.

Can't remember what headphone it was (but definitely not Audeze) but I did see one before that was measured at a different freq (although it was indicated), and when I saw the graph the response there was a lot stronger than at 1000hz. Not that it confirms Audeze does it that way but at least one other actually did. Definitely not one of the more popular ones here though - the response graph was hard to find.

 

[PaganDL]

Yeah it's got enough power. Not gonna be my first choice to recommend but OP already has it.

@ProtegeManiac, my reason for recommending too !

Hope you have a great day !