Question about impedance

[587191]

Hey everyone, I don't really understand how impedance works. I've heard that basically higher impedance = harder to drive (lower volume), lower impedance = easier to drive (high volume). But I have the Sennheiser HD 560S (120ohm), Sony XBA-A3 (32ohm) and Sennheiser IE 200 (18ohm), and the higher the impedance, the louder they sound. While my HD 560S can sound like an actual nuclear reactor almost breaking in half because of how loud they can get, my IE 200 sound just "pretty loud", and the Sony's are somewhere in between. So did I missunderstand something? Thanks!

 

[o0genesis0o]

Hey everyone, I don't really understand how impedance works. I've heard that basically higher impedance = harder to drive (lower volume), lower impedance = easier to drive (high volume). But I have the Sennheiser HD 560S (120ohm), Sony XBA-A3 (32ohm) and Sennheiser IE 200 (18ohm), and the higher the impedance, the louder they sound. While my HD 560S can sound like an actual nuclear reactor almost breaking in half because of how loud they can get, my IE 200 sound just "pretty loud", and the Sony's are somewhere in between. So did I missunderstand something? Thanks!

you need to consider sensitivity as well (dB/mW). Higher impedance gear requires more voltage to achieve certain loudness but not much current, and vice versa.

In the IEM world, I’m much more concerned about IEMs with low impedance and low sensitivity. Those are truly “hard to drive”.

 

[587191]

you need to consider sensitivity as well (dB/mW). Higher impedance gear requires more voltage to achieve certain loudness but not much current, and vice versa.

In the IEM world, I’m much more concerned about IEMs with low impedance and low sensitivity. Those are truly “hard to drive”.

Could you give me an example of some hard to drive IEM's? IE 200 are 18ohms with a sensivity 101dB/mW, and they don't get "very" loud Although I suppose they must be pretty easy to drive still

 

[o0genesis0o]

Could you give me an example of some hard to drive IEM's? IE 200 are 18ohms with a sensivity 101dB/mW, and they don't get "very" loud Although I suppose they must be pretty easy to drive still

Symphonium Crimson and FatFREQ Scarlet are some recent IEMs I have reviewed that are quite difficult to drive. The crimson can make normal audio jacks like my ROG Ally clipping

 

[megabigeye]

Could you give me an example of some hard to drive IEM's? IE 200 are 18ohms with a sensivity 101dB/mW, and they don't get "very" loud Although I suppose they must be pretty easy to drive still

Symphinum Audio Titan are the hardest to drive that I've read about: 3Ω and 105dB/1V = 79.8dB/1mW. With that low an impedance it's probably one of the hardest to drive headphones on the market.

 

[WILLJS]

you need to consider sensitivity as well

this is very true, consider Sennheiser HD6xx (300 Ohms) vs DT770 Pro (mine are 250 Ohms). the HD6xx has a higher impedance but is substantially easier to drive.
i believe impedance means how much of the original power to gets to the driver, and sensitivity is how loud that amount of power causes the headphone to be.
this is hard to explain in simple terms.

 

[WILLJS]

this is very true, consider Sennheiser HD6xx (300 Ohms) vs DT770 Pro (mine are 250 Ohms). the HD6xx has a higher impedance but is substantially easier to drive.
i believe impedance means how much of the original power to gets to the driver, and sensitivity is how loud that amount of power causes the headphone to be.
this is hard to explain in simple terms.

i may be wrong though - please correct me if so.

 

[megabigeye]

this is very true, consider Sennheiser HD6xx (300 Ohms) vs DT770 Pro (mine are 250 Ohms). the HD6xx has a higher impedance but is substantially easier to drive.
i believe impedance means how much of the original power to gets to the driver, and sensitivity is how loud that amount of power causes the headphone to be.
this is hard to explain in simple terms.

Impedance determines the ratio of voltage to current. Higher impedance requires relatively more voltage, lower impedance requires relatively more current.

Efficiency is how loud the headphones get with a given power (I.E., milliwatts). Sensitivity is how loud the headphones get with a given voltage.

Two headphones that have the same efficiency but different impedances (one high and one low) will require the same amount of power to reach a given SPL, but the high impedance one will require more voltage and less current; the low impedance one will require more current and less voltage.

 

[o0genesis0o]

i may be wrong though - please correct me if so.

Someone explained to me in the past that it’s just ohm law. Given the same amount of power to get the same loudness (dictate by sensitivity), higher impedance = needing more voltage but less current and vice versa. That’s why some IEMs with 3ohm impedance can be a nightmare to drive.

 

[Somafunk]

A very simplistic explanation but good enough to get you through 1st year at university

 

[WILLJS]

Someone explained to me in the past that it’s just ohm law. Given the same amount of power to get the same loudness (dictate by sensitivity), higher impedance = needing more voltage but less current and vice versa. That’s why some IEMs with 3ohm impedance can be a nightmare to drive.

i guess the same reason some massive speakers are 4 Ohms and need 150 watts minimum to sound good.

 

[castleofargh]

Hey everyone, I don't really understand how impedance works. I've heard that basically higher impedance = harder to drive (lower volume), lower impedance = easier to drive (high volume). But I have the Sennheiser HD 560S (120ohm), Sony XBA-A3 (32ohm) and Sennheiser IE 200 (18ohm), and the higher the impedance, the louder they sound. While my HD 560S can sound like an actual nuclear reactor almost breaking in half because of how loud they can get, my IE 200 sound just "pretty loud", and the Sony's are somewhere in between. So did I missunderstand something? Thanks!

You get confused because many people use "hard to drive" to mean just about anything. Higher impedance does not mean harder to drive, there is no such rule. It doesn't even ensure how loud a headphone or IEM will be. So of course people who conflate those concepts can say many confusing things. It's not you, it them ^_^.

As suggested, it's the sensitivity/efficiency that tells you how loud something is going to be. Even that only tells you about how loud it is at 1kHz(so the tuning of the headphone/IEM also matters for how you perceive the overall loudness. Imagine a very V shaped tuning, 1kHz might be a little misleading for how loud it will feel).
Also, you have to be careful about the units expressing "sensitivity". What you see as sensitivity spec on websites is measured by setting the amp so that the headphone gets say 1volt(Sennheiser does that) from a 1kHz tone, and they measure how loud the headphone gets. Simple enough, and the result is a decibel value expressed in SPL for 1V.
But more often those specs are expressed for 1mW instead of 1V. With the relation being P=V²/R . The confusion might be avoided if we just called one efficiency and one sensitivity or something like that, but audiophiles and websites don't seem to care if people get mighty confused.
So check the units and if you can't find the unit, don't assume anything.

Anyway, that's for loudness.


For an IEM, almost anything will get them loud. So "hard to drive" is almost never about loudness.
Instead, you run into 2 main issues with IEMs:

1/ the signature changes noticeably from one amp to another. I discuss and demonstrate that poorly here: https://www.head-fi.org/threads/feedback-about-gears-stop-doing-it-wrong-impedance.866714/
Long story short, it's about the impedance output of the amplifier and the impedance curve of the IEM. Someone will take a given IEM, dislike the signature, try another amplifier and like it better. His misinterpretation of the change could very well be "this IEM is hard to drive".
In your case, the IE200 is a single dynamic driver so the impedance curve is expected to be about flat(not much happening beside resistance, so it should keep its signature on most amplifiers. While the WBA-A3 is a 3way design, and you might get audible changes in tuning from different amplifiers. I couldn't find an impedance graph for either, so I'm just guessing possible behaviors, don't take my word for it. But in general, multidrivers or just a single BA driver will have a non-flat impedance curve.


2/ The IEM's impedance goes too low somewhere(the value you see on specs is again only at 1kHz and the impedance might be lower somewhere else):
Then sometimes the amplifier can't handle the very low impedance. For an amplifier, the lower the impedance of the load(IEM) the more it starts looking like you just short-circuited the amp with a wire. Not all amplifiers are designed to drive extremely low impedance loads, just like not all amps are designed to be silent(no hiss) into something as sensitive as an IEM. Different needs made engineers design different amps. Anyway, you may sometimes plug your really low impedance IEM into an amplifier that wasn't designed to handle that. It might just get hot(most of the energy is dissipated by the amp instead of being used by the IEM). And some other amp might distort like crazy(even though the total power is still small, the amount of current might be too much for the design). Someone surely could experience that and declare that particular IEM as "hard to drive". Seems fair enough, but clearly we're facing a different issue entirely.


My general advice is to be on the lookout for people saying that a particular IEM or headphone is hard to drive, because even if most time it has no immediate meaning, it might be an indication that the IEM/headphone is an outlier in some way(I hate extreme designs just as much as elite audiophiles adore them). Such outlier design might really require more care for what will drive it. Just keep in mind that the always suggested "more power" might not in fact be the magic bullet for your particular situation, and that "hard to drive" is ultimately one of those for me.

But then again, on the forum I tend to feel the same about "neutral", "power", "balanced", "dynamic", "fast"...

 

[587191]

You get confused because many people use "hard to drive" to mean just about anything. Higher impedance does not mean harder to drive, there is no such rule. It doesn't even ensure how loud a headphone or IEM will be. So of course people who conflate those concepts can say many confusing things. It's not you, it them ^_^.

As suggested, it's the sensitivity/efficiency that tells you how loud something is going to be. Even that only tells you about how loud it is at 1kHz(so the tuning of the headphone/IEM also matters for how you perceive the overall loudness. Imagine a very V shaped tuning, 1kHz might be a little misleading for how loud it will feel).
Also, you have to be careful about the units expressing "sensitivity". What you see as sensitivity spec on websites is measured by setting the amp so that the headphone gets say 1volt(Sennheiser does that) from a 1kHz tone, and they measure how loud the headphone gets. Simple enough, and the result is a decibel value expressed in SPL for 1V.
But more often those specs are expressed for 1mW instead of 1V. With the relation being P=V²/R . The confusion might be avoided if we just called one efficiency and one sensitivity or something like that, but audiophiles and websites don't seem to care if people get mighty confused.
So check the units and if you can't find the unit, don't assume anything.

Anyway, that's for loudness.


For an IEM, almost anything will get them loud. So "hard to drive" is almost never about loudness.
Instead, you run into 2 main issues with IEMs:

1/ the signature changes noticeably from one amp to another. I discuss and demonstrate that poorly here: https://www.head-fi.org/threads/feedback-about-gears-stop-doing-it-wrong-impedance.866714/
Long story short, it's about the impedance output of the amplifier and the impedance curve of the IEM. Someone will take a given IEM, dislike the signature, try another amplifier and like it better. His misinterpretation of the change could very well be "this IEM is hard to drive".
In your case, the IE200 is a single dynamic driver so the impedance curve is expected to be about flat(not much happening beside resistance, so it should keep its signature on most amplifiers. While the WBA-A3 is a 3way design, and you might get audible changes in tuning from different amplifiers. I couldn't find an impedance graph for either, so I'm just guessing possible behaviors, don't take my word for it. But in general, multidrivers or just a single BA driver will have a non-flat impedance curve.


2/ The IEM's impedance goes too low somewhere(the value you see on specs is again only at 1kHz and the impedance might be lower somewhere else):
Then sometimes the amplifier can't handle the very low impedance. For an amplifier, the lower the impedance of the load(IEM) the more it starts looking like you just short-circuited the amp with a wire. Not all amplifiers are designed to drive extremely low impedance loads, just like not all amps are designed to be silent(no hiss) into something as sensitive as an IEM. Different needs made engineers design different amps. Anyway, you may sometimes plug your really low impedance IEM into an amplifier that wasn't designed to handle that. It might just get hot(most of the energy is dissipated by the amp instead of being used by the IEM). And some other amp might distort like crazy(even though the total power is still small, the amount of current might be too much for the design). Someone surely could experience that and declare that particular IEM as "hard to drive". Seems fair enough, but clearly we're facing a different issue entirely.


My general advice is to be on the lookout for people saying that a particular IEM or headphone is hard to drive, because even if most time it has no immediate meaning, it might be an indication that the IEM/headphone is an outlier in some way(I hate extreme designs just as much as elite audiophiles adore them). Such outlier design might really require more care for what will drive it. Just keep in mind that the always suggested "more power" might not in fact be the magic bullet for your particular situation, and that "hard to drive" is ultimately one of those for me.

But then again, on the forum I tend to feel the same about "neutral", "power", "balanced", "dynamic", "fast"...

"It might just get hot(most of the energy is dissipated by the amp instead of being used by the IEM)."

I'm having this problem with my current portable (kinda more of a dongle) dac+amp. It heats up quite a bit and it has a lot of that hiss noise / static - ground noise to it. I have also observed that my XBA-A3 can sound somewhat distorted at higher volume.

 

[earmonger]

It sounds like your dongle is malfunctioning. Does Apple sell in Moldova?

 

[Roseval]

Try this one: https://www.head-fi.org/threads/headphone-amp-impedance-questions-find-the-answers-here.607282/