Popular very low efficiency headphones?

[Thomas savage]

Where’s the sense or advantage to owning/making low efficiency headphones ?

 

[graz_lag]

Where’s the sense or advantage to owning/making low efficiency headphones ?

As our audio sources are getting smaller and smaller, headphone makers are more and more offering high-performance (efficiency) headphones with the lowest impedance possible, equal or below 32 Ohms.
For what I have understood, an efficiency is considered in the higher range when it gets above 100 dB/mW, and in the lower range when it gets below 90 dB/mW.
Headphones designed for our phones have impedance below 32 Ohms and efficiency around 125 dB/mW.

All that said, I prefer to connect my Beyerdynamic DT-880 600 Ohms to my phone rather than a low-impedance headphones to my Primare SPA-23 AVR ...
The only risk for the 1st option is that the playback level is too low (very much ...)
The advantage ? No risk to bring overload to the phone.

@amirm Pls. correct me if I am wrong.

 

[solderdude]

Alternatively, for a small budget, you can consider the AKG K92, they offer a level of sound quality that goes very much beyond their budget price tag of $50 ...
Ohh ... AKG offers the best comfortable headband and soft ear pads on the planet ...

measurements/akg/k92/

Nom. power rating: 0.2W
Nom. voltage: 2.5 Vrms
Nom. current: 80 mA
Max. S.P.L. 121 dB
Impedance: 32 Ω
Efficiency: 98 dB/1mW (113 dB SPL/V)

 

[solderdude]

Where’s the sense or advantage to owning/making low efficiency headphones ?

I reckon linearity ?
.... at least for planars like the HE6 and Susvara.
With inefficient headphones one does not have to worry about amplifier noise levels.

No idea if there are any other advantages.

 

[maverickronin]

Alternatively, for a small budget, you can consider the AKG K92, they offer a level of sound quality that goes very much beyond their budget price tag of $50 ...

AKG's site say's they have a sensitivity of 113 dB/V and 32 ohm impedance. Is that the version you're talking about?

Where’s the sense or advantage to owning/making low efficiency headphones ?

There is no advantage to super low efficiency per se, it's just a trade off for something else, most often in planars now days. I could could be cost (fewer and/or lower grade magnets), thinner and/or or smaller magnets for a more open grid around diaphragm, to reduce acoustic impedance, standing waves, reflections or something. The HE-6's traces are gold instead of the usual aluminum or copper which seems to be for the purpose of increasing bass slam with extra moving mass coupling more vibration to your skull at the expense of efficiency.

Neodymium magnets of pretty much lick the problem of efficiency with conventional dynamics. I know AGK used to make some epicly low sensitivty 'phones back in the day. IIRC there were some that would take 7 or 8 VRMS to get to 100dB.

Going to far the other way is an issue too. 120dB/mW plus balanced armature IEMs exist which are basically just a crystal away from trutning into a radio headset. To avoid background hiss you either need a dead quiet amp or some kind of inline l-pad adapter.

 

[graz_lag]

AKG's site say's they have a sensitivity of 113 dB/V and 32 ohm impedance. Is that the version you're talking about?

The pair I bought for my wife for her Xperia phone were rated @ 32 Ohms and 96 or so dB/1mW, so + or - 113 dB/V.
AKG assembles in two plants : Austria and China.
I am a small "collector" of the K701 model, I own five versions of it, of which two (Quincy Jones's edition) have come out from the Chinese plant ...
The Made in Austria units sound differently, better to my taste, I am 100% positive on that.

Perhaps, at the stage of product design, they target different markets, the Chinese one as far as the local division is concerned, or more with a western's taste for the items that come out from Austria.

Just my guess.

 

[graz_lag]

measurements/akg/k92/

Nom. power rating: 0.2W
Nom. voltage: 2.5 Vrms
Nom. current: 80 mA
Max. S.P.L. 121 dB
Impedance: 32 Ω
Efficiency: 98 dB/1mW (113 dB SPL/V)

It looks like a "Tour de France" stage on the Alps !!!
It's too easy to bet on who's going to win it ... C Vroome Froome ...

 

[Tircuit]

2nd on the Fostex T-series. Had to buy a Topping A30 just to hear them. Not as good as HE-400i, but not bad. Also they are closed so a bit of a different flavor from the Senn 600 and
the 400i.

 

[amirm]

Alternatively, for a small budget, you can consider the AKG K92, they offer a level of sound quality that goes very much beyond their budget price tag of $50 ...

They are on sale for $39 so went ahead and ordered it.

 

[Mad_Economist]

Where’s the sense or advantage to owning/making low efficiency headphones ?

For planar magnetic headphone designers, I can think of a few, depending on how you define "low efficiency". Fewer and smaller magnets may be used, reducing weight and cost. The trace impedance can be raised, making the headphone an easier load for the amplifier. Additionally, some tuning and ergonomic options (earpad design, damping, etc) will reduce sensitivity, so a less strict target in that respect can give you additional options.

None of this needs to result in something that requires a power amplifier, of course, but given that the current trend in headphone amplifiers is to have far more power on tap than a sensitive headphone will ever require, you can perhaps see why designers aren't afraid to shave off a few dB of sensitivity here or there.

 

[Mad_Economist]

On the thread topic, the Russian planar magnetic brand "Myst" has the distinction of producing one of the few headphones to apparently clip the rather highly powered headamp Tyll Hertsens used for his test bench (note the 100dB THD), although if you are trying to provoke misbehavior in headamps, a lower-impedance headphone (perhaps one of MrSpeakers' <20 ohm designs) might be better.

 

[Headphonaholic]

erm... ear plugs for the high volume testing?

I don't go to many concerts but after a few I realized that almost all are entirely way too loud and will result in hearing loss of some kind. So I got some musicians ear plugs and I can actually enjoy the concerts now. It didn't seem to really do too much to ruin the sound quality it merely brought the volume down to a comfortable level.

It was funny because when the ear plugs arrived I decided to test and see how they worked. I grabbed a pair of headphones and got them to a borderline painful volume. Then I put the plugs in and listened and I was shocked! I had even chosen a song with shrill female vocals and it wasn't an issue. I then cranked the volume a bit more and was still fine. I took the plugs out and put the headphones near my ears and nearly had my ears blown off lol.

Also since we were just talking about it in another thread Amir, the minidsp ear rig might be useful in testing for distortion without blowing up your actual ears

 

[amirm]

I tried my etymotic ER-20 plugs. Unfortunately they don't fit my ears so not useful. I need to get something that fits much better. With IEMs I have to use the foam ones to get good enough seal.

 

[Zilfallion]

So I got some musicians ear plugs and I can actually enjoy the concerts now. It didn't seem to really do too much to ruin the sound quality it merely brought the volume down to a comfortable level.

It was funny because when the ear plugs arrived I decided to test and see how they worked. I grabbed a pair of headphones and got them to a borderline painful volume. Then I put the plugs in and listened and I was shocked! I had even chosen a song with shrill female vocals and it wasn't an issue. I then cranked the volume a bit more and was still fine. I took the plugs out and put the headphones near my ears and nearly had my ears blown off lol.

I've got some Etymotic ER20. Used them at a convention a couple months ago. Man was I glad I had them. Especially since some panels and the speakers had the gain way too high and some cables that would blast static if touched or moved outside it's optimal position. They're totally worth having some kind of plug.

I did find that they don't do a great job at bass frequencies, as I'm sure is expected. When testing them out with my HD 6XX, they sound noticeably warmer and bassier. Though other than that, they sounded quite natural. Balance of the mids to treble region is fairly decent, and doesn't completely kill the treble. Likely explains why you found the female vocals fine. I'd try a song with a fair amount of bass and see how the sound signature changes.

 

[Headphonaholic]

I tried my etymotic ER-20 plugs. Unfortunately they don't fit my ears so not useful. I need to get something that fits much better. With IEMs I have to use the foam ones to get good enough seal.

I don't recall what brand mine are but it actually came with 2 sizes, 1 of which was way too large, the other fit nicely.

I did find that they don't do a great job at bass frequencies, as I'm sure is expected. When testing them out with my HD 6XX, they sound noticeably warmer and bassier. Though other than that, they sounded quite natural. Balance of the mids to treble region is fairly decent, and doesn't completely kill the treble. Likely explains why you found the female vocals fine. I'd try a song with a fair amount of bass and see how the sound signature changes.

Oh that's interesting, when I did that test I wasn't paying super close attention to the details. I'll have to test them a bit. I would agree that they sounded natural. I was honestly expecting them to butcher the sound. I wouldn't be surprised if some detail is lost or some unevenness in the attenuation but most concerts hardly have perfect sound setups so in that regard I'm not losing any sleep. For what Amir is trying to accomplish I am unsure of how well it will work. It'll definitely protect his ears, that much is certain.

 

[Thomas savage]

I tried my etymotic ER-20 plugs. Unfortunately they don't fit my ears so not useful. I need to get something that fits much better. With IEMs I have to use the foam ones to get good enough seal.

You can get ones made for you with attenuation that’s flat over the frequency range so won’t effect the sound, they aren’t really expensive either.

 

[Headphonaholic]

Also thinking about the headphones I own that are less efficient and crave more volume... these come to mind:

Mrspeakers Aeon Flow Closed - 92db/mw | 13 ohm
Fostex T50rp MkII (Modded) - 98db/mw | 50 ohm
Sennheiser HD6XX - 103db/mw | 300 ohm
Audio Technica R70x - 99db/mw | 470 ohm

 

[TungstenC]

I tried my etymotic ER-20 plugs. Unfortunately they don't fit my ears so not useful. I need to get something that fits much better. With IEMs I have to use the foam ones to get good enough seal.

Etymotic also makes the ER20XS which has interchangeable tips (the ER4 foams will fit on them)

 

[solderdude]

In this case with efficiency the efficiency per applied volt is important, not in Wattage.

Mrspeakers Aeon Flow Closed - 92db/mw | 13 ohm = 112dB/1V so not that suited but planar so can be attenuated
Fostex T50rp MkII (Modded) - 98db/mw | 50 ohm = 107dB/V
Sennheiser HD6XX - 103db/mw | 300 ohm = 103dB/V (98dB/mW)
Audio Technica R70x - 99db/mw | 470 ohm = 113dB/V

I suggest to use HD650 and use an attenuator with low resistance values to protect the hearing
Have made a list with the efficiency of most popular over and on-ear headphones

 

[JJB70]

I think these days it is getting harder to find hard to drive headphones. Even planar magnetic models can be very efficient, the Oppo models don't need a headphone amp and can be driven easily enough from device headphone outputs. Even the AKG K812 studio monitor headphone is pretty easy to drive.