Question about Headphone amplifiers

[PenguinMusic]

Hi,

In the quest for a headphone amplifier, I would have some questions.

I've read the graphs and reviews posted by Amir. And I thought I understood those until I got to the question of the "output impedance".

It seems that the "output impedance" of a headphone amplifier is an important factor.
I've tried to read about this, but I must say that I don't quite understand what it all means.

Now, it turns out that I just bought an headphone amp which seems to have pretty high output impedance.
I think it was measured at 11 Ohm but that was not given on the manufacturer's website.

It seems that if you have high output impedance in the amp and not too high impedance on the phone, there is or might be a "mismatch" between both.
My headphone has 32Ohm impedance.

My questions are quite simple (I think) :
- will the use of a headphone amp measured at 11Ohm output impedance (potentially) damage the headphone ?
- will the use of a headphone amp measured at 11Ohm output impedance create bad sound on a 32Ohm heaphone or can it still sound good ?
- will the use of a headphone amp measured at 11Ohm output impedance allow me to use the full "volume adjustement" or will I already have super loud sound at step 3 ?

Thanks for your answers.

Regards.

 

[Blumlein 88]

Might help if you told us your headphone amp.

It won't damage your headphones.

It may or may not sound good. You could have trouble getting enough power with such a mismatch. You probably will get some frequency response that isn't flat due to the mismatch. Whether that sounds okay, good, worse or better is a crapshoot.

Whether you'll always have the volume turned up depends upon the particular amp you are using and how much power it has.

If you already have the amp try it and see if you think it is okay.

If not, and you can return it, return it and get a better made headphone amp. JDS labs Atom or something similar.

 

[PenguinMusic]

Hi,

Thanks for your answer...

And my : that was quick

So if I read you correctly :
- no damages to headphone drivers ;
- possible sound distorsion (but may be there or not and be audible or not).

The headphone is the Oppo PM-1 that I really like.
The amp to arrive is the Aune X7s.

It has been tested here, but I think I did not really paid attention to the last lines about output impedance...
The link about this is here :
https://www.audiosciencereview.com/...aune-x7s-and-arcam-rhead-headphone-amps.4270/

I must say I probably did stick too much to the first lines where it says that the performance is really good.
But maybe I got a little confused.
And yes, in case it's needed, I cna return the amp.

Question : the x7s is advertised as a "Pure Class-A" amplifier (don't reall y understand what that means).
Will this have any influence on the "output impedance" and it's measurement ?

I think if I do not like the Aune X7s I'll return it and may go for the Topping A50s... which is in the same price range.

 

[PenguinMusic]

Hi,

Just received the Aune x7s headphone amp.
I hooked it up.

So my configuration so far looks like this.

The files are stored on my computer. The computer is Linux powered and the player used is Lollypop. The sound manager used is the regular Pulse Audio where I disabled the default "resampling" feature.

The files are transmitted via Toslink cable. The toslink output is build directly on the Mobo. The cable used is a Chord optical cable (most probably snake oil and I admit I never was able to hear a difference between that cable and another one. And I am almost sure that there is indeed no difference. So I won't claim it changes anything... But hey. My pleasure ).

The DAC used is a BAT-30 from Fiio. Small 80€ DAC that can be used as Bluetooth emitter and also as BT receiver. It is here used as DAC.

Output is passed to x7s using a pair of analog Linn cables (not sure they'll make a difference, but those were the only ones I had, besides the really thick and heavy analog cables that would seem somewhat inappropriate in this set-up. They are also most probably snake oil, but probably of a snake oil that is slightly less greasy that the optical cable Here again... My pleasure. And those cables were there since decade, so...

Aune x7s is hooked up to Oppo PM-1 using the OCC cable provided by Oppo.

After what I have read here and also a little elsewhere, I was afraid that I could not really use the x7s and would have to return it.
Because of distorsion or lack of power.
Well, concerning "power" : I think I do not have to worry about that. the FiiO BTA-30 is up to 75% of it's output. The Aune x7S is at about 50% of it's output (if I can trust the buttons position) and I already plays really loud, probably louder than I usually listen too...
Going back to more acceptable levels (that most would probably consider as "quiet") I must say that I don't hear distorsion.

OK. To be really honest, I do not really know what distorsion means, so I would probably not be able to name it even if I'd step on it...
So if anyone would be kind to tell what I should pay attention to to determine if I suffer from said distorsion, I'd be really glad.

BUT : what I can say for sure, is that I really like what I am hearing as I type this. I will not describe what I feel like, as it is not scientific at all. But : I like it... A lot. So far I listend to following tracks :
- Alan Parsons Project : Sirius/Mammagamma
- DVORAK 9th, first movement, by Karajan with berliner Philarmoniker and on Decca with ART recording (really good one I think)
- Francis CABREL D'une ombre à l'autre (live) "Le pas des ballerines" (wonderful live recording if I may say)
- Loreena McKENNITT, "Santiago" from the Live at Royal Albert Hall
- Pink Floyd, Yet another movie from the Delicate Sound of Thunder Live
- Melissa Etheridge, Kingdom of Heaven from The Awkening album
- Pink Floyd, Hey You from The Wall
- Johnny Cash, Ain't no Grave + Redemption day from American Recordings IV

So far, all sound really gorgeous to me. I am under the impression to discover things I never heard before. But I assume that can only be an impression. But if that is confirmed, I think the x7s is a keeper.

But I must say that I am curious to listen to something like the A50s that has STELLAR measurements and has output impedance more adapted to my headphone ! I must be fabulous... Still I like the looks of the x7s much more And that has a major influence on sound

 

[AnalogSteph]

The Oppo PM-1 is a planar magnetic headphone. These tend to have a basically ruler-flat impedance response and as such should react very little to extra output impedance. From the measurement I've found, you might expect perhaps 0.24 dB of peak deviation compared to a 0 ohm output, which is generally inaudible. You won't be losing a great deal of level either, around 2.5 dB tops.

So in short, nothing much to worry about from that perspective. Enjoy your gear.

BTW, the PM-1 is quite sensitive for a planar (~96 dB/mW, 110 dB/V), so you're unlikely to run out of power either.... the X7S will comfortably produce 70 mW (+18.5 dBmW, 114,5 dB SPL), and even 800 mW if need be (+29 dBmW, 125 dB SPL), both being beyond even rather conservative estimate for output level needs.

 

[PenguinMusic]

The Oppo PM-1 is a planar magnetic headphone. These tend to have a basically ruler-flat impedance response and as such should react very little to extra output impedance. From the measurement I've found, you might expect perhaps 0.24 dB of peak deviation compared to a 0 ohm output, which is generally inaudible. You won't be losing a great deal of level either, around 2.5 dB tops.

So in short, nothing much to worry about from that perspective. Enjoy your gear.

Hi,

A huge huge thank you for taking the time to reply my question.

I admit that with the x7S amp from Aune I also ordered their x5s digital player.

Since both units arrived, I am listening to music and I enjoy every minute I wear my headphones.

It may be real or pure placebo. I will probably never know. But I am happy and I enjoy it. That is more than enough for me -)

 

[MOCKBA]

Aune X7s is also in my list. I really intrigued by pure A class schematic of the amplifier, which is hard to find nowadays. Therefore your impression is very valuable for me