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Topic: Do AKG Headphones REALLY Benefit From An Amp? (Read 11454 times) previous topic - next topic
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Do AKG Headphones REALLY Benefit From An Amp?

I have a set of K240s and there are some broken 702s on the way which I expect to be able to repair, and about which I am very excited. I have 2 very capable headphone amps. BUT...

There is virtually universal agreement that AKG headphones, and these 2 in particular, need to be amped for best results. However, I have yet to come across a technical explanation as to why this might be. They have a high enough impedance that most portable devices will be able to damp them and provide enough current, but low enough that both my Fiio X1 and X3II can drive them beyond sensible volumes. This is even true if you look at the few frequency/impedance charts. They are also sensitive enough that the voltages provided by most reasonable quality audio devices will be enough with some headroom remaining.

How might they benefit from an amp, assuming that the source's built in amp already has low output impedance and distortion?

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #1 –
Quote from: nintendoeats on
There is virtually universal agreement that AKG headphones, and these 2 in particular, need to be amped for best results.

Um, as far as I know any pair of headphones has to be connected to an amplifier or it will produce no music at all.  It also needs a wire from the amplifier to the 'phones. 

If you plug them into your phone, well your phone has a built in amplifier.  If it is good enough why would you want a second one added in?
Ed Seedhouse
VA7SDH

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #2 –
Quote from: Ed Seedhouse on
Um, as far as I know any pair of headphones has to be connected to an amplifier or it will produce no music at all.  It also needs a wire from the amplifier to the 'phones. 

If you plug them into your phone, well your phone has a built in amplifier.  If it is good enough why would you want a second one added in

That actually isn't strictly true since the DAC outputs a weak signal which goes on to be amplified, so your headphones could potentially still reproduce it. But that's not the point.

Some headphones really do need a beefy amplifier, be it built in or not, just to work at decent volumes. However, there is an awkward in-beteen situation where headphones will work but might be current limited or improperly damped and introduce distortion. In those situations an improvement in sound quality will be found by using a standalone amplifier.

However, as far as I can tell this is not the case with AKGs and I'm wondering if this is an example of the Hi-Fi industry completely deluding itself.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #3 –
Quote from: nintendoeats on
Quote from: Ed Seedhouse on
Um, as far as I know any pair of headphones has to be connected to an amplifier or it will produce no music at all.  It also needs a wire from the amplifier to the 'phones. 

If you plug them into your phone, well your phone has a built in amplifier.  If it is good enough why would you want a second one added in

That actually isn't strictly true since the DAC outputs a weak signal which goes on to be amplified, so your headphones could potentially still reproduce it.

A headphone output always has an amp. A line out does too, but with a lower current limit. Technically without an amp you can't even get a signal off chip.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #4 –
Quote from: saratoga on
A headphone output always has an amp. A line out does too, but with a lower current limit. Technically without an amp you can't even get a signal off chip.

Interesting, are you saying that even a DAC chip needs to have a pre-amp in it in order to get the signal to the primary amplifier?

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #5 –
Quote
There is virtually universal agreement that AKG headphones, and these 2 in particular, need to be amped for best results.
I'm sure there's "universal agreement" in some circles and I'm sure that 90% of AKG owners don't own a headphone amp...

Quote
...that both my Fiio X1 and X3II can drive them beyond sensible volumes.
    From what I've read, most of the Fiio products are good, so if you're getting enough volume there's probably not much benefit to a separate amp.

There are two issues....   Power/loudness (related to voltage, current, impedance, and the sensitivity of the headphones), and impedance.    If the amplifier's source impedance is not low compared to the headphone's impedance, the headphone's impedance variations over the frequency range can result in frequency response variations.      But, part of the problem is that the source impedance is rarely published...  Usually they only give you the recommend load (headphone) impedance.     

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #6 –
I suppose that I should say universal agreement among reviewers and enthusiasts who post on the internet, neither of whom can be entirely trusted. This is really what I'm trying to get to the root of.

Fiio actually does post output impedance which is nice, and low enough to be irrelevant in both cases. They do indeed make excellent products, but the X1 is a small hundred dollar device with modest specs for a piece of Hi-Fi gear (though probably very good by cell phone standards).

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #7 –
Quote from: nintendoeats on
Quote from: saratoga on
A headphone output always has an amp. A line out does too, but with a lower current limit. Technically without an amp you can't even get a signal off chip.

Interesting, are you saying that even a DAC chip needs to have a pre-amp in it in order to get the signal to the primary amplifier?

For most devices the headphone amp is built into the DAC. But if you're goi g to put the headphone amp off the DAC chip then you will need a buffering amp to send the voltage off chip.  There is way more load on an output pin then a normal transistor can handle.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #8 –
Quote from: saratoga on
Quote from: nintendoeats on
Quote from: saratoga on
A headphone output always has an amp. A line out does too, but with a lower current limit. Technically without an amp you can't even get a signal off chip.

Interesting, are you saying that even a DAC chip needs to have a pre-amp in it in order to get the signal to the primary amplifier?

For most devices the headphone amp is built into the DAC. But if you're goi g to put the headphone amp off the DAC chip then you will need a buffering amp to send the voltage off chip.  There is way more load on an output pin then a normal transistor can handle.

Thanks. Interesting, I'm going to do some reading on this.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #9 –
Recommending an amp without considering the source usually means that someone doesn't understand amps and should be ignored. An amp is needed if the output impedance of a source is too high relative to a load impedance or if a device requires a very high output voltage. Furthermore those two situations likely call for different amplifiers. Recommending an amp without understanding why one is needed is a pretty big tell that someone isn't worth listening to.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #10 –
Quote from: nintendoeats on
That actually isn't strictly true since the DAC outputs a weak signal which goes on to be amplified, so your headphones could potentially still reproduce it. But that's not the point.

And just how does the "weak signal" from the DAC come about?  Magic?  No, the signal from the DAC comes through an amplifier.  Without an amplifier no signal will be there to be further amplified.
Ed Seedhouse
VA7SDH

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #11 –
Quote from: nintendoeats on
There is virtually universal agreement that AKG headphones, and these 2 in particular, need to be amped for best results.
Maybe that is the consensus .... of audiophiles which don't even know Ohm's law.

Quote from: nintendoeats on
How might they benefit from an amp, assuming that the source's built in amp already has low output impedance and distortion?
As you have correctly identified, the K240 has high impedance so it will not load down the source. Heck, even some line-outs can drive 600 ohm loads.
The other part to the equation is sensitivity. IF measurements say 90dB SPL @ 0.5 to 0.9 Vrms. Aiming for a 110 dB target and given a 2Vrms source you'd need an amp with a gain of 2.5x to 4.5x resulting in 5 to 9Vrms at full volume and input.

Given a portable player with 1Vrms output you'd "only" achieve 96 to 91 dB SPL. That still may be loud enough given sufficiently compressed material.

So no, you don't need an amp unless the SPL you reach is insufficient.


The K702s are a different story: about 60 ohm, 90 dB SPL @ 0.3 Vrms. Lower impedance usually increases distortion, crosstalk. So depending on your source, an amp may cause an audible improvement.


PS: If you connect a 30 ohm headphone to a source that cannot output a lot of current you will immediately hear it. It will sound like a dying tweeter. ;)

"I hear it when I see it."

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #12 –
Quote
How might they benefit from an amp, assuming that the source's built in amp already has low output impedance and distortion?
There are a couple of other potential advantages to a separate headphone amp -

It probably has a volume control knob, and maybe even a remote control, which may be more convenient than adjusting the software-volume.   (Of course, with a portable player any additional equipment is less convenient.)

Some headphone amps have a crossfeed control to blend the left & right channels. Some headphone listeners feel that some recordings sound more natural with crossfeed.  (Of course, that can also be done in software.)

If you have a soundcard/player with a noisy output, that noise is usually not reduced when you reduce the volume in software.   So at low listening levels your signal-to-noise ratio is degraded and the noise becomes more noticeable (and/or more annoying).     The volume control on your headphone amp allows you to keep the digital/software volume high (for a good signal-to-noise ratio) and when you turn-down the amp's volume the signal and noise both get turned-down together.  (That's assuming any noise generated in the headphone amp itself is inaudible.)      ...Under these conditions an amplifier can be beneficial as an attenuator. 

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #13 –
Quote from: Ed Seedhouse on
Quote from: nintendoeats on
That actually isn't strictly true since the DAC outputs a weak signal which goes on to be amplified, so your headphones could potentially still reproduce it. But that's not the point.

And just how does the "weak signal" from the DAC come about?  Magic?  No, the signal from the DAC comes through an amplifier.  Without an amplifier no signal will be there to be further amplified.

A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #14 –
Quote from: nintendoeats on
A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.
"DAC" can refer both to the chip as well as featureful devices that only cover the D/A part of a full-blown audio interface.
"I hear it when I see it."

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #15 –
Quote from: xnor on
Quote from: nintendoeats on
A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.
"DAC" can refer both to the chip as well as featureful devices that only cover the D/A part of a full-blown audio interface.
In this case I was only talking about a pure DAC chip with no amplification stage.

By the way, Your previous comment contained much interesting information but at some point I lost track of your thesis. Could you please restate it?

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #16 –
::

Read here or this one, please.

::

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #17 –
Quote from: nintendoeats on
Quote from: xnor on
Quote from: nintendoeats on
A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.
"DAC" can refer both to the chip as well as featureful devices that only cover the D/A part of a full-blown audio interface.
In this case I was only talking about a pure DAC chip with no amplification stage.

If you're sending voltage off chip there is probably an amp. Pretty hard to have MHz frequency in the DAC switching close to a milliamp of current.  You need a current buffering amp at least, maybe voltage gain too.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #18 –
Quote from: Surfi on
::

Read here or this one, please.

::
I've read those several times. That is really the source of my original question. I'm wondering if people saying that AKGs benefit from beefy amplifiers are wrong. The sense I'm getting is that my original intuition was correct and the answer is yes.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #19 –
Quote from: xnor on
Quote from: nintendoeats on
A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.
"DAC" can refer both to the chip as well as featureful devices that only cover the D/A part of a full-blown audio interface.
And if it doesn't amplify it's output your headphones will never hear it.  If you can hear it through a headphone or a loudspeaker it has been amplified unless it's the output from a crystal phonograph cartridge.  If you want to avoid all amplification you could go back to shelac 78 RPM records where the needle vibrates a diaphragm mechanically and a horn amplifies it so you can hear it.  Oh wait, that's being amplified too, except not with electricity.  And of course even your ears contain an amplifier of sorts.
Ed Seedhouse
VA7SDH

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #20 –
Quote from: Ed Seedhouse on
Quote from: xnor on
Quote from: nintendoeats on
A DAC is literally a device which converts digital information into an analog signal. That is not a form of amplification.
"DAC" can refer both to the chip as well as featureful devices that only cover the D/A part of a full-blown audio interface.
And if it doesn't amplify it's output your headphones will never hear it.  If you can hear it through a headphone or a loudspeaker it has been amplified unless it's the output from a crystal phonograph cartridge.  If you want to avoid all amplification you could go back to shelac 78 RPM records where the needle vibrates a diaphragm mechanically and a horn amplifies it so you can hear it.  Oh wait, that's being amplified too, except not with electricity.  And of course even your ears contain an amplifier of sorts.

I think maybe that you have missed my point, which was actually just an aside and not that important anyway.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #21 –
Quote from: Surfi on
::

Read here or this one, please.

::

Those articles apply to a large number of headphones and IEMs made by a large variety of manufacturers, not just AKG.

Since this thread specifically mentions AKG headphones, they are in a sense off-topic.

The articles give reasons why headphones require headphone amps that are actually engineered with some care, and why some DACs and headphone amps are not suitable for whole classes of headphones and IEMs manufactured by a variety of manufacturers.

A fair number of audiophiles seem to want to believe that they have to obtain extra-heavy duty amplifiers because of other equipment choices (usually headphones and/or speakers)  that they have made. Sometimes they are right ut often  they are blowing smoke. 

There seems to be some bravado that is associated with speakers and headphones that are "hard to drive". This belief is often used to justify the acquisition of overbuilt and/or overpriced gear.  I've researched these comments, and found that maybe half of them or more are complete BS.

The source is often salesman's patter. Power amps and headphone amps that are overbuilt for the application may not give any audible clues that they are excessive. However, they can leave tracks composed of fried speakers and headphone drivers.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #22 –
Quote from: Arnold B. Krueger on
Power amps and headphone amps that are overbuilt for the application may not give any audible clues that they are excessive. However, they can leave tracks composed of fried speakers and headphone drivers.
A few years ago, when I was still wasting time on huddler fi, I regularly saw people complain how their new amp, which they had to buy according to other audiophiles, had a way too touchy volume control. Of course, people had suggested these newcomers (not much less knowledgeable than the people making the suggestions) ludicrous combinations resulting in crazy gain mismatches.
This also resulted in raising the noise floor of their sources to audible levels...
Others damaged their drivers with great amps that would output large DC offsets on power on/off.

And speaking of compulsion, I even remember a poor bloke complaining about the noise coming from his drawer while he was trying to sleep - he had to break in his headphones for several days as suggested by others.
"I hear it when I see it."

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #23 –
I briefly posted questions at Head-Fi, mostly in the science section. Even the people I spoke to there who still use the site acknowledge that the whole place is a basically a cult.

Re: Do AKG Headphones REALLY Benefit From An Amp?

Reply #24 –
Quote from: Arnold B. Krueger on

There seems to be some bravado that is associated with speakers and headphones that are "hard to drive". This belief is often used to justify the acquisition of overbuilt and/or overpriced gear.  I've researched these comments, and found that maybe half of them or more are complete BS.

May I ask what kind of research you did? Was it hands on blind testing or something else?