[estreeter]

@sobbingwallet, thanks for that - I absolutely *get* the wire-with-gain ideal, but I also believe that its not what many Head-Fiers actually expect from an amp - in many cases they want a band-aid or a protein pill.
 
In the band-aid case, they want an amp to magically imbue their bass-light cans with 'thumping' bass or, worse, they want an amp to tame the sibiliance/piercing highs in their source. I 100% agree with Voldemort and others that recording engineers deliberately make recordings bright (and compressed ..) - ok for speakers, not so for headphones.
 
The other end of the spectrum is people who feel their cans are too laid-back - in their case, some of the budget amps I've heard might be what they are looking for - the 'protein pill'. Or not - its still putting the horse before the cart - cheaper to just buy another pair of cans. 
 
Its all about that 'magic smoke' I alluded to earlier, and that's a powerful marketing device. Head-Fiers pay a lot of lip service to the concept of 'neutrality', but I wonder how many are prepared to walk that walk with their current sources/cans. In my case, I could throw out a lot of my music (FLAC and 256K AAC) and invest in immaculately recorded classical CDs, but where's the fun in that ?  I certainly wont shoot the messenger if the O2 shows up the holes in my modest collection of electronic toys, but I've avoided neutral kit from Meier and others for precisely that reason.  
 
 
 

 

[mikeaj]

If you want your signal chain to intentionally provide an EQ effect (or whatever else), there's some software for that...IMHO.  Very useful stuff, and you can tweak it all the time without having to keep buying new gear! 

 

[wazzupi]

question I plan on using the O2 with my q701's i was wondering would the amp actually bring them to a higher level as far as what the q701's are known for preferably it's soundstage which i would like to see a gain in... or else I might have to mod it i'm purchasing mine from epiphany's acoustics since I dont know how to solder but I'm actually in the near future planning on building my own buT i really needed it now and would like to do a little a&b

 

[Willakan]

Aside from the fact that soundstage has little to do with amplification, the O2 will drive any of AKG's dynamic flagships with ease. As for modding, the designer would generally advise against it, as the best-case scenario is no improvement at all, relying on bias mechanisms to produce a difference, which your brain will likely oblige, admittedly.

 

[EddieE]

I've been told before that poor crosstalk measurements can result in a fuzzier less defined sound stage. I don't know if that's true but if so a better performing amp could lead to a soundstage that sounds cleaner and more precise.

 

[Willakan]

Technically true I suppose, but the crosstalk would have to be pretty awful for such a thing to occur.

 

[wazzupi]

hmm I like if it sounds clean and precise sense it already has bad ass soundstage

 

[cheapskateaudio]

 
Quote:

Aside from the fact that soundstage has little to do with amplification, the O2 will drive any of AKG's dynamic flagships with ease. As for modding, the designer would generally advise against it, as the best-case scenario is no improvement at all, relying on bias mechanisms to produce a difference, which your brain will likely oblige, admittedly.

I'd say best case scenario is you mod it and LOVE how it sounds. The scope is not an eardrum. Humans are not manufactured according to strict tolerances, we also have vastly different experiences, some are professional musicians, others work construction.
 
 
I also disagree considerably with the concept that measurements are == transparency. First you have the philosophical angle, what *is* transparency? Is it what you *hear*, or what *is*? Because if you can't hear what *is*, then how do you experience transparency?
 
In that same vein, one thing that bothers me about NwAvGuy's approach is that while he dismisses clearly better performing parts as "not worth it" (OPA627 for example), he also pushed the amp to the lowest possible noise floor imaginable, a noise floor so low that I'd say it's 20% beyond "not worth it". But at the same time contends increasing the slew rate to the max that Blu Ray can handle, is "not worth it". 
 
So whats really not worth it? A noise floor and distortion figures well beyond human hearing? Or at least meeting the specified capability of blu-ray?
 
Point is, a human can be just as biased about how they approach being objective. 
 
 

 

[SobbingWallet]

Quote:

 

I'd say best case scenario is you mod it and LOVE how it sounds. The scope is not an eardrum. Humans are not manufactured according to strict tolerances, we also have vastly different experiences, some are professional musicians, others work construction.
 
 
I also disagree considerably with the concept that measurements are == transparency. First you have the philosophical angle, what *is* transparency? Is it what you *hear*, or what *is*? Because if you can't hear what *is*, then how do you experience transparency?
 
In that same vein, one thing that bothers me about NwAvGuy's approach is that while he dismisses clearly better performing parts as "not worth it" (OPA627 for example), he also pushed the amp to the lowest possible noise floor imaginable, a noise floor so low that I'd say it's 20% beyond "not worth it". But at the same time contends increasing the slew rate to the max that Blu Ray can handle, is "not worth it". 
 
So whats really not worth it? A noise floor and distortion figures well beyond human hearing? Or at least meeting the specified capability of blu-ray?
 
Point is, a human can be just as biased about how they approach being objective. 
 
 

 
When it comes to headphones, your fundamental viewpoint has a lot of merit:  Headphones are extremely difficult to reliably measure, because they require an accurate microphone to recapture sound (rare to nonexistant, much like accurate drivers), and the positioning and geometry is going to be totally different from your outer ear, etc.  Transparent headphones are basically headphones that sound subjectively lifelike to you, given a "proper" acoustic recording.  (IEM's are even harder to measure, since they bypass the outer ear entirely.  This will make the experience match up with "real life" much differently for different people than it does with speakers or full-size headphones.)
 
However, amplifiers are different:  An electric signal is easily measured with the proper equipment, and a transparent amp is one that amplifies the signal with as little distortion, noise, etc. as possible.  This can be objectively measured very accurately, and it is, so transparency is well-defined here.  A transparent electrical signal is simply one that measures well across the board, and there's no subjectivity or magic to it.
 
You can legitimately judge the transparency of an amp + headphone combo by ear, and your subjective assessment will basically trump any objective measurements for you (because of how difficult headphones are to reliably measure, and how much the headphone experience varies individually).  With your particular headphones, a colored amp might produce the most transparent final output.  However, you cannot accurately judge the transparency of an amp by itself via subjective means, because you can only experience it indirectly through inaccurate headphones.  In the best case scenario (low-impedance and high-sensitivity headphones with a low output impedance source), you can look for differences between the unamplified signal and the volume-matched amplified signal.  More commonly, the best you can do is ballpark it ("this amp sounds warm, given it's warm with headphones A, B, and C, and C is not known to be a warm headphone"), and objective measurements have the final say on the transparency of an amp by itself.  By itself, the amp's signal transparency is a simple matter of objective metrics, and "sound" doesn't even enter into it, because an amp deals with electricity, not sound.
 
To sum it up, the unmodified O2 is essentially transparent by itself, but the final sound you hear is only guaranteed to be fully transparent if you pair it with a fully transparent headphone model.  On the one hand, it's unlikely that you'll find a pair of headphones that matches your ears perfectly.  Even with extreme high end flagships, you can only get closer and closer to the pot of gold at the end of the rainbow.

  On the other hand, it's similarly unlikely that adding an extra hardwired layer of error via a colored amp will change this situation.  (An easily configurable software DSP would be a much better bet, unless your enjoyment of trial and error soldering with random components outweighs its inefficiency for you.)
 
Instead, what the unmodified O2 guarantees (under most conditions) is that it will present headphones as they actually are rather than presenting the sum of two inaccurate components.  It removes a source of error from the equation, and for me this greatly simplifies the matter of finding the right headphones.  (Once you mod the O2, you're fundamentally changing it from "just an amp" to an "amp plus analog sound processor," which reenters the grueling world of trying to find synergy with a particular set of headphones.)  It won't compensate for errors your headphones make, but it won't pile on and magnify them either.  If you want to use or try multiple sets of headphones with different sound signatures, that's really the best thing you can ask from an amp.
 
I should also note that it's extremely important for headphone design that amps like the O2 (and Violectric amps, and Benchmark DAC1 amp, etc.) exist:  Headphones themselves have long been the weakest link in the DAC+amp+headphones+ears chain, and neutral amps give manufacturers a concrete reference point for engineering and tweaking the sound of their headphones.
 
On a side note, the emphasis you place on one objective metric over another will indeed be influenced by subjective bias.  I will concede that the designer might possibly be putting too much emphasis on an out-of-this-world noise floor beyond the point of diminishing returns, such that other metrics may be suboptimal in extreme situations (like the max slew rate you mentioned).  Still, that's a more nuts and bolts issue rather than an issue of principle.  At the very least, you know you won't be hearing much hiss or hum from the O2.

  Rather than a serious flaw, I'd consider it more of a minor issue to consider addressing in future designs (much like or even moreso than the input overloading issue), given any other known sub-$1000 range amp with a theoretically better max slew rate is going to be crushed on more audible metrics like frequency response, noise, or distortion.
 

 

[mikeaj]

Whether or not this is the correct goal (I would say "a" correct goal), it's to produce the least audible distortions and thus represent the input signal as closely as possible.  Whatever you perceive as transparent or whatever has nothing to do with that.
 
Some people do have relatively low-noise ambient environments (at least sometimes, and particularly with IEMs stuck in their ears) and 120+ dB SPL / 1V IEMs.  Some of those IEMs are popular high-end models.  With -115 dBV A-weighted noise from the amp, you should get audible noise in some circumstances.  Distortion measurements below the 0.002% range have not been well proven to be audible, nor has slew rate much higher than what is required by the music, and so on.
 
That said, some decisions are tradeoffs (keep in mind some things are to limit costs, board space, power consumption for battery life, etc.), while others are not.  And I'm sure a better job could have been done; nobody's treating this like a perfect design, even from a performance rather than functionality/size standpoint, just one where it's hard to argue requiring much better for performance with most headphones.  Of course wanting better and shinier stuff for its own sake, or experimentation for the sake of experimentation, is a different matter.

 

[Willakan]

Transparency in amplifiers is reproducing the input signal louder, and nothing else. It is extremely hard to make an argument for subjective transparency without distorting the meaning of the word.
I would not say any of the O2's measurements are seriously into the domain of pointless overkill. The distortion is extremely low into high impedance loads, but only so it can still be very low into more difficult loads. Likewise, the noise floor is important for driving IEMs hiss-free.
 
Besides, trying to modify a design which has been carefully optimised with expensive instrumentation and mathematics by shoving other parts in almost at random* and listening is like trying to improve a Van Gogh painting with poster paints and your tongue. Whilst blindfolded.
 
I genuinely don't want to insult you, but what you're doing is simply silly.
 
 
*Peering into an opamp datasheet, seeing a few numbers are better and deciding it will clearly work fine in the same circuit as a completely different opamp is generally wholly inadequate.

 

[tomjtx]

SobbingWallet, mikeaj and Willakan,
 
Thanks for doing all the heavy lifting with such articulate and well reasoned responses to cheapskate audio.
Now all I have to say is:
 
"what they said"  
 

 

[wakibaki]

 

 

I'd say best case scenario is you mod it and LOVE how it sounds. The scope is not an eardrum. Humans are not manufactured according to strict tolerances, we also have vastly different experiences, some are professional musicians, others work construction.
 
I also disagree considerably with the concept that measurements are == transparency. First you have the philosophical angle, what *is* transparency? Is it what you *hear*, or what *is*? Because if you can't hear what *is*, then how do you experience transparency?
 
In that same vein, one thing that bothers me about NwAvGuy's approach is that while he dismisses clearly better performing parts as "not worth it" (OPA627 for example), he also pushed the amp to the lowest possible noise floor imaginable, a noise floor so low that I'd say it's 20% beyond "not worth it". But at the same time contends increasing the slew rate to the max that Blu Ray can handle, is "not worth it". 
 
So whats really not worth it? A noise floor and distortion figures well beyond human hearing? Or at least meeting the specified capability of blu-ray?
 
Point is, a human can be just as biased about how they approach being objective. 

Quote:

When it comes to headphones, your fundamental viewpoint has a lot of merit:  Headphones are extremely difficult to reliably measure, because they require an accurate microphone to recapture sound (rare to nonexistant, much like accurate drivers), and the positioning and geometry is going to be totally different from your outer ear, etc.  Transparent headphones are basically headphones that sound subjectively lifelike to you, given a "proper" acoustic recording.  (IEM's are even harder to measure, since they bypass the outer ear entirely.  This will make the experience match up with "real life" much differently for different people than it does with speakers or full-size headphones.)

It's often tempting to avoid a head-on confrontation, but unfortunately, in my view, cheapskateaudio's argument has very little to recommend it in any circumstances.
 
Without taking the points in order:-
 
He takes an ad hominem approach by accusing nwavguy of being biased, justifying this with an argument about noise floor and slew rate.
 
csa, you should realise by now that you are simply not qualified to understand the implications of these measurements. There is a difference between the opinion of an expert and a tyro. nwavguy is a designer, you are a customer. He has been doing it for years and has moreover studied and passed exams in the subject, you are working on the basis of what you have picked up in the last 5 minutes. Not that all professionals are worth their salt, or that customers are incapable of insight, but insight is normally accompanied by a modicum of humility. Do you really imagine that dozens of self-proclaimed experts haven't produced these selfsame valueless arguments down the years? That's what we're about here, debunking all that bunk.
 
It's well known that sighted evaluations performed by a single individual are not reliable. Many people choose to ignore this, particularly in audio, but that's why only blind tests are accepted as evidence throughout the scientific community.
 
Philosophy plays no part in the objective evaluation of performance, even where no instruments are employed. What 'is' is decided by consensus. You ask a lot of people what 'is', and what the majority agree 'is' is what 'is'. Sorry about all the is's, but that's the way it is. Sometimes a smaller group of experts is consulted, but if you don't trust those results, you can go to a larger group drawn from the general population. Headphone evaluation can be approached in just this way, so that when a CNET review says that Klipish Image S4's are outstanding value for money, then that's where to bet your bottom dollar.
 
w

 

[EddieE]

The simple fact is that amps don't have a sound because they do not make a sound. Unless you count the clicking of switches or knocking on the case, they are silent devices. They therefore can not be judged or reviewed subjectively when it comes to sound, and only their measurements matter, as you cannot listen to their sound - only to the sound of the headphones plugged into them.
 
Transducers make sound, and if an amp measures perfectly and you don't like the sound the headphones make - you don't like the sound of the headphones not the amp.
 
And if an amp which measures with obvious flaws makes those same headphones sound better to you - this is still a statement about the headphones not the amp. The amp is flawed and what it might coincidentally do to a set of headphones that weren't right for you has no bearing on that at all.

 

[LizardKing1]

Quote:

The simple fact is that amps don't have a sound because they do not make a sound. Unless you count the clicking of switches or knocking on the case, they are silent devices. They therefore can not be judged or reviewed subjectively when it comes to sound, and only their measurements matter, as you cannot listen to their sound - only to the sound of the headphones plugged into them.
 
Transducers make sound, and if an amp measures perfectly and you don't like the sound the headphones make - you don't like the sound of the headphones not the amp.
 
And if an amp which measures with obvious flaws makes those same headphones sound better to you - this is still a statement about the headphones not the amp. The amp is flawed and what it might coincidentally do to a set of headphones that weren't right for you has no bearing on that at all.

You're assuming amps are perfect. The proof that they do make an unwanted (by neutral lovers) sound is the coloration they cause. An amp should be a silent device, but it isn't, the same way as an engine should 100% performance, but it doesn't. You can't say something like "amps don't have a sound because they do not make a sound" and then go "the amp is flawed". They contradict each other. I think that's what an amp should do, but unfortunately it's not the truth. But hey that's why we're in this thread =)