Showing 1 of 1259 conversations about:
Luxifer
24
Feb 26, 2018
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Are more precise THD % numbers available? I think we would all expect THD <1%, but that does not tell us much relative to other amps which may go to four or five decimal places of measurement accuracy.
Feb 26, 2018
Jimster480
376
Feb 26, 2018
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Yes exactly, the specs posted are nothing special..... When we don't even know the price it really shows nothing compared to say Topping A30 which has 5 digits of precision on its measurements...
Feb 26, 2018
Swampy
190
Feb 26, 2018
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The price is listed as $349.99.
Feb 26, 2018
achristilaw
65
Feb 26, 2018
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The price is listed at $349. Seems to good to be true? I'll try on some new think to be sure at that price.
Feb 26, 2018
hohsis
31
Feb 26, 2018
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Yeah, 1% doesn't make much sense when they can't get to the specifics.
Feb 26, 2018
shimage
218
Feb 26, 2018
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THD <1% is for the power output specs, which is industry standard. They give fairly detailed THD specs right below that, so I'm not sure what people are asking for? Or did they only just add that in the last 20min?
Feb 26, 2018
Jimster480
376
Feb 26, 2018
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Its true they added for 1mw and 100mw... the thing is for the higher impedance especially it makes little sense since really nothing runs at 1mw or 100mw.... A HD650 needs around 212mw to reach 90db SPL so....
I do actually appreciate the metrics though
Feb 26, 2018
shimage
218
Feb 26, 2018
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Just out of curiosity, where are you getting those numbers from? Based on specs, the HD650 should hit 90dB @ 0.16mW, and Tyll measured 90dB SPL with 0.13mW input. Hardly anything needs more than 10-20mW to hit 105dB (and you should only be hitting those levels on transients anyway), so I feel like 100mW is more than sufficient.
Feb 26, 2018
Jimster480
376
Feb 26, 2018
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Wait what, I read this on HeadFi (i was just trying to find the article but I couldn't find it) where some Jude did some testing to see how much current was required to achieve a specific level of sound. https://www.head-fi.org/threads/headphone-sensitivity-power-requirements-compared.476345/ http://nwavguy.blogspot.com/2011/06/sennheiser-hd-650.html
The one above isn't 90db as I can't seem to find that one right now. 0.16mw is far too low http://nwavguy.blogspot.com/2011/09/more-power.html ^Read that also to see how much power is required because its based on impedance also...
Feb 26, 2018
mesaone
82
Feb 26, 2018
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-140 dB is a THD ratio of 0.00001%
Feb 26, 2018
shimage
218
Feb 26, 2018
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0.16mW is the right number. Nominal sensitivity of the HD650 is 97dB@1mW, and so based on the chart in the link you provided, 6.3mW is enough to hit 105dB SPL (Jude's table is for 120dB, which is enough to cause physical pain). And no, none of this depends on impedance, because we aren't talking about voltage.
Feb 26, 2018
CEE_TEE
3383
Feb 27, 2018
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THD: -143 dB 300 Ω@ 1 mW = 0.000007% -140 dB 300 Ω @ 100 mW = 0.000010% -125 dB 32 Ω @ 1 mW = 0.000056% -123 dB 32 Ω @ 100 mW = 0.000071% -120 dB 16 Ω @ 1 mW = 0.000100% -118 dB 16 Ω @ 100 mW = 0.000126% IMD: -123 dBSMPTE 70 Hz + 70 kHz, 300 Ω = 0.000071% -124 dBDFD 18 kHz + 19 kHz, 300 Ω = 0.000063% Crosstalk: -127 dB, 300 Ω = 0.000045%
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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At what frequency?
Feb 27, 2018
All parameters measured at 0 dB gain, 1 kHz, with balanced inputs and 300-ohm load unless otherwise noted
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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What about single ended input and balanced output? Is it possible?
Feb 27, 2018
Absolutely @Jimster480 . SE input permits SE and Balanced output, at full power.
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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Awesome, this is perfect for my DX7. It's the amp I've been looking for! I'll be ordering one for sure.
Feb 27, 2018
Luxifer
24
Feb 27, 2018
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Thank you very much! I'm sorry if the conversion is trivial to perform, I wasn't sure how to get to percentages.
Feb 27, 2018
Luxifer
24
Feb 27, 2018
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Would you mind explaining how that conversion works? I'm not skeptical, I really don't know.
Feb 27, 2018
shimage
218
Feb 27, 2018
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I'm not sure where you're going with this, but they don't say and neither do Tyll, NwAvGuy, or Jude. Probably it is an average of some sort. I can't help but point out that 1) the 97dB/1mW figure is the one used by NwAvGuy and 2) Jude's figure of 167mW for 120dB is equivalent to 0.16mW for 90dB in the links you posted.
Feb 27, 2018
shimage
218
Feb 27, 2018
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Feb 27, 2018
Jimster480
376
Feb 27, 2018
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Yes I know. I was just saying that the power is not required linearly across the frequency response.
Feb 27, 2018
shimage
218
Feb 27, 2018
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But your figure of 212mW is more than 30dB higher than everyone else's. I think if there was a 30dB spike anywhere in the FR the HD650 wouldn't be as popular as it is.
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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No, there is another test that Jude did recently talking about typical usage while playing music. based on the numbers you are suggesting, even the cheapest of cell phone or mobile player would be able to fully drive any headphone and there would never be a need for any amp whatsoever.
Feb 27, 2018
shimage
218
Feb 27, 2018
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Phones are actually a lot better at driving headphones than audiophiles give them credit for, but what you're looking for is the max voltage output. Phones generally don't have the voltage swing for transients on high impedance cans (even efficient ones like the HD6X0), an issue which is exacerbated by the fact that pretty much everyone listens at volumes higher than they should.
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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That's questionable, I have an HTC 10 which is a great phone for driving headphones and yes it can drive most everything perfectly. however I also have a moto E and a desire 510 and neither of those are too great at driving headphones. I think you are right in that voltage is the factor here. I'm someone who listens at lower volumes and there is still quite a large difference even from one of my pcs with an ALC892 to my HTC 10.
Feb 27, 2018
shimage
218
Feb 27, 2018
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I guess when I said "phones" I meant phones that actually have decent output stages (primarily [ex-]flagships from Apple, Samsung, and LG). Are you hearing differences between the pc and phone in blind tests or sighted comparisons? Also, what headphone? I am assuming you are comparing the two using a switch box even for sighted comparisons (audio memory is ~3-5s). If you are listening to HD650s at, say, 75dB (low volume), then you only need around 225mVrms even for the transients, which most phones can manage (as in, most phones, not just good ones). Generally speaking, an amp has to be pretty bad before it has a larger impact on perceived sound quality than psychology.
Feb 27, 2018
mesaone
82
Feb 27, 2018
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Feb 27, 2018
Jimster480
376
Feb 27, 2018
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It also depends alot on output impedance. I think to say every amp has no effect on sound is a pretty bold statement. What I find funny is that every time I find a difference with something that people don't agree on they claim it to be expectation bias. But when I first tested my phone vs my desktop I had no DAC / AMP. Just the integrated Realtek. I didn't test it with the idea of one being better or worse, I just had to use the phone that day vs the desktop since I was using the desktop for phone calls. I noticed the phone to be noticeably better and went back to a/b test with the computer and spent time to level the volume out. the computer simply lacked dynamics and really sounded flat compared to the phone, something I didn't expect or have any idea of because I never thought about it. this was with some Panasonic RP-HT360 $40 headphones... later on I tested the computer vs a Fiio K1 and found the K1 to be similar to the phone... The phone sounded slightly warmer but overall both sounded very similar. now I have a DX7 and an O2 / A30 some years later and the A30 sounds different to the O2 especially due to output impedance. My ipod touch sounds very different vs the K1 especially with even 1More quad driver IEM or Panasonic RP-HD10. I also tested my Aeon and AH-MM400 with various sources from my HTC 10 to the O2 to the K1 and there are differences in sound. But with the Aeon there is very little difference in sound from the K1 to the O2.
Feb 27, 2018
Luxifer
24
Feb 27, 2018
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Thank you!
Feb 27, 2018
shimage
218
Feb 27, 2018
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I never said anything about expectation bias. I have "heard" nonexistant differences that I totally didn't expect to on numerous occasions. I really don't understand why people think the fact that they didn't conciously expect a difference means anything. Also, I didn't say that amps "have no effect on sound". But you're right, I should have been more clear that there are some things amps can do that have a significant impact.
High Z out changes the frequency response in a headphone-dependent way, so obviously that is going to be audible some of the time (though, again, not as much as audiophiles like to think; in particular, planars are mostly unaffected, see below). Any amp with flat FR, low Z out, sufficient power/voltage output, and sufficiently low distortion (say, <0.01% for both THD and IMD), is going to sound very similar to any other amp that meets these criteria (blind, obviously). Pretty much any mediocre or better SS/hybrid amp will meet these criteria (not sure how many portables qualify). When people say this amp is bright or harsh or warm or whatever, this ought to be visible in the FR, because these terms refer to specific features in the FR. I own way more audio gear than is healthy, because I hear differences in sighted listening. However, in blind tests, the differences are exceedingly subtle once you get beyond entry-level gear (say, beyond a magni 3).
The Aeon (mine is closed, not that it matters much) is fairly difficult to drive, on account of low impedance and low efficiency. It needs a fair amount of current drive. Desktop amps are fine, but not all portables can drive it without soft-clipping. It is not affected by output impedance, though, aside from an overall drop in loudness. If you hear a difference in tonality between the A30 and O2 with the Aeons, it is not due to output R.
Feb 27, 2018
Jimster480
376
Feb 27, 2018
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The voltage should still swing a bit with a output impedance mismatch. I do also have the closed Aeon and it does require some current to Power it but my K1 can power it just fine at the volume I listen with.
Nwavguy did write a post about output impedance and voltage swing which should be audible despite frequency response.
But you are right sometimes it's not audible really at all. And sometimes it is just subtle, it really depends on the headphone, the music, and how big of a mismatch there is.
Feb 27, 2018
shimage
218
Feb 28, 2018
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I'm curious to know what "output impedance mismatch" means to you, because to me it doesn't mean anything in the context of audio. In any case, the FR of the Aeon (or any planar headphone, for that matter) does not depend on output R, because the planars are purely resistive devices (which means that impedance does not vary with frequency). The end result is that the overall level drops if the output R is finite (NwAvGuy's first, irrelevant, bullet point), but the FR is not affected; therefore, tonal balance is also not affected by output R (second bullet point).
I have not seen any proof that damping factor in and of itself has anything to do with headphone performance (third bullet point, note NwAvGuy has no measurements of this alleged bass distortion, just handwaving). I am not an expert on this matter, but I know that Jan Meier of Corda Audio has stated that planars are already well-damped by the air around the diaphragms (he also says some other weird things, but I'm going to ignore that for now). Note that in that same innerfidelity article, Tyll's main concern is frequency-dependence of impedance, which as we've established is not an issue for planars. Last couple of links are from Frans at diyaudioheaven, who is at least as much an expert on audio as NwAvGuy. He states, "The reason for this change in tonal balance is not caused by the damping factor (as many still believe) but simply caused by voltage division" (emphasis his).
https://nwavguy.blogspot.com/2011/02/headphone-amp-impedance.html https://www.innerfidelity.com/content/musings-headphone-amplifier-output-impedance https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/ http://diyah.boards.net/thread/533/resistance-impedance-damping-factor-cables
Feb 28, 2018
Jimster480
376
Feb 28, 2018
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NwAvGuy does talk about voltage division if you read his whole article about it. That is actually his primary point outside of dampening factor affecting the SPEED of the headphones. The problem is that there are relatively no measurements on this subject, but I can tell you from personal experience I have heard differences even with planars. The voltage division math makes perfect sense honestly, but dampening factor can also be a thing... Either way the differences aren't as big as some may suggest.... Either way lower output impedance has proven in time to be better than high output impedance. What I define as "output impedance mismatch" is an output impedance of an amp that is higher than 1/8 the impedance of the headphone itself. In the case of the Aeon with the A30 if using the 3.5mm output you are using a 30 ohm output impedance with a 14 impedance headphone. The differences are the most noticable using this device because its the same amp, same source and you just need a 6.35mm -> 3.5mm adapter to be able to just swap the plugs back and forth. Not only is the 3.5mm jack quieter but with my Aeon for example I notice that the volume of the bass will rise at a faster rate than the vocals or other midrange sounds... effectively making it warmer sounding as I turn the volume up.
Feb 28, 2018
shimage
218
Feb 28, 2018
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I saw that he talks about the voltage division, it's his second bullet point, which I noted and addressed in the first paragraph of my last post. As I mentioned then, it doesn't apply to planars, because (as he points out), the effect comes from frequency dependence of the headphone impedance, and planars always have frequency-independent impedance. Your evidence comes from sighted comparisons of gear, which as I've already mentioned are not particularly trustworthy (not "your comparisons", but sighted comparisons period, from anyone). It's fine that that's how you hear it, I don't object to that. My point is that it is not generalizable to people that aren't you, which means you have to be careful when providing advice based on that experience.
I have the A30, IMO it's not possible to compare the two outputs properly, because you can't volume match in a timely fashion. As a practical matter, I can't test the A30 against anything else I own because it's the only amp I can't volume match with a multimeter (I don't have a way to measure SPL with enough sensitivity, unfortunately). One time when comparing two amps, I thought one had slightly more bass than the other, but really it was just a 0.2dB volume mismatch. Once I fixed that, I couldn't tell the two apart.
Feb 28, 2018
Jimster480
376
Feb 28, 2018
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I was just doing as you were talking about and if i really really mess with the volume between my O2 and my Aeon I haven't been able to tell a difference in the last couple songs. Usually I pick a specific part of a song that I know or some part of a song with vocals, usually a 3-12 second part of a clip and I play it back and forth over and over again. But this is the case with the Aeon but not necessarily with the PM-2 which doesn't have a completely flat FR Impedance curve.
Btw since you are so into objective measurements and hardcore subjective testing you should sign up at the audiosciencereview forums. Its certainly a better discussion board than this comment section, and its not censored like HeadFi.
Feb 28, 2018
shimage
218
Feb 28, 2018
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I didn't realize the PM-2 had a resonance like that, had to look up the measurements. It's small enough the FR shouldn't be affected by high output R, but the distortion spike is a little troubling (though probably not audible).
I like reading audiosciencereview, he has interesting measurements you don't find in many other places.
Feb 28, 2018
Jimster480
376
Feb 28, 2018
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Yes, its performance isn't exactly like other planars in that regard. My friends and I have tested the PM-2 with the A30 and it has a "veiled" sound through the 10 ohm output, its not big but even my wife noticed it without me telling her. She said "it sounds a bit more clear now" when I plugged it into my O2. I'm not sure exactly what causes this to happen since I don't have any other HP that exhibits that specific characteristic when I plug it into my A30 vs the O2.
Feb 28, 2018
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