[autoteleology]

I don't know too much about how loud something sounds in correspondence to the decibel system. Isn't a +3 dB difference doubling the perceived volume?

 
I believe it's +10dB.
 
+3dB is how much it takes for the required voltage to double.

 

[shadow419]

10dBspl is a perceived doubling of volume.

 

[dfferent]

@mikeaj
Thanks for info and suggestions.
Looking at schematic, i see what you mean about ac direct to battery, so overall any short circuits around power supply would be there even with battery.
 
@adydula
Thanks for suggestions, have done all the visual checks a few times, halfway competent at DIY stuff so was confident it would work first time which it did and still does with batteries.
Will probably plug it into wall wart and do all testing suggested on blog, there's nothing specific in troubleshooting unfortunately that refers to this type of issue.
Good to know that the amp shouldn't be able to kill the power supply, this was my thoughts too hence the confusion as to why and how it's happened.
 
At this stage I am chalking it up to bad luck and possibility of bad electrical supply in this room.
 
PS The 02 and ODAC are outstanding. (full stop. no buts, no 'within this range' etc)

 

[miceblue]

Ah okay. Thanks for the quick replies! So then you're saying the O2 should sound fine with an HE-500 after all?

 

[shadow419]

Quote:

@mikeaj
Thanks for info and suggestions.
Looking at schematic, i see what you mean about ac direct to battery, so overall any short circuits around power supply would be there even with battery.
 
@adydula
Thanks for suggestions, have done all the visual checks a few times, halfway competent at DIY stuff so was confident it would work first time which it did and still does with batteries.
Will probably plug it into wall wart and do all testing suggested on blog, there's nothing specific in troubleshooting unfortunately that refers to this type of issue.
Good to know that the amp shouldn't be able to kill the power supply, this was my thoughts too hence the confusion as to why and how it's happened.
 
At this stage I am chalking it up to bad luck and possibility of bad electrical supply in this room.
 
PS The 02 and ODAC are outstanding. (full stop. no buts, no 'within this range' etc)

It's possible you just got a couple of duds the first couple of times on the ac-ac adapters.  Just make sure that the ac adpter is measuring correctly.

 

[mikeaj]

Quote:

Ah okay. Thanks for the quick replies! So then you're saying the O2 should sound fine with an HE-500 after all?

 
Pretty much.  Or at least it will have enough power, unless you listen to ridiculous volumes.  O2 power levels were designed around getting every (non-electrostatic) current-production headphone other than the HE-6 to 110 dB SPL, which is a lot, and then exceeding the target by a little bit.  That's not to necessarily say that it has some magical optimal level, but many amps are around this powerful or more and really shouldn't be considered underpowered in general.
 
Now, for whatever reasons (no comment on reason why or validity here), some people may or may not like the sound or the pairing.  That's up to you.

 

[miceblue]

Quote:

Quote:

Ah okay. Thanks for the quick replies! So then you're saying the O2 should sound fine with an HE-500 after all?

 
Pretty much.  Or at least it will have enough power, unless you listen to ridiculous volumes.  O2 power levels were designed around getting every (non-electrostatic) current-production headphone other than the HE-6 to 110 dB SPL, which is a lot, and then exceeding the target by a little bit.  That's not to necessarily say that it has some magical optimal level, but many amps are around this powerful or more and really shouldn't be considered underpowered in general.
 
Now, for whatever reasons (no comment on reason why or validity here), some people may or may not like the sound or the pairing.  That's up to you.

Sweet, that's reassuring. Thank you for taking the time to answer my questions.

 
I'm still wondering as to how so many people say the HE-500's need 1 W of power to "sound good". I often read the HE-6 needs a lot of power, and yes it does relative to the HE-500, but I don't see it unreasonable for a decent amp to be able to deliver enough power to it. I always see these bizarre amp pairings for the HE-6 that cost over $600..... :/
 
Tylls commented:
Quote:

The HE-6 (my post on Head-Fi about the HE-6 is here) has been a difficult headphone for many people to get their arms around, and I believe the primary reason for that is their very demanding nature---they require far more amplifier power to sound good than just about any other modern-day headphone made.
...
The EF-6 outputs 5 watts per channel into the 50 ohm impedance of the HE-6, which in my opinion is about the minimum amount acceptable for truly unfettered performance from this juice-sucking can.

 
Skylab commented:
Quote:

If you can afford the HE-6, I would rush to hear them any way you can IF:
...
2. You have a high-quality speaker amp you can dedicate for use with the HE-6, or a headphone amp with much, much more power than is typical

 
 
Maybe I'm missing something important because these are all consistent findings and thus making the O2 not suitable for such a headphone.

 

[mikeaj]

First of all, maybe IF's measurements of one headphone are not indicative of all samples of that headphone in the wild.  With some of these smaller operations, maybe there is more manufacturing variance?  Or they're changing the design or manufacturing from one batch to another?  But I'd hope not, not at the prices they're asking.  Anyhow, a few dB difference between some samples wouldn't be unusual.  All these calculations are just based on the sample that Tyll measured.
 
As mentioned before and as you say, HE-6 takes way more power for equivalent volume than most sets, so it's the odd one out.  O2 can only get that a little above 105 dB SPL.  If you want even more than 110 dB SPL (say 114 dB SPL), then 5W sounds right.  But it's not like many orders of magnitude different from other headphones.
 
Don't listen that loud, or listen to music with a pretty small dynamic range?  O2 and many other "lesser" amps may be enough.
 
 
Anyhow, there is just an expectation and some kind of intuition that you need to pair expensive headphones with expensive electronics.  It's maybe more a psychological thing than anything else.  People can't really visualize electronics that well, so they probably don't have a good intuition on their operation and requirements.  The hi-fi press doesn't help either, and neither does the sense of needing to keep up with the Joneses and so on.  Also, a lot of audiophile options, like a lot of the cheaper tube amps, would really have trouble with the kinds of high power levels we're talking about, so people could legitimately be using multiple amps that don't really work that well before settling on something overkill.

 

[shadow419]

Quote:

 
Pretty much.  Or at least it will have enough power, unless you listen to ridiculous volumes.  O2 power levels were designed around getting every (non-electrostatic) current-production headphone other than the HE-6 to 110 dB SPL, which is a lot, and then exceeding the target by a little bit.  That's not to necessarily say that it has some magical optimal level, but many amps are around this powerful or more and really shouldn't be considered underpowered in general.
 
Now, for whatever reasons (no comment on reason why or validity here), some people may or may not like the sound or the pairing.  That's up to you.

 
Quote:

Sweet, that's reassuring. Thank you for taking the time to answer my questions.

 
I'm still wondering as to how so many people say the HE-500's need 1 W of power to "sound good". I often read the HE-6 needs a lot of power, and yes it does relative to the HE-500, but I don't see it unreasonable for a decent amp to be able to deliver enough power to it. I always see these bizarre amp pairings for the HE-6 that cost over $600..... :/
 
Tylls commented:
 
Skylab commented:
 
 
Maybe I'm missing something important because these are all consistent findings and thus making the O2 not suitable for such a headphone.

 
Will the HE-500 get pretty loud with an O2, sure.  May or may not be the ideal pairing, but personally I'd go for a more powerful amp. The math shows that an O2 should get it loud enough for most music, but your ears should be the final say. The HE-6 is a whole different beast.  It's sensitivity is really low for a headphone driver. 

 

[thoughtcriminal]

So the he6 aside (and not counting 'stats of course), will the o2 drive pretty much anything you can throw at it? I come from the school that an amplifier should amplify and by that nature any change in sound besides said amplification is undesirable. I understand that on power hungry cans proper amping can tighten everything up, reduce distortion, etc. But I don't want to hear the amp itself. This makes the build philosophy of the o2 very appealing.

 

[RustA]

Quote:

So the he6 aside (and not counting 'stats of course), will the o2 drive pretty much anything you can throw at it? I come from the school that an amplifier should amplify and by that nature any change in sound besides said amplification is undesirable. I understand that on power hungry cans proper amping can tighten everything up, reduce distortion, etc. But I don't want to hear the amp itself. This makes the build philosophy of the o2 very appealing.

 
O2 with ODAC have plenty of power to drive high-end phones like HD800 or LCD-2 even on unity gain... Even if I apply replaygain, I am still able to use unity gain to properly power both.

 

[MrMateoHead]

Quote:

Plugged into the wall, extrapolating between known values, O2 on AC power can deliver probably something above 700 mW into 50 ohms.  Anyhow, even being really conservative, you're losing out on less than 2 dB compared to something that can output 1W.  You know how much different 2 dB sounds, right?

 
I think that you are correct about 700 mWs or so into 50 Ohms. BTW people - the HE-400 have been measured by different sources at about 50, not 32 Ohms. Power output of the O2 is regulated however, so while you can reach approximately 700 mWs, you only get there by twisting the knob far, far to the right. You won't be able to, because your ears will hurt.
 
Also Mikeaj, you are correct - the difference between 700 mWs and 1,000 mWs is completely moot. What matters more or should matter more is the dynamic range of the recordings you are trying to play. It is not without irony that I would suggest classical listeners seek more power than rock/pop/techno listeners.
 
Quote:

 
I believe it's +10dB.
 
+3dB is how much it takes for the required voltage to double.

Another way to say it is, you must approximately double your power for each 3 dB gain in volume. To get "twice as loud", you need 10 times the power.
 
Even with a headphone as relatively "inefficient" as the HE-400, I once estimated needing something like a half a watt or so in order to have the headroom for most all listening conditions. For the most part, that has proven to be a big overestimate!

 

[JakeJack_2008]

Quote:

 
...
 

 
 
 
50% more bit depth is kind of a weird way of putting it, because properly you could say it's 12800% more resolution (smallest possible difference between distinct samples... though I could be butchering the terminology as I'm not a DSP guy), though less in practice if you look at effective number of bits of actual hardware.  50% more bits per sample.
 
 
Sound science subforum here ran a recent blind test that included 24/96 vs. a file that was converted  24/96 -> 16/44.1 -> 24/96, and people couldn't reliably (and blinded) distinguish the two.  I've tried these kinds of things and not heard the differences, but some people are better at catching small things than I am.
 
 
 
By the way, some technical minutiae:
 

 
That is not correct.  To do sample rate conversion down by a factor of two (properly), you need to lowpass filter the original.  Then you throw away every other sample (technically this throwing away every other sample is known as downsampling; abuse of terminology is rampant, and I'm an offender too).
 
If you don't lowpass filter first, then you can end up content in the original 88.2 kHz file above 22.05 kHz getting aliased down into the 0-22.05 kHz range of the 44.1 kHz file, because the 44.1 kHz file cannot properly represent info above the Nyquist 1/2 frequency of 22.05 kHz.
 
I guess you can do sample rate conversion in many different ways, including skipping the filtering (or say, doing a linear interpolation or whatever else), but these are not by-the-books correct and may introduce aliasing or whatnot.

 
Thanx a lot. Some things you said are above my head because I am not an engineer or a DIY-er.
So, the downsampling is a more complex process than I had thought.
 
I'll take a look at the thread that discusses 'test: 24/96 vs. a file that was converted  24/96 -> 16/44.1 -> 24/96'

 

[Dano91]

Quote:

First of all, maybe IF's measurements of one headphone are not indicative of all samples of that headphone in the wild.  With some of these smaller operations, maybe there is more manufacturing variance?  Or they're changing the design or manufacturing from one batch to another?  But I'd hope not, not at the prices they're asking.  Anyhow, a few dB difference between some samples wouldn't be unusual.  All these calculations are just based on the sample that Tyll measured.
 
As mentioned before and as you say, HE-6 takes way more power for equivalent volume than most sets, so it's the odd one out.  O2 can only get that a little above 105 dB SPL.  If you want even more than 110 dB SPL (say 114 dB SPL), then 5W sounds right.  But it's not like many orders of magnitude different from other headphones.
 
Don't listen that loud, or listen to music with a pretty small dynamic range?  O2 and many other "lesser" amps may be enough.
 
 
Anyhow, there is just an expectation and some kind of intuition that you need to pair expensive headphones with expensive electronics.  It's maybe more a psychological thing than anything else.  People can't really visualize electronics that well, so they probably don't have a good intuition on their operation and requirements.  The hi-fi press doesn't help either, and neither does the sense of needing to keep up with the Joneses and so on.  Also, a lot of audiophile options, like a lot of the cheaper tube amps, would really have trouble with the kinds of high power levels we're talking about, so people could legitimately be using multiple amps that don't really work that well before settling on something overkill.

Maybe I'm wrong with my calculations, but - on Hifiman site HE-6 sensitivity is rated 83.5 dB/mW and 50 ohm impedance. That should translates to 96.5 dB/V (mW + 30 - 10 x log impedance). With 83.5 dB/mW and 96.5dB/V you need 447mW and 4.73V to reach 110 dBSPL.
O2 amp on AC can deliver 4.5V / 613mW at 33 ohm and 7.15V / 639mW at 80 ohms. HE-6 with it's 50 ohms lays pretty much inbetween. 
So to put it simply, I think O2 amp should have enought power for HE-6 to run them on 110dBSPL.

 

[RustA]

Quote:

Maybe I'm wrong with my calculations, but - on Hifiman site HE-6 sensitivity is rated 83.5 dB/mW and 50 ohm impedance. That should translates to 96.5 dB/V (mW + 30 - 10 x log impedance). With 83.5 dB/mW and 96.5dB/V you need 447mW and 4.73V to reach 110 dBSPL.
O2 amp on AC can deliver 4.5V / 613mW at 33 ohm and 7.15V / 639mW at 80 ohms. HE-6 with it's 50 ohms lays pretty much inbetween. 
So to put it simply, I think O2 amp should have enought power for HE-6 to run them on 110dBSPL.

 
Yes... the author himself stated that O2 "should be able to power even the hard-to-drive headphones like hifimans - with not much headroom to spare" (something like that, not exactly in these words).
 
" I suspect with some worst case headphones (like some of the planars from HIFiMan) the O2 will merely get genuinely loud at full output. But for more typical headphones, the O2 will be well under its full output."