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shimage
228
Jan 29, 2018
Topping A30 can drive them fine. They show up periodically on here. Magni 3 is a bit better for a bit more money. The A30 will be marginally warmer (probably not audibly so) than the magni 3, on account of the higher output impedance.
The thing with the DT990 is that it's a pretty bright headphone (beyer spike in full effect), and the 600Ohm version is not going to get all that much warmer even with high output impedance amps (say, 120Ohms). So just buy what looks nice and has enough voltage output.
ProRules
55
Jan 29, 2018
shimageSo anything with 100mw+ per channel on 600 Ohms should be enough? or what stats would be good enough?
shimage
228
Jan 29, 2018
ProRulesSolderdude has a table of headphones and recommended power/voltage levels for amps. He recommends 13mW into 600Ohms for the DT990.
https://diyaudioheaven.wordpress.com/tutorials/power-impedance-etc/
ProRules
55
Jan 30, 2018
shimageThats so low lol Never expected that. But like, you never want to reach max gain.
shimage
228
Jan 30, 2018
ProRulesThat's to hit 105dB, which accounts for headroom. Listening at 85dB or louder will cause permanent hearing damage. You can see how much headroom you need by checking the music you listen to at the site below, but realistically 15-20dB is about the max anyone needs.
http://dr.loudness-war.info/
ProRules
55
Jan 30, 2018
shimageYeah.. 105db is a lot for sure. It would even damage the headphones. But usually people recommand heaving a lower source volume, while leaving most of the work to the amp. Which would require more than 13mw. Some people say that O2 is not always enough for these. Hell I don't know man.
shimage
228
Jan 30, 2018
ProRulesYou're confusing power with gain. The A30 has 3 gain settings: 0dB, 9dB, and 18dB. Also, I disagree that you should lower the source volume. SNR will be highest if you set the source at max and adjust volume with the amp. With adjustable gain on the amp, you choose the one that gets the volume pot in a reasonable spot.
People that think the O2 doesn't have enough power are likely either also confusing gain with power, or they're deaf, or they're confusing placebo with power. Don't get me wrong, placebo is a valid and important source of enjoyment in audio, but it doesn't make the O2 underpowered. In any case, the A30 has about the same power output as the magni 2 uber, and I don't recall anyone saying that was a problem.
ProRules
55
Jan 30, 2018
shimageCould you please explain a bit more about gain and power? I am very new to this world. How can an o2 with 88mw output at 600ohma. Be equivalent to a30 with 143mw at 600 ohms?
shimage
228
Jan 30, 2018
ProRulesGain is the amount by which the input signal is amplified. So, for example, a gain of 0dB is a factor of 1, and the input signal is the same as the output. A gain of 9dB means the output is about 3 times larger than the input. If the input signal is small, then the required gain will be greater than if the signal is large. Also, if you like to listen at high volumes, you will need more gain to reach the desired output levels.
Power is a separate issue. It's more about whether the amp is up to the task of providing the output levels you are asking of it. So say the amp has enough gain (eg, your load is an Aeon, which is 14Ohms). Can it also provide enough power to that load with acceptable levels of distortion? Typically this is given as the max power output into a resistive load for a given amount of distortion (for example, 1% THD).
With low-impedance loads, nearly all amps are current-limited, meaning that the voltage will start sagging before it reaches the max output voltage (this is also called soft-clipping). Clipping is one way that a signal can distort, and typically it's the distortion that we care about with power ratings. With SS amps we aren't going to care about low-impedance loads, as their current output limits are quite high. Tubes cannot supply much current, so OTL tube amps sometimes have trouble with low-sensitivity low-impedance cans like the Aeon.
With high-impedance loads, SS amps will be voltage limited, meaning that the amp will hard-clip when the output signal hits the max voltage limits. This is very audible, and not subtle at all. When people complain about an amp not having enough power, this is not what they are hearing. One other thing to point out is that the sensitivity of the headphones are important. The HE-6 has a notoriously low sensitivity (I've seen suggestions it's ~75dB/1mW). The Focal Clear has a sensitivity of 104dB/1mW. As a result, the Clear is a much easier load to drive, and can be more or less adequately driven by cellphones with good output amplifiers. The HE-6 absolutely cannot be driven by any cellphone, period.
Lastly, I didn't mean to suggest that the O2 is equivalent to the A30, it isn't. I'm just pointing out that O2 isn't underpowered, as it is so popular to say these days. 88mW into just about any normal pair of headphones will blow your eardrums out (not the HE-6, but it's in a class of its own). 143mW will do the same, just more so. If the O2 isn't getting loud enough, then the problem is that they don't have enough gain. If it is getting loud enough, but it is distorting heavily, then yes, it is not powerful enough. But in that case, either 1) they are going deaf very quickly, and who cares what they think about audio gear at that point, or 2) their hardware chain is broken somewhere and that's why it's distorting.
ProRules
55
Jan 30, 2018
shimageThank you so much for the explanation! Much appericiated :)
Ashw99
31
Jan 31, 2018
shimageWould it be easier to get a warmer sound with the 250ohm version then?
shimage
228
Jan 31, 2018
Ashw99Solderdude has a measurements for the 250Ohm version here: https://diyaudioheaven.wordpress.com/headphones/measurements/brands-a-i/dt990-pro-250%cf%89
Using an amp with 120Ohm output impedance gets you a 1dB bass boost, which isn't very audible. He recommends EQ for fixing the treble/subbass.
ProRules
55
Jan 31, 2018
shimageWhich amp is actually warmer - Schiit Magni, or Topping A30?
shimage
228
Jan 31, 2018
ProRulesYou're not going to like this, but short answer, buy the one with the features and aesthetics you prefer. That said, it is still possible that in sighted listening you would prefer the other one. I do not give amp/dac advice based on sighted comparisons, because that is mostly psychology and there is no particular reason your mind should work like mine.
Longer answer, in a valid blind test, you will not hear a difference between the two, unless the output impedance of the A30 affects the frequency response of the headphones used. However, the A30 does not have a high enough output impedance to make a difference with the DT990. With, multi-armature IEMs, or something like the Focal Clear, the 1/8" jack would make a difference (1/4" jack probably wouldn't).
Like Solderdude, I don't hear differences between (working) amps. Basically all half-decent amps have a flat frequency response and negligible distortion and noise (this is true even for most tube amps). Frequency response is always going to be the most audible aspect of any piece of gear, which is why headphones and EQ are so important. The main audible differences between amps are output impedance and (a lack of) power output. Large output impedances are easily audible with the right headphones (low impedance, strong resonance in the bass) because it affects the frequency response. Power is only important until you have enough, then it doesn't matter. Not enough power results in clipping, which you can see in the frequency response.
I have not seen anyone a/b different (properly working) amps in blind tests (I have seen marv's "tests" on SBAF, but they aren't well controlled and sample size is way too small to make judgements). Tyll says he can, and I believe him, but 1) he has a lot of training in this regard as the founder of one of the first commercial headphone amp companies, and 2) his descriptions of the differences are exceedingly subtle (eg, amp A makes him want to dance more than amp B). I have never been able to replicate his (unique) technique for performing blind tests, maybe because i don't like to dance.
shimageYou're not wrong on the 85dB per se but I wanted to add that hearing damage is a factor of multiple things: 1) Sound Pressure (measured in decibels) 2) Time of exposure (you can take 85db a lot longer than you can 105db without hearing damage) 3) Frequency/ies emitted.
ProRules
55
Jan 31, 2018
ElectronicVicesWhich frequencies are usually the ones emitting most damage to the ears?
Ashw99What shimage is alluding to is a reduced dampening factor resulting from an output impedance exceeding roughly 1/8 of the nominal impedance of the headphone. This typically results in greater distortion within the bass frequencies which some people perceive as "warm" but what you are getting is distortion and frequency response alterations. You are going to have a really difficult time getting a 600 ohm headphone to change much as you typically don't find output impedances that exceed 120 ohm which is 1/5 the nominal impedance of the headphone. I would not recommend inducing an impedance mismatch as you will not be getting what the designer intended for the headphones response.
ProRules
55
Jan 31, 2018
ElectronicVicesHow would the Aune T1 SE MK3 be for these headphones? (Its on a drop at this moment).
shimage
228
Jan 31, 2018
ElectronicVicesThat's not really what I'm talking about. Nearly all non-planar dynamic headphones have a resonance in the bass region. You can see this easily in impedance plots. You can treat the output impedance with the headphone as a voltage divider, so that a spike in the impedance will result in a spike in delivered energy. The warmth you see in solderdude's FR graphs comes from this voltage divider effect rather than from distortion (duh, since it doesn't measure distortion at all).
If the resonance is weak (small peak in impedance), then the effect of using high output impedance is not as pronounced. This is the case with the DT990, which is why even the 250Ohm version is not strongly affected by a 120Ohm output impedance. Foster drivers also have fairly weak resonances. HD6X0 have a stronger resonance, as do the Focals, and they are more responsive to high output impedances. Ortho-dynamic ("planar") headphones are purely resistive (more or less), which means their frequency response is not affected by output impedance.
Also, "impedance matching" is not really a thing at these frequencies/power levels, unless you mean something other than what that phrase normally means in EE.
One last thing regarding "what the designer intended". I remember reading somewhere that 120Ohms is a kind of stardard, and some headphones are designed with this in mind. Consider that Beyerdynamic's own headphone amp has an output impedance of 100Ohms, and the HDV820 is supposedly around 40Ohms. My opinion is that people should use whatever they like best. Garage 1217 has an amp (polaris?) that has variable output impedance (designed by solderdude), so you can pick whatever suits your mood or headphones.
ProRulesThere isn't much practical influence on the frequency front as one rarely encounters noise/sound isolated to a certain frequency band but in general 1-5kHz is the region in which our ears are the most sensitive. ANY frequency played loud enough and long enough will damage hearing. A general rule of thumb would be to speak normally while playing your music... if you can still hear yourself then you are typically in the safe range for a "standard " listening session. If you listen for 4+ hours a day I would take it even lower.
ProRules
55
Jan 31, 2018
ElectronicVicesWell it dependse if you have closed or open headphones. I'm pretty sure the volume of your own speaking would vary between headphones.
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