Headphone amp/DAC + sound card for surround sound.

Discussion in 'Headphone Amps (full-size)' started by Kol12, Aug 14, 2017.
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  1. ProtegeManiac Contributor
    A white paper already figured out before that it was ultrasonic noise getting added by excessive oversampling. People do not necessarily have to hear the noise but the drivers behaved differently playing it. In any case, check the manual or ask Creative how to set it so that it samples at whatever freq the file is at, that way you don't upsample 16/44.1 but you don't downsample 24/48 DVD and 24/96 high res CD/FLAC/BluRay.
  2. Kol12
    Early Xmas present! Picked them up off a guy who has been heavily into HiFi for 40 years, he's brought the HiFiMan HE1000's.

    I plugged them into the SB AE-5 and initially they sounded very tinny. I recalled the talk of how despite being a 35 ohm headphone that they still require some grunty amplification. I switched the AE-5 to high gain 150-300 ohm and that's when it's happened, they came alive! This is my first open headphone and they are very airy with quite a wide soundstage. The difference in tone to my Pro 80 was quite significant, the HE400i sound very neutral and accurate to the recording. They are highly unforgiving to poor recordings... I found the bass to be a little lacking, switching to high gain helped but a 1-2 DB boost at 60-100hz results in very warm punchy bass. The treble is very smooth and easily distinguishable in the mix, it's amazing, you can hear hi hat and snare patterns in so much more detail.

    In the few days that I've them I realise I have some amazing sounding headphones. The previous owner recommends upgrading the cables for better sound quality and using quality amplification. He was using LQi cables.

    Now to a couple of issues. I am getting some slightly different sounding audio pops during playback since getting the HE400i. I wonder, could I be clipping the signal running in high gain mode from the AE-5? How the HE400i benefits from grunty amplification while being a 35 ohm headphone doesn't exactly make sense to me. The other issue is the Sound Blaster Connect software and the Acoustic Engine for gaming. It appears that some of these settings significantly boost the volume (Smart Vol). I am currently playing The Witcher 3 DLC and using the RPG preset. Geralt's footsteps, grass, wind and dialogue are all crisp, clear, warm and deep but some of the monsters are very screechy and harsh in the treble. I will have to continue adjusting EQ and better understanding how the Acoustic Engine operates. My main concern is that some of these settings boost the volume and I would hate to be clipping my new headphones.

    Cheers and Merry Xmas!

  3. ProtegeManiac Contributor
    Gain doesn't put more power, it just pours it in at a faster rate. Think of it like a transmission and engine. The engine makes the power, that's like the amp's output stage and power supply. The gain is like the transmission. Setting it to higher gain is like getting taller gears. You accelerate faster, likely finish the quarter mile or some circuits faster, but it's not because you actually have more power from the engine.

    If you notice a difference you're likely also listening louder, which if anything could be that you can't even get that loud on low gain. One other possibility why they might sound more alive is because the high gain gets higher impedance, so you'll also get some distortion. Not as much as with dynamic drivers for sure but that can still be audible.

    it still works like the engine and transmission. Taller gears makes you accelerate faster, but you hit the rev limiter faster, which is why just making the gears taller and taller isn't a solution since you end up rowing through the gears too much you lose time - whether on a circuit or even on a straight line - shifting with the power not getting to the tyres. 35ohms or 300ohms doesn't matter.
  4. Kol12
    "If you notice a difference you're likely also listening louder, which if anything could be that you can't even get that loud on low gain"

    My perception of the gains seems to have totally changed. Maybe the volume control in the apps were very low (would be unusual) or the cable wasn't plugged in properly (also unusual) but there is now plenty of volume with the medium gain and that tinny sound I first heard when I plugged the HE400i in on low gain is no longer there, even low gain has enough volume. Bit confused about that. :confused: Does gain have any effect on the fidelity of the audio signal or is it just simply a control/resistance to the power flow? It seems clear now anyway that they don't need high gain to get volume and I should be more concerned in matching the headphone impedance to the gain setting. Also being careful not to over drive the drivers if using high gain to cause distortion. So when people refer to the HE400i needing quality amplification or Planar Magnetic drivers needing lot's of power they're not referring to the gain or impedance I take it? Is there anything significant about gain/impedance with Planar Magnetic drivers or should they just simply be level matched?
    Last edited: Dec 29, 2017
  5. ProtegeManiac Contributor
    Gain sometimes affects the output impedance, but this is not always the case and even then some manufacturers don't state it. Schiit does though.

    That in turn can introduce an EQ effect. It's a lot milder on planars vs dynamic drivers but it's still there.

    Impedance and gain have no direct relationship. Impedance affects power output - ie the higher the impedance the lower the output, but this is flipped on OTL amplifiers - and therefore only becomes a problem really if gain is too high or too low that you can't even get to hearing damage levels. That isn't just a matter of high impedance making the amp produce less power but also if the headphone has lower impedance and lower sensitivity/efficiency, ie, even if it's 35ohms the HE400i has only a sensitivity of 93dB/1mW, which isn't literally 93dB as soon as the volume setting isn't zero.

    On the flipside, some high efficiency and usually low impedance headphones/IEMs can get really loud as soon as the volume setting goes above the minimum, and if there's an analogue potentiometer, that results in one channel louder than the other. Noise is usually an issue on very high efficiency, low impedance headphones/IEMs also.

    You can still do that even on low gain, it's just easier to get that on high gain. If the low gain isn't too low you can push the amp to clip with a given headphone at, say, 80/100; the only difference putting that same amp circuit on high gain is that clipping can happen before you hit 80/100. And then there's that problem of uneven output across both channels on high sensitivity drivers.

    Think of it again as a transmission. Engine redline and power output remain the same, but you rev faster with shorter gear settings, which can affect your times because you're shifting too frequently or worse, you end up having to upshift or lifting the throttle before exiting a 2nd gear hairpin (which can slow down the momentum at exit, or worse, make the car/bike unstable losing grip upon lift like a Porsche fishtailing or a bike dropping, or the short gear provides waaaaay too much throttle steer you end up fishtailing the same Porsche or wasting laptime doing wheelies on a bike).

    They're referring to the lower sensitivity. HE400i can be 35ohms so it's at the meat of most amps' powerband but its sensitivity is 93dB/1mW; the HD650 is 300ohms and so on any amp that is not OTL the voltage delivery has the power dropping at that impedance, but its sensitivity is 98dB. If you have a theoretical target of 120dB for example you will need roughly 1200mW for the HE400i and only 500mW for the HD650 (graph is logarithmic, not linear).

    It just happens that most planar drivers for now have lower sensitivity than a lot of dynamic drivers in the same price range (and even lower price brackets for the dynamic drivers). 93dB/1mW is still relatively high compared to the 86dB/1mW of the first HiFiMans.
  6. Kol12
    Sorry for delayed reply and happy New Year.

    Yes it was the low sensitivity of the HE400i that I forgot about. So does sensitivity and gain have any relationship to each other or is it sensitivity and impedance? It would appear that sensitivity is another form of resistance or a control of how much power flows to the drivers, it also affects power output is that correct? What part in the headphones actually determine sensitivity and make it work?

    Is low resistance and low sensitivity the common configuration for Planar headphones? Is there any advantage to both low resistance and low sensitivity?

    I'm kind of confused about the high impedance headphones. If the meat of the amps power band is at around 32 ohms like the Schiit above, how does a headphone like the HD650 300 ohm get the power it needs from 270mW? This comes back to the question does sensitivity also contribute to how much power the amp can output?

    I forgot, does the SB AE-5 have a 1ohm output? What is the advantage of low output impedance on the amplifier? On a slightly different note, the HE400i have a very nice light stock cable but it is very short, so I have had to plug it into my Proel extension. Apparently these headphones are very sensitive to the cables used with the stock cable being slightly veiled. I guess plugging it into an average extension lead is going to further increase that veil.. Should an aftermarket cable be something I should look into before any other upgrades?
    Last edited: Jan 2, 2018
  7. ProtegeManiac Contributor
    As a very rough example, think of a car again. Sensitivity is like weight, amp power is like engine power delivery, gain is like the transmission. If you have a very light car with really, really, really low gear ratios it will still be sluggish, but you can't exactly use a car too heavy for its engine with high gear ratios or else it will seem like it pulls hard but then you don't get all that fast before you have to shift. In the same manner a similar scenario will be like my Meier amp's -10dB low gain that gets to max volume and the Beyer T1 is barely scratching my eardrums, the other would be like an old Rega Ear with +26dB gain that clips the signal a lot sooner.

    It has a lot to do with the coil and magnet design as well as the diaphragm weight. On the last one it's a lot harder to do since a lighter diaphragm usually means a structurally weaker diaphragm that will introduce a lot more distortions to the sound. I'm not speaking broadly here - instead of just the colorations introduced by drivers you'll end up with outright bad sounding distortion, ie, driver break up. Hence the use of exotic materials so you can have a strong and lightweight material, but just like how titanium and ceramic composite armour are expensive (and every fictional armour made of some kind of fictional metal like vibranium in Marvel or Gundamium in Mobile Suit Gundam Wing).

    Low impedance yes. Haven't seen one with coil design to make for high impedance, and in their case, possibly different physics. In dynamic drivers higher impedance very generally can increase efficiency.

    No advantage to specifically design for low sensitivity, it's a by product of shooting for other parameters, ie, a diaphragm with very low driver distortion. That's why cheap headphones get loud easily but distort at high volume while bettter headphones sound better provided you can force more power into them. Think of the difference as a Tata mini car chassis vs a heavier but stiffer and altogether more expensive Audi space frame.

    Low impedance has one advantage though - it puts the driver at the meat of the power band of most amps, which is usually at 32ohms, sometimes slightly higher or lower (only OTL amps have their peak at 300ohms). So if you know that high impedance won't help with sensitivity might as well shoot for where most amps are kicking out the most power, like shifting early on lower rev engines with smaller turbochargers because you don't always need to redline at every shift on every engine.

    What do you mean by "all the power it needs from 270mW?" 270mW is all the power it needs; tht would be like asking how a Lotus gets all the power it needs from 350horsepower. Think of the car comparison again. Low sensitivity headphone with a powerful amp is like a heavy car with a big engine; high sensitivity headphone is like a lightweight car with a small engine. It's like comparing an old Bentley to a Lotus (don't thnk of newer Bentleys and Audis for now as their acceleration and handling owe a lot to Quattro intelligent AWD spreading the torque around so there's less "spinning in place smoking rubber" and a lot more "actually moving forward").

    Lower output impedance on amp and higher load impedance means higher damping factor, ie, more control of driver movement by the amplifier.

    You can try spending on an aftermarket cable but beyond not going for anything too long with too thick (nor ridiculously thin) conductors I wouldn't really worry about it. I'd get a longer one just to avoid using an extension cable for no other reason than I don't like using extension cables, not really anything about the sound.
  8. Kol12
    So if sensitivity is in part to do with the design and materials used it is still these materials that determine how loud the drivers will get with said amount of power. Is that how you would describe how sensitivity works? I am trying to distinguish the relationship between sensitivity and impedance as both appear to have an effect in the power delivery..

    If a low sensitivity design results in low driver distortion wouldn't that be an advantage?

    What I mean is that a 300 ohm headphone isn't at the meat of most power amps (32 ohm). I seem to be missing something. 1300Mw at 16 ohms is a lot more power than 270Mw at 300 ohms and I thought the higher resistance headphone needed more power to get volume? Or is it that the higher resistance headphones are generally high sensitivity requiring less to get loud? Or am I failing to understand some basic resistance/current stuff?

    What's bad about extension cables if they have no effect to the sound or do they? Aren't the stock HE400i cable known to be slightly veiled?
  9. ProtegeManiac Contributor
    It's not just the materials. Other design features like the coil design also affects everything. Magnet material for example also differs in how well they work per gram, so some drivers use smaller magnets not because the manufacturers are cheap but because they use more expensive raw material, or in some cases like planars, there really is a need to have a larger magnet. AFAIK planar drivers have magnets on both sides of the diaphragm.

    Impedance affects power delivery more directly. Different impedance, different output from the amp. Like 1000mW at 32ohms and 250mW at 300ohms off the same amplifier.

    Sensitivity has no effect on power delivery. It doesn't matter if one 32ohm headphone has 101dB/1mW sensitivity while another has 35ohms but 93dB/1mW, they'll still get the same amount of power (maybe a little bit less on the latter). What it does affect is how much power you need to achieve the same output, ie, in decibels. Again note that this isn't literally 101dB or 93dB as soon as you move the volume dial since gain involved, but assuming that is a constant, here's a way to guesstimate how to get the 120dB peak target: start out with the sensitivity rating and for every +3dB you need to double the output.

    The first headphone will hit 101dB with 1mW, 104dB with 2mW, 107dB with 4mW...until you hit 120dB with roughly a little over 70mW.

    The second headphone will hit 93dB with 1mW, 96dB with 2mW, 99dB with 4mW...until it hits 120dB with around 512mW.

    Assuming its the same low output impedance amp and can hit over 512mW at 35ohms (ie it will not be clipping), the THD+N levels will always be higher at 512mW level vs 70mW. On a good amp even noise will not be audible at 512mW and higher and distortion isn't necessarily easy to pick out as distortion, and theoretically inaudible.

    That's why assuming ambient noise vs isolation isn't a factor cheap headphones will get loud off practically any decent mainstream device, unless said device has some kind of design issue like EU state volume limits that totally ignore sensitivity and hence why better headphones can sound even worse off an EU market smartphone.

    You're totally ignoring one part of my explanation. Impedance affects power delivery from the amp. Sensitivity affects how much power is needed by the headphone to reach a certain output level.

    Let's repeat the example above with a 35ohm, 93dB/1mW headphone (HE400i) vs a 300ohm, 98dB/1mW headphone (HD650).

    The HE400i will hit 93dB with 1mW, 96dB with 2mW, 99dB with 4mW...until it hits 120dB with around 512mW.

    The HD650 will hit 98dB with 1mW, 101dB with 2mW, 104dB with 4mW....until it hits 120dB with very roughly 192mW.

    If you have an amp rated for 1000mW at 32ohms and 300mW at 300ohms, and at both output levels the THD+N are the same, then it will perform just as well on both headphones. It's just that older dynamic driver designs higher impedance also has a contribution on sensitivity. Now you have the HD660S which has around 99dB/1mW but with 150ohm impedance, so a rough estimate means that it only needs 128mW to hit 120dB, so on the same amplifier you'lll be dealing with even less distortion than the HE400i and HD650. That said, any difference in sound between the HD650 and HD660S would have a lot more to do with the HD660S' smoother response graph (which of course along with the lower impedance and higher sensitivity, is objectively all around better than the HD650) than the lowered stress on the amp.

    I just don't like having a heavy point of contact in the middle. I move, that point of contact can also move. It's not about the quality of the sound assuming I'm sitting still.

    The only benefit I've heard from aftermarket cables if any are slightly better isolation from electrical noise (and in some cases slightly worse), apart from IEMs where physical noise (ie microphonics - try tapping the cables to see what that's like, though that's not crucial when sitting still and not running to catch a train or whatever) can be a problem and in very rare cases slightly louder (ie lower resistance). I'm not going to blow $300 to get a fraction of a decibel louder from a cable when if I really need to go louder without adding distortion I might as well add that $300 to a better amp later.
    Last edited: Jan 3, 2018
  10. Kol12
    Ok I think sensitivity makes sense now. Sensitivity may not affect the power delivery directly but it does go hand in hand with impedance... I'm guessing this is why most high impedance headphones are usually high sensitivity also right? Less power to get loud..

    Can I ask what qualities we would look for in an amplifier for driving planar headphones like the HE400i? Suppose I wanted to use a pair of high impedance dynamic headphones also would we need to balance what we were looking for? Compared to the Sound Blaster AE-5 what is a better amp than that going to have in it in terms of specs and hardware and how is that going to affect the sound of my headphones?
  11. ProtegeManiac Contributor
    Just note that there are low impedance headphones with relatively high sensitivity. Like a lot of cheap headphones. On the decent ones there are Grados with the eSeries at over 100B/1mW, the Beyer T5P at roughly the same level, and then there's the HE400S at 96dB/1mW (ie what I was suggesting at the start precisely because of that +3dB advantage in sensitivity).

    Look at the estimated calculations above. So the HE400i needs very roughly 512mW, the HD650 needs roughly 192mW. To make everything easuer, go with an amp that can hit at least 700mW at 32ohms and 300mW at 300ohms.

    AudioGD NFB-11 specs

    Meier Corda Classic
    w/ HE400i : https://www.audiobot9000.com/match/hifiman/he-400i/with/meier-audio/corda-classic
    w/ HD650 : https://www.audiobot9000.com/match/sennheiser/hd-650/with/meier-audio/corda-classic
    w/ LCD-2 : https://www.audiobot9000.com/match/audeze/lcd-2/with/meier-audio/corda-classic

    Violectric V200 (A little bit extreme in terms of power output but in practice that's if you get it to switch over to Class B; with the HE400i and HD650 chances are it will just operate in Class A)
    w/ HE400i : https://www.audiobot9000.com/match/hifiman/he-400i/with/vioelectric/hpa-v200
    w/ HD650 : https://www.audiobot9000.com/match/sennheiser/hd-650/with/vioelectric/hpa-v200
    w/ LCD-2 : https://www.audiobot9000.com/match/audeze/lcd-2/with/vioelectric/hpa-v200

    AudioGD NFB-11. Cleaner sound at higher volume. Whether you're going to hear the difference is something I can't answer clearly enough for anyone other than myself.

    Think of it like going from a tall roofed, primarily family sedan chassis Lancer with a 4G63T with an upgraded (but laggier) turbo that when driven Too Fast Too Furious kinda feels like that part when the Evo got hit with the EMP harpoon (except you don't have an actual EMP harpoon, then going off in a more composed, purpose-built for aerodynamics and performance Lamborghini Diablo. But I can't tell exactly if you'll also go 10/10ths on it as you did to upset the Evo chassis since you'll now be carrying even more speed into the corners of that small track you play at every weekend (let alone the public road en route to that track).
  12. Kol12
    Sorry for the delayed reply. That headphone/amp compare site is handy. So when we look at the different headphones matched with a particular amp on that site what are the important specs to note? Obviously the amp specs don't change. Is it the peak SPL and damping factor that's worth noting?

    That's ok. Obviously a discussion about how one amp is better than another could shoot off in all sorts of complex directions. I was just curious as to some simple factors in a pricier powered amplifier and they would differ or better than the SB AE-5. With what you know about the AE-5 how would you descibe it's quality?
  13. Anarion
    Well, I can give my opinion. I have Massdrop Objective 2 amp (1x & 3,3x gain version) and I did the RMAA comparison with AE-5:
    SoundCore3D ADC limits the AE-5's noise level and dynamic range results and may be a bottleneck in some other areas too. But I guess this gives some insight and reference. I used Direct and Direct HP mode, ASIO for recording and playback. I used low gain for AE-5 (AE-5 has low, standard and high) and low gain for O2. Low gain on AE-5 seems to be equal to O2 1x gain.

    I don't know if my O2 is performing as it should but this kind of difference is very audible. I can tell you though that the AE-5 HP out is really, really good. It's probably one of the best DAC+AMP combos you can buy for the money.
    Last edited: Jan 13, 2018
    ProtegeManiac likes this.
  14. Kol12

    This is great! A great reference for the AE-5 and amp comparison is general. What is that software?

    Now I just need to better understand what those numbers mean. I have some basic understanding but could do some more homework.

    What software are you using ASIO for playback and recording because I could not get the AE-5 to function as an ASIO device in FL Studio.

    I agree, the AE-5 has a very punchy clean signal and I am very happy with the HE400i running off of it. :)
  15. Anarion
    The software is RMAA (RightMark Audio Analyzer). Basically these results mean that AE-5 gives cleaner output, much better dynamic range and way better stereo crosstalk (it makes stereo imaging and soundstage much more accurate on AE-5 - probably the individually amped channels makes the difference here). AE-5 results were limited by the ADC so in reality it probably has even larger advantage. All other results except noise level, dynamic range and stereo crosstalk are pretty much within the margin of error. ADC is probably the limiting factor in those.

    In any case though the difference is (to my surprise) very noticeable in practice. I didn't expect them to have any real difference but that's not the case. I don't know how representative my O2 amp is but this is the case with the unit that I have here. AE-5 is much ahead, different class in terms of audio quality. To get close one would need to get something that's a lot better than O2.

    I've had some problems with the ASIO too but it did work in RMAA. Creative has some bugs left in their drivers.
    Last edited: Jan 20, 2018
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