[ADUHF]

That is pretty typical for most people who EQ. I don't think many people are doing gross corrections with EQ unless they are creating an RIAA curve or something like that.

You're referring to a turntable preamp function, I assume. Like this...

I hadn't really thought about using a digital EQ for something like this before. But I suppose it is possible. (?)

I don't see a preset for this in Equalizer APO's Config Editor. At least not one that's readily obvious. (Maybe the Peace add-on has this as an option though?)

Most headphones are in a general enough ballpark to not need huge corrections.

I'm relatively new to digital EQs. But have been using some form of equalization (either analog graphic EQ's, tone controls on mixers, or digital EQ) with all of my headphones for at least the last 5 to 6 years... since I began reading Inner Fidelity, and deciding to upgrade to something a little better than the dimestore stuff I was using previously.

Before that, I think my favorite cheapie headphone was the Koss Pro 35. I don't know how neutral or accurate they were (probably not very). But the titanium drivers made the dialogue and what have you a little easier to understand on TV shows and movies. The cables were always breaking though. So I was continually replacing them. And I mostly used those for watching TV, VHS tapes and DVDs, esp. at night. And also listening to the occasional CD. (I wasn't really into MP3's, and still don't own an MP3 player to this day!)

I've tried various forms of EQ though, with at least a handful of different headphones since that time, including the AKG K553 (my main headphone for the previous 5 years), the Beats Solo2, Sennheiser HD 380 Pro, one of the cheaper open-back 5 series Sennheisers that Best Buy/Magnolia used to carry (though I can't remember the exact model number), AudioTechnica M50x, Sony MDR-ZX100, and my current DT-770's. And maybe a couple others I'm forgetting. And in my experience, EQ tends to work best with headphones that are close to your target sound signature... if you know what that is!

It also seems to work better with closed headphones than open ones. Especially if you want to tinker with the bass response, or desire more extension in that area. Most of the headphones I've used since the Pro 35 have had good extension in both the bass AND the treble though. Because I like to ensure that I'm getting a decent amount of detail up top, as well as down low.

If you're having to make large EQ adjustments though, greater than about 5 or 6 dB either up or down, to achieve your preferred sound, then perhaps it might be worth thinking about getting some different headphones to try instead that are a bit closer to the sound you want.

 

[ADUHF]

I won't get into the volts and watts again, until I understand all that stuff a little better. From what I think I'm able to understand though, it seems as though the ADI-2 was designed with accuracy, neutrality, precision, and also flexibility in mind. As opposed to a certain sound signature.

That could describe just about any DAC.

Yes. I should have been more clear in that statement that I was referring to both the DAC and the built-in headamp. And also the built-in parametric EQ features in terms of its flexibility or adaptability for use with different sounding headphones.

I was a little surprised that RME used such a low impedance on its main headphone output though. Since they included a separate jack for lower-impedance headphones as well. I guess lower impedance amps are better at maintaining a more flat response though with headphones of different impedances. (That's what some of the articles and info I've been lookin at seem to imply anyway.)

I still don't completely understand the relationship between source and load impedances though. And how those effect sound quality, except for their impact on distortion. Nor do I understand how the voltages and current are intertwined with those. About the best that I've been able to glean so far from my reading is that higher impedance headphones seem to like more voltage. While lower impedance headphones seem to be more efficient or better designed for using current. So they do not place as high voltage demands on portable devices.

I also understand that the volume control on an amp usually (though not always) varies the amount of voltage to the headphones. So that is what allows their volume to be adjusted.

 

[bigshot]

I don't think impedance ratings have much to do with sound quality. As long as an amp and headphones are properly matched, they sound good. There are great sounding high impedance cans, and great sounding low impedance ones. I suspect that the proliferation of different specs is more of a marketing strategy to create incompatibility and ensure brand loyalty than it is striving after better sound quality. If they sell you high impedance cans, you are a guaranteed sale for an amp. And if you buy an amp, they can upsell you to a DAC too. ...or you can just plug great sounding low impedance headphones into your iPhone and be done with it simply.

 

[skhan007]

Another thing I noticed when swapping headphones between three different amps: Headphone A was 300 Ohms and Headphone B was 200 Ohms. We would expect that headphone A would be tougher to drive in this scenario, but WRONG! We have to take into account dynamic driver (headphone A) vs. planar (headphone B). Headphone B was tougher to drive. Someone previously pointed out to me, that I must be wrong in my comparison of these two. Nope, not wrong. We have to take into account components within the headphone's construction as well and this goes beyond impedance of headphone and power of amp.

 

[ADUHF]

I don't think impedance ratings have much to do with sound quality. As long as an amp and headphones are properly matched, they sound good. There are great sounding high impedance cans, and great sounding low impedance ones. I suspect that the proliferation of different specs is more of a marketing strategy to create incompatibility and ensure brand loyalty than it is striving after better sound quality. If they sell you high impedance cans, you are a guaranteed sale for an amp. And if you buy an amp, they can upsell you to a DAC too. ...or you can just plug great sounding low impedance headphones into your iPhone and be done with it simply.

I honestly don't know the answer on this. I tried both the 80 and 250 ohm version of the DT-770 though. And for whatever reason, I found that I liked the sound a little better on the 250 ohm version. That may have had something to do with the impedance bridging on the amp, since I was using a higher impedance amp at the time. But I'm not certain that was the only factor.

The only difference between the two headphones that I know of was the thickness of the voicecoil, which is thinner on the 250 ohm version than on the 80 ohm version.

 

[castleofargh]

Another thing I noticed when swapping headphones between three different amps: Headphone A was 300 Ohms and Headphone B was 200 Ohms. We would expect that headphone A would be tougher to drive in this scenario, but WRONG! We have to take into account dynamic driver (headphone A) vs. planar (headphone B). Headphone B was tougher to drive. Someone previously pointed out to me, that I must be wrong in my comparison of these two. Nope, not wrong. We have to take into account components within the headphone's construction as well and this goes beyond impedance of headphone and power of amp.

Impedance was never synonymous of driving difficulty. At least not alone. That was mentioned several times here, but maybe you didn't get the stuff about sensitivity.
Without repeating what has been said, just consider that headphone specs give both impedance and sensitivity. Both do matter.
The higher the impedance the lower the current flowing in the circuit and obviously into the coil. So contrary to popular beliefs, higher impedance actually makes the job easier for an amp.
But then comes sensitivity, telling us how much power needs to be used to get a 1kHz tone to xxxdB SPL. If sensitivity is low for headphone A, we'll need more power to get it as loud as hp B. The impedance of those headphone will determine if that power will be ”Made” more of voltage or of current, but in the end we'll still have to get that total power value to reach xxxdB at 1kHz.


When you look at an amplifier’s spec you'll get a bunch of power values into various loads. That's when you need to know the impedance of your amp. So you can get the power of the amp into that load(headphone). And from there, it's about the sensitivity of the hp and that power spec. How loud you go deciding how much power you'll want.






IMO, talking about driving as a subjective impression should not be mistaken with electrical needs. On occasion, sound impressions will tell us about electrical issues. But I confidently claim that most comments about driving ability and power have nothing to do with electrical power. I do not know how someone could separate basic subjective preference, from analytical description of an amplifier by ear. Put differently, people should stick to sighted impressions describing impressions and preferences. And leave objective data to objective approaches. If any comment about the amp’s ability to drive a headphone, could be replaced by ”I like this one better than that other one”, then the poster probably should have stuck with that.

 

[castleofargh]

I honestly don't know the answer on this. I tried both the 80 and 250 ohm version of the DT-770 though. And for whatever reason, I found that I liked the sound a little better on the 250 ohm version. That may have had something to do with the impedance bridging on the amp, since I was using a higher impedance amp at the time. But I'm not certain that was the only factor.

The only difference between the two headphones that I know of was the thickness of the voicecoil, which is thinner on the 250 ohm version than on the 80 ohm version.

Are the coils making the same weight? If not you're not testing just impedance.
Are the headphones showing an audibly identical FR? Probaly not, as even 2 pairs of the same model probably show a dB or 2 here and there as variation. Maybe the amp also had a say in the final responses.
Then I guess that you didn't blind test them, so more biases could have sneaked in.

This is kind of typical in the sense that we effectively test for several variables while wrongly assuming we're only changing one. By making the conclusion about that variable, how often do we get lucky? And how often do we simply reach a false conclusion? IDK

 

[ADUHF]

There were some superficial differences in their FR. The 250 ohm appeared to be slightly better extended in the bass and treble. And this appeared to be more-or-less confirmed in Crinacle's plots of the two DT-770 impedances.

Perhaps that is related in some way to the impedance bridging or voltage of the amp though. And maybe a different and lower impedance amp could have made the 80 ohm sound more identical to the 250 ohm on a higher impedance amp. (?)

 

[bigshot]

even 2 pairs of the same model probably show a dB or 2 here and there as variation.

I was told by a designer of headphones that the industry standard for sample variation is between 3 and 5dB. In a particularly sensitive frequency range, that could be significant.

Good reason to only buy headphones from a seller with a no questions asked refund guarantee.

 

[castleofargh]

There were some superficial differences in their FR. The 250 ohm appeared to be slightly better extended in the bass and treble. And this appeared to be more-or-less confirmed in Crinacle's plots of the two DT-770 impedances.

Perhaps that is related in some way to the impedance bridging or voltage of the amp though. And maybe a different and lower impedance amp could have made the 80 ohm sound more identical to the 250 ohm on a higher impedance amp. (?)

I wouldn't know. It the kind of headphone I got to casually try many times in many places, but I never owned or measured any.
I did tend to prefer the higher impedance versions of that model. But why? Your guess is as good as mine.

 

[skhan007]

I can't tell if I'm completely missing the mark here, but it seems like people are getting a little carried away with the details and not really answering this question. Or maybe it was answered somewhere in this thread's seven pages and I simply missed/forgot it. Or maybe I'm misreading what you're saying and understand.

In all my years of poking around Head-Fi, I don't think I've ever come across a meaningful definition of "properly driven" according to most audiophiles. I even tried asking this question a few months ago, but I don't think it was ever answered at all. A lot of people seem to have a notion of some magical amount of power a headphone has to have in order to sound "good" or "its best" or "properly driven," but they never seem capable of answering how they arrived at that number. Those are all subjective terms, so definitions are subjective.

What it looks like you're asking, though, is how much power you need to get to a given SPL with a given headphone. That's easy to answer if you know how loud you want the loudest transients, and your headphone's impedance and sensitivity. I honestly have no idea how loud I listen and so I (almost arbitrarily) pick 120dB as the peak. I know that that's a lot louder than I'd ever want, but I figure it gives me plenty of leeway with my music and with my volume knob. In my (not 100% informed) opinion, it doesn't matter how dynamic your music is; you simply don't want to go above 120dB. So 120dB works as a concrete cutoff.

Each +10dB requires 10x power, so to determine how much power you need:
P_T = 10^(T-S)/10
Where P_T is target power, T is target volume, and S is headphone sensitivity.
Since headphone measurements are in milliwatts, this equation spits out milliwatts.

Using 120dB as T with your headphones:
P_T = 10^(120-93)/10
P_T = 10^2.7
P_T = 501mW

Then figure out the necessary voltage using Ohm's Law:
P = V²/R
where P is power, V is voltage, and R is impedance. In Ohm's Law, power is always in watts, so divide mW by 1,000.
Using your headphones again:
0.501W = V²/300Ω
V = √(0.501W*300Ω)
V = 12.3V

If you want to get technical, you should add the headphone's impedance (R_L = load impedance) to the amp's output impedance (R_S = source impedance), which would be important for an amp with very high output impedance, like an OTL.
P = V²/(R_L+R_S)

If your headphone's sensitivity is given in dB @ 1V (like some Sennheisers), use V_T = 10^(T-S)/20 to figure out target voltage, and then use Ohm's law to figure power.

Bumping the thread with a quick follow up question. I have often come back to this post to reference the math. Question: When doing the calculation for Power (mW), why are we choosing a target of 120 dB? If my listening levels are much lower, let's say 80 dB and add 10 dB for headroom, would that be appropriate, or do we use a really high target of dB for some specific reason?

 

[bigshot]

Peak headroom?

 

[skhan007]

Peak headroom?

Understood. As someone who listens at 80 dB or less, do I need to target an additional 40 dB of headroom or is it incorrect to do my math using a target of, let's say, 100 dB?

 

[VNandor]

Bumping the thread with a quick follow up question. I have often come back to this post to reference the math. Question: When doing the calculation for Power (mW), why are we choosing a target of 120 dB? If my listening levels are much lower, let's say 80 dB and add 10 dB for headroom, would that be appropriate, or do we use a really high target of dB for some specific reason?

I think the basic idea behind targeting 120dB SPL is that 120dB SPL is often quoted as the threshold of pain on a lot of these "how loud things are" charts. So it's rather arbitrary target but safe to say, it's more than enough for an enjoyable listening experience.

I noticed that when discussing headroom and listening levels on this forum, people mean different things by "headroom" and "listening levels". For example, when someone says their listening level is at 80dB, what they usually mean it's probably 80dB based on absolutely and utterly nothing at worst and based on getting a microphone and putting it against their headphones at best, which is still so inaccurate that it's just an unrepresentative number.

As for headroom, some people use it as it's typically used in other contexts, they say they listen at 70dB SPL, their music peaks above the average level by 20dB, therefore they need 20dB headroom to reproduce the peaks which means they want an amp that can push their headphones to 90dB. In this sense, 10dB of headroom is only enough for music that has been considerably compressed or limited already.

On the other hand, what some people mean by headroom is that they say they listen at 80dB, their music peaks above the average level by 20dB, and they want 20dB (of unused) headroom above the peak levels, so they want their amp to push their headphones to 120dB. In that sense, 10dB of headroom is 10dB more than what is actually needed.

 

[castleofargh]

Understood. As someone who listens at 80 dB or less, do I need to target an additional 40 dB of headroom or is it incorrect to do my math using a target of, let's say, 100 dB?

We aim for 115 or even 120dB SPL simply because it's the output level that is painful. So we assume that nobody will wish to use their headphones louder than that.
If you have different needs, you're welcome to set a different target level for yourself. I listen to music very quietly, I often read about how my HD650 requires high voltage(being high impedance), but I almost never send more than 0.5V into mine.
Now, that doesn't mean I don't have any need for more than the equivalent power to reach 0.5V. I use EQ, I apply replay gain, and more DSPs afterward. So in effect I need the power to get 0.5V plus the amount of gain to compensate with the amplifier for the various digital attenuations I'm causing.
For a simple example, if I take everything but the bass down on my EQ by 4dB(to boost the bass), I will need my amplifier to apply a gain of 4 more dB so that the overall music is still as loud, while the bass becomes be louder.
It so happens that all in all, I end up with maximum needs that aren't that far from the 115dB SPL often used as a target to estimate amplifier needs. It's dumb luck in this case.
As the maximum on the specs is usually when the amp distorts like crazy at 1kHz, it might be wise, depending on circumstances and amplifier architecture, to still allow a little extra headroom^_^ in case the amp misbehaves sooner at some other frequency into the particular load of your headphone, again at that frequency. While I'm one to always complain about the silly habit of people acting like the answer to everything is more power, I also don't suggest walking on purpose on the edge of what an amplifier can do.
A little extra for one reason or another is probably going to come handy or avoid potential issues with whatever DAC and headphone later on. I do believe there is such a thing as too much gain, so it's important to figure out where you in particular stand and what are your habits and needs. Because while you won't enjoy something too quiet, or something that distorts when it's loud enough, you also won't enjoy a volume knob where the slightest move goes from too quiet to too loud, or getting some background hiss(which is more likely with high gain amps and average to sensitive headphones).