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Understanding easy to drive headphones vs 600OHM monsters and the impact of/requirement for, a headphone AMP

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#21
They really aren't ..

I plug those DT990 600OHM into my Xbox Controller or straight into my PC, and I am struggling to get half decent volume, and I am for sure not deaf.... It's everything maxed out to get JUST, JUST loud enough, depending on the source material.

Don;t feel like there's much headroom there!!
I ABSOLUTELY AM I am new to this headphone stuff so please tell me am I buying the wrong amp ??
Haha, John isn't going to tell you you're buying the wrong amp with the L30. He built it. But the measurements back it up. In real world terms you probably wouldn't notice any difference on the 600 ohm cans between atom and L30 at same volume, but it has better gain structure for the denons and other low impedance (but not low sensitivity) cans
 

3125b

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#22
And do pay attention to output impedance as well.
If the headphones have a differing impedance per frequency (many dynamic hps will have a bump in the upper bass region for example), driving them on a high output impedance amplifier will cause a higher relative SPL in that frequency range (voltage divider).
But even on headphones with a flat impedance curve that will matter as per output power. If say the headphone and the amp have the same impedance, half the voltage drop will occur within the amp, therefor severely limiting output power.
I have measured a few different headphone outputs of different devices:
1606156203733.png (does not discriminate against clipping, actual useable power might be lower on some of those devices).

You can see that decent mainboards tend to have around 80R Zout, Amir found the same on a Gigabyte.
And with that you can see that the have just about the same output power into a 32R5 and a 218R6 load - while lower impedance headphones tend to require more power for the same SPL.
A voltage limit doesn't hurt the output signal of the amp just limits the max SPL more than you might like, a current limit means clipping and therefor coarse or distorted etc. sound.
I can tell you from experience that the AKG K702 for example sounds horrible driven from my mainboard, while the 250R Beyer T90 does just fine for normal listening levels.

The L30 will tick all the boxes and work just fine with every normal headphone, be it very sensitive IEMs (low gain option, super low noise floor) or your 600R DT 990 (6Vrms with 2Vrms input at 3x gain).

Edit:
The Denon 5200 for example would require four times the source voltage with a 80R output impedance amp as compared to 0.1R.
The sound wouldn't change much, +1dB in the lower bass area.
 
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wrigglycheese

wrigglycheese

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Thread Starter #25
Edit:
The Denon 5200 for example would require four times the source voltage with a 80R output impedance amp as compared to 0.1R.
The sound wouldn't change much, +1dB in the lower bass area.
I'm gonna have to re-read your whole post tomorrow and DIGEST it..... BOTTOM LINE the L30 is a match ? Or..... Trying to get plenty of opinions here.

BTW My PC motherboard is a bag of cheap ass - the MSI B550 PRO-VDH WiFi - cheapest bottom of the line ass I could find to do the job. AT THAT TIME I wasn't chasing audio fidelity.
 

NTomokawa

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#27
It's a somewhat common misconception that lower-impedance headphones are somehow "easier" to drive than higher-impedance ones, while the opposite is true.

A high-impedance headphone more closely approaches a voltage load. All the amplifier needs to do is to swing voltage around. The worst case is that your headphones don't play very loud.

A low-impedance headphone more closely approaches a current load. Now the amplifier actually has to deliver current into the headphones. If the output impedance of the amplifier is high, it becomes very poorly-matched to the headphones and will have very poor efficiency. The worst case is that your amp burns out - imagine shorting the outputs of a high-powered amp.

There are some 2 ohm speakers out there that easily burn or blow out power amplifiers.
 
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wrigglycheese

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Thread Starter #29
It's a somewhat common misconception that lower-impedance headphones are somehow "easier" to drive than higher-impedance ones, while the opposite is true.

A high-impedance headphone more closely approaches a voltage load. All the amplifier needs to do is to swing voltage around. The worst case is that your headphones don't play very loud.

A low-impedance headphone more closely approaches a current load. Now the amplifier actually has to deliver current into the headphones. If the output impedance of the amplifier is high, it becomes very poorly-matched to the headphones and will have very poor efficiency. The worst case is that your amp burns out - imagine shorting the outputs of a high-powered amp.

There are some 2 ohm speakers out there that easily burn or blow out power amplifiers.
OK OK definitely coming back tomorrow with one less beer..... Need to re read and really absorb all this.
 
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#30
Understood and the measurments are solid - however, what do YOU think ?
You need to move your mind away from the opinion of some random guy on the Internet. Or any number of random folks opinion.

I think the measurements are solid. Just about the best in fact. I own the amp, but my opinion of its sound is worthless. What I can tell you (as I and others have already) is that if you are looking to drive both low and high impedance cans with the same amp, the L30 is a very solid choice. Bags of power and the ability to control it finely.
 

3125b

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#31
Oversimplifying it; the APx555 is 1,000-10,000 times better at revealing imperfections than your ears (up to ~130dB SNR, ~122dB SINAD) - and it has no biases.
 

solderdude

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#32
Both the Atom and L30 are equally good for the job driving low impedance headphones when it comes to sound, technically the L30 is 'better' in measurements.
The DT990-600 can be driven louder from the Atom, certainly when you are going to EQ it.
L30 = metal case, more gain options. Atom = plastic case, higher gain.
 
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wrigglycheese

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Thread Starter #33
Both the Atom and L30 are equally good for the job driving low impedance headphones when it comes to sound, technically the L30 is 'better' in measurements.
The DT990-600 can be driven louder from the Atom, certainly when you are going to EQ it.
L30 = metal case, more gain options. Atom = plastic case, higher gain.
I don't plan to blow my ears off so L30 seems like a sensible choice at the significantly cheaper price. And I only mentioned the DT990 600 OHM as a reference they are not what I am using currently or plan to use ever again, I'll be selling them.

Currently using the Denon AHD5200EM and are the reason I am buying the AMP.
 
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wrigglycheese

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Thread Starter #34
Compared to what? How are you currently driving the low impedance headphones that would then be driven from a dedicated headphone amp?

Also, why do you make your post unnecessarily hard to read? Maybe a little more structure would help. Also, no need to post in ALL CAPS, when you can have parts of your post in bold or underlined text.
WHO DA FOOOK IS THIS GUY

WHAT ??

Note - I'll do what DA FOOK I want. What are you, a Mark Knopfler fan ?

DON'T come at me, in any way, for any reason, and I won't tread on your shit.
 
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wrigglycheese

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Thread Starter #38
As I suspected - they guys a prick.

I knew I sensed horrible atitude. I think I'm a jedi
 

amirm

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#39
As I suspected - they guys a prick.

I knew I sensed horrible atitude. I think I'm a jedi
Watch your language. This is a professional forum. We don't speak to each other in this manner.
 

dfuller

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#40
Well, that was pointlessly combative.

Anyway, you need less voltage swing but more current for a low impedance load (headphone, in this case) and more voltage swing but less current for a high impedance load. It's Ohm's law in action: Power = current^2 multiplied by resistance (impedance), but also power = voltage^2 divided by resistance (impedance).

High impedance headphones need more voltage swing for the same power output, so higher voltage power supply rails in the amplifier are required to avoid clipping. Low impedance headphones need more current, so the headphone amp needs to have a lower output impedance and a robust enough power supply to sufficiently power the headphones (you can sort of think of output impedance as how good a headphone amp is at supplying current - lower output impedance = better current supply).

The other thing to factor in here is sensitivity. This is measured with a given power (or voltage) input. For example: Sennheiser HD650s are rated at 101dB with 1 milliwatt input at 1KHz. This means that at 1KHz, a 1 milliwatt input will produce 101dB of sound pressure. This is the more determinant factor for how easy or hard headphones are to drive than the impedance is.

When people say headphones are "power hungry", really what they mean is that they're not sensitive. For example, HifiMan HE400i's have a sensitivity of 93dB - that means that at 1 milliwatt of power, they produce 93dB of sound pressure. Because the decibel is a logarithmic unit, that means that they need a great deal more power to reach the same sound pressure level as the HD650. Interestingly, at the same voltage input, the HE400i's are actually slightly more sensitive (105dB for the HD650s vs 107dB for the HE400i's). Once again, this is Ohm's law in action.

But, because the HE400i's are considerably lower impedance than the HD650s (40R vs 300R), they need much more current to reach that same power level.
 
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