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

[wrigglycheese]

Watch your language. This is a professional forum. We don't speak to each other in this manner.

EDITED out. Due to pure respect for the way BDWoody handled this.

 

[wrigglycheese]

Well, that was pointlessly combative.

Yes - he came at me, POINTLESSLY

 

[wrigglycheese]

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 volt input will produce 103dB 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.

This is literally nothing short of epic - Thank you Sir

I do have a question but my account will be ended by the time I wake up tomorrow. So I will just have to figure it out.

I go out on my terms.

 

[BDWoody]

...you may now proceed to ban me (happens to me a lot...

Do you always take yourself so seriously?

I go out on my terms.

Guess that's a yes.

I do and speak in any POTTYMOUTH I want and no VERY BAD WORDS forum 'MODERATOR' (Who happens to be the site host, and who does much of the amazing work here) will TELL ME what to do how to speak...blah blah blah blah blah

Are you trying to give no options? This forum is not quick to ban anyone, but if you feel like this is how you need to respond to the site host, you may want to work on your manners.

 

[wrigglycheese]

This forum is not quick to ban anyone, but if you feel like this is how you need to respond to the site host, you may want to work on your manners.

Can't not respect that.

You might be the coolest forum 'MODERATOR' I have ever encountered - it's a breed I generally have a problem with.

I will attempt not to over react again.

 

[wrigglycheese]

Do you always take yourself so seriously?

It's complex and during this current lockdown a little bit yes, my bad. I should be better - working on it.

Your edit of my post was funny ;P

 

[wrigglycheese]

Being easy to drive and loud enough are two different things. ?

This is the magic right here.

And which is why I started this thread entirely.

I bought the Topping L30 to go with the Denon AHD5200EM (which are loud plugged into ANYTHING!) Which is why I was wondering about all this.

I am currently using the L30 on 0 gain (middle)

I normally use LOW gain on any AMP (otherwise I will change amp lol) but for some reason 0 seemed to attract me instead of the +/-, which do you recommend ? I once read that low gain is best in general but what is low gain on this AMP? 0? or -9? I guess what I am saying is, is 0 'AS INTENDED' like the sweet spot for the AMP.

Cheers.

 

[solderdude]

You set the gain so that you have a proper volume control range.
When 0dB works for you it is fine.

 

[wasnotwasnotwas]

This is the magic right here.

And which is why I started this thread entirely.

I bought the Topping L30 to go with the Denon AHD5200EM (which are loud plugged into ANYTHING!) Which is why I was wondering about all this.

I am currently using the L30 on 0 gain (middle)

I normally use LOW gain on any AMP (otherwise I will change amp lol) but for some reason 0 seemed to attract me instead of the +/-, which do you recommend ? I once read that low gain is best in general but what is low gain on this AMP? 0? or -9? I guess what I am saying is, is 0 'AS INTENDED' like the sweet spot for the AMP.

Cheers.

John has stated 0db is the "best" from a measurement perspective. But as solderdude says , the reality is that the one that suits your desired loudness and listening is "best" for you. Low gain is -9 dB btw- so you have -9, 0 and +9 to go at. I suspect the Denon's will sit well at somewhere past noon on low gain and noonish on "mid" gain- depending on any EQ, levelling etc you have.

PS- the switch labels what the gain settings are.

 

[wrigglycheese]

John has stated 0db is the "best" from a measurement perspective. But as solderdude says , the reality is that the one that suits your desired loudness and listening is "best" for you.

Awesome cheers this is what I was after. I happen to be perfect on 0db so that's good.... From a measurement perspective!

Volume knob sits happy on around 10-11 o'clock and that's loud!

I use EQ APO with -4db pre amp, and just a few tweaks within the 1-3db range on a few frequencies and I'm thrilled with the sound.

 

[wasnotwasnotwas]

Awesome cheers this is what I was after. I happen to be perfect on 0db so that's good.... From a measurement perspective!

Volume knob sits happy on around 10-11 o'clock and that's loud!

I use EQ APO with -4db pre amp, and just a few tweaks within the 1-3db range on a few frequencies and I'm thrilled with the sound.

Sounds about right- on similar specced cans to the Denon I am around 11/noon but have some EQ / pre amp and also turn the DAC down a few notches so I can use its remote volume function rather than getting up to the amp knob.