Help clarify headphone Impedance

[wraper]

I see lots of mobile 'phones and similar in that list, compare with say hifi or mixing desks or such (Which are the proper use of the DT100 and friends) and you will find that well north of 10R is normal.

10R or even 50R output impedance is completely fine for 400R headphones but not for 16R headphones.

[wraper]

This is what Sennheiser says dumbed-down for commoners.
https://sennheiseruk.happyfox.com/kb/article/260-headphone-and-amplifier-impedance/

If the headphone impedance is lower than the output impedance of the device they are plugged into, this lowers the damping factor, which may result in a significant change from the published frequency response and also cause distortion in the headphones.

[Yamin]

Is there anything which can go in between the headphone outputs of a mixer and the DT100, eg: transformer or small headphone amp. I couldn't find any plug and play solution around the web.
It would be great to build one myself.
How would a op-amp HP amplifier design vary if using the line outputs of the mixer or if I'm using the headphone output of the mixer as the input for the op-amps?

Thanks

[Bassman59]

Holy moly there are some fundamental misunderstandings here!

OK, so you guys remember that V*A=W, right? Good.
And you remember Ohm’s law? OK.

Holy Moly - you never read any book on Impedance matching (nor even carefully reading others responses).   Guess what?  You made a fool of yourself and so arrogantly as well!   Right?  -No and there is more to electronics than Ohm's law in a DC circuit and that includes the subjects here.   How really silly of you!

Holy Moly!

Despite the name "power amplifier," in audio the device which drives the speakers (including headphones) is really a voltage amplifier which is capable of sourcing and sinking the current required by the generally low-impedance loads.

(Yes, impedance matching is done for RF power amplifiers ...)

There is no impedance matching in modern audio. Everything is bridged: output impedances as low as possible (made easy by op-amps) and moderate input impedances (10 k-ish for line level audio). Instrument amplifier inputs are high impedance (1 M is common) so as to not load down passive pickups (usually between 5 k and 10 k).

[tooki]

Holy moly there are some fundamental misunderstandings here!

OK, so you guys remember that V*A=W, right? Good.
And you remember Ohm’s law? OK.

Holy Moly - you never read any book on Impedance matching (nor even carefully reading others responses).   Guess what?  You made a fool of yourself and so arrogantly as well!   Right?  -No and there is more to electronics than Ohm's law in a DC circuit and that includes the subjects here.   How really silly of you!

 

I’ll be the first to tell you that I don’t really understand transmission lines — but I also know that headphones (and audio in general) doesn't fall into that category. Luckily, others here that do understand both audio and transmission lines have already confirmed what I said and explained why.

[tooki]

Is there anything which can go in between the headphone outputs of a mixer and the DT100, eg: transformer or small headphone amp. I couldn't find any plug and play solution around the web.
It would be great to build one myself.
How would a op-amp HP amplifier design vary if using the line outputs of the mixer or if I'm using the headphone output of the mixer as the input for the op-amps?

Thanks

I suppose that in theory a transformer would work, but whether appropriate models are even made any more, I don’t know.

A simple op-amp headphone amplifier (running off proper dual rail power of appreciable voltage, like ±9V at minimum) would work fine. You can buy them as finished amps, as Chinese boards on eBay, or build your own in an afternoon.

[NiHaoMike]

I'm surprised a mixer is having difficulty driving headphones, given that sort of thing is usually a professional or prosumer bit of hardware.

[David Hess]

Is there anything which can go in between the headphone outputs of a mixer and the DT100, eg: transformer or small headphone amp. I couldn't find any plug and play solution around the web.
It would be great to build one myself.

A transformer or headphone amplifier would be suitable.  Suitable high fidelity transformers are very expensive but headphone amplifiers can be found for a reasonable price.

How would a op-amp HP amplifier design vary if using the line outputs of the mixer or if I'm using the headphone output of the mixer as the input for the op-amps?

The only variation would be the gain or input attenuation to accommodate different signal levels.

[GeoffreyF]

Holy moly there are some fundamental misunderstandings here!

OK, so you guys remember that V*A=W, right? Good.
And you remember Ohm’s law? OK.

Holy Moly - you never read any book on Impedance matching (nor even carefully reading others responses).   Guess what?  You made a fool of yourself and so arrogantly as well!   Right?  -No and there is more to electronics than Ohm's law in a DC circuit and that includes the subjects here.   How really silly of you!

 

I’ll be the first to tell you that I don’t really understand transmission lines — but I also know that headphones (and audio in general) doesn't fall into that category. Luckily, others here that do understand both audio and transmission lines have already confirmed what I said and explained why.

I never imagined that you know jack about transmission lines.  However, I still am the first  to tell YOU that you know nothing about impedance matching which applies to more than transmission lines.  You know nothing about power transfer - and you still think you have something to contribute instead of something to learn.  Read some books on electronics - read past the page on Ohms law.

[tooki]

Bruh... I know my limits. Learn yours, since you’re the one spouting abject nonsense. 

[wraper]

However, I still am the first  to tell YOU that you know nothing about impedance matching which applies to more than transmission lines.  You know nothing about power transfer - and you still think you have something to contribute instead of something to learn.  Read some books on electronics - read past the page on Ohms law.

The most efficient power transfer is when source has much lower internal resistance than load. Impedance matching you talk about but don't explain is some sort of nonsense.

[Zero999]

Holy moly there are some fundamental misunderstandings here!

OK, so you guys remember that V*A=W, right? Good.
And you remember Ohm’s law? OK.

Holy Moly - you never read any book on Impedance matching (nor even carefully reading others responses).   Guess what?  You made a fool of yourself and so arrogantly as well!   Right?  -No and there is more to electronics than Ohm's law in a DC circuit and that includes the subjects here.   How really silly of you!

 

I’ll be the first to tell you that I don’t really understand transmission lines — but I also know that headphones (and audio in general) doesn't fall into that category. Luckily, others here that do understand both audio and transmission lines have already confirmed what I said and explained why.

I never imagined that you know jack about transmission lines.  However, I still am the first  to tell YOU that you know nothing about impedance matching which applies to more than transmission lines.  You know nothing about power transfer - and you still think you have something to contribute instead of something to learn.  Read some books on electronics - read past the page on Ohms law.

I did transmission lines in college so have a fairly good understanding of them, but I've not used most of it, so I admit I'm rusty.

Yes, impedance matching does apply to areas, other than transmission lines (more later) but audio is not one of them, unless you're talking about old telephone lines, which is not what this thread is about.

How long are your headphone speaker cables? The wavelength of 20kHz is 15km through a vacuum, but it will be a bit shorter in a cable, so call it 10km, assuming a velocity factor of ²/₃, so unless your cables are hundreds of metres long, impedance matching is a non-issue.

The only other reason we might want impedance matching is for maximum power transfer, but this in't applicable to modern amplifiers. To achieve maximum power transfer, the load impedance, should be matched to the source impedance, but assuming the source impedance is resistive, the maximum efficiency will be 50%, as half of the power is dissipated in the source. To get a decent efficiency, the source impedance needs to be much less than the load, ideally zero. Old valve amplifiers had a very high output impedance, so a transformer was required to enable it to drive a low impedance speaker efficiently, but nowadays it's completely unnecessary. Modern amplifiers have a very low output impedance, so impedance matching transformers are obsolete. 

[wraper]

the maximum efficiency will be 50%, as half of the power is dissipated in the source.

Actually it can be higher. With class D you can go over 90%, AB (most of analog amplifiers) can do over 60% efficiency.

[Zero999]

the maximum efficiency will be 50%, as half of the power is dissipated in the source.

Actually it can be higher. With class D you can go over 90%, AB (most of analog amplifiers) can do over 60% efficiency.

I know, re-read my post and if you still don't understand it, Google maximum power transfer.

EDIT:
Hint: if the source impedance is matched to the load, you have a potential divider.

[wraper]

I know, re-read my post and if you still don't understand it, Google maximum power transfer.

Ok, I missed power transfer thing.