Headphone and Amp Impedance (2011)

Well I have some great news for you!

In 2024, you don’t need to spend mega bucks to get a good DAC or amp. You might not need one at all!

One of the better performing and measuring DACs out there right now is the $9 Apple USB-C dongle: https://www.audiosciencereview.com/forum/index.php?threads/r...

I’m not suggesting you need to rush out and buy it, but it’s a good reminder that modern tech is so good that even a $9 Apple part measures so well that nobody could hear the difference between it and a more expensive DAC.

As for amps: The amp story has been exaggerated a lot. A $70-$100 amp could give you more power and better performance than you could ever need (barring exotic headphones that need specialty amps). That’s if you even need one at all.

Don’t drink the kool-aid or take advice from people who learned about Hi-Fi from 1990s or 2000s tech.

> I guess what I hate about gear, is what others love, that there's no one right, no one truth, and that subjective experience has to be taken into account..

Sadly, subjective and placebo are two sides of the same coin in the audiophile world. People will swear up and down that their $1000 amp or DAC or cables are superior to their $100 version, but the claims disintegrate under blind testing conditions.

Because the effects are negligible and trivial to overcome with even basic attention to design.

The distortion of speakers or headphones is orders of magnitude higher than the distortion from even a basic headphone amp design in the modern era.

Why are you even considering the case of a zero Ohm load with a 16 Ohm source impedance? Modern headphone amps (including really cheap ones) have source impedances in the range of 1 Ohm or less while headphones can range from 30-ish to 300 or more.

If you don’t understand the problem with your post, trying flipping the roles to match reality: Assume a 16 ohm load and a 0 (or realistically, 1 Ohm) source impedance: Now the “no power absorbed” side of this equation is the amplifier. All (or nearly all) power goes to the headphones. That’s exactly what we want.

> Loads higher than 16 ohms will result in less current flowing.

I think this is where you’re confused. Headphone amps are generally voltage limited sources. If you get to the point of current limiting then it’s going to distort intensely and people would turn the volume down because it’s so unpleasant. Any source impedance subtracts from the maximum voltage you can apply across the load, because the source impedance forms a resistive divider. These aren’t high frequency transmission lines where we’re trying to send GHz signals over impedance matched lines.

You don’t maximize power delivered to the headphone by adding an identical source impedance. You actually reduce it massively relative to a modern If this still doesn’t make sense, consider why putting a 300 Ohm resistor in your headphone jack before connecting your 300 Ohm headphones isn’t going to improve anything. You’re just burning power in the source-side impedance and fighting against a fixed voltage limit.

- cables are available even from hardware stores, and also so are bus adaptors which connect two or three or five cables together, pin for pin; these do exist for 3.5mm jacks but are less common

- spiral 4p4c cables are cheap and easily available

- it doesn't short the power rails together as you're plugging it in

- the cables are all pretty high quality, which is not true at all for the 3.5mm audio cables

they also have some disadvantages:

- the cables are much larger than 3.5mm cables

- the jacks are much larger than 3.5mm jacks

- instead of absentmindedly plugging earphones into my data logger or programmable load and blowing up the earphones, the danger is that i (or a child, say) might absentmindedly plug the data logger into the phone jack on my cable modem, which is something like 50 volts on-hook and 90 vac when it rings

- 3.5mm jacks are an evolution of phone switchboard connectors, so they should be good for thousands of insertions and the plugs for like a million or so, and i'd be surprised if rj-11 or 4p4c connectors made it to hundreds

it would still probably burn out my earbuds if i put 5 volts at 100 milliamps on the tip connector once the plug was fully inserted