[SilentNote]

I’m getting a new IEM with fairly low impedance at 16 ohms. My iPhone has an output impedance 4-5ohms.

I’ve read that it’s best to have an output impedance 1/8 - 1/10 of the headphone impedance.

Will I benefit from having some kind of resistor adaptor added?

 

[SilentNote]

So after some research, impedance adaptors actually increase output impedance.

Faux output impedance decreasing adaptors are either a diy thing and wastes power.

The simplest solution to my problem is actually getting a lighting to 3.5mm adaptor that Apple sells. It has 1ohm output impedance that will match nicely with the 16ohm IEM.

 

[castleofargh]

-solid objective answer:
it depends.

-vague attempt at explaining:
ensuring a good damping ratio helps reduce the potential variations that could occur. so it's usually advised as a pretty simple trick to increase overall stability between amp and transducer. or simply because that's been the electrical standard for a few decades now. but it's not meant to claim that things will go wrong as soon as you don't have a good damping ratio.
as for some impedance adapters, again, the general rule of thumb is not to use them because it will come at a cost for the system. so it's not recommended by default. but every time we're in a situation with a serious issue and an adapter can help reduce or remove that issue, of course it's probably going to make sense to apply that band-aid, considering that it's well worth the smaller side effects if it fixes our big problem.

-solid general advice(but you do what you want, I'm not the police):
don't try to fix a problem before you're sure you have it.

 

[bigshot]

don't try to fix a problem before you're sure you have it.

That advice puts 90% of audiophile sales in jeopardy.

 

[buonassi]

What iem? Curious what its impedance curve looks like. Driver damping is not the only consideration, but tonal changes can occur as well with too high an output impedance.

 

[SilentNote]

Acoustune HS1670SS paired with iPhone SE. The 1670 has a nominal impedance of 16ohms.

As far as I can tell from ifixit teardown, the SE has the same audio chip as the 6s which means the output impedance is somewhere from 4.5-6.9 ohms, depends on who measured it.

I’ve gotten the iPhone 7 lightning to 3.5mm adaptor laying around. The adaptor has an output impedance of 0.4 ohm. So I should be set to compare the sound between the built in 3.5mm and the adaptor.

 

[iridium7777]

looking around on their website the impedance is actually quoted at 24 ohms, not 16, so you won't be that far off. i recently picked up n5005 with the current massive sale going on which are rated at 18 and have been exclusively listening with my iphone SE and i don't have any perceived issues of a mismatch.

 

[SilentNote]

looking around on their website the impedance is actually quoted at 24 ohms, not 16, so you won't be that far off. i recently picked up n5005 with the current massive sale going on which are rated at 18 and have been exclusively listening with my iphone SE and i don't have any perceived issues of a mismatch.

Hmm you are right. I misread the specs. I think they should work ok together then.

I’ll still test it over the apple adaptor and see if there’s any difference, when it gets delivered.

Thanks for checking it out.

 

[buonassi]

even if it was 16 ohms, it's a single dynamic driver and not nearly as prone to FR skew due to a wild impedance curves like many multi BA units. I really think you'll be fine with the headphone out