I’m trying to wrap my head around something but can’t quite figure it out. I used to think the if a pair of headphones or IEMs require power, it would mean that if you don’t amp it correctly you just get very low volumes. However I’ve read on multiple occasions that it seems that just enough volume does not necessarily mean that it gets enough power, since the headphones or iems in question (P1 comes to mind) will “open up” on better amps with more power.
My questions are
How then can I find out whether an amp has enough power for the headphones I would like to use? What are the actual numbers I need to look at?
I have a Shanling UP2 which sounds perfectly fine with IEMs, but sometimes seems to struggle with my Koss headphones and HE400i, like it looses it’s balance and doesn’t get enough power, even though I don’t have the volume all the way up and it’s loud enough. Is this what you get when the amp doesn’t have enough power?
I’m new to this so correct me if I’m wrong. But…Yes. It seems like power and volume aren’t 100% the same all the time. You can listen to a set of headpones at the same volume (ie the loudness you percieve) on different powered amps (1w vs 6w for example) and it sounds different. Fuller, cleaner, … depending on the headphones.
So that would mean
Ask around! Look at people’s opinions on headphones and amps. Check people who have the same headphones as you. What amps do they use? How do they talk about them? The numbers on the amp to look at is the miliwatts (mW) at a certain resistance (for example 500mW at 32ohm)
Reading on this forum for a while it seems like different headphones experience ‘not enough power’ differently ahahaha
To figure out what you need to get there is the sensetivity per (milli-) Watt and the amplifiers power output at the impedance of the driver.
So the intersting numbers are “dB SPL per mW” and Impedance in Ω for the headphone, then the output power at that impedance from the headphone amp.
There are some rather complex dynamic interactions between the inductor that is the voice coil and the current flowing through it. Combine that with internal feedback and you may have a situation where the headphone presents a very low impedance at some frequency making the amplifier “overcorrect” and dampen the driver too much.
This ties into amplifier classes and topologies and requires some electronics knowledge to understand.
Generally if you have enough volume and it sounds decent it’s probably fine.
Volume is voltage, you can compute it given the impedance of the headphone, the power of the amp into that load, and the sensitivity of that headphone.
If you do the calculation you’ll find most headphones take much less that you would expect.
It gets more complicated because Dynamic headphones aren’t constant resistive loads, the HD6XX is nominally a 300 Ohm headphone, but it’s a 600Ohm headphone when playing bass notes and most amps will put 1/2 as much power into 600 Ohms as they do into 300.
There is however more to it than power as to why headphones open up on some amps.
I can drive a Hifiman Susvara (a notoriously hard to drive headphone) more than loud enough from a 2W amp, but most people suggest much more powerful amps, and my experience is that it behaves better on my 9W(3W class A) Cavalli amp than it does on my cheaper amps.
Some of this has to do with the ability of an amps power supply to cope with instantaneous changes in demand and this might explain why people like Susvara’s on Speaker amps, because despite they fact they are no more powerful into headphone loads than some headphone amps, the power supplies are massively overbuilt for those loads.
Some of it is just the quality of the amplification, some amps are just better than others.
Some of it has to do with synergy of components, some amps behave better with some loads.
Dampening, that is what it sounds like what I hear happening from my UP2 when I drive my Koss headphone or HE400i, it’ll behave fine and then it sounds like it’s being held back all of a sudden, but not evenly and not on both drivers equally.
Maybe this is caused by:
