IEM amping

Quote:

Originally Posted by autumnholy 

If loud enough = good enough,

That might be (mostly but not entirely) true of high impedance full size headphones, but not IEMs. Those are typically capable of ear damaging loudness from almost any device (thus an amplifier with greater than 0 dB voltage gain is not needed), but are more affected by the following:

- noisy sources

- high output impedance

- too sensitive volume control, and channel imbalance at low volume, due to excessively high gain

- issues generally related to driving any low impedance loads, like capacitor coupled outputs, and increased distortion

Basically, it is a mistake to assume that if something has low impedance then it is automatically "easy to drive and does not benefit from an amplifier". Other than the amount of voltage required, low impedance is actually harder to drive in most aspects. Even a very high sensitivity can be a bad thing, since it makes the first and third issue on the list above worse.

At first motivation for the JH3A was an Active crossover network but that did not go to well. The main selling point of the JH3A is the real time adjustment of phase with the amplifier's(or DAC) DSP equaliser in order to keep JH16's driver network time correct. Other than that, stv014 has all the points up there.

Some sources like old players/receivers or some amps with high gain or somewhat poorer implementations tend to be noisier. Soundstage I feel is a summation of frequency and time and amps like tubes and such are said to throw a wide soundstage because of changes in phase and response. 

Quote:

Originally Posted by autumnholy 

If loud enough = good enough,

 

I wonder why does JH Audio sells an amp to compliment its JH16?

Most IEMs I know are having impedance <60 Ohm,

And hence, how does amping help on IEMs?

Generally speaking,

High impedance headphones require more voltage to achieve a reasonable volume

Low impedance headphones require more current to achieve reasonable sound quality

So basically a low impedance headphone saps a lot of current from your source. There is little resistance to the "flow" of electricity for a given voltage.

If your amp cannot keep up with the current demand, the sound quality will be affected.

It really depends. Plus you say you are using an E7. While its an Ok amp its really nothing special when you move up to higher quality portable amps. You won't have a hum issue or hiss on the UHA4 or UHA6 MKII. Its a black background and is great at attenuating sources that would otherwise present that hiss. While an ipod or mp3 player may give you enough volume on an IEM that doesn't mean it will drive it properly. The idea it to get all the detail at a lower volume and having a good portable amp with low output impedance, and a good volume pot will help to do this. Now if you IEM is very efficient the point will be mostly moot. But you have to take into consideration the impedance/sensitivity of the IEM. Plus are their cross-overs involved which will make things more complicating to properly power? Even some of the more expensive dynamic IEMs can be a  bit more tricky to power and benefit some from a good portable source.
 

Quote:

Originally Posted by autumnholy 

My experience happens when using E7 to drive SE535. I hear a faint hum from the E7, but not directly from the headphone jack of iPod Classic. That's when I wonder how exactly can SE535 be amped optimally.

 

Well, nothing of those mentioned by stv014 touches on the audiophile jargon like soundstage, tight bass, smooth treble etc. I guess I've to read more on understanding how amping works.

 

1. Noisy source as in?

 

When the source is adding an additional noise to the music, something like a hissing sound. If its in the source, then an amp won't help. 

Quote:

Originally Posted by autumnholy 

proton007, I'm sure it's the amp itself, because I just plugged in the IEM into the headphone jack of E7 without it connected to any music player.

And then I heard the hum. Not like a hiss.

E7 is known to have 90 Hz / 180 Hz hum, just at a pretty low level.  Most people don't notice or complain about it.

SE535 is just really sensitive.

Then i guess its this ^^.

That said, I seriously doubt you need the amp with a SE535. I'm using the SE425, and I haven't really noticed much of a difference with an amp.

What I do notice, however, is that the volume curve is not linear. Meaning, if I turn up the volume beyond 70% it doesn't really go that much louder, though its loud enough for my needs. Maybe its got something to do with the current requirements being higher. 

I don't notice this with my Sennheiser HD239.

Quote:

Originally Posted by autumnholy 

I thought that the lower the current the better the performance since I thought that's what the purpose of high impedance is there for, to reduce the current into the headphone drivers.

Umm.. yes, but its not the whole picture.

Higher impedance is most of all a consequence of the design. You can use a higher impedance headphone with an amp with a high output impedance (maintain damping factor), using the same with lower impedance headphone would result in distortion. This has been the traditional design process, because amps in the past used to have(tube amps, even today) higher output impedances.

Also, you can use multiple high impedance headphones with the same audio equipment without stressing it out (reduce current as you say), for example studio usage.

Lower impedance is more of a modern design requirement because of portable devices. Batteries cannot usually provide very high voltage, but are much more generous with current, hence lower impedance and higher current for the same power.