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The Sub-$200 Portable Amps Shootout – 13 (+11) amps compared - Page 7

post #91 of 448
Thread Starter 
50 ohm isn't exactly low impedance, but it is very high either. Unless this headphone is ultra-sensitive, I doubt it will be affected by hiss much.
post #92 of 448
Anyone else have any thoughts on my amp question?
post #93 of 448
50Ohm is kind of in-between low-impedance headphones that need high current ( <32Ohms) and high impedance headphones (>150Ohm) that are best driven with high voltage. If you get an amp good at both, you should be ok. I'm pretty sure all of ClieOS' top amp picks will be adaquate; I think the O2 would probably be the best for my 62 Ohm AKG Q701 headphones, but I'm not sure if I want to spend that much for a device of that size.

Edit: I was tired and typed the wrong thing. Edit in bold. Sorry for the confusion.
Edited by Evshrug - 9/9/12 at 7:17am
post #94 of 448
Wait so one needs high current and one is best driven by high current? I don't understand that statement. :/
post #95 of 448
Thread Starter 
Basically it goes like this: The higher the impedance of a headphone goes, the more voltage it needs; the lower the impedance of a headphone goes, the more current it needs. Yes, they are opposite of each other. So if everything else is equal, an 8 ohm headphone needs a lot more current than a 80 ohm headphone, while the 80 ohm headphone needs a lot more voltage than an 8 ohm headphone. A good amp should be able to supply both adequately.
post #96 of 448

I think one of the challenges for new amp buyers is the difference between high current, high voltage & high gain.  I know it confuses me!  All I know is that low-impedance headphones tend to hiss and sound bad if the amp's gain is too high - but I really don't know why - I'm guessing it is because gain is actually a voltage increase?  And if the amp gain is too high for a low-impedance 'phone, then you can overdrive the 'phone (supply too much voltage) - is that correct?

post #97 of 448
What is gain lol? And between the 3 I asked about, which one is best for 50 Olmert headphones?
post #98 of 448
Thread Starter 
For all intended purpose, gain = voltage. Actual the full term should be 'voltage gain'. On most solid state amp, how much current is generally limited by the opamp internal design. Take O2 for an example, the output stage has two opamp (in parallel) to literally double its current output. Sometime, you will see a buffer stage as well (no voltage gain, purely for current output). Some opamp (say AD8397) has a buffer stage built into the chip to output higher current. The typical case is, as long as the load doesn't need more current that what the amp can supply, the effect of current is much less audible to the ears. Voltage on the other hand has much more obvious 'side effect' when you set the gain too high. In fact, most opamp perform best when there is no gain (gain factor of 1). Once you increase the gain, you are actually amplifying the input signal and thus causing noise/distortion (because there is no such thing as a 'perfect amplification'). The higher the gain, the worst it goes. At some point, you will go outside of the chip's spec and noise becomes a problem. For most sensitive IEM, actually an 0~3dB gain is more than enough when you are dealing with iPod's level line-out signal (which is only 0.5Vrms, far shorter from the standard 2Vrms).

Unlike current, you can control the voltage using the volume knob. With low impedance headphone, the problems are two folds: first, if the gain on the amp is too high, a slight turn on volume knob can make the headphone too loud. Since many volume knob also have imbalance issue on very low position, you will also get imbalance issue as well. That's the first sign your amp's gain is too high for your headphone. Often, it is also a sign your headphone doesn't need any voltage gain at all. In cases like this, digital volume control (which doesn't suffer from imbalanced) and zero voltage gain are preferred, because it is really the current you are interested at this point. The second issue is, high gain brings higher noise level, which comes in the form of hiss. That can be easily picked up by a low impedance, high sensitivity headphone, like custom IEM.
Edited by ClieOS - 9/9/12 at 9:49am
post #99 of 448

Excellent - thank you!  beerchug.gif

post #100 of 448

Wow, sounds complicated, I have no idea what to get now. :/

 

When I get it, what do I do with the gain settings and whatever? I'm confused about the fiddling with the settings and stuff also and how turning up the gain causes distortion and whatever. The ibasso t3 has +10 db gain,Maximum Output power:120mW+120mW, Signal to Noise Ratio:-98dB. What does that mean? This amp buying buisness is so confusing lol.blink.gif


Edited by clairyvic - 9/9/12 at 12:04pm
post #101 of 448

What would you guys say about the Fiio E11 vs the Audinst AMP-HP? I know the Fiio E11 is half the price, but considering it's amp is "better" than the E17's, and my options are an E11 or an Audinst (or some thing comparable to the Audinst), I figured I'd ask anyways.

post #102 of 448

The e11's amp is better then the e17, well I guess that just leaves the choice between the t3 and e11. What's frusterating is that is says the MD's require at least 100 mw per channel for best effect, but I can't find how much mw per channel each of these amps have on the internet. :/

post #103 of 448
Quote:
Originally Posted by hojomojo96 View Post

What would you guys say about the Fiio E11 vs the Audinst AMP-HP? I know the Fiio E11 is half the price, but considering it's amp is "better" than the E17's, and my options are an E11 or an Audinst (or some thing comparable to the Audinst), I figured I'd ask anyways.
It seems that if you want something around $150, and you aren't looking for a tube or integrated DAC, the general consensus of headphone enthusiasts is that the Objective2 (ClieOS' reference in this round-up) offers an unbeatable measured value. People who know they want a particular sound signature/coloration to season the taste of their particular headphone's signature may prefer something else: that's why everyone says "Your Milage May Vary."
post #104 of 448
Quote:
Originally Posted by clairyvic View Post

Don't know what a dac does. The EQ i'm not really interested in. I'm not sure what impedance means or a lot of this stuff means or else I would just look at the stats myself which is why i'm asking you guys.



 But this headphone has 50 olms impedance, I don't know if that's a lot or a little. I guess I want minimal hissing because a lot of my music has a lot of atmospheric silence and hissing tends to bother me. So for power/lack of hissing what would be the best choice for a 50 olm headphone between the e11, e17, and t3? I don't really care about the money difference. For the sake of conversation lets just pretend they where all the same price, so even if one is just a little bit better despite the price difference I would want to get it.



Ok, going back to this post I am quoting... The reason we know (or are learning) what the stats mean is that we want to match an amp to our headphone. The whole voltage/current requirement isn't that difficult to wrap your head around.

A good amp for a low impedance headphone (measured in Ohms) doesn't have much output impedance (so it can supply plenty of current). Meanwhile, a good amp for a high impedance headphone will need more and more voltage as the impedance goes up, and it will probably have enough current once you've got enough voltage. Basically, my understanding is that if you start with an amp that has a very low output impedance, and enough voltage to drive your headphone to acceptable volume decibel levels (preferably without turning the amp up to max), you have a good amp for your headphone.

If all that is still a mystery to you, or you can't find manufacturer listed specs for output ohms and voltage, then consider that ClieOS has found 19 options and measured them for you, and reviewed their sound character too. If you STILL can't decide what has priority for you, then just get the all-around very good Objective2 amp, and consider that part of your headphone audio DONE.
post #105 of 448
Thread Starter 
Quote:
Originally Posted by hojomojo96 View Post

What would you guys say about the Fiio E11 vs the Audinst AMP-HP? I know the Fiio E11 is half the price, but considering it's amp is "better" than the E17's, and my options are an E11 or an Audinst (or some thing comparable to the Audinst), I figured I'd ask anyways.

By amp section alone, I won't say E11 is better than E17. It is more like 'different'.
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