[Patent Pending]

Having precisely 0 experience with high-end audio equipment (my best headphones so far are Sennheiser HD485s, and I have a pair of Denon C551s on order) I fear that by asking this question I am opening myself up to discovering just 'how deep the rabbit hole goes'... but nevertheless, I'll ask it.

What is the function of an amplifier? (The name 'amplifier' to me simply suggests that they make the sound louder.) Why do people deem it necessary to use an amp to mediate between an iPod and a pair of headphones?

Apologies if this question has been answered a myriad times already...

 

[TylerEaves]

Because an iPod is designed to power small earbuds. Trying to drive proper audiophile grade headphones with it directly makes about as much sense as sticking a lawnmower engine in a sportscar...not enough power for the job at hand.

 

[tomb]

Why Amplify? To power the device used to provide sound.

The question is not "Why Amplify" - every sound device has an amplifier prior to the connection to the headphones (or speakers). The real question should be, "Is that amplifier adequate?"

In the case of many devices from an audiophile perspective and quality headphones, the answer is almost always NO. Hence, the use of separate, add-on amplifiers that either augment or replace the existing amplifier.

In the specific case of iPods, that's why you also see the effort toward LOD's, so the internal amplifier can be bypassed completely. It results in even better sound from the high-quality external amplifier.

 

[MONVMENTVM]

Alright, but nobody said what amps really do.

I don't listen to my music any louder when using the headphones directly out of the source or with an amp between. I use the amp because it delivers more bass and tighter bass. They also open the sound a bit, treble gets smoother and everything sounds less muddy.

Edit: I just should have mentioned that I use Grados which have low impedance. For high-impedance phones, plugging them directly into the source might give too low volume and then they're really underpowered.

 

[Brewmaster]

My understanding is that a good amp will provide enough current and voltage to allow the headphones to properly respond to the changes in sound from the source. This allows the headphones to respond dynamically as close as possible to the source as the design permits.

Not having an amp may allow you to reach the same volume level (average sound pressure level), but you will not have the same dynamic response as the motion of the headphone driver is not as well coupled to the original signal.

 

[WaxMan]

A lot of people ask me what the reason is for owning an amp. I always get, 'Won't you blow out your eardrums?' or 'How loud do you need to listen to your music?' - They are all good questions but they seem to revolve around one thing, and that is that an amplifier is used solely to make things really loud. This is not true. It is true that an amp will amplify an audio signal, but an amp is not used to make the volume really loud. I have an SR-71, 80 gb Ipod Classic, Westone UM2's, and HD600's. I barely even need to touch the volume when I'm using my Westone's, and with the HD600's I rarely get to the 12 o' clock position on the volume knob. I think the best way to describe what an amp can do is like this: think of listening to your music without an amplifier like looking at the world through dark sunglasses, now listen with an amp and the sunglasses are gone. Another point of thought would be not to ask a question only your ears should answer! Good luck and welcome to a great hobby, and a great bunch of people to share it with! Eric.

 

[bada bing]

Amps are - in the simpliest definition & disregarding gain - impedance converters. The input into an amp is very high - typically 10k or 50k ohms. The output impedance is very low, a few ohms or even a fraction of an ohm.

With an amp in the audio chain, a source has to only vary the voltage - hardly any current flows because the amp has high input impedance. This is where alot of the SQ benefits come from. A source like an Ipod behaves differently (better) when it doesn't have to provide hardly any current.

One analogy is to think of an electric signal as a supply of compressed air. In this analogy a source would be an air compressor and the load a tire. An air compressor has to work much harder to pump up a truck tire (a low impedance load), than it does to pump up a bicycle tire (a higher impedance load). In both cases the pressure (equivalent to voltage in this analogy) may be identical but the work - and performance of the compressor (an Ipod?) - is much different. The air compressor will provide a somewhat steady pressure while filling bike tires, but will have a harder time filling truck tires. The pressure(voltage) in the compressor's reserve tank (Capacitors in this analogy) will sag more while filling truck tires.

This post probably confused more than it helped.

 

[Patent Pending]

Quote:

Originally Posted by bada bing /img/forum/go_quote.gif This post probably confused more than it helped.

Only 'cause I don't know the difference between resistance and impedance

 

[mrdeadfolx]

Quote:

Originally Posted by TylerEaves /img/forum/go_quote.gif Trying to drive proper audiophile grade headphones with it directly makes about as much sense as sticking a lawnmower engine in a sportscar.

Well said, I will repeat this the next time I am asked this question, which i have been asked about 10,000,000 times. This month.

 

[Happy Camper]

The recording has much more information that poorer amps have to be turned up to unbearable volumes to be heard if at all. A better amp will be able to dig out that information and present it with much less volume. It presents a more even spectrum without one part being dominate over another. Instrument decay, harmonics, venue reflective ques, soundstage and sound positioning is easier to hear.

To think of an amp as only a loudness component is wrong. It actually lets you listen to more details with less volume.

 

[schaqfu]

Quote:

Originally Posted by Patent Pending /img/forum/go_quote.gif Only 'cause I don't know the difference between resistance and impedance

Here's an explanation completely stripped of any technical information whatsoever (building on Happy Camper's good stab): The highest quality music in all respects sits on the iPod, but no matter who you are or what you do, it never ever reaches your ears with the same amount of quality. This is because every single item it touches along its way to you (the wires of your headphone, the speakers in your headphone, the wires and circuitry in the iPod itself, and the mini amplifier in the iPod too) degrades the quality some small amount....

Which brings me to the one sentence answer to your question: one uses a dedicated amplifier instead of the mini amplifiers that are built into iPods because dedicated amplifiers degrade sound quality less than does the iPod's internal amplifier. (Note: of course, some people use them to make the audio louder too, but among audiophiles the purpose and motivation --and thus, conversation-- principally revolves around quality rather than volume.)

Hope that helps. If you need a more compelling answer than that, you will have to begin to learn some of the technical terms and concepts others have begun to present above. Having come in to this hobby with virtually no technical background knowledge several years ago, I can say with great confidence that this community is an excellent place to learn such things with many people who will be willing to teach you. Just remember to complement them on how nice their long white beards look, to keep them happy.

 

[Boom Shaka Laka]

He he, the rabbit hole goes even deeper when you start comparing Solid State and Tube amps to match your source and then finally matching that with a good pr of cans. Then come the tweaks & mods after weeks/months glued to this forum in R&D and suddenly a year later you find your savings dwindling as you just became a Head-Fi junkie. Enjoy the journey!

 

[schaqfu]

Quote:

Originally Posted by Boom Shaka Laka /img/forum/go_quote.gif He he, the rabbit hole goes even deeper when you start comparing Solid State and Tube amps to match your source and then finally matching that with a good pr of cans. Then come the tweaks & mods after weeks/months glued to this forum in R&D and suddenly a year later you find your savings dwindling as you just became a Head-Fi junkie. Enjoy the journey!

Amen!