[Bigfieroman]

Based on some of the reviews here and my previous experience, I have recently purchased some Koss cans. I know Koss has a somewhat poor reputation for anything except the ksc-75, ksc-35, and portapro lines, but I have had 7 years of spectacular service from a $14 set of Koss UR-30s I bought at Best Buy. They sound great, they are light, and they fit well. I just want to get better quality within reason.

I got some KSC-75s for portable use and Pro4AATs for home use. They are burning in right now. Holy crap, the Pro4AATs sounded ****** until after 20 hours of burn in, I am going for 200 to get the full effect. It seems the reviewers who liked the Pro4AATs gave them an extensive burn in, and the people who disliked them don't mention the burn in at all, or only gave them ~20 hours.

Anyway, I notice that almost everyone here uses a headphone amp, and claims that the amps are priceless for sound quality and volume with both of the above cans.

This is where I am confused; many people are claim vastly improved sound when using an amp...this doesn't make sense. From what I can tell, most people turn the source close to or at maximum volume, and then use the amp to adjust final volume. If there is distortion in the signal, why would it not be amplified? In other words, how does an amp make a set of cans sound better, not worse?

I understand the need for an amp with phones like the Pro4AATs, they are 250 ohm. But, my computer has more than enough power to drive them to a easily sufficient volume, so I am having difficulty justifying a $100 amp purchase. I don't listen to music very loud, and after my mp3 player is delivered today, I wouldn't be surprised if it had enough power to power them to a decent volume.

My best guess as to why an amp would create better sound quality compared to a battery powered source is because of the increased voltage. Volume is increased by increasing the current, but amps start with higher voltage to achieve the same power. For instance, my mp3 player uses 1 AAA battery, unless it is transformed, it is only 1.5v, (rechargable is 1.2v). Most portable cmoy amps use at least 1 9v, sometimes 2. Is that why people say amps improve sound quality?

 

[ilovesocks]

It's true that if you're amplifying a poor source, then the amp can't really make the sound quality better. If you can bypass a source's own amplifier though, you may get better sound quality.

Examples I can think of are

1) You can get better sound quality from an iPod by using a line-out to bypass the iPod's amplifier.

2) Some CD players have built-in headphone amps so you can plug headphones into the front of them. This amp might not be so great, but it can be bypassed by plugging an amp into the CD player's RCA-outs. This way, the CD player is being a transport and a DAC, and the amplification is left to a device that's better-suited for the job.

Therefore, it might not be worth buying an amp if your soundcard doesn't have a very clean line-out. I'd recommend going to the Computer-as-Source forum and reading up on favored soundcards.

 

[tomb]

Your conjecture is somewhat close, but you don't get a cigar, yet.

You are confusing a volume control with amplification. Even the lowliest portable can drive many heaphones to ear splitting volumes. However, most of that volume will be produced by the peak power capability of the amplifier circuit at a very limited set of frequencies, and the rest will be distortion.

As a for instance, one of the first introductions to hi-fidelity sound is that you notice that higher quality equipment can produce higher volume without as much irritation. Most easily see this comparison with speakers; it is very little different with headphones.

Music consists almost entirely of transients on top of a baseline of more-or-less constant tone, depending on the music. Quality amplification (translated: separate headphone amp) will have plenty of power to produce the constant tone for an overall acceptable volume level, but will also have plenty of power in reserve for any transients. Besides transients, there is also the problem of differing power levels needed for different frequencies. Bass frequencies require more energy and require more power. There again, another reason for a huge amount of power over and above the simple rating of a headphone's Sound Pressure Level (SPL) efficiency.

All of this is pretty much an afterthought in basic component players, including iPods, etc. There are many more design considerations to deal with that have a greater influence on affecting overall product design. That's one of the reasons you see only earbuds or very efficient headphones with portables. They simply do not have the necessary design for a better power supply. Simple Physics dictates that more power is possible with much less effort if the voltage is higher (Power is dependent on the current squared). Unfortunately, batteries are probably more limited in voltage than current, but pretty much limited in both.

That's why you a see a culture of headphone amplifiers with power supplies up to 24V, and many with batteries up to 18V. It simply isn't possible for mfrs to include this stuff in portables meant for the masses. So, the extra headphone amp is all to ensure that every frequency, every transient gets all the power a quality pair of headphones want. The result is not necessarily an ability to turn the volume up, but a crispness, airiness, and prescence that never existed before in your headphone listening.

 

[Bigfieroman]

My computer is a laptop, but it has an excellent soundcard. My MP3 player does not have a line out, only a headphone jack.

So, to get optimal sound quality, if not using a line-out, the best option is to leave the source volume low, say 1/3 or 33%, and amplify the signal to a comfortable level?

I have heard that one should turn the source up to near maximum, but it sound as if this will add significant distortion to the signal...

 

[003]

Just because it can get loud does not mean it is being properly amped.

 

[donunus]

Do it the headfi way. Buy a new source/dac, amp, and headphones in the 500 dollar level and up

 

[Bigfieroman]

Yeah, I know...I was a little unhappy with the quality of my $15 UR-30s, (turned out to be a really crappy source), found this place and all the sudden I dropped $150 on headphones and an MP3 player, might be buying a $100 amp soon....

 

[F107plus5]

Another good word used a lot around here is "Synergy"!

I'm still a noobe when it comes to such things. but what I seemed to pick up on was the difference between output stages of the different CD players and receivers. Some apparently use a simple resistor across the output amp stage to make the phone jack output more suitable for the vast number of"generic" headphones. The other way is to slap an op-amp in the output, giving a built-in generic headphone amp intended to be used also by the entire world of cans. These outputs may or may not be anywhere close to the quality of the components used in the available headphone amps, and they may or may not be anywhere near optimum for the headphones in use.

It's a jungle out there!

 

[drizek]

Quote:

Originally Posted by Bigfieroman My computer is a laptop, but it has an excellent soundcard. My MP3 player does not have a line out, only a headphone jack. So, to get optimal sound quality, if not using a line-out, the best option is to leave the source volume low, say 1/3 or 33%, and amplify the signal to a comfortable level? I have heard that one should turn the source up to near maximum, but it sound as if this will add significant distortion to the signal...

It should be turned up to 70% ive read if youre using hte headphone port.

 

[kramer5150]

I pretty much agree with whats been posted.... the amp provides additional current reserve and voltage reserve for transient peaks. A phone thats starving for either, can get useably loud, but will lack dynamics and transient "speed".

My take on it...
Personally I like colored amps... tubes, tube hybrids and the pint come to mind right off the bat. But as I've stated before in my other threads my strategy is to pick an amp more for its ability to color and EQ the sound. IMHO the ability to "amplify" and boost the signal is secondary. Lets face it, headphones only really need ~8-10 milliwats to get painfully loud (YMMV). Theoretically the RCA output coming out of most DACs is more than hot enough to drive the phones directly, and the amp is there merely to EQ/color/attenuate the sound to taste and present a stable impedence load to your source. So your question "how can the amp improve sound?"... Well... it can be used to EQ and color the sound to taste. OP amp and tube rolling is just a form of EQ-ing... (GASP!!)

Garrett (flame suit ON)

 

[kramer5150]

mods should move to the amp forum.

 

[Bigfieroman]

Yeah, sorry for posting this in the headphone forum, I though my original post was kind of split between the two forums, but the thread has quickly become much more amp-oriented.

 

[nsjong]

You sir, need to use the search button.

 

[JWolf]

I've plugged the output of the Creative Labs Audigy 2 ZS into my PA2V2 and my computer speakers (some model Cambridge Soundworks) and they do sound noticably better. Also gives me access to the headphone port in case I want to swap.

 

[Audiofiler]

Quote:

Originally Posted by nsjong You sir, need to use the search button.

the search tool is wonderful toy indeed...many threads on this topic with great reference therein.