# Why do amps appear to improve soundstage, tighten bass and generally improve sound?



## DrR0Ck

I know this may be a newb question, but can someone explain to me why it is that an amp (not a DAC - I know what a DAC does) improves the sound heard from a given pair of headphones?
   
  I have seen many times in these forums people saying that the addition of an amp tightens bass, improves soundstage and similar improvements.  That even though a headphone may be driven adequately by a device directly, that it will shine with the addition of an amp. 
   
  What I do not understand is why this is the case.  If a pair of headphones are driven directly by a device to a particular volume level, or if an amp is added to the chain to drive the headphones to the same volume level, I would think that the total power output would be the same in both scenarios.  Why would the amped scenario result in a positive improvement to the sound quality?
   
  Thanks for any and all responses and apologies if this has been asked and answered before; if it has, just point me to the appropriate location.


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## PurpleAngel

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drr0ck said:


> I know this may be a newb question, but can someone explain to me why it is that an amp (not a DAC - I know what a DAC does) improves the sound heard from a given pair of headphones?
> I have seen many times in these forums people saying that the addition of an amp tightens bass, improves soundstage and similar improvements.  That even though a headphone may be driven adequately by a device directly, that it will shine with the addition of an amp.
> What I do not understand is why this is the case.  If a pair of headphones are driven directly by a device to a particular volume level, or if an amp is added to the chain to drive the headphones to the same volume level, I would think that the total power output would be the same in both scenarios.  Why would the amped scenario result in a positive improvement to the sound quality?
> Thanks for any and all responses and apologies if this has been asked and answered before; if it has, just point me to the appropriate location.


 
  My two cents.
  Manufacturers of audio devices use the cheapest (crudest) thing they can get for use as a headphone jack, just to save a few pennies.
  also I believe lots of "headphone jacks" are really line-out jacks that also pretend to also function as headphone jacks.
  True headphone amplifiers are more finally tuned (designed) to give headphones the correct signal feed to function better.
  As I said, my two cents.


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## DrR0Ck

So if I understand you correctly, if is not simply the amount of power, but the quality and nature of the power that determines the performance improvement.  Can you or anyone else explain from a technical standpoint how a quality signal would be defined?  What are the qualities that make a several hundred dollar amp more desirable than a $30 amp?
   
  Again, apologies if these are really basic questions but I'm generally interested.
   
  Thanks


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## PurpleAngel

Quote: 





drr0ck said:


> So if I understand you correctly, if is not simply the amount of power, but the quality and nature of the power that determines the performance improvement.  Can you or anyone else explain from a technical standpoint how a quality signal would be defined?  What are the qualities that make a several hundred dollar amp more desirable than a $30 amp?
> Again, apologies if these are really basic questions but I'm generally interested.


 
  More of my two cents
  Well for one thing, in most people way of thinking, a $500 amplifier is not desirable option simple because of the price.
  When you run more power into an amplifier you also get more "noise" added into the analog audio signal, so you need to use more quality parts to keep noise from being generated in the first place or removing/controlling noise from the audio signal, which adds expensive to the amplifier.
   
  For those that want the best quality reproduction of audio, the amplifier needs to be sensitive to the whole analog audio signal, the world is full of analog signals, which means the amplifier has a chance of picking those up too. Having good shielding blocks unwanted analog signals, but adds expensive too.
   
  So a cheap amplifier needs to be low powered for there to be less noise and to be "insensitive" so as to not pick up unwanted analog signals that it does not have to ablitiy to deal with.
  Being insensitive also means your not going to hear the full quality analog audio signal that some sound studio engineer put together.


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## DrR0Ck

This is really good information and makes a lot of sense.  Thanks very much. 
   
  When someone says they like the sound of one amp over another, or that they prefer the sound of (for example) tube amps, am I to assume that for lack of a better term that the amps "color" the sound to some degree?  In other words, I would assume that the amp should ideally do nothing other than provide clean power and the signal should be completely neutral, but I get the sense that some amps add a bit of flavor as well.  Or is this as simple as a small boost in bass or the presence or lack of rolloff in certain frequencies?


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## PurpleAngel

Quote: 





drr0ck said:


> This is really good information and makes a lot of sense.  Thanks very much.
> When someone says they like the sound of one amp over another, or that they prefer the sound of (for example) tube amps, am I to assume that for lack of a better term that the amps "color" the sound to some degree?  In other words, I would assume that the amp should ideally do nothing other than provide clean power and the signal should be completely neutral, but I get the sense that some amps add a bit of flavor as well.  Or is this as simple as a small boost in bass or the presence or lack of rolloff in certain frequencies?


 
  I'm guessing amplifiying the original audio signal and keeping it clean and sounding the same as it was before the amplification is a great thing.
  To build the perfect amp is an expensive job, it's cheaper to build an amplifier that only does one or two things well (bass or vocal or treble or soundstate, etc)
  and the cheaper to build, the cheaper you can sell it for, the cheaper it is to sell it for, then the more of them you can sell.
   
  Tubes have a second harmonic that add "warmth" and "soul" to audio.
  When you push tubes with lots of juice, the sound can change in "funny" ways and some people like that.
  You can also swap a tube in 10 seconds, so it's easy to change the sound of a tube amp.
   
  Solid state amps are cheaper and more reliable then tube amps.


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## DrR0Ck

Thank you again for taking the time to provide this information.  I'm relatively new to the world of decent headphones, and I have been doing a lot of reading and research for the last two months.  This really clears up a most of what I was wondering about, and you have explained it really well in an easy to understand manner.


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## Spillages

volume =/= power

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## DrR0Ck

Quote: 





spillages said:


> volume =/= power


 

 Can you elaborate on this statement?  I would assume that increasing the volume requires an increase in power.  I know that it is more complicated than this from a technical standpoint, so perhaps you can explain.
   
  Thanks


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## PurpleAngel

Quote: 





drr0ck said:


> Can you elaborate on this statement?  I would assume that increasing the volume requires an increase in power.  I know that it is more complicated than this from a technical standpoint, so perhaps you can explain.


 
  I believe the simple truth is that the more power the higher the volume, which is cheap to do.
  It's getting quality sound at high power is the big expense.


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## mikeaj

Everything with a headphone jack has something buffering the output that you could call a headphone amp.  It's a matter of (integrated or not) headphone amp A vs. headphone amp B.  A dedicated headphone amp hopefully uses a higher-end, sophisticated design that may be more expensive and/or larger.
   
  Pretty much, the job of the amplifier is to keep the output signal looking like the input signal (no matter what the input is, as long as it's in the audio frequencies), no matter what it's connected to.  Headphones are relatively low-impedance loads, so they require some decent current.  It's non-trivial to set up electronics with the performance characteristics to "copy" the shape of the input signal and then maintain that, into any headphone.
   
  If you look at the electrical output of any headphone amplifier, you will notice that it deviates from the input by some amount (sometimes by a trivial amount that humans can't possibly pick up).  Even though the output level magnitude from amp A may be the same as from amp B, the signal may be more distorted going through amp A.  A more accurate headphone amplifier will deviate by less, into a wider range of headphones, at more output levels, with different kinds of input signals.  This could be perceived as any number of improvements I guess.
   
  For tightening bass, bass control, etc., look particularly at the damping factor.  If one amp has lower output impedance, it will have higher damping factor into a given headphone.  However, note that a lot of dedicated headphone amps don't have very low output impedance, even though something like a $20 FiiO E5 does.  This is just one factor out of many though, and this is arguably very much not as important for headphones as it is for speakers.
   
  The rest of the difference reported between amps is mostly placebo.  People expect amps to sound different, so they hear it that way.


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## Spillages

Not the best at explaining this stuff, I always failed my English classes, so I like to do the copy/paste thing for you here.

This is on a bit of a different topic, but same concept if you can understand it.



There is some confusion about the relationship between watts and volume (loudness). There is much discussion about how this many dB is twice as loud as that many and that many dB is double the power and blah blah…… lot’s of techie rambling but no real world explanations. Let’s say you have a guitar amp with a knob to adjust the power (watts). Now say this amp is 20 watts at its maximum power setting and 1 watt at the lowest knob position. It would be reasonable to assume that 20 watts should be loud enough to play with the band and 1 watt would be whisper volume. Anyone who has had the opportunity to test this theory has found quite the contrary. 20 watts through a reasonably efficient speaker is quite loud. 1 watt through the same speaker is also quite loud. What’s up with that? Have you ever seen the specs for a 12” speaker? A typical guitar speaker will produce about 95 to 100dB at 1 meter (about 3.3ft) with 1 watt of input power. Now put 2 or 4 of that same speaker in a cabinet and the output is even higher. What this is saying is that even with a mere 1 watt of power, that speaker will put out the volume about equal to a person yelling. Obviously not “TV watching” volume. To obtain that whisper volume, you might need as little as 1/10 of a watt but…….at that low a volume, most guitar speakers start to sound terrible. In addition, there is a phenomenon that occurs with human hearing that is documented by Fletcher and Munson (two really smart guys) that graphs the way we hear things at different volumes. Look it up on the internet. The Fletcher/Munson curves show how our ears, at lower volumes, are less responsive to low and high frequencies. That means the quieter you play, the more we tend to want to boost the bass and treble to compensate for our own hearing. Ever seen the “loudness” contour switch on a home stereo? That is what the switch does. It boosts the treble and bass to make it sound better quiet. On a guitar amp you often find knobs for boosting the low and high end in the power amp section. Typically these controls are called Presence for the high end boost and Resonance or Depth or Density (Egnater) for the low end. At low volumes you typically turn those controls up but the louder you play, the more you find you need to turn them down. Fletcher/Munson again.
Because we make guitar amps with variable power (Rebel) and switchable power (Tourmaster and Modular), we get inquires about this all the time. Often players will use one of our amps and it appears that the power cut feature doesn’t do much. Please allow me to explain.
Let’s say you are playing an amp at home or in a music store at relatively low volume. Recall what was said earlier about how little power it really takes to get a fairly loud volume. If you’re playing quiet, you might be using even less than 1 watt to obtain the loudness you’re at. If you have a chance, try this on a Rebel. Play fairly quiet and turn the WATTS knob from 20 watts to 1 watt. What do you hear? Very little change! Why? Because at that volume you probably are not even using up 1 watt let alone 20 watts. Sort of like driving a car at 5MPH. It doesn’t matter if the engine is a 100HP or 500HP, you are still only going 5MPH and using very little HP to maintain that speed. Same with your amp. To cruise along at low volume requires very little power (watts). Having the extra horsepower (watts) doesn’t make the amp louder when you play at low to medium volume. 
Now try this with your Rebel. Set the power to 20 watts, turn the master full up and turn up the gain knob until you start to hear some distortion. It will be loud. While you’re playing turn the WATTS knob down. You will clearly hear and feel the way less power creates a spongier, lower volume tone. Some players are saying the knob isn’t really cutting the power but is reducing the headroom. Call it what you will, the result of reducing power is more of a “feel thing” than a volume thing. Ultimately the idea is to set it to where you like the sound and be happy…..play your guitar. 
While we’re on the subject of the Rebel, there has been some talk about how when panning from the 6V6 tubes to the EL84 tubes, the tone difference is not what some expected. It is believed that by simply changing power tubes you can make a Fender (6L6 power tubes) sound like a Marshall (EL34 power tubes) or a Vox (EL84 power tubes). What you are hearing in the Rebel when you go from 6V6 to EL84 is the real difference in the sound of those two types of tubes. It may not be quite as dramatic as many believe but that is the reality of it. The tonal difference between various types of tubes is more subtle than many believe. A few people have even been disappointed when using the TUBE MIX features because their expectations of what should happen were really not based in fact. What you are hearing in the Rebel is “the truth” about power tubes.

And, credit to those with the time to write this original post.

http://www.thegearpage.net/board/showthread.php?t=470811

Sent from my Galaxy Nexus using Tapatalk


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## bellsprout

An amp doesn't know what vocals are or what instruments make up a soundstage. An amp brings a signal to a higher voltage at low levels of noise and not significantly change the frequency and phase response. If that's all done right, it won't degrade any aspect of the sound. Although you can't design a perfect amp, as you will have noise and distortions to some level, it's relatively easy, and cheap, to build an amp that keeps non idealities to sufficiently low levels. I mean relatively as compared to headphones, which can't help but be measurably and audibly non ideal, whereas in the case of amps you have to actually try pretty hard to come up with an amp that doesn't have a ruler flat frequency and phase response across the audible range.
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purpleangel said:


> To build the perfect amp is an expensive job, it's cheaper to build an amplifier that only does one or two things well (bass or vocal or treble or soundstate, etc)


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