Criticisms for iPod's sound and what are the Physics reasons why?

[liluoke]

What are the physics reasons for something like a ipod having "inferior sound"?

A song has numerous sounds, which are frequencies. When a DAP like the ipod, samsung P3, or whatever play a song, what exactly is going on that makes one play sound "superior" to another?

Commonly cited reasons are inferior bass (what does this really mean in physics terms anyways? a high amplitude low frequency sound? why can't every player produce this?), "better midrange" (again, what does this REALLY mean?), and flatness of spectrum (does this mean all frequencies of the sounds are at the same amplitude?)

I tried looking in the geek section, but I find no discussions on what are the phenomena that occur making one player superior to the other and the scientific reasons why, so I thought of starting this thread.

Whoever would like to contribute, please do so! You may assume that I have an understanding of basic wave properties.

[CrowdAds]

[sumx4182]

To be honest, alot of "sound quality" is very very subjective. Sometimes DAP can use the same sound chips, the same components, and produce very different sound. To me, I like a flat EQ. It lets me listen to the songs as they were mastered (for better or for worse). I tend to feel like my Zune doesn't add anything artificial to the sound. Other people like to have the EQ to tweak it so that certain frequencies are amplified more than others or others are attenuated more than others. But what sounds good versus what sounds bad is very very subjective IMHO. Another problem you may read about is frequency rolloff and is where high and low frequencies above and below a certain point are highly attenuated so that they are essentially lost. It has to do partially with the circuitry within the device and how the audio is filtered. Improper cutoff frequencies can leave you feeling like something is missing. You may hear this when people say there is little to no bass or that the highs are missing. It can be cause by the audio components as well as things like the bitrate of the file...

[saratoga]

Originally Posted by liluoke

What are the physics reasons for something like a ipod having "inferior sound"?

Mostly people liking to bash ipods. Combined with the general difficulty most people have in comparing sound quality effectively.

Originally Posted by liluoke

A song has numerous sounds, which are frequencies. When a DAP like the ipod, samsung P3, or whatever play a song, what exactly is going on that makes one play sound "superior" to another?

Flat frequency response, low non-linear effects. An ideal DAC has no non-linear effects and flat frequency response.

Originally Posted by liluoke

Commonly cited reasons are inferior bass (what does this really mean in physics terms anyways?), "better midrange" (again, what does this REALLY mean?), and flatness of spectrum (does this mean all frequencies of the sounds are at the same amplitude?)

They're all just different ways of talking about how linear the frequency response is.

Originally Posted by liluoke

I tried looking in the geek section, but I find no discussions on what are the phenomena that occur making one player superior to the other and the scientific reasons why, so I thought of starting this thread.

Generally the performance of DACs is analyzed using two different complementary types of analysis, linear and non-linear systems. Linear deals with the frequency response and stereo cross talk (noise on one channel as a result of signal on the other). Non-linear deals with whatever is leftover, and is collectively referred to as distortion by most people. It is subdivided into things like harmonic, inter-modulation, etc distortions. These are generally phenomena where one or more frequencies generate additional completely new frequencies not present in the original signal due to nonlinearity in the components making up the DAC or amplifier.

[liluoke]

Thanks for the tips guys. I had no idea that bad bass was due to attenuating of the amplitude of the lower frequencies due to a filter frequency too close to that range.

There's some jargon here that I'm unfamiliar with and I'll love to look up what these things mean.

Anyone else with any input on the matter?

[Marvin the Martian]

Originally Posted by liluoke

Thanks for the tips guys. I had no idea that bad bass was due to attenuating of the amplitude of the lower frequencies due to a filter frequency too close to that range.

There's some jargon here that I'm unfamiliar with and I'll love to look up what these things mean.

Anyone else with any input on the matter?

Those two previous posters are engineers, so a regular guy like me sure can't add anything to that. Interesting to read, however.

[sumx4182]

Originally Posted by liluoke

Thanks for the tips guys. I had no idea that bad bass was due to attenuating of the amplitude of the lower frequencies due to a filter frequency too close to that range.

There's some jargon here that I'm unfamiliar with and I'll love to look up what these things mean.

Anyone else with any input on the matter?

well filtering is part of it. If you look at a plot of the frequency response, you'll see rolloff for EVERY player...but where that rolloff occurs can tell you alot about how the player will sound. Many times you can see a clear shift higher or lower in that corner frequency. I believe dfkt has posted some frequency responses of player or headphones in the past and they really can give you insight into how a player will sound.

It may not even be due to true, intended filtering. Parasitic capacitance and inductance probably has alot to do with it too.

[The DarkSide]

To the OP: You asked for it, now you got it!!!! Damn, I'm proud of this site, and all you guys as well.

[Blahaha]

Well I can't add anything other than the fact that I have a ipod nano and an Cowon S9 and i can hear a difference.

[The DarkSide]

Originally Posted by Blahaha

Well I can't add anything other than the fact that I have a ipod nano and an Cowon S9 and i can hear a difference.

I had the Touch 2G, and I have a Samsung Q2 and a Cowon S9. Do you notice which one is stated as "had"? And no amount of apps or games could improve the SQ. Some use an LOD, I'm not carrying around an amp. HP out or nothing!!!

[Marvin the Martian]

Originally Posted by The DarkSide

I had the Touch 2G, and I have a Samsung Q2 and a Cowon S9. Do you notice which one is stated as "had"? And no amount of apps or games could improve the SQ. Some use an LOD, I'm not carrying around an amp. HP out or nothing!!!

So the PA2V2 is now your desktop amp?

[The DarkSide]

Originally Posted by Marvin the Martian

So the PA2V2 is now your desktop amp?

Not really, just a paper weight unfortunately.

[musichound]

I don't think the SQ of the ipod is that bad, but average instead. However, I think the EQ settings of the iPods gets some deserved bashing because they are downright horrible. Listening to one with no EQ, however, is a more satisfying experience.

[Blahaha]

Originally Posted by musichound

I don't think the SQ of the ipod is that bad, but average instead. However, I think the EQ settings of the iPods gets some deserved bashing because they are downright horrible. Listening to one with no EQ, however, is a more satisfying experience.

I agree...and really my nano sounds pretty decent for it's size. It's good for yard work and the gym...but that's about all I'll ever use it for again.

[Marvin the Martian]

Originally Posted by musichound

I don't think the SQ of the ipod is that bad, but average instead. However, I think the EQ settings of the iPods gets some deserved bashing because they are downright horrible. Listening to one with no EQ, however, is a more satisfying experience.

My sister has a 5.5G 30GB iPod Video, and with the EQ off, it sounds just fine with either my Grados or PX100's. But my other phones, that need EQ, that's another story

[Enigmatic]

Originally Posted by sumx4182

To be honest, alot of "sound quality" is very very subjective.

Very true. Often one can ask a listener to compare a signal to an identical signal, and many of these listeners will express a preference. Please see, for example, http://www.theaudiocritic.com/back_i...ritic_16_r.pdf, PDF page 25:

One of my favorite dirty tricks is to go through the motions of conducting a single-blind A/B amplifier or preamplifier comparison which is actually an A/A comparison because I only pretend to switch to B but never do. Lo and behold, some of the audiophiles in attendance claim to hear major differences in front-to-back depth, imaging, “air,” etc., and are quite certain they can pick out A and B blind.

[The DarkSide]

my only gripe w/the Touch 2G is not having a custom EQ. The presets just add distortion. It's 1 fault is being too "bright", not enough bass and too much treble. If I could have custom tuned it, I'd be playing w/my iTunes library right about now.

I'd still have my little Q2, and my new clip (in sexy ass red), but the Touch would have been my primary player. And I tried, even getting overly bassy hp's (EB700's, really just good sounding - claiming they're extra bass is BS on Sony's part). I'll see cx when the 3G Touch hits, or will it be the ZHD - or the new Zii??? Decisions, decisions!!!!

[saratoga]

Originally Posted by sumx4182

well filtering is part of it. If you look at a plot of the frequency response, you'll see rolloff for EVERY player...

Thats not true. Look at the Sansa Clip. A good DAC shouldn't have a roll off within its pass band.

Originally Posted by sumx4182

but where that rolloff occurs can tell you alot about how the player will sound. Many times you can see a clear shift higher or lower in that corner frequency. I believe dfkt has posted some frequency responses of player or headphones in the past and they really can give you insight into how a player will sound.

The roll off of the player itself doesn't have a huge effect on how a player sounds. Most of the time its much too small to matter, or for a good player its absent entirely. I think you're confusing the DAC and the headphones. The frequency response of the headphones definitely defines how they sound. But the DAC shouldn't unless its poor.

Originally Posted by sumx4182

It may not even be due to true, intended filtering.

May not? I don't think anyone designs a DAC, realizes its too good, and then throws in some more costly filters to reduce its sound quality

Originally Posted by sumx4182

Parasitic capacitance and inductance probably has alot to do with it too.

Those are generally not such a big deal at audio frequencies, they're more of a problem for digital systems operating in the MHz or GHz range. Non-flat frequency response more often due to caps added on the board itself to couple the headphones to the HP amp. On the very old ipods people used to swap them out for larger caps to compensate roll off (reduce the impedance at low frequencies). On other players like the Clip, the headphones are not capacitively coupled, and so theres no roll off to begin with.

Very true. Often one can ask a listener to compare a signal to an identical signal, and many of these listeners will express a preference.

That doesn't mean its subjective, it just means that audiophiles (and most other people too) are really terrible at audio

Show them how to do it with proper listening tests and you'll find that they can give much smarter answers.

[sumx4182]

Originally Posted by saratoga

Thats not true. Look at the Sansa Clip. A good DAC shouldn't have a roll off within its pass band.

I remember seeing some frequency responses posted here that had questionable roll off. It wasn't necessarily that the 3db frequency was in the audible range, but that the roll off started rather early and happened to have a fairly gentle slope such that the 3db frequency was still far enough below the 20hz range to seem acceptable but I would anticipate a lack of low punch because it did start to roll off rather early.

[dfkt]

Here's a few comparisons:
http://rmaa.elektrokrishna.com/Compa...1,%20Vibez.htm
http://rmaa.elektrokrishna.com/Compa...p,%20Vibez.htm
http://rmaa.elektrokrishna.com/Compa...l%20Volume.htm

[saratoga]

Originally Posted by sumx4182

I remember seeing some frequency responses posted here that had questionable roll off.

It sounds to me like you're probably confusing the clip with some other player, but post the results if you've got them handy. I'd be interested in seeing them.