[xkfow]

To my ears my macbook pro has markedly better bass response than my iphone. It has gotten me wondering what the difference actually is, ie is the iPhone bass response cut, or is the macbook boosted, or am I imagining it?
 
I am wondering how I would go about working out what the technical difference is. Are there web sites that have graphs showing the frequency output response? Or am I going to have to find some way to work out the graph myself.

 

[khaos974]

Both are extremely flat, likely to +- 0.1 dB throughout the entire hearing range. What you experience is either expectation bias or the the iPhone and the MBP have a different output impedance which impacts the frequency response.
If you don't mind running Windows, a short RMAA test should give you an answer.

PS: I don't know about the iPhone but the 2010 Core i5 MBP is ruler flat.

 

[cjl]

If there's actually a difference, output impedance is likely to be the culprit. After some quick googling, I was unable to find any actual output impedance values for either the iPhone 4 or the macbook pro, but it's just about the only possibility (aside from placebo), assuming that khaos is right about the frequency response. What kind of headphones are you using? Output impedance would significantly affect low impedance headphones with a significant variance in impedance depending on frequency (probably the best example of this would be a balanced armature IEM), but it wouldn't significantly affect headphones with basically constant impedance at all frequencies.

 

[xkfow]

 

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First of all, thanks for the feedback, much appreciated.
 
I am reasonably confident that its not bias, I will do a blind test with my wife tonight to confirm
 
With my older Bose On-ear headphones, all I could tell was that the macbook pro seems to sound better.
With my new Beyerdynamic DT1350 headphones, it seems that the difference in the bottom end is now clearly noticeable.
 
 What is a good reference site to learn about how output impedance affects frequency response?
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[cjl]

One thing to pay attention to while blind testing is that people are amazingly sensitive to level mismatch. A very small difference in volume is often perceived as a quality difference in favor of the slightly louder source, so if you want to do an accurate test, you'll need to make sure that the two are as close as possible to perfectly volume matched (unfortunately, matching by ear isn't really good enough to be sure that the difference is inaudible - you would need to use a meter). If you can't do that, it could still definitely be worth testing, but the results aren't as guaranteed. One possible way around that would be to start at zero volume in every case, and turn it up as desired from there (during every test). If nothing else, that removes any consistent bias to one or the other. Of course, you'd have to be able to turn each one up without realizing which was which...
 
I looked up the impedance of your Beyerdynamics, and they look relatively flat (with a small jump in impedance, but not in the bass). So, their frequency response is unlikely to be hugely affected by output impedance. Depending on the design though, there could still be a change in the bass - if they rely on electrical damping, they will be underdamped when used with a high output impedance, which would cause the bass to become more prominent but lower quality. So, that's still a possibility for what you are hearing between the two.