Question is a simple one - and I really want to find the answer. Was posed on the X5 thread - where this comment was made:
I found my iphone 5 to have a bit of a mid bass hump compared to the x5. This hump is not present with my Theorem 720 DAC/Amp or Xonar STX sound card either.
Also the detailing of the X5 beats all my other sources. I have one song that plays perfectly on every one of my sources except the X5 where I can hear obvious compression artefacts. I was rather surprised with this, considering the T720 is more than 2x the price of the X5.
To be honest I don't mind using the iphone 5 as a source for IEM's as long as I'm using foam tips. For some reason, on my Atrio MG7's, silicone tips add a mid bass hump. When I add the iphone 5's mid bass hump to the equation it makes for a bad mix. But with foam tips it sounds pretty good for an ultra portable setup.
I am currently testing Moto X sound quality but it's too early to make conclusions. I can't find any obvious faults like distortion or excessive floor noise (well, more floor noise then X5, less than T720 on low gain for 2x of my 32ohm IEM's) but it could benefit from some EQ.. I hear less sub bass and mid bass compared to the X5 on FW2.0 (surprisingly) and there's a slight peak in the highs which I've only noticed on one song so far. All things considered, the X is still my favourite smartphone, even after playing with or owning a majority of the smartphone flagships of 2013/2014. It's only slightly wider than the iphone 5 with similar height, yet houses a 4.7" screen. I don't like big phones, but I like big screens, nomsayin? It makes the HTC One look massive in comparison, even though they have the same screen size. Ultra thin bezels get my thumbs up.
I just noticed recently that the Kingston Class 10 MicroSD card I bought for my X5 only has 10 MB/s read/write. I went to the local headphone shop and tried the owner's Sandisk 45MB/s card and track switching was definitely faster. The SAD, SAD part was, I didn't even read the product specs on the website before I left my house to buy the card! For $2 more I could have gotten a 45MB/s read, 10MB/s write card from the same store! I completely forgot that class 10 doesn't mean anything lol. I dunno.. considering I'm a tech enthusiast/custom PC builder/licensed technician that's really a rookie mistake =/
I replied with this :
Ken Rockwell had the iPhone 5 on a scope (http://www.kenrockwell.com/apple/iphone-5/audio-quality.htm). Measured basically flat from 20Hz to 20 kHz.
If you're finding a mid-bass hump - it's not the iP5 that's adding it.
Well the thing about source and amp frequency response curves is that they dont tell you anything about the sound signature. Almost all good amps and sources measure perfectly flat almost end to end. But the signature varies vastly. The x3 measures flat too. But it sounds very warm. So perhaps what he hears isnt technically a midbass hump. But yes it definitely comes from the iphone, and it definitely sounds like a midbass hump. Why the measured frequency response charts for amps and dacs dont give a picture of the signature like the charts of headphones do, i'm not too sure. But i know for a fact that they don't
Perhaps you can show measured the frequency response for the X3 and we can compare?
If there is a mid-bass hump on the iP5, it should show up in a frequency response curve. The only way I can see that it would otherwise show up is if the iP5 had a high impedance on the headphone out and the Atrio MG7 had an incorrect damping factor. But the iP5 has an output impedance of 4.5 ohms (a little higher than I'd prefer) and the Atrios are rated at 32 ohms - so damping shouldn't come into it.
If the iP5 was underpowered - this could also have an effect - but given that the Atrios have a sensitivity of 112dB 30 Hz/Mw - and the iP5 will be able to drive them to deafening levels well under the output full volume, then this is negated also.
So no issues with power or impedance mismatch on the IEM's he was talking about. So where does the mid-bass hump come into it? Simple answer - it can't come from the iPhone.
And culminating in this link to the X3 measured response:
You can find the measurements here
So - If a DAP is described as "Warm" or having a frequency bump - why doesn't it show on Freq response curves? Any help appreciated.