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Skeptico Saloon: An Objectivist Joint
Apr 11, 2015 at 8:07 PM Post #1,156 of 1,671
uchihaitachi said:
  Does high impedance at the source, result in a predictable deviant behaviour for the IEM frequency or, is it erratic?
Click to expand...

 
Short answer, yes, its not erratic. It depends primarily on the input impedance of the IEM. Most transducers input impedance varies with frequency. The amplifier output splits between the amplifier internal impedance and the headphone impedance, so different fractions appear at different frequencies. This manifests itself as a variation in output amplitude when a swept tone is input. The variation in voltage seen by the headphone is minimised when the amplifier impedance is low. The input impedance of the IEM is also likely to be complex, i.e. have capacitive and inductive components.
 
The output impedance also affects something called damping factor, which is a kind of measure of the amplifier's ability to make the diaphragm in the IEM comply with its commands. You can see the necessity for damping when a square wave is input to the transducer and overshoot occurs. Transducers also have internal mechanical damping, so a headphone or speaker can be designed to operate with a quite wide range of damping factors, so although a high damping factor is generally called for, it's not always the case. 
 
Apr 12, 2015 at 12:40 AM Post #1,157 of 1,671
where are the measurements coming from? all from the same place? all RMAA or are they something more reliable? is the FR difference taken at the headphone output or is it an electrical measurement with a load? that changes a lot of things.
but still they show the usual thing, how something far from exceptional can measure super good with no load (like the pono on stereophile
very_evil_smiley.gif
).
 
now my specific memories of the J3(years back now and I didn't know about impedance's stuff at the time, so take it with a big rock of salt), was that it felt like it had no sub bass without EQ most of my IEMs were close to 16ohm, only my good old super tiny Qjays were going above. it felt slightly warm on most of my IEMs, but I was missing on my rumble addiction. I never knew the J3's impedance, but if it's really around 2ohm as mentioned by Maverick, then I would bet there was something else going on in the low frequencies, outside of the usual impedance variation of the IEM.
I'm sorry those are only memories and I can't make any claim.
 
on a side note, I got several cowons and loved them, because most had really low hiss background, making them right to use with most sensitive IEMs without whining too much about hiss like I did on the sony DAPs. a real portable solution. but I did use them all with a lot of EQ and DSPs because the default sound wasn't all that great for me.
 
Apr 12, 2015 at 4:01 AM Post #1,158 of 1,671
wakibaki said:
   
I don't like the frequency response. It's 40-15000Hz for a start, when I'd prefer to see 20-20,000. If these are the manufacturers figures, I suspect the flatness is a lot worse for the extended range.
 
With 32 ohms, a -1.66 dB dip is quite noticeable. 0.1 dB is a perceptible difference.
 
I looked up the output impedance, 2 ohms. This is at the very top end of acceptable and values of a fraction of an ohm are achievable. You can see the sensitivity to load in the difference between the loaded and unloaded values, and note how well the Sansa Clip does @ 16 ohms.
Click to expand...

 
If the V-Moda is a dynamic model that does not have any major impedance dips (I could not find measurements), then the Cowon may also use ~220 uF output capacitors in addition to the 2 ohms of resistance. That would explain bass roll-off with low impedance headphones and IEMs.
 
Apr 12, 2015 at 4:55 AM Post #1,159 of 1,671
castleofargh said:
  where are the measurements coming from? all from the same place? all RMAA or are they something more reliable? is the FR difference taken at the headphone output or is it an electrical measurement with a load? that changes a lot of things.
but still they show the usual thing, how something far from exceptional can measure super good with no load (like the pono on stereophile
very_evil_smiley.gif
).
 
now my specific memories of the J3(years back now and I didn't know about impedance's stuff at the time, so take it with a big rock of salt), was that it felt like it had no sub bass without EQ most of my IEMs were close to 16ohm, only my good old super tiny Qjays were going above. it felt slightly warm on most of my IEMs, but I was missing on my rumble addiction. I never knew the J3's impedance, but if it's really around 2ohm as mentioned by Maverick, then I would bet there was something else going on in the low frequencies, outside of the usual impedance variation of the IEM.
I'm sorry those are only memories and I can't make any claim.
 
on a side note, I got several cowons and loved them, because most had really low hiss background, making them right to use with most sensitive IEMs without whining too much about hiss like I did on the sony DAPs. a real portable solution. but I did use them all with a lot of EQ and DSPs because the default sound wasn't all that great for me.
Click to expand...

 
They seem to be DFKT's old measurements.
 
Apr 12, 2015 at 5:41 AM Post #1,161 of 1,671
Apr 12, 2015 at 11:43 AM Post #1,162 of 1,671
Thank you all for the informative feedback.
 
Could the lack of sub-bass account for the 'thin' sound then?
 
Apr 12, 2015 at 12:39 PM Post #1,163 of 1,671
Apr 12, 2015 at 2:19 PM Post #1,168 of 1,671
My phone sadly has too much hiss and not enough storage.
 
A touch screen with basic controls, again audiophile daps tend to be large POS bricks ......
 
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