Little Dot Mk V Output Impedance?
Apr 4, 2012 at 6:20 AM Post #16 of 25

Labbetuss

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I understood it as such; an impedance adapter will increase the total load. One couples the adapter in series with the headphones which increases the total load. Example; 25ohm headphone + 120ohm impedance adaper = 145ohm load. With Mk V this will increase the damping factor significantly. As far as I've read Little Dot includes such an adapter in the package for use with low impedance phones.
 
Actually the Mk V just arrived. Very neat "little" thing. It works relatively "well" with the LCD-2 and 272HD, though (as one should expect) it doesn't perform anywhere near the Auralic Taurus. That said, it's a very good amp for the buck! I hope to try i t out on a higher impedance can in the future. For example T1 or HD800 :)
 
Apr 4, 2012 at 9:45 AM Post #17 of 25

stv014

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Quote:
Example; 25ohm headphone + 120ohm impedance adaper = 145ohm load. With Mk V this will increase the damping factor significantly.

 
No, it actually decreases to about 0.2, assuming that the amplifier itself has near zero output impedance.
 
 
Apr 4, 2012 at 10:49 AM Post #18 of 25

derbigpr

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Quote:
Good to know....thanks. So it shouldn't be a problem with the k70X I don't think since they're double that.... but possibly with phones under 32 ohms? In my own experience with some 25 ohm headphones there's no issues, but perhaps there's some frequency response deviations that I'm not aware of.
 
 



I dont like my Q701 with MkV that much. Its too bright, thin and lacks bass, even compared to something like Asus Xonar STX integrated amp.
 
Apr 4, 2012 at 11:41 AM Post #19 of 25

lejaz

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Indeed it is, though lots of folks have complained about those issues with other amps....and I'm assuming some of those amps had lower output impedance than the mkV. I doubt the amp is making them sound thin or lacking in lows. I think that's the phones themselves, since other, lower impedance, cans don't sound at all thin or lacking in bass out of the mkV. An impedance mismatch like the mkV and 70X wouldn't make them sound thin I don't think. It certainly doesn't make my 55 ohm k240S sound thin, nor my even lower impedance phones. And if anything they sound bass heavy out of the mkV....the v6 and the k240, that is.....also my old 80 ohm dt250 was heavy in the lows out of the mkV and rolled off in the treble. There might be some frequency response deviations, but they may be small enough to be not noticeable. I'm not questioning your experience with the STX amp, only that I think the mkV is probably quite transparent, even with the 70X. I guess I'll only know for sure if I get to try them with something like the O2 which has a very low output impedance.
 
Quote:
I dont like my Q701 with MkV that much. Its too bright, thin and lacks bass, even compared to something like Asus Xonar STX integrated amp.



 
 
 
Apr 4, 2012 at 12:42 PM Post #20 of 25

mikeaj

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It's common for a lot of headphones to have a resonant hump somewhere around 80 Hz.  Impedance is higher there, so with a higher output-Z source you're tilting the FR towards more bass in that region.  Also impedance often goes up in the highest treble.
 

 
With 32 ohms output impedance I wouldn't suspect that effect is strong enough to make K701 sound thin though.  I don't think anybody really has, but let's not overreact on this issue.
 
Anyway, if you want to try a low-Z output source, something like FiiO E5 / E6 (or most of their others) or Sansa Clip+ are cheap and achieve that and have flat enough frequency response, so it's easy to find a "reference" source in terms of just FR.
 
Apr 4, 2012 at 4:50 PM Post #21 of 25

lejaz

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Quote:
It's common for a lot of headphones to have a resonant hump somewhere around 80 Hz.  Impedance is higher there, so with a higher output-Z source you're tilting the FR towards more bass in that region.  Also impedance often goes up in the highest treble.
 

 
With 32 ohms output impedance I wouldn't suspect that effect is strong enough to make K701 sound thin though.  I don't think anybody really has, but let's not overreact on this issue.
 
Anyway, if you want to try a low-Z output source, something like FiiO E5 / E6 (or most of their others) or Sansa Clip+ are cheap and achieve that and have flat enough frequency response, so it's easy to find a "reference" source in terms of just FR.


Informative graphs, thanks. That might explain the big bass bump on the k240S. I'll have to compare them out of the Clip some time. From memory I think the k240S has as big a mid bass hump out of the clip as out of the mkV.....I'd have to do a back to back listen to be sure though. I'll try plugging the 702 into the clip and see if it's less bright than out of the mkV. 
 
 
Apr 4, 2012 at 8:15 PM Post #22 of 25

Labbetuss

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Quote:
 
No, it actually decreases to about 0.2, assuming that the amplifier itself has near zero output impedance.
 


 
Wouldn't the higher load increase the damping factor? 
 
 
DF = Zload/Zsource

25ohm load/32ohm output = 0,78

145ohm load/32ohm output = 4,53
 
 
or have i misunderstood something along the way? The output impedance on Mk V is 32ohms.
 
Apr 4, 2012 at 9:20 PM Post #23 of 25

mikeaj

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Short answer is that the impedance you add (anything that's not the headphone itself) more or less counts as part of the source impedance, not as the load, for the perspective of looking at the damping factor.
 
For connecting passive speakers, it's known that you shouldn't use too thin and long of a wire, since the greater the impedance of the wire in between the amp and the loudspeakers, the lower the damping factor will be.  It's the same idea.
 
Apr 5, 2012 at 12:50 AM Post #24 of 25

2000impreza

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Quote:
 
Wouldn't the higher load increase the damping factor? 
 
 
DF = Zload/Zsource

25ohm load/32ohm output = 0,78

145ohm load/32ohm output = 4,53
 
 
or have i misunderstood something along the way? The output impedance on Mk V is 32ohms.



stv014 is correct. To clarify, the impedance adapter of 120 ohm's in your example increases the output impedance which will decrease the damping factor. The correct damping factor based on your example:
 
25ohm load/ 152ohm output = 0.16
 
Using impedance adapters is usually a bad idea and cause more issues than they are worth. Frequency response is just one issue with a damping factor this low. 
 
 
 

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