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The Astell & Kern AK240 - Page 47

post #691 of 8541
Quote:
Originally Posted by goodvibes View Post

It's all low voltage. The only difference between a line out and headphone out is a V control that's bypassed here and a line out doesn't need to be low z but low z is always good. It's all up to execution. There is no inherent drawback in this application. "sounded really good" from a critical listener would indicate to me that it works well.

So is this specific to AK240 implementation but not the earlier models? Calyx M is also recommending similar approach. If this was already there in early AK models how come people needed to spend hundreds of dollars to re-route the output so to bypass headphone amp? I am a bit confused...
post #692 of 8541
Quote:
Originally Posted by Edwood View Post

Yes, I have the HM-901.  I was using mine directly comparing the same audio files back and forth between the AK240 and my HM-901.

Don't get me wrong the AK240 sounds great.  Just not quite up to par with the HM-901.  But the HM-901 has a very slow and cumbersome User Interface.  The AK240 has a vastly superior User Interface. 

But the real kicker is that if the AK240 is going to cost $2400, you could instead buy an entry level HM-901 AND a pair of Custom JH Audio Roxanne's for the SAME PRICE. 
I have the 901 and the Roxanne is ordered so I am happy smily_headphones1.gif
post #693 of 8541
Quote:
Originally Posted by Mimouille View Post

I have the 901 and the Roxanne is ordered so I am happy smily_headphones1.gif

SE846 and Roxanne on the way. Mim, your on a roll..
post #694 of 8541
Quote:
Originally Posted by CosmicHolyGhost View Post


So is this specific to AK240 implementation but not the earlier models? Calyx M is also recommending similar approach. If this was already there in early AK models how come people needed to spend hundreds of dollars to re-route the output so to bypass headphone amp? I am a bit confused...

 

Well, if you are referring to the RWAK100-S / 120-S, there is more being done than re-routing the output to bypass the head amp.  The d/a's are changed to WM8741.  They are configured to run in "hardware mode" (not software mode), so there is no longer volume control of the dac, period.  The d/a's are configured to use their internal minimal phase filter option that the 8741 offers (not a linear phase filter, so there is no 'pre-ringing' of the output signal - so it sounds much more natural).  In the case of the 120-B, a true balanced line-out is send to a new output jack (the SE out of the AK120-S also goes to a new jack).  So there was more to it than just re-rounting to bypass the headphone output.  But as for your question:

 

As far as the AK240 line out implementation, unless there is some internal switching going on (solid state or relay based) that actually bypasses the headphone amp, AND somehow they configure the dac to bypass the input from the digital volume control at the same time, then I suspect that it really is a "pseudo line out."  Meaning the volume is set to max and locked via software, and the signal is still going through the headphone output stage.  I'm sure this will be clarified by A&K at some point.  I'll be taking a peek to see what is going on. ;)

 

A true, fixed-level line out is one that follows the d/a chip's analog output stage (and there is not volume control in the path - not even a maxed-out one).  Line-out can typically drive as low as a 5k load without strain, but not low impedance of headphones (like 600 ohm, 100, or 32 ohm, as a headphone stage is needed to provide enough current for lower impedance).  

 

Hope this info is helpful,

 

Vinnie

post #695 of 8541
Quote:
Originally Posted by CosmicHolyGhost View Post


SE846 and Roxanne on the way. Mim, your on a roll..

 

ROXANNE!!!  :cool:

 

 

 

 

Sorry - the song just jumped into my head and I couldn't help myself! :o


Edited by Vinnie R. - 1/10/14 at 8:01pm
post #696 of 8541
Thanks, Vinnie!
I truly respect your work on the AK100/120, really amazing!
My question is to confirm if it is technical feasible to do this internal switching. I look forward to your impressions and future work.
post #697 of 8541
So this thing is really gonna cost over 2k? Considering I just purchased a Burson Conductor and Audeze LCD-2's for under 2k, I think in comparison that seems almost silly/insane. Though I admittedly have no intereste in a audiophile level portable player, and certainly not at that price.
post #698 of 8541
Quote:
Originally Posted by CosmicHolyGhost View Post

SE846 and Roxanne on the way. Mim, your on a roll..
Well more of a bank roll wink.gif
post #699 of 8541
Quote:
Originally Posted by Vinnie R. View Post
 
Quote:
Originally Posted by CosmicHolyGhost View Post


So is this specific to AK240 implementation but not the earlier models? Calyx M is also recommending similar approach. If this was already there in early AK models how come people needed to spend hundreds of dollars to re-route the output so to bypass headphone amp? I am a bit confused...

 

Well, if you are referring to the RWAK100-S / 120-S, there is more being done than re-routing the output to bypass the head amp.  The d/a's are changed to WM8741.  They are configured to run in "hardware mode" (not software mode), so there is no longer volume control of the dac, period.  The d/a's are configured to use their internal minimal phase filter option that the 8741 offers (not a linear phase filter, so there is no 'pre-ringing' of the output signal - so it sounds much more natural).  In the case of the 120-B, a true balanced line-out is send to a new output jack (the SE out of the AK120-S also goes to a new jack).  So there was more to it than just re-rounting to bypass the headphone output.  But as for your question:

 

As far as the AK240 line out implementation, unless there is some internal switching going on (solid state or relay based) that actually bypasses the headphone amp, AND somehow they configure the dac to bypass the input from the digital volume control at the same time, then I suspect that it really is a "pseudo line out."  Meaning the volume is set to max and locked via software, and the signal is still going through the headphone output stage.  I'm sure this will be clarified by A&K at some point.  I'll be taking a peek to see what is going on. ;)

 

A true, fixed-level line out is one that follows the d/a chip's analog output stage (and there is not volume control in the path - not even a maxed-out one).  Line-out can typically drive as low as a 5k load without strain, but not low impedance of headphones (like 600 ohm, 100, or 32 ohm, as a headphone stage is needed to provide enough current for lower impedance).  

 

Hope this info is helpful,

 

Vinnie

 

Hey Vinnie, we are sporadically having the same "pseudo line out" discussion in the DX50 thread due to the DX50 line out being affected by the volume control. Does what you are saying about the AK240 apply to the DX50 as well as it is said to bypass the internal amp (rendering a different signature than HO) coming out directly from the WM8740 with the digital volume controlled within the WM8740? Please excuse any novice inaccuracies as this is not my area of expertise. If so, what is the downside or issues - lost bits, noise?

post #700 of 8541
Quote:
Originally Posted by CosmicHolyGhost View Post

Thanks, Vinnie!
I truly respect your work on the AK100/120, really amazing!
My question is to confirm if it is technical feasible to do this internal switching. I look forward to your impressions and future work.

I believe Vinnie uses the same analog topology as stock after the DAC other than perhaps bypassing a resistor. I say possibly because i wouldn't know if he feels it necessary for his LO only versions. Of course it gets upgraded physical paths and connections etc along with that so still upgraded along with the great DAC chips.

 

As he said, we don't know what they're doing in the 240 but the earlier versions seemed to work great this way. LO sounds better on some units because they have less refined amp stages with high output impedance, class D on the SOC or marginal coupling caps, etc.

 

If you use these units as only a LO or only a HO, having a single analog path is not a bad thing.


Edited by goodvibes - 1/11/14 at 12:39am
post #701 of 8541

I am wondering if AK bought a RWAK100-S / 120-S from Vinnie to see what he did and then improved the AK240. LOL.

 

Personally I believe 2-piece stack is the best choice/balance for sound quality and portability. Just keep the dap simple by flying directly from dac to LO and eliminating all other junks (headphone jack, etc). Separate the dap from amp for clean circuit, clean power, less junk and less interference. It's just hard to beat a 2-piece quality stack with all-in-one compact brick. That's why you see most of the audiophiles who bought the hi-end daps still end up with external amping.

post #702 of 8541

LOL, I think AK have a clue or Vinnie wouldn't use that platform in the 1st place. The 240 is likely not going to be a mod candidate but you never know.

post #703 of 8541

Has anyone run into problems with the "Library scan" function? I have two microSD 64GB cards installed, the scan count gets stuck at 2,765 songs, even if I let it run overnight. Have to reboot the unit and restart, works fine otherwise. Any help appreciated. Thanks.

post #704 of 8541
Quote:
Originally Posted by PLA01 View Post

Has anyone run into problems with the "Library scan" function? I have two microSD 64GB cards installed, the scan count gets stuck at 2,765 songs, even if I let it run overnight. Have to reboot the unit and restart, works fine otherwise. Any help appreciated. Thanks.
If this is a ak100 or ak120 question, please ask in the appropriate thread.
post #705 of 8541

Have you noticed on the right of the picture this  Docking Station  for the AK240 that was used by AK to connect the AK240 to their big AMP (not DAC) ?  It has a "cap" that plug in the headphone jack !   is it some sort of "line-out docking station" ?? :-)

 

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