* Help: Best Inexpensive Tube (or SS?) Amp for AKG K702 *
Jan 24, 2012 at 2:53 PM Post #76 of 114
 
Can't remember if I've posted this link in this thread.
Too lazy to go thru old posts.
wink_face.gif

 
Some info about the whole power, voltage, current, impedance thing:
http://www.head-fi.org/a/headphone-impedance
 
Jan 24, 2012 at 3:29 PM Post #77 of 114
I like the water analogy, Liamstrain, thanks!  And thanks for the link Chris, looks extremely helpful.
 
So I messed around with the gain switches again, and though I may be entirely wrong, to my ears there is a huge difference in sound quality between running the M-Stage at 10dB with the K702, and running it at 0dB.
 
At 10dB, the volume knob indeed sits at a comfortable 4 - 5, which as we say, "looks right."  It's also great because it gives it more room to go if I plug two headphone sets in, or on a quieter passage of music or whatever.  
 
But...
 
When I switch back to 0dB, the knob may have to move to about 6.5 - 7 to get the same volume, but what results is a much broader, and more detailed soundstage in the K702.  I am going to double-check tonight yet again, but this is already the second time I've noticed the difference.  And it is a big difference.  Plus, with trance, I noticed the music was fatter and more present at 0dB as well.  10dB and above thinned the sound out and placed it farther distant, with the effect intensifying with each raise of the dB of gain.
 
After double checking again, if I prove right on this then the question becomes why the rise in gain has this effect.
 
Jan 30, 2012 at 12:44 PM Post #79 of 114


Quote:
kouzelna said:
I like the water analogy, Liamstrain, thanks!  And thanks for the link Chris, looks extremely helpful.
 
So I messed around with the gain switches again, and though I may be entirely wrong, to my ears there is a huge difference in sound quality between running the M-Stage at 10dB with the K702, and running it at 0dB.
 
At 10dB, the volume knob indeed sits at a comfortable 4 - 5, which as we say, "looks right."  It's also great because it gives it more room to go if I plug two headphone sets in, or on a quieter passage of music or whatever.  
 
But...
 
When I switch back to 0dB, the knob may have to move to about 6.5 - 7 to get the same volume, but what results is a much broader, and more detailed soundstage in the K702.  I am going to double-check tonight yet again, but this is already the second time I've noticed the difference.  And it is a big difference.  Plus, with trance, I noticed the music was fatter and more present at 0dB as well.  10dB and above thinned the sound out and placed it farther distant, with the effect intensifying with each raise of the dB of gain.
 
After double checking again, if I prove right on this then the question becomes why the rise in gain has this effect.
Click to expand...



Thanks for the info.
 
I spent some time this weekend going back and forth between 0, 10 and 18 dBs of gain.  I used Q701s.
 
I preferred 0 and 10, for some reason, I have a hard time telling the difference between 0 and 10 dB.  Obviously I had to readjust the volume. Again thanks for suggesting 0 dB!
biggrin.gif

I did not like 18 dB of gain.
 
From a technical point of view, I could not figure out why this would happen.
For all those folks who dislike feedback (I used to be one): 0 dB is more feedback, 18 dB of gain is less feedback.
Perhaps more feedback creates a more controlled sound which you respond positively to?
In addition, 0 dB gives you more bandwidth, But in my opinion, 18 dB (with that Op Amp) should be enough bandwidth for audio.
 
Bottom line is I will stick with 0 or 10 because I enjoy that sound.
 
Regards,
CJ
 
 
Jan 30, 2012 at 3:16 PM Post #80 of 114
What does feedback actually do, anyway?  Why is it there?
 
I stick with 0db and then move it to 10db if I'm attaching 2 sets of headphones to listen with a friend, as it requires more umph to power both headphones with enough volume to hear adequately.
 
Jan 30, 2012 at 3:30 PM Post #81 of 114
Jan 30, 2012 at 8:04 PM Post #82 of 114
Thanks LiamStrain.  I'll look up this link and try to grasp it.  I guess what I'm interested in is how exactly this all translates into the sound you hear.  Will update this post tonight sometime after I read the link.
 
Jan 31, 2012 at 6:37 PM Post #86 of 114


Quote:
kouzelna said:
What does feedback actually do, anyway?  Why is it there?
 
I stick with 0db and then move it to 10db if I'm attaching 2 sets of headphones to listen with a friend, as it requires more umph to power both headphones with enough volume to hear adequately.
Click to expand...



This might be a bit easier to understand than the "feedback" Wiki.
 
Good Wiki on Op Amps and feedback:
 
http://en.wikipedia.org/wiki/Op_amp
 
I only recommend it because it deals with Op Amps and feedback.  The two sections on "Operation" and "Op Amp Characteristics" are probably all you really need. 
 
Jan 31, 2012 at 6:45 PM Post #87 of 114


 
Quote:
spongeworthy said:
Nevermind, I found out that the headphone outs on the A1 are pure tube driven instead of hybrid like the line out, so it probably wouldn't play too well with the AKGs.
Click to expand...



Hard to say, the Schitt Valhalla works well with AKG K70x series.  The Valhalla has a 20 ohm output impedance.
I often plug my Q701s into my La Figaro 336C, works well for jazz and acoustic music.
To be fair, I got the 336C for 600 ohm Beyers and a Matrix M for the AKGs.
 
 
Jan 31, 2012 at 9:14 PM Post #89 of 114
Thanks for the new link Chris.  Ditto for me on the A1/K70x if anyone has them...
 
 
Just a new edit here, I got my O2 amp today and will be putting it through the ropes against the M-Stage, and writing about it soon after.  
 
Amazing FYI, if you've seen my for sale ad, the photos of the O2's gold case are terrible.  In actuality, the case is totally gorgeous.  The fit and finish is perfect, and the color awesome, except of course around the cutouts on the faceplate, which could be worked just a littler finer, painted, and rubber seals put in to give it a professional look.  Something I assume any DIY person can do in about half an hour.
 
It's really awesome.  I'll try to get some better photos of it.  And while not "fitting into a pocket" this amp is definitely what I would consider portable!  It's very tiny.
 
Feb 2, 2012 at 1:32 PM Post #90 of 114
 
 
OK boys and girls, I spent an hour with them last night side by side, and here's the drill on the comparison:
 
The O2 by far is more clear, neutral and detailed.  The M-Stage is a dark sounding amp, with a more "tube like" character in a sense.  I would choose the O2 hands down because of its truly "transparent" clarity, and its seeming incredible ability to really pump out each and every detail of the recording.  
 
BUT - 
 
The problem I am having with the O2 is that they are not really able to power the K702 as well as the M-Stage.  At least, that is how it seems to me, just from a "hearing" perspective.  This is what I mean:
 
I LOVE the O2.  But there is simply not enough depth and body during more complex parts of songs as you hear with the M-Stage.  When a song really gets going, it seems that part of the bottom drops out, whereas the M-Stage has lots of depth and "uumph," though at with the sacrifice of that pristine clarity and just superb detail that the O2 has.  From my experience with amps and the K702, I am thinking as a relative newbie anyway, that this means the K702 is not being properly driven with the O2.  At least, that is the sound: it seems as if the M-Stage is pumping that K702 full of energy and moving the stuff around in there, whereas the O2 gives it enough juice to play well, but not really "groove" and shake its booty around.
 
Would love comments, but consider the O2 up for sale as of this moment.
 
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