[Vader2k]

Hi all.
 
Kinda jumping into this thread feet first with a fairly specific question.  Apologies in advanced if this has already been discussed somewhere before.
 
I have the Fidelio X1s and I use them pretty extensively off the headphone-out of my Marantz AVR (SR6005) with Dolby Headphone.  The X1s are known to have somewhat uncontrolled bass, but I feel it is more pronounced on my AVR.  The Marantz doesn't have a dedicated headphone amp, but rather the signal from the left and right speaker amps is attenuated by a resistor.  I've never been able to find the output impedance of the headphone-out, but I was told the output voltage is 1V @ 16 Ohms, 2V @ 32 Ohms.  I suspect this high voltage, and probably not much damping, is the cause for the bass bloat.
 
Currently, I just EQ the bass to -2 dB to help take some of the edge off.  However, I've been pondering double-amping the DH processed signal through an O2 amp to hopefully better control the bass and not have to resort to taking some of it away.
 
I have two questions regarding going this route:

• Would I be fine with the stock gain of 2.5x / 6.5x or would I be better served with 1.0x / 3.5x?  I know the X1s are easy to drive and want to make sure I have enough play on the pot.
• What would be a recommended volume to set the AVR at?  The headphone-out is of course variable and can go from –80.5 dB to 18 dB.  I normally listen around -28 db.

 
Thanks!

 

[goober-george]

o2 dac/amp is back to life after ordering a new wall plug! As to the question reguarding the x1s the o2 amp should have no problem driving them. It is a neutral amp with a slightly bright sound and nice flat bass.

 

[adydula]

I would not double amp ....if the amp is the culprit for the bass you don't like adding an amp is not going to filter that out.... especially the 02 which whatever you put into it goes out amplified.
 
If you get an O2 with an ODAC you will actually hear what your headphones actually "soundlike: without any EQ.
 
The amp at unity gain and or 2.5 will be more than enough to drive your headphones.
 
All the best
Alex

 

[Solrighal]

Just as a point of interest Alex, if I can get the same adequate volume with unity gain as I can with 3x gain is there any other advantage in using unity?

 

[adydula]

Yes technically if you use the lowest gain you will have the lowest distortion levels.
 
If there is distortion and there is in most things electrical, the higher gain the distortion gets amplified as well and distortion and or noise etc.
 
I most always use unity gain on the o2 and my ODA.
 
But depending on your headphones and there sensitivity it may be necessary to step in a little,,,,
 
Alex

 

[liamstrain]

  Yes technically if you use the lowest gain you will have the lowest distortion levels.
 
 

 
With that said, the distortion levels on the o2 are so far below audible, that there is no reason to suggest a benefit from an actual listening standpoint. Merely the theoretical. 

 

[goober-george]

   
With that said, the distortion levels on the o2 are so far below audible, that there is no reason to suggest a benefit from an actual listening standpoint. Merely the theoretical. 

Interesting, I feel I don't get enough volume for most of my headphones unless I adjust to the higher gain. Is there an optimal  setup when hooking up the o2 dac/amp? I just try to match the volume until it becomes a comfortable listening experience at 12 o'clock. 

 

[headwhacker]

Interesting, I feel I don't get enough volume for most of my headphones unless I adjust to the higher gain. Is there an optimal  setup when hooking up the o2 dac/amp? I just try to match the volume until it becomes a comfortable listening experience at 12 o'clock. 

 


That exactly is what the gain (or an amplifier in general)is for. To get more volume. The optimal setting is where you get the volume you want.

 

[Solrighal]

Many thanks Alex & everyone. That was actually what I was thinking myself but it's good to have it confirmed. I can generally get by on unity except for some older recordings which need a bit more. I realize I can't actually hear distortion but, well, I'd still rather it wasn't there in the first place.

I'm loving my O2 by the way. The whole setup never disappoints.

 

[adydula]

No its not theoretical.... yes the THD measurements are inaudible but by using the higher gains with certain
"hot" recorded material you will cause the O2 to clip and introduce distortion that you can hear. The O2 doesn't have clipping leds or any indicators to let u know this might be happening.
 
Many people have reported hearing distortion when using higher gain settings.
 
Me included and u can see these on a scope.
 
My ODA has clipping less and when playing music with higher -db gain recordings the amp clips readily.
 
Having your gain setting set so you get a "good" safe volume is a general way to look at this but not very exact.
 
Alex

 

[Solrighal]

I've never heard it clipping myself but I've certainly read many reports of it doing so. I don't think I listen to "hot" music much. I'm not even sure I've ever listened to those recordings but it would be interesting to try just for reference.

 

[Vader2k]

  I would not double amp ....if the amp is the culprit for the bass you don't like adding an amp is not going to filter that out.... especially the 02 which whatever you put into it goes out amplified.
 
If you get an O2 with an ODAC you will actually hear what your headphones actually "soundlike: without any EQ.
 
The amp at unity gain and or 2.5 will be more than enough to drive your headphones.
 
All the best
Alex

 
I don't feel the Marantz is bad at handling bass, though.  I think it's just not pairing well with the X1s.  When I owned the K702 Anniversarys, they worked really nicely with the Marantz.  I was hoping that a second amp in the chain would be better able to handle the signal coming off the AVR and refine it in a way that is more compatible with the X1s.  Is what I'm trying to achieve possible with any amp?
 
If I was doing music listening, I'm sure the X1s would sound awesome off the amp/DAC combo, but I primarily game and watch movies and I really like the Dolby Headphone processing effect, so throwing a DAC in the mix would remove that option.

 

[liamstrain]

  No its not theoretical.... yes the THD measurements are inaudible but by using the higher gains with certain
"hot" recorded material you will cause the O2 to clip and introduce distortion that you can hear. The O2 doesn't have clipping leds or any indicators to let u know this might be happening.
 
Many people have reported hearing distortion when using higher gain settings.
 
Me included and u can see these on a scope.
 
My ODA has clipping less and when playing music with higher -db gain recordings the amp clips readily.
 
Having your gain setting set so you get a "good" safe volume is a general way to look at this but not very exact.
 
Alex

 
Hmm.. well, I have never experienced clipping or distortion with the O2/ODAC combo, despite needing to use high gain to drive my LCD 2's... but then, I don't go for earsplitting. I also usually use software to attenuate recordings that butt up against the redline (bad mastering).
 
The 02's THD chart stays very low - even the worst performing chip stays under .01, pretty much right up until you get to where is will clip... I don't think audible distortion is the amp at that point, but either the headphones or the recording... 
 

 

[adydula]

Exactly....
 
The distortion you hear from running at high gain settings with hot dubbed source material comes from the source not the amp per say...I had a set of LCD 2's R2's for awhile and could easily hear distortion when the amp actually clipped at 6.5x....
 
No reason to run it that high of a gain anyway.
 
Using JRiver you can see the gain settings applied to the material being played unless u use replay gain to average things out, you can get songs that easily clip at 2--4x gain settings.
 
How do you enjoy your lcd2s?
 
Alex

 

[adydula]

If you like your Marantz for the Dolby processing that's fine. The O2 amp being very neutral or transparent should not add or detract from what u put into is within its design.
 
Most likely the damping factor of the Marantz is helping cause the bass to what it is etch..
 
You could just try an o2 and odac to see how they compare.
 
Good Luck
Alex