[HotIce]

These are a set of good articles WRT distortion types and their audibility studies:

http://www.audioholics.com/room-acoustics/human-hearing-amplitude-sensitivity-part-1
http://www.audioholics.com/room-acoustics/human-hearing-phase-distortion-audibility-part-2
http://www.audioholics.com/room-acoustics/human-hearing-distortion-audibility-part-3
http://www.audioholics.com/room-acoustics/human-hearing-reprise-part-4

http://www.axiomaudio.com/distortion

 

[riverlethe]

Thenks. I think that's where j got my 1% THD figure.

Of particular interest is Cheever's paper, mentioned in the distortion article:

http://next-tube.com/articles/Cheever/cheever.pdf

He mentions transient IMD and how it only appears in feedback amplifiers.

 

[Pingupenguins]

Wow, good read. Lots of good objective info unlike some of the other amp threads. However, this is the O2 we're talking about. hahaha.
 
I definitely think the O2 runs under the small footprint desktop amp category. Which would work great for my cluttered desk due to space constraints. Anyone know if the O2 is only made by JDS labs? I've always been a bit hard pressed to find another O2 manufacturer and it seems via JDS blogs that there are only 2 or so companies with the schematics for the amp.

 

[Bibo]

  Wow, good read. Lots of good objective info unlike some of the other amp threads. However, this is the O2 we're talking about. hahaha.
 
I definitely think the O2 runs under the small footprint desktop amp category. Which would work great for my cluttered desk due to space constraints. Anyone know if the O2 is only made by JDS labs? I've always been a bit hard pressed to find another O2 manufacturer and it seems via JDS blogs that there are only 2 or so companies with the schematics for the amp.

US
 
Mayflower Electronics: https://www.mayflowerelectronics.com/product-category/headphone-amplifiers/
 
Europe
 
Epipany Acoustics: http://epiphany-acoustics.co.uk/products-page/
Head´n Hifi Walter: http://www.headnhifi.com/

 

[riverlethe]

Does anyone know if there are TIMD specs for the O2?

 

[mcnordst]

Hello!
I have a distortion problem. I have now tried different wiring solutions for my O2 + ODAC setup but I always hear distortion when using the ODAC's signal (line level out) to my receiver. I want to have the possibility to use the ODAC's signal straight from my computer via USB to my stereo amplifier, but unless I turn on the power of the O2 I get massive distortion. I tried to disconnect the ODAC completely and noticed there was no distortion i.e. no problem with the ODAC itself.
Does anyone else experience the same problem and if, how have you fixed it? Or is the only solution to have the O2 and ODAC separate or always turn on the power of the O2? That sucks...

 

[castleofargh]

  Hello!
I have a distortion problem. I have now tried different wiring solutions for my O2 + ODAC setup but I always hear distortion when using the ODAC's signal (line level out) to my receiver. I want to have the possibility to use the ODAC's signal straight from my computer via USB to my stereo amplifier, but unless I turn on the power of the O2 I get massive distortion. I tried to disconnect the ODAC completely and noticed there was no distortion i.e. no problem with the ODAC itself.
Does anyone else experience the same problem and if, how have you fixed it? Or is the only solution to have the O2 and ODAC separate or always turn on the power of the O2? That sucks...

nope, I often use the line out/line in plug and never had a problem with the O2 powered off. the only time it becomes a problem is when using that plug as a line input for the O2 while still having the USB active(need to remove the usb and it's normal, else I'm sending 2 signals to the amp at the same time). but in your configuration, never had any kind of trouble.
maybe a silly idea, but are the distortions still there if you lower the volume on the computer a little? would be pretty surprising, but maybe it's your receiver clipping? (wild goose hunt right there!)

 

[KeithEmo]

 
nope, I often use the line out/line in plug and never had a problem with the O2 powered off. the only time it becomes a problem is when using that plug as a line input for the O2 while still having the USB active(need to remove the usb and it's normal, else I'm sending 2 signals to the amp at the same time). but in your configuration, never had any kind of trouble.
maybe a silly idea, but are the distortions still there if you lower the volume on the computer a little? would be pretty surprising, but maybe it's your receiver clipping? (wild goose hunt right there!)

 
With some circuitry, the input becomes a non-linear load when the circuit is not powered, which will introduce distortion when other devices try to drive that load. So, if the output of your 0DAC is trying to drive both the input of the O2 and your receiver, the input of the O2 may in fact distort the signal when it is off. If your setup allows it, arranging the connections so the output of the 0DAC goes straight to the receiver, but adding a small value resistor (2.2k) in series with the input of the O2, may prevent it's input from affecting the signal between the 0DAC and the receiver.

 

[bracko]

I have been considering O2 for my HE-400i (35 Ohm, 93 dB) and Fidelio X2 (30 Ohm, 100 dB). Should I go with the standard gain or should I customize the gain? I mostly use my CD-player and turntable as a source. Thanks for your help.

 

[Bibo]

Low gain should by 1x for the Fidelios.


High gain depends on the output voltage of your source. Source output voltage * gain should be < 7V

 

[bracko]

  Low gain should by 1x for the Fidelios.
  High gain depends on the output voltage of your source. Source output voltage * gain should be < 7V

Thanks. Source output voltage is at the most 2 V (CD player). That probably means that 1x/2,5x or 1x/3x would be nice.

 

[Bibo]

3x or even 3.3x would be the best decision if you plan to connect more demanding headphones in the future. 3.3x would be the maximum if the source puts out 2.1V like the ODAC rev. B does for example.

 

[deaconblues]

  Hello!
I have a distortion problem. I have now tried different wiring solutions for my O2 + ODAC setup but I always hear distortion when using the ODAC's signal (line level out) to my receiver. I want to have the possibility to use the ODAC's signal straight from my computer via USB to my stereo amplifier, but unless I turn on the power of the O2 I get massive distortion. I tried to disconnect the ODAC completely and noticed there was no distortion i.e. no problem with the ODAC itself.
Does anyone else experience the same problem and if, how have you fixed it? Or is the only solution to have the O2 and ODAC separate or always turn on the power of the O2? That sucks...

What's your O2+ODAC's configuration?  Does it have the separate line out from the ODAC in the back or does the O2's line-in do double duty as input and output?
 
If it has separate line in and line out, the O2 should disconnect the ODAC when you plug a cable into the line-in jack.  Just connect the line-out to your amp and plug some cable into the line-in.  It doesn't even have to be connected to anything on the other end.  This should allow you to use the ODAC without turning on the O2. 
 
If you have the double duty line-in + line-out (or if you have separate jacks but it wasn't properly configured) then this won't work.

 

[diamondears]

ALL sources reduce the number of bits if you use the source itself to turn down the volume.
(To turn down the level you make the numbers smaller; smaller numbers are smaller and so use less bits.)

However, the Sabre's internal 32 bit digital volume control won't do this (at least not at normal levels).
Many DACs also have digitally controlled analog volume controls (not on the DAC chip itself).

However, in both of these cases, that will only help if the source can "talk" to the DAC and use that better volume control.
Unless they specifically say otherwise, the source device has no way to USE the better volume control in the DAC.
DO NOT assume this to be the case unless the manufacturer of your DAC SPECIFICALLY says that it is with the particular player you're using. (It's also possible for a USB DAC to "co-opt" the Windows system volume control, in which case the software volume control will be disabled and the better one in the DAC will be used no matter what player you use. However, if that's the case, they WILL tell you - since it's an important feature.)

Keith, so if I'm using the iPhone as source/DAC/amp, its always better to use an external amp, assuming the ext amp is completely transparent? I always hear the iPhone 6+ to always sound better when I use the FiiO E06.

 

[castleofargh]

 

ALL sources reduce the number of bits if you use the source itself to turn down the volume.
(To turn down the level you make the numbers smaller; smaller numbers are smaller and so use less bits.)

However, the Sabre's internal 32 bit digital volume control won't do this (at least not at normal levels).
Many DACs also have digitally controlled analog volume controls (not on the DAC chip itself).

However, in both of these cases, that will only help if the source can "talk" to the DAC and use that better volume control.
Unless they specifically say otherwise, the source device has no way to USE the better volume control in the DAC.
DO NOT assume this to be the case unless the manufacturer of your DAC SPECIFICALLY says that it is with the particular player you're using. (It's also possible for a USB DAC to "co-opt" the Windows system volume control, in which case the software volume control will be disabled and the better one in the DAC will be used no matter what player you use. However, if that's the case, they WILL tell you - since it's an important feature.)

Keith, so if I'm using the iPhone as source/DAC/amp, its always better to use an external amp, assuming the ext amp is completely transparent? I always hear the iPhone 6+ to always sound better when I use the FiiO E06.

pretty safe to say that your preference has no relation to bit depth.