[sphinxvc]

I sometimes hear a slight crackling in the background during loud passages.  It's very subtle.  Is this the same thing you clippers are hearing?

 

[wje]

My Triad power adapter died after 2 months this past weekend.  I've never kept it plugged into a socket for more than 8 hours.  I'd move the amp around, so it would have time to cool, etc.  I did find an adapter at Radio Shack that is adjustable from 9V AC to 13V AC.  The end plug was the same size as that on the O2 amp, so no additional modifications were needed.  However, Radio Shack does charge $22.99 for the adapter, plus tax.

 

[upstateguy]

Quote:

Only the people NOT hearing the issues are calling it 'clipping'.  
 

What do the people hearing the issues call it? 

 
Quote:

I fail to see how, even by silly subjective standards, two people saying they felt the O2 sounded strained at higher volumes, one of which stated repeatedly that the effect seems to be diminishing, can be termed an issue, let alone multiple issues.

It should be noted that on default low gain, the O2 amp sounds incredible, and my unit is starting not to have issues on high gain either. 
 
As far as the strained sound I thought I heard, I'm not sure what's going on at the very end of the pot, but no one listens there anywhere, it's too loud.  For all I know it's an issue with the wipers in the pot that might be going away with use.
 
If I have time, I still intend to try to record what I'm hearing.
 


Quote:

I sometimes hear a slight crackling in the background during loud passages.  It's very subtle.  Is this the same thing you clippers are hearing?

Nope.  No crackling.  Dead quiet background.
 
I'm not convinced that what I heard was clipping.  I called it distortion.  But what ever it was it sounded like when you turned a radio up too loud, past the point of maximum sound quality.  I'll check again later tonight and see if it's still there.
 
@ wje:  Regarding the Triad adapter:  I have it plugged in all the time.  I hope it doesn't fail.

 

[MikeW]

Well, my O2 definitely  has clipping in High Gain with a 2.1 V dac output. but it's completely expected. No surprise there, I knew it would before I even built it. High gain is for weak sources like a dap(.5 V output).. this is working as intended.
 
It's a design limitation, and well documented. You can get around it when you build it if you set low-gain to 1x, and high gain to 3x, it will never clip. But that gives you less flexibility when using weak source.

 

[Anaxilus]

Quote:

What do the people hearing the issues call it?  

 
Some examples below.  To me it's just a similar treble signature to what I get from the Bechmark DAC1 via HO and I doubt that is clipping.  Seems more akin to what has been referred to as digititus or digital glare effect found in some SS gear.  Some notice it others don't for a number of possible reasons.  It's a tonal character I am very sensitive to and do not appreciate personally.  Do you have a 'darker' phone like the HD650 or LCD2 r.1 to try?  I bet you won't notice it as much if at all.
 
Quote:

 
I'm not sure clipping is the right diagnosis.  What I initially reported was 'some' type of distortion on high gain, which was diagnosed by a number of guys, a few pages back, as "clipping".
 
the other thing I notice is that if I turn the volume up really high, like past 3:00 the sound gets strained.  Do you notice this?

 
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Do you find a place (around 3:00 with my T-1s) where the SQ changes and gets grainy/shrill?

 
Quote:

 
Shrill is exactly how I'd describe it too.
 
In a way it's good because I hate when I sometimes creep up to this stupidly high volume, but also weird that it happens. I don't have this same level of sibilance, or such a point of immediate sharpness with my other amps, as I do the O2. Wonder what the reason could be for it?

 
 
Quote:Originally Posted by sphinxvc /img/forum/go_quote.gif

I sometimes hear a slight crackling in the background during loud passages.  It's very subtle.  Is this the same thing you clippers are hearing?

^ That sounds like something else altogether.  I haven't heard that from either of the O2 builds I've sampled.
 
 

 

[Willakan]

@Upstateguy
I have a cunning plan theory as to where some of the harshness could be coming from. It is still a psychoacoustic trick, but now with 100% more reasons!
As others have said, changes in volume affect perceived FR, to the point where the O2 could seem harsher at higher volumes. Seems strange that it is only harsh in a specific section of the volume control's travel - roughly the last quarter or so, would you say?
 
The reason I'm asking is because the pot used in the O2 comes in two different tapers: both have been used in builds as the O2 has proved to be remarkably good at burning through Mouser's stock. Likewise, both tapers provide the same ultimate degree of volume adjustment, but one has the volume change perceptually spread out over the whole range of the pot, whilst the other has volume increasing relatively slowly, until it increases perceptually faster in the last 1/4 of the pot's travel.
 
Volume suddenly increasing faster than expected at around 3:00 onwards (

) could quite possibly give the impression of the O2 suddenly becoming "harsh" sounding.
 
 

 

[upstateguy]

Quote:

@Upstateguy
I have a cunning plan theory as to where some of the harshness could be coming from. It is still a psychoacoustic trick, but now with 100% more reasons!
As others have said, changes in volume affect perceived FR, to the point where the O2 could seem harsher at higher volumes. Seems strange that it is only harsh in a specific section of the volume control's travel - roughly the last quarter or so, would you say?
 
The reason I'm asking is because the pot used in the O2 comes in two different tapers: both have been used in builds as the O2 has proved to be remarkably good at burning through Mouser's stock. Likewise, both tapers provide the same ultimate degree of volume adjustment, but one has the volume change perceptually spread out over the whole range of the pot, whilst the other has volume increasing relatively slowly, until it increases perceptually faster in the last 1/4 of the pot's travel.
 
Volume suddenly increasing faster than expected at around 3:00 onwards (

) could quite possibly give the impression of the O2 suddenly becoming "harsh" sounding.
 
 

That's interesting, but I didn't notice that the last quarter got louder faster....  I'll have to check it out tomorrow.  I've lost my perspective for tonight.
 
Did you get the PM?
 

 

[upstateguy]

Quote:

Quote:
 
Some examples below.  To me it's just a similar treble signature to what I get from the Bechmark DAC1 via HO and I doubt that is clipping.  Seems more akin to what has been referred to as digititus or digital glare effect found in some SS gear.  Some notice it others don't for a number of possible reasons.  It's a tonal character I am very sensitive to and do not appreciate personally.  Do you have a 'darker' phone like the HD650 or LCD2 r.1 to try?  I bet you won't notice it as much if at all.
 
 
 
 
 

^ That sounds like something else altogether.  I haven't heard that from either of the O2 builds I've sampled.
 

It seemed just as noticeable with my 650s.  But on the other hand, I'm not sure what it is or even if it is really there.  I'm going to have to listen some more.

 

[upstateguy]

Anaxilus, Naim.F.C, & Co.....
 
 
I made Audacity recordings of both low and hi gain last night, and there is a difference in the waveform.
 
It seems that the 2v output from my North Star is indeed the clipping culprit.
 
PM me if you would like to listen to them yourself.
 
 

 

[ballcall2]

Folks do you know where I can order the parts for the O2? I want to build it myself but I don't find a store where I can order all the necessary parts

 

[Willakan]

Mouser is probably your best bet, with Farnell also of use if you're in the UK: but this is all documented in great detail on the blog. I can't even joke about NwAvGuy helping you put the items in your basket because he explains that as well.

 

[limpidglitch]

Quote:

Anaxilus, Naim.F.C, & Co.....
 
 
I made Audacity recordings of both low and hi gain last night, and there is a difference in the waveform.
 
It seems that the 2v output from my North Star is indeed the clipping culprit.
 
PM me if you would like to listen to them yourself.
 
 

That's a relief
Did you use sine waves or music?
 

 

[MikeW]

Im not really understanding whats' going on here. 
 
If you use a dac with more then 1.8 V RMS output, (most are 2.0 V) it WILL CLIP ON HIGH GAIN. There's no question about this, it's not broke, it's not maybe it will clip, it will clip, period. It's by design, and on purpose. So what is the issue again? 
 
Most DAPs have half a volt... .5 V RMS, that is why you need high gain. 

 

[upstateguy]

Quote:

That's a relief
Did you use sine waves or music?
 

Music.  PM me if you want to hear it.
 
 


Quote:

Im not really understanding whats' going on here. 
 
If you use a dac with more then 1.8 V RMS output, (most are 2.0 V) it WILL CLIP ON HIGH GAIN. There's no question about this, it's not broke, it's not maybe it will clip, it will clip, period. It's by design, and on purpose. So what is the issue again? 
 
Most DAPs have half a volt... .5 V RMS, that is why you need high gain. 

Why didn't you say so in the first place.... 

 
 

 

[maverickronin]

You know, I think I have another idea about what's up with USG's O2.
 
The O2 has no charging indicator so if the AC was plugged in but not making contact for some reason you wouldn't know apart from testing for the clipping point.  If you keep using it like that the battery will run down and the clipping point will get lower and lower making the sound worse.  If after a few cycles of plugging and unplugging it finally does make contact it will charge, run off the rails you expect, and the problem will go away.
 
On battery power 4.5/gain give you the maximum input before clipping and 4.5/2.5 = 1.8 which would make a 2V input clip.  On stuff with a decent amount of dynamic range it might even end up being pretty subtle and only obvious at higher volumes.
 
I'm not sure that this really explains everything that USG said he heard but I don't really know how else it could have got better over time.