[PelPix]

Is that voltage peak or RMS?
 
Quote:

Using the Maverick D1's solid state output.
 
Max input before clipping is  7/gain on AC and 4.5/gain on battery.
 
I don't know why there would a threshold beyond whatever you could manage to hear.

 

 

[mikeaj]

 
Quote:

Is that voltage peak or RMS?

 
That's rms (pure sine wave).  Multiply 2 * sqrt(2) for peak-to-peak.

 

[upstateguy]

Quote:

I remember MrSlim mentioning something about wanting to upgrade the AC adapter for users with power hungry cans. I went with the upgraded adapter and I'm having no problems running High Gain(6.5) with my T50RPs. I don't know if this could cause your clipping but thought I'd toss it out in case its something to look into: Quote:

There was some discussion that the 12v 200ma adapter may be a little "under spec'd " for the job. Earlier, NwAVGuy had re-assured me that there should not be any issues with this adapter for anyone but those that have very power hungry headphones, and I decided to just keep things as they were. This is the adapter that I have been testing with, and I can confirm that anyone with reasonably efficient headphones, will not have any problem with using this adapter, at all. The reason I am bringing this discussion back up, is that since I'll have to place an order with Mouser anyway, I would like to offer any North American users who have more power hungry headphones( I know at least one person mentioned "Thunderpants" and/or Fostex TP-50's ) the opportunity to upgrade to a more powerful AC Adapter (either the 16V 400ma or 16V 1000ma units depending on availability) for the cost of the price difference

I opted for the upgraded adapter, but to be sure, the one I have says Triad model WAU16-400.  (Output is 16VAC @ 400mA)  Is this what you have?


Quote:

 
My modded T50RPs are at least a little more power hungry than the K701 which is USG's most power hungry 'phone and they're fine a 2.5x from a ~2.2V DAC on AC with the 12V adapter and at 6.5x from my Cowon D2+ on batteries.

I'm using my T-1s.  Not very power hungry.  Maybe it's not clipping, maybe it's some kind of distortion?  But the funny thing is that what ever it is, it seems to be decreasing with use. (maybe I'm just tired tonight)
 

 

[arirug]

re upstateguy
 
My source is a desktop computer paired with a Cambridge DacMagic,

 

[Draygonn]

I opted for the upgraded adapter, but to be sure, the one I have says Triad model WAU16-400.  (Output is 16VAC @ 400mA)  Is this what you have?

Yes

 

[stv014]

Quote:

No, not a blind test, just an a-b comparison.

That is not too reliable when the differences are small, like they are supposed to be between good amplifiers. But if the change is real, maybe you have a faulty unit ?
 

 

[Willakan]

 
Quote:

I opted for the upgraded adapter, but to be sure, the one I have says Triad model WAU16-400.  (Output is 16VAC @ 400mA)  Is this what you have?

I'm using my T-1s.  Not very power hungry.  Maybe it's not clipping, maybe it's some kind of distortion?  But the funny thing is that what ever it is, it seems to be decreasing with use. (maybe I'm just tired tonight)
 

16VAC is plenty enough to ensure the power rails never drop out of regulation. As long as the input stage isn't overloaded, your amp should be working fine. It shouldn't overload even on high gain with the Fuze (pretty sure the Fuze doesn't pump out over 1.1V RMS) although it will clip with prettymuch anything higher - high gain is really only meant for use with MP3 players and other low-output sources as even 1.5V RMS USB DACs will clip with it.
 
Nice to see your enjoyment of the O2 is increasing,anyhow.

 

[upstateguy]

Quote:

That is not too reliable when the differences are small, like they are supposed to be between good amplifiers. But if the change is real, maybe you have a faulty unit ?
 

That thought has been bothering me, but what ever the problem was, it seems to be dissipating.... why it should do that eludes me.
 


Quote:

 
16VAC is plenty enough to ensure the power rails never drop out of regulation. As long as the input stage isn't overloaded, your amp should be working fine. It shouldn't overload even on high gain with the Fuze (pretty sure the Fuze doesn't pump out over 1.1V RMS) although it will clip with prettymuch anything higher - high gain is really only meant for use with MP3 players and other low-output sources as even 1.5V RMS USB DACs will clip with it.
 
Nice to see your enjoyment of the O2 is increasing,anyhow.

W -
 
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?
 

 

[mikeaj]

It's hard for circuits like these to be marginally faulty in terms of performance.  (The power management may be more finicky.)  Either it will work 100% or it won't work at all, mostly.
 
The position of the volume control should have next to no difference on the sound other than volume, with less change than most other amps.  The exception is if you're using headphones with impedance maybe under 64 ohms or so, and you're maxing out the volume with a certain gain and source level, such that you're clipping the output of the device.  And that would sound really obvious (suddenly with a small change in the volume knob, you go from a clean sound to extreme clipping), so that's not what you're hearing.  To run into volume issues on lower-impedance headphones, you'd pretty much need to be using HE-6.  Many amps have similar characteristics or worse into lower-impedance headphones, in terms of clipping behavior.

 

[upstateguy]

Quote:

It's hard for circuits like these to be marginally faulty in terms of performance.  (The power management may be more finicky.)  Either it will work 100% or it won't work at all, mostly.
 
The position of the volume control should have next to no difference on the sound other than volume, with less change than most other amps.  The exception is if you're using headphones with impedance maybe under 64 ohms or so, and you're maxing out the volume with a certain gain and source level, such that you're clipping the output of the device.  And that would sound really obvious (suddenly with a small change in the volume knob, you go from a clean sound to extreme clipping), so that's not what you're hearing.  To run into volume issues on lower-impedance headphones, you'd pretty much need to be using HE-6.  Many amps have similar characteristics or worse into lower-impedance headphones, in terms of clipping behavior.

So what do you think is going on?
 

 

[limpidglitch]

Quote:

It's hard for circuits like these to be marginally faulty in terms of performance.  (The power management may be more finicky.)  Either it will work 100% or it won't work at all, mostly.
 
The position of the volume control should have next to no difference on the sound other than volume, with less change than most other amps.  The exception is if you're using headphones with impedance maybe under 64 ohms or so, and you're maxing out the volume with a certain gain and source level, such that you're clipping the output of the device.  And that would sound really obvious (suddenly with a small change in the volume knob, you go from a clean sound to extreme clipping), so that's not what you're hearing.  To run into volume issues on lower-impedance headphones, you'd pretty much need to be using HE-6.  Many amps have similar characteristics or worse into lower-impedance headphones, in terms of clipping behavior.

What about the potentiometer, could it be causing this?
 
I remember the first times I used the O2 the pot was really scratchy, but it smoothed out in practically no time.
From a lack of any other clear suspects, I assumed it to be caused by some slight oxidation on the windings inside the pot.

 

[MikeW]

I agree with the above, it does sound like it could be a problem with the pot, might want to make sure that S2 (gain switch) was properly installed and is not shorting to the VIA (small hole on the PCB). As it was a design problem that was later addressed. It's unlikely but possible.
 
 
Quote:

S2 PROBLEM – The September version of the PCB artwork (9/14/11 release) has the via between R21 and S2 located too close to the corner “foot” on S2. While most have not had any problem, it’s highly recommended to slightly bend the leg in that corner of the switch inward, or if you have some heavy cutters, trim that leg shorter (don’t use small “precision” cutters as you’ll likely damage the blades). At the least, make sure there is no contact when you’re soldering S2 in place.

 

 

[Willakan]

 
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?
 

In the interests of science, I turned up my volume to 3:00 (which is coincidentally 3X my normal listening level if we go by degrees of rotation.) I'm afraid I was unable to maintain this listening volume for very long (with my normal setting of unity gain) due to the fact it was uncomfortably loud.
 
I'm not entirely sure what an amplifier straining sounds like: I presume some subjective failure to deliver the dynamics and bass impact associated with a high listening level (Good God I hate this kind of terminology!) On that front the O2 did not appear to be straining: drum hits shook my eardrums unpleasantly violently and everything seemed to be in dischordant order.
 
I would repeat this experiment on the 3X gain setting, but at that point it would be so loud that any commentary on the sound would be confined to expletives.
 
Anyhow, as you say, it appears your problem is slowly fixing itself.
 
EDIT: It is unlikely that the gain switch is shorting to the feed-thru via, as that would result in *massive* channel imbalance.

 

[upstateguy]

Quote:

In the interests of science, I turned up my volume to 3:00 (which is coincidentally 3X my normal listening level if we go by degrees of rotation.) I'm afraid I was unable to maintain this listening volume for very long (with my normal setting of unity gain) due to the fact it was uncomfortably loud.
 
I'm not entirely sure what an amplifier straining sounds like: I presume some subjective failure to deliver the dynamics and bass impact associated with a high listening level (Good God I hate this kind of terminology!) On that front the O2 did not appear to be straining: the drum hits shook my eardrums unpleasantly violently and everything seemed to be in dischordant order.
 
I would repeat this experiment on the 3X gain setting, but at that point it would be so loud that any commentary on the sound would be confined to expletives.
 
Anyhow, as you say, it appears your problem is slowly fixing itself.
 
EDIT: It is unlikely that the gain switch is shorting to the feed-thru via, as that would result in *massive* channel imbalance.

This in itself is really weird.  What's up with that?????
 
With low default gain, slowly advance your volume.  Do you find a place (around 3:00 with my T-1s) where the SQ changes and gets grainy/shrill?  If you can't find the change in low gain, try high gain, and slowly advance the volume.  See if there is a place where the SQ changes.
 
I agree with you, I can't keep it up there very long... too loud and it doesn't feel like it's doing the headphones any good.
 

 

[Willakan]

I have previously experimented with gradually raising the volume out of curiosity: I could perceive no shift in tone or anything else that I wouldn't expect from turning it up.
As I built my O2 myself and it was my first audio-related DIY build, I experienced a certain paranoia as to its performance, not helped by the fact I wired the output jack backwards initially! In the end, however, I have been unable to find the O2 reproducing anything that isn't on the original recording - and my paranoia has led me to check several times!
 
EDIT: As regards your comments on the GS-1 thread (thought I would respond here to keep everything together), I'd agree that the O2 doesn't use the nicest jacks/switches by default. That said, the input/output jacks are spec'd for 5000 insertions whilst the on/gain switches boast 10,000 cycles.
Regarding Dynalo parts cost, I think it is around $200, but I don't think that includes casework or a linear power supply (have to use a switching DC wallwart). I built my O2 for about $100 (tad over £60 once I added up postage), with nice jacks (Neutrik) and all - I did DIY the front panel though, which saved me a little. And it is an incredibly ugly build to look at, as I broke all the clear acrylic I ordered off Ebay with my first three attempts at the front panel so had to use some yellowish stuff instead.