In your last screenshot, A-weighted THD+N is higher than unweighted. You might want to check the measurement setup.
In your last screenshot, A-weighted THD+N is higher than unweighted. You might want to check the measurement setup.
I remember scratching my head when VA (Visual Analyzer) software gave similar results, so much so, I scrapped using it, back in the day.
I figured there was a computational error in the coding. Thoughts?
Pretty weird though, how did they botch that driver...What I see that got improved with this ASIO4ALL vs. the original ASIO drivers from ASUS was the nasty spikes around 12 KHz, sometimes around 8 KHz and other freqs too. Also, noise-floor is a tad lower and more...constant then it used to be with manufacturer's drivers.
I've used 28mm/f2.8 CANON and 105mm/f2.8 SIGMA 1:1 macro lens, hand-held pics, no tripod used even the time was pretty high. Let me know if you think some pics might need to get re-taken/swapped.
Many thanks!
I've no idea, but usually ASUS is not the best drivers-integrator ever, I also have Essence One and the Head-Fi thread is full of issues (especially on Win10 and USB3-related), not mentioning the U7 too.Pretty weird though, how did they botch that driver...
A 45mm tilt-shift might serve you better in this regard.
Or, since you're into Macro, use focus-stacking. Too little information in shallow DOF shots to be useful picts.
Not trying to criticize or anything.
But something i have to say.
First of all. 0.002% is indeed where it should be.
I have that amp too i measured myself as well.
There are some downsides of the design.
1, output impedance is a bit high.
2, it shines at low impedance load but high output impedance is non ideal for low impedance load.
3, output voltage is a bit low for discrete design. so not so fancy for high impedance load either.
4, noise floor is actually very high. anything that's remotely close to sensitive can produce noise.
Then about o2. I modded o2 then it only produce 0.8uV at half point of volume pot and 0.5uv at maximum. THD into 32 ohm 1mw is 0.00006%. 0.0001% at 10mw. How about that, king of mods?
One burson's website i believe it is 3ohm(my bad). What i believe it's that it's no global feedback. So it's possible to have higher output impedance. And i have measured their v6 opamp which can gondown to 0.0001% thd. So the noise and 0.002% at even low output indicated no global feedback.Hi there,
Criticising it's all about this forum after all, right? All we care is how the audio equipment is built and how these are measuring, so I do appreciate your posts here.
1. I've seen no resistors or inductors in signal path, I wonder if the 3 Ohms output impedance would come from the internal impedance of the output transistors themselves...but this sounds about impossible (a similar output stage is included inside PLAY and this amp has 0.5 Ohms output impedance). I'd like to find a way to dive deep into lowering the output resistance of the output stage, but honestly I find to much trouble involved into taking out the PCB board...there are just too many screw and hours involved into this. However, I've A/B tested CV2 and O2 and HPA-3B amplifiers with my 16 Ohms IEMs and I got the same extended low-end like a 0.3 Ohms impedance amplifier (volume matched by oscilloscope), so this 3 Ohms output impedance is a lowlight only on the paper, not in real life...so I don't care much about this.
2. I found not an issue with my 600 Ohms Beyers, but I haven't tested with other high impedance cans, so please let us know what cans might be incompatible with this amplifier and in what exact way. Although, given the powerful output stage made with 8 x TO220 transistors and without low-pass filter on the outputs, I see no reasons why not pairing perfectly with high impedance cans at all, but of course...YMMV.
3. About 12V RMS/600 Ohms means almost 0.5 W/channel, that would be 5 times more than my Beyers DT880 600 Ohms can sustain.
4. This amp was simply not designed for IEMs (given the lack of adjustable gain and the max. 12V RMS output voltage), but I personally find the internal noise being pretty low for an amplifier designed without an adjustable gain-stage between voltage-gain and output-stage. It's noise is audible-comparable in A/B tests with the noise produced by my O2 when choosing the gain of 3.5X (volume matched for my 16 Ohms IEMs). In a very low room environment (nightly) I do hear a low amount of noise coming from my 16 Ohms IEMs (100dB/mW), but I don't find it disturbing. However, Objective2 with a gain of 1.5X is my IEM's amplifier anyway...this amp is totally quiet indeed, even with max. volume.
Could you please share something about the O2 mods, please? It might be interesting for others to follow your steps.
The mods I've done to my O2 were mostly related to RCA and 6.3mm jack plugs, swapping opamps, decreasing output DC and adding decoupling caps, but output noise wasn't really improved in any way.
P.S.: I do love amps made with no opamps in output stage, or no opamps at all, and I appreciate a bit of R&D done by manufacturer. This is why I purchased Matrix HPA-3B and Burson CV2+ actually.
Global feedback without output resistors will lower the output impedance to less than 0.5ohm. And the distortion will be lower and become frequency dependent. It sure has local feedback. No circuit doesn't have local feedback.I measured CV2's output resistance and it's about 3 Ohms (@1 KHz sines). Given it's low THD I guess it does have NFB after all.
O2 already has a very low noise by default, I see no reason to reduce the noise even further, unless for fun of DIY; see Neurochrome's measurements.
What you've done to your O2 headamp is a dramatically change of the original schematic, you've crippled the design (from I understand) and not a modding. Loosing the input gain stage make your O2 a simple output buffer and not an amplifier, but maybe I'm wrong...