Agreed.
I have subjective differences where the likes ofRMIAA and Diffmaker do not show substantial objective differences.
Could it be that FFT indicated small (<<2-3 dB) differences of higher order harmonics albeit at seemingly vanishingly low levels are what make the differences between good and especially good reproduction.
As I stated earlier, on my netbook 1/2"speakers I heard the difference in the two files within the first 10 or 12 seconds....all that I listened to.
To me the first (the bypass recording) sounded cleanish, not quite right, and uninvolving.
To me the second recording sounded 'fat', and 'blatty' , ie essentially distorted.
I can understand that participants voted for the 'coloured' version, but to me, neither recording is quite there.
Dan.
SY, as you know, I have placed here much more measurements than only amplitude responses and 1kHz FFT. I will not be repeating myself every second day.
FYI, I have collected thousands of measurements in the last years. Time domain, frequency domain, small and smallest amplitudes, full scale amplitudes, small signals amplified at +40dB to reveal the noise floor, mains components FFT measurements, HF and VHF measurements up to 3GHz. None of these measurements are able to explain sonic differences, of course I speak about circuits above certain technical levels. My measurements are clean, they do not contain 50Hz, 60Hz and their multiples etc., as the other guys very often have. My measurements are reliable and repeatable. There is always some difference in two components (like slew rate 135V/us vs. 20V/us vs. 2000V/us), but never these differences are able to explain sound difference perceived. And my results in ABX are really not bad, we all can pass the Klippel tests and record the results.
FYI, I have collected thousands of measurements in the last years. Time domain, frequency domain, small and smallest amplitudes, full scale amplitudes, small signals amplified at +40dB to reveal the noise floor, mains components FFT measurements, HF and VHF measurements up to 3GHz. None of these measurements are able to explain sonic differences, of course I speak about circuits above certain technical levels. My measurements are clean, they do not contain 50Hz, 60Hz and their multiples etc., as the other guys very often have. My measurements are reliable and repeatable. There is always some difference in two components (like slew rate 135V/us vs. 20V/us vs. 2000V/us), but never these differences are able to explain sound difference perceived. And my results in ABX are really not bad, we all can pass the Klippel tests and record the results.
Can you get FFTs for blue and green like the ones in my example?
These are 1M sample FFTs analyzed in Audacity and exported to the gnumeric spreadsheet and plotted from there.
FFTs may or may not show the problem, depending on what the problem is ;-)
If the lack of smoothness is high frequency noise it might show up in the FFT.
I think high frequency noise is significant even below -120dB. I'd want to see a plot like the pink one to rule it out. The pink one sounds smooth enough to me. The pink line is mostly harmonic distortion which is smooth at least for low order harmonics and noise at the limit of resolution.
The blue one is an analogue loopback like you did for the blue chain but one I did myself on my xonar essence (which does not have its original op amps so does not represent the product as sold). The ground loop referred to on the plot is the ground connection from audio line out ground to audio line in ground (which are connected internally on the card and so form a loop). You can see there is a lot of cruft in it which would all be near the bottom axis and possibly just off the bottom on your posted FFT plots.
I think it would also be interesting if you could do a 1M sample FFT loopback with a short cable where one end of the shield is not connected for comparison.
I bought the studio master copy of the original and have seen a few interesting peaks in both blue and green which look suspicious compared to the original.
I agree on this completely. Unfortunately, I was not able to prepare something much better by the D/A - A/D process. Only with classical music, maybe, but I do not know how many members would be willing to test with this kind of music.
I have been listening to the master data yesterday (that means not D/A-A/D-D/A, but only D/A) for quite a long time. They are much better than D/A-A/D blue file .... but .... during critical listening, they are not perfect as well. When we repeat certain part of the song over and over, we are easily able to find the faults.
I admire your amp and also voted for "Green" but please do test as earlyer suggested by use solid core for both hot signal and ground then that hardness + small grain disappear and direct becomes winner given good relationship between source and load is in place. Then i also vote "Blue" for musicality.
That buffer is warm biased and repair in a way the multicore coxial drawbacks compared to solidcore wire or PCB traces. Little ala pickup with to little pressure on vinyl up against correct heavier weight.
If it holds true, "Green" chain can be tried again maybe it also like solid core ?
We members can't do the test because lack of actual setup chain.
Some members has mentioned less is better which i agree in so please give a try, even if your make some living in buffer fabric.
Last to be said if under Windows and tracks on HDD with DMA buffer in system is ON then pay attention that blue track from poll is worse with hardness and small grain first time played after restart, further replays is then buffered in memory which adds some warmth ala mini PMA buffer.
Regards Ricky
This is what I can get from the system used, and it would be almost same for blue and green, without additional amplification. If I need more resolution, I use +40dB amplifier to make the noise floor of the DUT visible.
P.S.: I have dig out the noise floor measurements of 'blue' and 'green'. Green is 2 channel measurement and channel difference is the inherent problem of the 'blue' soundcard. You will find no difference in red traces.
I am sorry I will not repeat or make new measurements on your request, as everything you are asking has already been done without reflecting any significant difference. That means no higher harmonics generated, no high frequency noise even at different levels. Blind track.
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Actually, I think the ground loop could explain all the results:
Blue has a ground loop which is sampled at full ground loop amplitude.
Green has a ground loop which is attenuated by the two low pass filters in your preamplifier and then sampled at reduced amplitude.
The low phase frequency distortion is from your coupling capacitor.
Job done.
TYVM.
Wrong again, and completely.
Ground loop would result in 50Hz line and multiples.
You could have seen absolutely clean FFT 1kHz in the low frequency area.
The noise level of the card shown hereabove (blue_noise level) is measured without loop with only 50R resistor in the input.
I apologize I will not continue replying your questions, takes too much time. You guys have still a lot to learn.
You are right, there doesn't seem to be a ground loop in the green case.
But you can see harmonics of the mains hum at -125 dB in your loopback FFT above (so that must be the blue loopback case right?). That's about 5dB below where it is in my loopback plot. Still significant I would say. I used a 2m cable, yours was only 35cm and the local RFI is probably different so a 5dB difference is easily explainable. You have already stated that the shield is connected at both ends of your cable so you do have a ground loop whether it shows up in your measurements or not.
There is no evidence of mains hum in your loopback noise plot with the resistor but there isn't a ground loop in that configuration so that is consistent with my hypothesis.
Your green noise plot doesn't seem to show a ground loop but you did use the same soundcard for line out and line in so perhaps your preamp breaks the ground loop.
So, my conclusion: there is a ground loop in the blue case and either no ground loop or an attenuated ground loop in the green case (and the low frequency phase distortion is from the coupling capacitor).
I think it couldn't be clearer.
OT post 
For everyone that participated in this and the opamp shootout, a new little teaser for you all
Come And Listen And Vote
For everyone that participated in this and the opamp shootout, a new little teaser for you all
Come And Listen And Vote
Yes it is. All the measurements are in loop except of the two noise levels. The -60dB measurement you refer to is an older one, not performed now during the test setup. -125dB re 2Vrms is 1.12 microvolts
I hope you understand that even this -125dB ia about 20dB below noise level integrated over 20kHz. I would appreciate more probable suggestions. This -125dB, burried 20dB in noise, is of course absolutely inaudible. I call it nit-picking.
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You like the adjective "small" better? It's not like Pavel's preamp turned Steely Dan into Bruno Mars. Most of us would notice that.
That -125dB 3rd harmonic implies high frequency noise fairly close below which would add to the noise in the blue recording making it less smooth than the green one.
It's at about the right level to be barely perceptible. The green and blue samples were 6dB down as well remember.
There's that and the potential of the extra DAC filtering in the green sample or some combination of the two.
I enjoyed this, it turned out to be very interesting.
Just a gentle reminder that the data from this poll shows NO 'tiny, but real, difference in sound'. To get our data to show this we must repeat the test preferably using ABC.
There's no point trying to find reasons for a difference until we establish that an audible difference exists.
heb1001, Max Headroom, a.wayne, Pano, BYRTT, please confirm that you heard differences and voted for green or blue.
Stuart, I'm interested in how you would do this. Can you tell us? Don't if it might be usable in our next evil test.SY said:
I have established one, in another test
http://www.diyaudio.com/forums/everything-else/246165-based-sonics-do-you-prefer.html#post3709017
and
http://www.diyaudio.com/forums/everything-else/246165-based-sonics-do-you-prefer.html#post3709108
Would you like to join? We may have fun there
Confirm i heard difference and voted for "Green". At same with vote i made the multiwire as a possible pollution for the little hardness and little grain which make the "Blue" bad. My experience is that direct link should be winner if not polluted no matter preamp is good (see my post http://www.diyaudio.com/forums/everything-else/245881-ultimate-listening-test-test-your-ears-audio-chain-31.html#post3709161).
I am a little sad because suddenly it became looking like a comercial and marketing for that preamp.
Regards Ricky
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