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Rolling (replacing) Op-amps in Topping D10 DAC

Killingbeans

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But if one say he hear no difference between good measured amps and dacs? That guy must be deaf.

Or maybe that guy just acknowledge that if a difference is faint enough to be overlooked in the light of even tiny amounts of negative bias, then it's not really worth spending time and money on.

That being said, I'm still very sceptical about the difference actually being there in the first place.
 

SIY

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Blind test, i agree. Double blind. No offense, that's the least useful thing in audio.

For make-believe, sure. For actual useful data, double blind and level matched is the most basic control. Don't do that and your evidence is of the same quality as reports of alien abductions with anal probing.
 

JohnYang1997

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For make-believe, sure. For actual useful data, double blind and level matched is the most basic control. Don't do that and your evidence is of the same quality as reports of alien abductions with anal probing.
Ok. I'll try to do it. So just double blind test to dacs that measure 0.0003% thd -110db multitone residue and flat response counts right? Or maybe double blind test 5534 to opa827 counts right? That is relatively easy.
 

JohnYang1997

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Or maybe that guy just acknowledge that if a difference is faint enough to be overlooked in the light of even tiny amounts of negative bias, then it's not really worth spending time and money on.

That being said, I'm still very sceptical about the difference actually being there in the first place.
dac/ amp sound much more different than opamp rolling. Even changing a resistor value or low resistance pot will make more difference than opamp rolling. Opamp difference can be overlooked i agree thats why many pro products use jrc4580 and 5532. But the difference caused by different circuits are not.
 

SIY

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Double blind, level matched. That's the basics. And be prepared to describe EXACTLY the procedure you used to accomplish both of those. You'll want to achieve statistical significance (e.g., 95% confidence), which will vary in number of trials depending on your format.
 

Killingbeans

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Do you feel 0.5-1db in frequency response a lot? That's the feeling of it.

You feel it, but can't measure it? I'm sure you can't blame me for my scepticism.

But the difference caused by different circuits are not.

Absolutely. I'd be mad to deny that. But it's not what this thread is about.

My point is just that if something is not measurable, it's very much likely not audible either.
 
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JohnYang1997

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You feel it, but can't measure it? I'm sure you can't blame me for my scepticism.
The feel of frequency response change not always mean the frequency response is different. It can be from distortion, phase problem, ringing in square wave, noise etc. I think if you try to find a lisa3 you will know what I was talking about. That's one of the most colored sound but flat frequency response.
 

SIY

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A bit of study of the Fourier theorem might also be useful as well as the ability to do some basic measurements that will go beyond a hand-waving recitation of buzzwords used by audio "reviewers."
 

JohnYang1997

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A bit of study of the Fourier theorem might also be useful as well as the ability to do some basic measurements that will go beyond a hand-waving recitation of buzzwords.
I study electrical engineering. So do you really think I don't know fourier transform? Oh come on. Tell me 0.001% distortion will contribute how much in frequency response? And noise? Can you say this little change in frequency response make change. Oh why would you even need fft in the first place if you can measure sine sweep. Nah you don't seem legit to me.
 

JohnYang1997

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A bit of study of the Fourier theorem might also be useful as well as the ability to do some basic measurements that will go beyond a hand-waving recitation of buzzwords used by audio "reviewers."
Also i have measurements equipments. I had focusrite forte and my own pre amplifier to measure noise. cs5381 has very low low volume distortion. Distortion can go as low las -125db for each individual harmonic. -20db loop measurements showed very low distortion. Now it's broken.
I just bought a motu 828es which has ak5574 adc. When at -22db the individual harmonics are lower than 0.00003%.
 
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JohnYang1997

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4c1c429fb1aa70a8.png
 

JohnYang1997

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Some of the old tests. I did not have the habit to name all the files. There were much more screenshots but these are the more readable ones.
 

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  • old tests.zip
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JohnYang1997

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i ended up using opa827 + opa2227p so the best looking one is probably opa827+opa2227p. but not sure it was april last year.
 

guenthi_r

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Changed the SOP8 OPA2134 OPAmps of the I/V-Stage to OPA1642 just for fun (the soldered ones, not the socketed!).
Quick listening Test, it sounds as good as before :p

Some more listening needed.

EDIT: LPF/Outputstage is an LME49720
 
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istinnstudio

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All strange things can happen to some Chinese DAC designs. For example, I use a Weiliang Audio SU5 dac [ess9038q2m based]. Not serious complains as it serves the job simply ok for now. But it had advertised i/v conversion with 2x OP275 + OPA2604 as low pass
  • Adopt dual OP275G as I/V converter to provide high audio performance
  • Adopt OPA2604 as LPF output to provide tube sound
at the end, it had 2xTL071 for the I/V and 1x OP275 for the LPF with some surround film capacitors having different size. The audible difference may be insignificant (who knows!), but it is a fact. Hopefully not fake parts there...
 

JohnYang1997

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All strange things can happen to some Chinese DAC designs. For example, I use a Weiliang Audio SU5 dac [ess9038q2m based]. Not serious complains as it serves the job simply ok for now. But it had advertised i/v conversion with 2x OP275 + OPA2604 as low pass
  • Adopt dual OP275G as I/V converter to provide high audio performance
  • Adopt OPA2604 as LPF output to provide tube sound
at the end, it had 2xTL071 for the I/V and 1x OP275 for the LPF with some surround film capacitors having different size. The audible difference may be insignificant (who knows!), but it is a fact. Hopefully not fake parts there...
What the hell is this...
 
D

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dac/ amp sound much more different than opamp rolling. Even changing a resistor value or low resistance pot will make more difference than opamp rolling. Opamp difference can be overlooked i agree thats why many pro products use jrc4580 and 5532. But the difference caused by different circuits are not.
This was interesting to read from you of all people. I came to similar conclusions aswell, confirmed with blind testing, though the common attitude is still that this is impossible...

My blind testing with op amps cant really be confirmed, there could be circuit issues (though I dont believe it).
Some actually conclusive blind tests were with different DACs and an o2 amp in the past. Mostly ODAC against Topping D50 but also iPhones, Realtek PC output, Soekris R2R. I actually started when I didn't like the sound of ODAC and bought the D50 to test for myself if there was an audible difference or not.
All these devices with low levels of distortion that are considered to be inaudible but all relatively easy to tell apart consistently in blind testing over many trials.
Also worth noting that the differences I thought I heard in long term sighted listening with these DACs, were the same differences that let me tell them apart in blind testing...
I have a D10S on the way to test against D50 next, the O2 amp will need upgrade too.

Would you (or have you?) consider doing more blind tests and recording results to post on here?
Although it is warranted, seeing people's sighting listening impressions being dismissed as being totally imaginary by people who are probably half deaf or never attempted any tests themselves when you already know it is possible starts to get frustrating after a while .
 
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Jimster480

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This was interesting to read from you of all people. I came to similar conclusions aswell, confirmed with blind testing, though the common attitude is still that this is impossible...

My blind testing with op amps cant really be confirmed, there could be circuit issues (though I dont believe it).
Some actually conclusive blind tests were with different DACs and an o2 amp in the past. Mostly ODAC against Topping D50 but also iPhones, Realtek PC output, Soekris R2R. I actually started when I didn't like the sound of ODAC and bought the D50 to test for myself if there was an audible difference or not.
All these devices with low levels of distortion that are considered to be inaudible but all relatively easy to tell apart consistently in blind testing over many trials.
Also worth noting that the differences I thought I heard in long term sighted listening with these DACs, were the same differences that let me tell them apart in blind testing...
I have a D10S on the way to test against D50 next, the O2 amp will need upgrade too.

Would you (or have you?) consider doing more blind tests and recording results to post on here?
Although it is warranted, seeing people's sighting listening impressions being dismissed as being totally imaginary by people who are probably half deaf or never attempted any tests themselves when you already know it is possible starts to get frustrating after a while .
Sight bias is a real thing, I went on an audio journey testing different DAC's. And yes you are right in that the long term listening I could tell a variety of DAC's apart. there were minute differences but I did pick them up. Later on when Amir tested these devices it turned out that my personal impressions were basically spot on with the performance he measured.
However I didn't have experiences where I thought something sounded good and then it scored poorly on the charts.
Also the performance of DAC's has gone up considerably from the time that I first started testing and I haven't spent any time really testing DAC's over the past year outside of various dongles and stuff on Vine.
 
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