Yes, tried from DSD64 thru DSD512. The sound really opens up a lot more to my ears once it gets up to DSD256 or DSD512. That has been the case for ESS and AKM dacs chips I have tried.
Of course, the particular conversion algorithm used can affect the final sound significantly. To see for oneself, there is a free trial version of HQ Player that has many settings to play around with.
If using AK4137 for upsampling to DSD in hardware then there aren't many conversion options to choose from. The upsampling filter and the DSD output sample rate are the two main choices. To me, the default interpolation filter and DSD 256 are the best options.
Of course, the particular conversion algorithm used can affect the final sound significantly. To see for oneself, there is a free trial version of HQ Player that has many settings to play around with.
If using AK4137 for upsampling to DSD in hardware then there aren't many conversion options to choose from. The upsampling filter and the DSD output sample rate are the two main choices. To me, the default interpolation filter and DSD 256 are the best options.
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Well, if you believe in measurements doesn't OPA1622 measure better (for the particular application) than AD8397 does according to the data sheets? Lower distortion, etc.? Also IIRC, OPA1622 is a newer design exactly to fill that low cost, low power, high fidelity headphone amp niche. Of course, others may feel differently.
Does it measure better? I'm not sure because they use different parameters in their graphs/specs, maybe looks like slightly lower noise for OPA1622, THD+n looks about the same, but there seems to be rising distortion around 20khz for 1622, unless that is a side effect of lower measurement bandwidth?
Aside from that the ad8397 runs hotter, undesirable in compact mobile devices but for desktop use i'd prefer that.
It's also faster (again it's hard to compare datasheet specs 1 to 1), which should be better suited for a DAC output.
Also has greater power output than the opa1622, I found subjectively the opa1622 does a better job driving headphones with at least 2 in parallel, even though it was nowhere near its max power output. ad8397 could be better in that regard.
Overall the ad8397 seems preferrable to me on paper. This is the first I heard of it, I also thought the opa1622 was the best choice for driving headphones.
Aside from that the ad8397 runs hotter, undesirable in compact mobile devices but for desktop use i'd prefer that.
It's also faster (again it's hard to compare datasheet specs 1 to 1), which should be better suited for a DAC output.
Also has greater power output than the opa1622, I found subjectively the opa1622 does a better job driving headphones with at least 2 in parallel, even though it was nowhere near its max power output. ad8397 could be better in that regard.
Overall the ad8397 seems preferrable to me on paper. This is the first I heard of it, I also thought the opa1622 was the best choice for driving headphones.
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This kind of marketing bullets they use to help sell opamps:
High-Fidelity Sound Quality
• Ultralow Noise: 2.8 nV/√Hz at 1 kHz
• Ultralow Total Harmonic Distortion + Noise:
–119 dB THD+N (142 mW/Ch into 32 Ω/Ch)
As opposed to things like:
High linear output current
310 mA peak into 32 Ω on ±12 V supplies while maintaining
−80 dBc SFDR
AD8397 is spec'ed more like a video amp. Fast opamps were sometimes reported to sound better with old 16-bit dac chips that had large clock pulses in the audio ouputs. However, most of those fast opamps people liked for earlier dacs turned out to be not as low distortion in the audio band as modern ESS and AKM dacs require.
However, it could possibly be that AD8397 is a fast amp that also excels at a level commensurate with the best of modern audio dacs. Or not. Thing is, there is still RF coming out of dacs. Some makes it through the I/V stage without doing too much damage, but it can be the differential summing stage that is more sensitive to remaining RF getting into it.
Could also be so for a HPA opamp, depending on the dac chip and the residual RF still making into an HPA.
In the case of the AK4499 eval board I measured twice the BCLK frequency at around two or three hundred millivolts P-P at the output of the I/V opamps. After the first passive filter after the I/V there is still RF visible on my better scope. Can't quite see it after the 2nd passive filter, but it was still there at a very low level.
I turned up the gain on a Neurochrome HP-1 all the way and could measure the same RF on HPA output, again high enough to see on the scope.
Might be if that junk gets into OPA1622 and or AD8397, that the latter will tolerate it better. If that were to happen I'm not so sure that we should say AD8397 is the better HPA part, say, rather than fix the RF problem coming out of the dac and then see how things look at the HPA stage.
So, I dunno. Still not convinced that AD8397 is necessarily better for HPA than OPA1622, although it maybe it is. If you have done thorough work to make sure you are getting the best one or two opamp HPA you can and you still like AD8397 better then I will gladly take it as a data point for future reference.
High-Fidelity Sound Quality
• Ultralow Noise: 2.8 nV/√Hz at 1 kHz
• Ultralow Total Harmonic Distortion + Noise:
–119 dB THD+N (142 mW/Ch into 32 Ω/Ch)
As opposed to things like:
High linear output current
310 mA peak into 32 Ω on ±12 V supplies while maintaining
−80 dBc SFDR
AD8397 is spec'ed more like a video amp. Fast opamps were sometimes reported to sound better with old 16-bit dac chips that had large clock pulses in the audio ouputs. However, most of those fast opamps people liked for earlier dacs turned out to be not as low distortion in the audio band as modern ESS and AKM dacs require.
However, it could possibly be that AD8397 is a fast amp that also excels at a level commensurate with the best of modern audio dacs. Or not. Thing is, there is still RF coming out of dacs. Some makes it through the I/V stage without doing too much damage, but it can be the differential summing stage that is more sensitive to remaining RF getting into it.
Could also be so for a HPA opamp, depending on the dac chip and the residual RF still making into an HPA.
In the case of the AK4499 eval board I measured twice the BCLK frequency at around two or three hundred millivolts P-P at the output of the I/V opamps. After the first passive filter after the I/V there is still RF visible on my better scope. Can't quite see it after the 2nd passive filter, but it was still there at a very low level.
I turned up the gain on a Neurochrome HP-1 all the way and could measure the same RF on HPA output, again high enough to see on the scope.
Might be if that junk gets into OPA1622 and or AD8397, that the latter will tolerate it better. If that were to happen I'm not so sure that we should say AD8397 is the better HPA part, say, rather than fix the RF problem coming out of the dac and then see how things look at the HPA stage.
So, I dunno. Still not convinced that AD8397 is necessarily better for HPA than OPA1622, although it maybe it is. If you have done thorough work to make sure you are getting the best one or two opamp HPA you can and you still like AD8397 better then I will gladly take it as a data point for future reference.
ipulse60,
Nice to hear you are happy with OPA1622, but IME its distortion will be lower and down where it should be if the ground pin is properly grounded.
Also perhaps interesting, once I had the experience of participating in a blind test of single opamp buffers. The idea was to ABX two of the opamps (each of which was recorded in an individual hi res wav file) and show someone could reliably hear a difference. I found ABX very hard to do on my system at the time which was not all that low distortion and noise. In order to see if I could ABX two opamps I decided to compare all the opamp wav files and pick the two I thought sounded most different. It was very hard to tell them apart, but I found if I only compared two at a time I could sort them in order of which sounded brighter verses duller (something like more detailed verses less detailed). So, I sorted four of the five in that brighter/duller order. By that point I was exhausted with the effort and had enough of it. So, I sent my sort order to the guy organizing the ABX tests before he announced any results. Before I sent them I decided to put the duller sounded opamps at the top of the list and brighter ones at the bottom. That's because I suspected that the brightness (and seeming increased detail) was actually due to higher harmonic distortion. Turned out my suspicion was right. The duller sounding opamps were the less distorted ones.
That experience led me conclude there is a 'false detail' effect that people sometimes mistake for better sound. I was reminded of this yesterday in a conversation with a friend, a professional high end audio designer. He also knows about the 'false detail' problem from his own experiences. He also finds that many people believe the false detail effect is a sign of better sound quality.
My friend and I feel that false detail can be a problem that sometimes distracts people from working to get distortion low enough so they can hear all or most all of the natural detail in recorded music. Personally, I find it challenging to get something like a dac I am working on to an audible performance level my designer friend calls 'very good.' (He is very stingy with praise
...but, I choose to take him to mean 'very good' by high end professional standards )
Okay. I told that story just because it happened to be on my mind, not because I suspect OPA1622 on an adapter is fooling you. I have no way of knowing that. Just thought the story might be interesting to some people who still follow the thread.
Nice to hear you are happy with OPA1622, but IME its distortion will be lower and down where it should be if the ground pin is properly grounded.
Also perhaps interesting, once I had the experience of participating in a blind test of single opamp buffers. The idea was to ABX two of the opamps (each of which was recorded in an individual hi res wav file) and show someone could reliably hear a difference. I found ABX very hard to do on my system at the time which was not all that low distortion and noise. In order to see if I could ABX two opamps I decided to compare all the opamp wav files and pick the two I thought sounded most different. It was very hard to tell them apart, but I found if I only compared two at a time I could sort them in order of which sounded brighter verses duller (something like more detailed verses less detailed). So, I sorted four of the five in that brighter/duller order. By that point I was exhausted with the effort and had enough of it. So, I sent my sort order to the guy organizing the ABX tests before he announced any results. Before I sent them I decided to put the duller sounded opamps at the top of the list and brighter ones at the bottom. That's because I suspected that the brightness (and seeming increased detail) was actually due to higher harmonic distortion. Turned out my suspicion was right. The duller sounding opamps were the less distorted ones.
That experience led me conclude there is a 'false detail' effect that people sometimes mistake for better sound. I was reminded of this yesterday in a conversation with a friend, a professional high end audio designer. He also knows about the 'false detail' problem from his own experiences. He also finds that many people believe the false detail effect is a sign of better sound quality.
My friend and I feel that false detail can be a problem that sometimes distracts people from working to get distortion low enough so they can hear all or most all of the natural detail in recorded music. Personally, I find it challenging to get something like a dac I am working on to an audible performance level my designer friend calls 'very good.' (He is very stingy with praise
...but, I choose to take him to mean 'very good' by high end professional standards )Okay. I told that story just because it happened to be on my mind, not because I suspect OPA1622 on an adapter is fooling you. I have no way of knowing that. Just thought the story might be interesting to some people who still follow the thread.
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Nice story, Mark.
I always thought that words like "natural", "audiophile" sounds can be trusted if they came from professionals having a big background listening live, real performed music.
I only can compare different music files with my own listening experience, which is source dependent. So, that is why I only have trust in measurements, but not in my "ears".
I always thought that words like "natural", "audiophile" sounds can be trusted if they came from professionals having a big background listening live, real performed music.
I only can compare different music files with my own listening experience, which is source dependent. So, that is why I only have trust in measurements, but not in my "ears".
Agreed - 100%
If you can achieve a natural sound without that artificial edge but with
resolution as opposed to artificial detail - that's not easy.
To make things more challenging, a lot of newer recordings come pre packed
with 'artificial detail' for free... just what we need!
TCD
You may have a point when describing musical performance. When it comes to electronically replaying music, it's the level of fidelity that determines the quality of equipment such as DAC.
I wonder if anyone has ever uttered the words "This sounds like **** and gives me a headache but it measures great. I'll just have to put up with pain."
That reminds me of some remastered recordings, I think from Sony Music, when in an excess of zeal their sound engineers also cleaned the squeak of the guitarist's finger on the strings...To make things more challenging, a lot of newer recordings come pre packed
with 'artificial detail' for free... just what we need!
I can relate to your story Mark and it could have been elevated highs but I dont think so. I've been playing with 15 bands equalizers in cars for 17 years so I usally pic up on tonality changes. It could be elevated IMD since thats not something I've trained my ears to pick up on. In my nonscientific test I could swap instantly from one opamp to another so I didn't have to rely on music memory. It sounded better in every aspect so thats good enough for me since this is just a hobby. The other opamps were cheaper alternatives like 5532 etc. and possible fake. Anyways, its been a year since I've done that test so its hard to recollect spesific differences. Op amps are like high refresh rate gaming monitors. Some said 60Hz were enough and the human eye couldn't percive any higher fps. I bought an 144Hz and its night and day better. Next for me is 240Hz screen since some aspects of high refresh rate makes it better. Now Nvidia has ways of explaining why higher fps feels better to a gamer, but it took 15 years for the science to catch up to something that was percieved all along.
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