I hadn't heard of that before. It stands to reason that if there's something to think about, someone is doing a PhD thesis on it.
I hate to drag this down in audiophoolery. I just don't know how to avoid it if you set the goal as "sound quality." There is a vast amount of extremely interesting stuff to learn within the realm of pure technology. No offense intended. Partly, I'm going here because I was so offended by my brief membership at ASR.
I hate to drag this down in audiophoolery. I just don't know how to avoid it if you set the goal as "sound quality." There is a vast amount of extremely interesting stuff to learn within the realm of pure technology. No offense intended. Partly, I'm going here because I was so offended by my brief membership at ASR.
If you really want to keep it technical and objective then you should reconsider your thought about " golden ears" because most of the ones that the big audio companies use are actually musicians with an acknowledged education in the field .If a non musician guy listen to a piece of music multiple times he might or might not recognize if some notes are played the right way or if domething is missing , but a good musician will tell you exactly what semitone was screwed in between two musical notes that were maybe a few hundred miliseconds apart from one another.That needs tens of thousands of hours of practice. Most musicians start off their musical education around 5 years old and get acomplished in their 20's...15 years x 1...200 days or 6 hours of daily training...that's about 15 000 hours of practicing playing and listening notes...and that is actually a minimum of practice for most good musicians with a classical education.
Do you really think you can equal that experience in a few weeks of trials?Unless you're a musician yourself I doubt that and i know a few good musicians that aren't interested in listening to the most neutral reproduction of a recording cause they are listening to their instruments with nothing in between for years already...but that also mean they can instantly pimpoint any misplaced reproduction of a single semitone played for a fraction of a second and they can tell you its name .I know guys able to listen to the exhaust pipe of your car and tell the exact note your car is singing...You then measure the frequency and find the guy knew the exact damn fundamental frequency of that note by ear. I also knew personally the guy who tuned thr Meze Empyrean headphones and what do you know? He is a musician for a few decades already...Three years ago he listened to the Neve RNHP amp on some headphones and he was thoroughly impressed with that.A recent technical review found RNHP amp having fantastically low distortions while audiophyle forums trashed RNHP a lot as it was too cheap for their taste... There's a reason for which Neve is Neve...it makes equipment for musicians not audiophyles or Rolex owners...
Do you really think you can equal that experience in a few weeks of trials?Unless you're a musician yourself I doubt that and i know a few good musicians that aren't interested in listening to the most neutral reproduction of a recording cause they are listening to their instruments with nothing in between for years already...but that also mean they can instantly pimpoint any misplaced reproduction of a single semitone played for a fraction of a second and they can tell you its name .I know guys able to listen to the exhaust pipe of your car and tell the exact note your car is singing...You then measure the frequency and find the guy knew the exact damn fundamental frequency of that note by ear. I also knew personally the guy who tuned thr Meze Empyrean headphones and what do you know? He is a musician for a few decades already...Three years ago he listened to the Neve RNHP amp on some headphones and he was thoroughly impressed with that.A recent technical review found RNHP amp having fantastically low distortions while audiophyle forums trashed RNHP a lot as it was too cheap for their taste... There's a reason for which Neve is Neve...it makes equipment for musicians not audiophyles or Rolex owners...
It actually turns out that I am a classical pianist. And not a very good one at that, because I started too late and don't have the time to practice six hours a day. But I can play advanced repertoire, however poorly. I don't have perfect pitch or any of the stuff you talk about. But one of the reasons I stopped being interested in sound quality is because I realized I could hear what's musically interesting in a recording without needing an audiophile-grade system.
It's not about semitones. It's about timing and dynamics and voicing. Yes, the equipment can affect that, but SQ is not nearly as crucial to a musician as it is to an audiophile.
Edit: And, evidently, I own a Rolex. So knock it off. I knew exactly what I was getting when I bought it.
It's not about semitones. It's about timing and dynamics and voicing. Yes, the equipment can affect that, but SQ is not nearly as crucial to a musician as it is to an audiophile.
Edit: And, evidently, I own a Rolex. So knock it off. I knew exactly what I was getting when I bought it.
Interesting slides. Now I know how to use scientific testing to cheapen my product without my customers noticing.
I've shared my board designs with a few people. I hope some folks eventually build these things and can post their reviews.
This is great fun and all, but I've had enough for now.
I've shared my board designs with a few people. I hope some folks eventually build these things and can post their reviews.
This is great fun and all, but I've had enough for now.
hpasternack,
Thanks for sharing. As usual, it was lots of fun!
See you at the next project ....
Thanks for sharing. As usual, it was lots of fun!
See you at the next project ....
Thank you Henry for your work and reports.
I'm wondering about the right PSU providing +/- 24V, 120VA.
Maybe I'm wrong about the values, extracted from the HPA-1 thread.
There are so many solutions : CRC, SMPS, CapMX, Super Regulator, Jeff's one.
I need some enlightment to pick the best one.
Could MeanWell IRM be selected : 2*60VA gives 120VA and +/- 24V, small footprint, stellar mtbf.
My question is : does SMPS way in this design worth a try or is it a nogo ?
I've got a Velleman 2*18V, 160VA, maybe oversized, but it's sleeping here 😉
Thanks
I'm wondering about the right PSU providing +/- 24V, 120VA.
Maybe I'm wrong about the values, extracted from the HPA-1 thread.
There are so many solutions : CRC, SMPS, CapMX, Super Regulator, Jeff's one.
I need some enlightment to pick the best one.
Could MeanWell IRM be selected : 2*60VA gives 120VA and +/- 24V, small footprint, stellar mtbf.
My question is : does SMPS way in this design worth a try or is it a nogo ?
I've got a Velleman 2*18V, 160VA, maybe oversized, but it's sleeping here 😉
Thanks
The amplifier draws about 260mA total for both channels. If your raw supply voltage is +-30V, the absolute minimum transformer you can get away with is 25VA, but you're better off doubling that.
The power supply in my breadboard uses a pair of 25VA transformers, or 50VA total. They run barely warm to the touch. 120VA is serious overkill. The Toroidy transformer I ordered is 100VA.
Aim for 50VA for a good, conservative design, and 100VA if you want to go nuts.
Switch-mode supplies are more efficient, and you definitely don't need 120W total power. The MeanWell modules are noisy and will require output filters, and probably a linear post-regulator. I'm sure you can find some ideas for that on the forum.
The transformer, filter, and regulator are said to be crucial to the sound of the amp. You should build Jeff's circuit if you want an "approved" implementation. I think the Super Regulator is working well in the application, but I have nothing to compare it to.
Using 2x18V transformers doesn't give you enough raw voltage. You'd need an LDO to get +-24V. 2X22V secondaries would be better.
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Edit: If you noticed an earlier version of this message that seemed odd, literally, my stupid cat crawled on the keyboard and edited, then posted it. Embarrassing.
Thanks.
When I get the A3 supply board done I will post it here and make the design files available. Meanwhile, I'm happy to answer any technical questions people may have about the A3 or my other amps.
The thing about the A3 is, the project comes with strings attached. Pass Labs may or may not have an interest in the design, if not legally, then morally. People have expectations, and there is scrutiny. There's pressure to build it right, and to listen to it right. No offense to anyone -- I'm happy for the interest. But I kinda want to get back to doing my own thing, without having to answer to other people. There's a downside to sticking your neck out. I need to think about it.
I like these circuits, particularly the last one (A3). The symmetrical operation, cascoding, well executed mirror, JFET input... Nice.
Just a couple of thoughts:
I prefer a Sziklai pair to darlingtons. Slower maybe, but more linear. You can even Sziklai the JFETS.
I am not a fan of servos. Have you tried it without one? You may be pleasantly surprised. You have used a good opamp for the servo, so the difference may not be huge.
If you are worried about DC offsets, try the JFE2140 from TI: a matched low noise part worth a look.
Just a couple of thoughts:
I prefer a Sziklai pair to darlingtons. Slower maybe, but more linear. You can even Sziklai the JFETS.
I am not a fan of servos. Have you tried it without one? You may be pleasantly surprised. You have used a good opamp for the servo, so the difference may not be huge.
If you are worried about DC offsets, try the JFE2140 from TI: a matched low noise part worth a look.
Patience, please. The original thought behind building A3 was to provide an opportunity to figure out why HPA-1 won awards and is still the standard HPA at Stereophile. If starting to change the design too soon then the intent is lost before there is ever a chance to understand something that may help in the long run.
Also, burn-in and listener-accommodation are both real. They are however easy to deal with if one can muster a little patience. The simplest answer is don't listen to the thing for a month, just let it stay powered on, maybe with some audio input signal running through it. Even more patience is needed to wait for power supply parts, then that bit of the circuitry will need to burn in. If the project is allowed to proceed with those things in mind then it doesn't have to be frustrating or feel like there is pressure.
Has it occurred to anyone else that some owners are like their pets? 🙂
Also, burn-in and listener-accommodation are both real. They are however easy to deal with if one can muster a little patience. The simplest answer is don't listen to the thing for a month, just let it stay powered on, maybe with some audio input signal running through it. Even more patience is needed to wait for power supply parts, then that bit of the circuitry will need to burn in. If the project is allowed to proceed with those things in mind then it doesn't have to be frustrating or feel like there is pressure.
Has it occurred to anyone else that some owners are like their pets? 🙂
This thread really has gone downhill. Now it's the usual talk about golden ears, burn in and lifetime experiences. No measurements of distortion profiles or residuals, only brabble as far as I can tell.
And one more thing on the "golden ears" talk: Statistically speaking, with my age being probably half the average in this thread, the fact that I can still easily hear past 10Khz and the fact that I have played an instrument for a decade - what's the likelihood that any one of you has any more "golden ears" than I do? 😉
And one more thing on the "golden ears" talk: Statistically speaking, with my age being probably half the average in this thread, the fact that I can still easily hear past 10Khz and the fact that I have played an instrument for a decade - what's the likelihood that any one of you has any more "golden ears" than I do? 😉
Measurements of Pass HPA-1 available at: https://www.stereophile.com/content/pass-labs-hpa-1-headphone-amplifier-measurements
In due time there may be some measurements of clones, once the builds are finished.
In due time there may be some measurements of clones, once the builds are finished.
It got to this point because I convinced myself I had to prove my worth by building this thing and correctly divining its secrets. This was interesting at first, but now it's tedious and undignified.
The other thing is, I can't keep going at this pace anymore.
Apparently, Mark has everything under control. Attached please find a zip archive containing the Gerbers, schematic, and partial BOM as described above. I don't want to know anything about this project anymore. PM me for questions about A1 and A2.
I've decided I am willing to support A3 builders. Best to contact me privately, but I will consider posting in public to save time if that makes more sense. I will not make any more subjective posts, except -- maybe -- in the most general terms. My hearing is garbage. Having made a sincere attempt to play at being an audiophile, I would rather deal with facts, not speculation and flights of fancy. I hope people with certified golden ears will build the A3 and report how it sounds. I will stick to things I can verify.
I'm slammed by my new job and have no current plans for new projects, sorry. Maybe later.
I am not that thin-skinned. But I'm not someone's pet.
I'm slammed by my new job and have no current plans for new projects, sorry. Maybe later.
I am not that thin-skinned. But I'm not someone's pet.
I’m surprised at the change in frequency response with level setting if I’m reading the curves correctly. You would expect some change due input device capacitance interacting with the source impedance but not as much as shown. The distortion is very high by any standards - 500 ppm at 2 V out and rising rapidly after that. Most phones will be very loud at 2 V pk-pk output - you would want the distortion profile to remain ultra clean until well beyond this since with phones (and a good set of ears as alluded to by knOppers). It’s possible with good phones to pick out an amazing amount of information on a recording generally not available using a good set of speakers.
Is its purpose to satisfy listeners or to satisfy AP machines? Do AP machines measure time-variant systems in a way that produces results that easy for humans to intuit the meaning of? In other words you have a set of assumptions about what is good and how to measure good. They ARE assumptions.
EDIT: The proof of the pudding is in the eating. If you want to know why Stereophile likes it and other people like you will probably have to build it and listen. Otherwise you are just guessing.
EDIT: The proof of the pudding is in the eating. If you want to know why Stereophile likes it and other people like you will probably have to build it and listen. Otherwise you are just guessing.
If I recall, you’re the one who rants on about DACs and being able to hear the difference between products producing less than -110dB distortion (hint: you have no chance), or defending adding ‘gunk’ to a DAC to improve the sound.
Secondly, I stand by my statement: the distortion is high for a headphone amp and the input impedance behaviour less than ideal.
Secondly, I stand by my statement: the distortion is high for a headphone amp and the input impedance behaviour less than ideal.
Your recollection is distorted. It was Richard Marsh that had gunk added to his dac. We found that it made his dac sound worse than my un-gunked dac. On the other issue, it was PMA who ran a blind listening test of unity gain audio opamp buffers. He measured distortion of each buffer, then made recordings of the same music through each buffer. When the listening test results were announced PMA gave me an Honorable Mention for sorting opamps in order of distortion by ear, and doing it blind. Opamps included TL072, 5532, etc. This was done despite the many other sources of distortion in the overall audio path, opamps in his ADC, distortion in my dac, power amp, speakers, etc. Yet I won't disagree that people probably can't hear a brass band buried 60dB under a recording of other music. How can that be? Seems most likely that something about auditory processing in the brain is not so linear and time-invariant as has been assumed in the past. We do know for example that EEG is highly nonlinear, time-variant, and nonstationary: https://www.ncbi.nlm.nih.gov/pmc/ar...EG signal is nonstationary,about 0.25 sec [4].
Might not be time variant...nonstationary... BS ...but it's definitely level dependent!
I simply got tired asking people to read Dolby C papers and I didn't say a damn thing about dolby SR or Telcom C4...It ca be easily proved that increasing the sound level the hearing treshold can go up by more than 60db while the background noise is found at a minimum 30db.if the music is around 0db we are barely able to hear 10...20db of dynamic range and we need a long time to recover when the levels go down by 50db.Anyone who used a machine gun knows that for a full hour after that we can barely hear anyone speaking to us in a loud voice from a distance of 1...2 meters .
Yet you can go to a stadium concert and stick to some kwatts of speakers for a few minutes then try go in the back stage and answer your phone if you can hear a damn thing...
These simple arguments are definitely against large dynamics range of listening.We can only hear soft sounds if the sound level don't pass them by 20...30 db.Once that limit is passed by another 10 db we need at least a few seconds of pure silence to be able to hear those soft sounds again .
Anyone claiming hearing microdynamics at -20db...0db listening level is full of s...t.
I simply got tired asking people to read Dolby C papers and I didn't say a damn thing about dolby SR or Telcom C4...It ca be easily proved that increasing the sound level the hearing treshold can go up by more than 60db while the background noise is found at a minimum 30db.if the music is around 0db we are barely able to hear 10...20db of dynamic range and we need a long time to recover when the levels go down by 50db.Anyone who used a machine gun knows that for a full hour after that we can barely hear anyone speaking to us in a loud voice from a distance of 1...2 meters .
Yet you can go to a stadium concert and stick to some kwatts of speakers for a few minutes then try go in the back stage and answer your phone if you can hear a damn thing...
These simple arguments are definitely against large dynamics range of listening.We can only hear soft sounds if the sound level don't pass them by 20...30 db.Once that limit is passed by another 10 db we need at least a few seconds of pure silence to be able to hear those soft sounds again .
Anyone claiming hearing microdynamics at -20db...0db listening level is full of s...t.