Cool, missed this entirely. But, very happy with my upgraded Hagerman Trumpet….and SOTA Sapphire 😉
A $500 phonostage designed to STAND OUT among the many choices seems like a difficult task.
From the article-
"We tested this against many phonostages that cost $150.00-$24,000.00 within a variety of environments with as many types of equipment as possible. The Pyxi phonostage (named for its size), rose through the ranks and the amount of clarity that was brought to every test was apparent."
So, it isn't far off from a $24K unit?
Think of all the money could be saved for those with $50K+ table setups...
Money saved could be used for the $400 "hot stamper" of Aja, Hotel California and a Diana Krall album!
Dear @mkiser : That phono stage was designed using op-amps and that’s why is so unexpensive but the design is not a discrete one but all through those op-amps that normally uses very high feedback. Today op-amps are way better than in the past but I prefer discrete overall SS circuits.
SOTA chhhhoosed Wynn for the design and this gentleman was working for several years in Analog Devices Corp. ( now he is a free-lance engineer ) designing between other parts op-amps and even he posted here in Agon that he was in the proccess to a phono stage design and that even that he in the past designed current mode op-amps ( that's the fashion today ) he choosed for a voltage design.
Yes, op-amps has low distortion/noise levels but as any kind of audio item/devices along that high feedback puts his color in the reproduced sounds, no matters what.
That they compared against a 24K phono stage means almost nothing with out know if that 24K unit was surrounded for a room/system of that level. I mean that a 24K phono stage normally is in a room/system way over 150K+ and there I think that any one could hear the differences and not for the better. I can be wrong because I never listened the SOTA.
Regards and enjoy the MUSIC NOT DISTORTIONS,
Several years? I was with ADI- designing a wide variety of ICs for almost forty years and was most fortunate to become an ADI Fellow and Senior Fellow.
I am not a free-lance engineer. I retired from ADI a few years ago and I design audio (and other gear) for fun and for free, and SOTA employed the design because they wanted something that truly was state of the art and it was brought to their attention by others that appreciated its qualities.
Your perspective on the effect of feedback is, in my opinion, facile, and does not recognize the psychoacoustic realities at play here.
The phono stage was explicitly designed to satisfy the known Psychoacoustic metrics and be explicitly neutral. Just because it eschews much of the audiophile preconceptions does not mean that it is inferior as substantial care was taken in all aspects of its design, from careful measurement and choice of components to the selection of an unusual architecture, to the actual creation of specs with each unit 100% tested to meet the critical ones.
Perhaps a little more introspection might be worthwhile.
Yeah, I know that is rare in audiophile circles, but perhaps warranted here.
The claim was not mine. There are certainly many compromises that need to be made in a commercial design required to sell for $300. However, the measured performance is remarkably good for a unit of this price- equivalent to or better than many that are far more expensive, and the subjective listening tests were extremely positive.
As Bruno Putzeys famously wrote, " the problem is not that there is too much negative feedback, but there is too little... This design was implemented to do exactly that- correct for there being " too little feedback", and it was deliberately intended to make a frontal attack on the usual audiophile tenets in an area- MC phono preamp design- that is notoriously difficult to do well.
Dear @wynpalmer4 : Here in México we say " free-lancer " to some experts that give support by free or through $$.
" Your perspective on the effect of feedback is, in my opinion, facile, "
I posted about only to say that no matter what and as any audio item has its own " color " not neutral. If that color is neutral for you fine with me.
Here is the recognized US definition of freelancer:
A freelancer is an independent contractor who earns wages on a per-job or per-task basis, typically for short-term work. Benefits of freelancing include the freedom to work from home or from a non-traditional workspace, a flexible work schedule, and a better work-life balance.
Sometimes in certain areas (such as journalism) free lancers evan work for free to build up a portfolio or a reputation.
This is not that. This is entirely a hobby. It is entertainment in these, my declining years, with no expectation of a reward of any sort, except, perhaps, to satisfy a degree of curiosity which, fortunately, has not declined with the passing of the years.
I got hold of a Pyxi and took it to a friend's place last night where a few others joined in. One friend, Mike, isn't an audiophile, he has Sonos speakers around his house. We listened to a track and then switched out the system owner's iFi iPhono 3 with upgraded power supply to the Pyxi, repeating the track. The difference was stark, and Mike immediately said, "wow, there's a lot more detail with this one."
The ear knows. The system owner will be selling an iPhono 3 once he gets his hands on a Pyxi. Mike was talking about getting a turntable and other decent components when I dropped him off at home.
If you read the thorough white paper written by @wynpalmer4 , one would not be surprised that this phono stage sounds excellent and competes with much higher priced phono stages.
How do I know? One of my phono stages uses opamps and it is fantastic. Competes with the many discrete and tube units I have owned over the years. The good designers of today will tell you that opamps have improved greatly over the years and I believe they are right. I would like to try this phono stage.
We need a blind test to sample a full feedback design vs. the no feedback design.
Maybe use a decent budget mm cart like an AT Vm95en or At vm95ml, and compare a few short samples using the Pyxie and a comparably priced discrete design such as the hagerman bugle or the Darlington labs mm5.
It may help to point out the sonic differences between the two design philosophies - assuming the differences can be discerned.
I have a extensive experience of experiencing through demonstration Phonostages, many of which have been compared using a control measure that keeps one system in use.
I am familiar with a Broad Range of Circuits and Topologies that cover both SS and Tube used with a particular system.
Comparing Tube to Tube, SS to SS or Tube to SS, will usually show a difference to the sonic being produced from the used system. It will be conjecture to suggest the same outcome will be repeated on another system.
What I have learned is that Phon's that share similar circuitry and topology, even though not identical, are quite easy to separate into a family sharing similar traits.
Another lesson learned is that even though I am at present a user of Tube Phon's as my preference, I have discovered SS Phon's that I would not hesitate to use for a owned system demonstration, and do believe these models will quite comfortably be considered as keeper devices.
The thing of interest is that Phon's that have been able to make this impression have been with a cost of less than a £1000 and as much as £10000, with a few models that will cost less than 50% of the most expensive.
Phon's that can make a very good impression can be discovered with a very reasonable cost attached to them. The experiences encountered pretty much suggests if a Phon' is discovered that will close the door on all other options, it will be a Phon' with a high retail price approaching the highest, or a model that is bespoke built to meets ones preferences.
If the Phon' in question in this thread is proving to be a match for the qualities being described, it won't be long before the 'cat is really let out of the bag'.
I’m with Raul on this one. To think we can measure everything the ear/brain system can perceive is Human arrogance. It was recently discovered that the brain responds to signals above what we can think we can detect.
Some of you probably know this, but an opamp does not have to be an IC. I prefer discrete circuits with little or no feedback, particularly of the global kind.
You folks take care,
The Pyxi architecture is, as far as I can tell, unique, or at least highly unusual.
The design is configured to be explicitly neutral. Your preferences are, frankly, inconsequential without some non-empirical basis to support them.
Despite the low-cost of the unit considerable care was taken to confer neutrality on the design, including very careful evaluation of the components and the layout.
As for, "It was recently discovered that the brain responds to signals above what we can think we can detect." what the heck does that even mean??
Dear @wynpalmer4 : I really do not disagree with your concept of neutrality in your design in what I'm not totally sure is in those " non-empirical " refered in your post:
" Your preferences are, frankly, inconsequential without some non-empirical basis to support them. "
In non-empirical basis researchs tells that human been can listen from as down 4hz to over 50khz because you and any one else " hear " with all our body not only the ears
We " listen " through the bones, through the body skin, through the hair, through the millions of nervous terminations in the body, through the muscles and so on.
But each human been whole body it's " damaged " in different ways against any other human been for ovbious reasons as age, health level, life experiences, mood, life type of nutrition and the like that along other reasons affects any single body cell. So what our brain detect is not exactly the same on each audiophile.
From all those and more comes the preferences. You said that your design is neutral and technically can be but I imagine you voiced it in different room/audio systems and I think that one way or the other you are biased ( with good reasons. ) to your design.
Of course only and opinion.
Regards and enjoy the MUSIC NOT DISTORTIONS,
You are a hard man. While I agree that we do hear with other senses this occurs with the lowest frequencies. I have not seen any evidence that we can perceive higher frequencies. I will hold judgment on the Pyxi until I have use one in my system which I expect will happen shortly. The reviewers will be positive but they will treat it like the diminutive, inexpensive unit that it is. After all, we all know something like the Pyxi could never approach the megabuck CH Precision. As an owner of a Sota turntable I am fully aware that a relatively inexpensive turntable can outperform tables costing many times more, so why not a phono stage?
What you need to do next is shove the Pyxi in a bigger box with a few more knobs and buttons. Then quadruple the price and it will sound better:-)
Never mind, I read the article. Flat RIAA, low noise, no added colorations. How does the designer determine this last part? I went to the SOTA site and it seems the device is available but the shopping cart is throwing an error.
Things don’t appear to be working at the moment. Please try again later.
The Sota web site is being updated to allow for EU (and UK) purchases of the Pyxi.
How did I determine "no added colorations?’. Well, I didn’t that was SoTa’s conclusion.
I just followed a philosophy which amounts to,
1. Flat RIAA- variations over the audio band below the subjective threshold.
2.Extremely high power supply rejection, and extremely low power supply/ground interaction between stages.
3. Distortion which is below the acoustic threshold (-110dB FS) measured whatever way you choose to do it.
There are other aspects, but you get the gist, hence the designed to be explicitly neutral.
Finally in subjective testing. It actually sounds neutral, with a very high degree of clarity.
The larger unit does not use the 14v wall wart. It, presently, uses a very different supply.
The Pyxi WILL NOT BENEFIT FROM A CHANGE IN THE WALL WART!!!
The 240v version uses a 15v wall wart due to availability issues.
Using a 15v wall wart in the US version could compromise the reliabilty. Even using a different 14v unit could do the same.
The filtering/regulation circuitry was carefully designed for the 14v wall wart that was used.
One other thing, I am well aware of the rather, how shall we say it, questionable (or at least questioned) results concerning the ultrasonic sensitivities of human hearing.
In any case what makes you so certain that those very sensitivities were not taken into consideration in the Pyxi etc. design?
In fact, the design is explicitly structured to ensure ultra-low distortion even for ultrasonic frequencies, and my test/evaluation methodology included signals up to 48khz (96kHz FS/2). Although the Pyxi does not have the extreme non-sensitivity that the Acrux has (read the paper, the multi tone tests which exceed the audio band say it all), it’s pretty darn good.
The Pyxi is not as good as I wanted it to be. SoTa had certain low cost goals that caused compromises to be taken. But it’s pretty darn good.
Dear @mijostyn : " with other senses this occurs with the lowest frequencies. I have not seen any evidence that we can perceive higher frequencies. "
Not exactly becauase exist that evidence. Thhe next information is only the preamble ( that unfortunately I can't share by a link ) and yes this will be a long post but interesting for some of us:
"" Your brain doesn't like to keep secrets. Studies at the University of Texas, Austin, have shown that writing down secrets in a journal or telling a doctor your secrets actually decreases the level of stress hormones in your body. Keeping a secret, meanwhile, does the opposite.
Your brain also doesn't like stress hormones. So when you have a secret to tell, the part of your brain that wants to tell the secret is constantly fighting with the part of your brain that wants to keep the information hidden, says neuroscientist David Eagleman.
"You have competing populations in the brain — one part that wants to tell something and one part that doesn't," he tells Fresh Air's Terry Gross. "And the issue is that we're always cussing at ourselves or getting angry at ourselves or cajoling ourselves. ... What we're seeing here is that there are different parts of the brain that are battling it out. And the way that that battle tips, determines your behavior."
Eagleman's new book, Incognito, examines the unconscious part of our brains — the complex neural networks that are constantly fighting one another and influencing how we act, the things we're attracted to, and the thoughts that we have.
"All of our lives — our cognition, our thoughts, our beliefs — all of these are underpinned by these massive lightning storms of [electrical] activity [in our brains,] and yet we don't have any awareness of it," he says. "What we find is that our brains have colossal things happening in them all the time."
Take a close look at yourself in the mirror. Beneath your dashing good looks churns a hidden universe of networked machinery. The machinery includes a sophisticated scaffolding of interlocking bones, a netting of sinewy muscles, a good deal of specialized fluid, and a collaboration of internal organs chugging away in darkness to keep you alive. A sheet of high-tech self-healing sensory material that we call skin seamlessly covers your machinery in a pleasing package.
If you were to injure your pinkie in an accident you'd be distressed, but your conscious experience would be no different. By contrast, if you were to damage an equivalently sized piece of brain tissue, this might change your capacity to understand music, name animals, see colors, judge risk, make decisions, read signals from your body, or understand the concept of a mirror — thereby unmasking the strange, veiled workings of the machinery beneath. Our hopes, dreams, aspirations, fears, comic instincts, great ideas, fetishes, senses of humor, and desires all emerge from this strange organ — and when the brain changes, so do we. So although it's easy to intuit that thoughts don't have a physical basis, that they are something like feathers on the wind, they in fact depend directly on the integrity of the enigmatic, three-pound mission control center.
Brains are in the business of gathering information and steering behavior appropriately. It doesn't matter whether consciousness is involved in the decision making. And most of the time, it's not. Whether we're talking about dilated eyes, jealousy, attraction, the love of fatty foods, or the great idea you had last week, consciousness is the smallest player in the operations of the brain. Our brains run mostly on autopilot, and the conscious mind has little access to the giant and mysterious factory that runs below it.
The brain works its machinations in secret, conjuring ideas like tremendous magic. It does not allow its colossal operating system to be probed by conscious cognition. The brain runs its show incognito. So who, exactly, deserves the acclaim for a great idea? In 1862, the Scottish mathematician James Clerk Maxwell developed a set of fundamental equations that unified electricity and magnetism. On his deathbed, he coughed up a strange sort of confession, declaring that "something within him" discovered the famous equations, not he. He admitted he had no idea how ideas actually came to him — they simply came to him. William Blake related a similar experience, reporting of his long narrative poem Milton: "I have written this poem from immediate dictation twelve or sometimes twenty lines at a time without premeditation and even against my will." Johann Wolfgang von Goethe claimed to have written his novella The Sorrows of Young Werther with practically no conscious input, as though he were holding a pen that moved on its own. """
Please read at the end of page 7 ( Significance results. ).
"""" Although hearing by air conduction is limited to ap�proximately 20 kHz, hearing by bone conduction ex�tends to at least 100 kHz [16-19J. Lenhardt et al. [17J demonstrated that speech modulating an ultrasonic car�rier could be understood to some degree, and Staab et al. [18J presented further speech recognition data using an ultrasonic hearing aid based on the work by Len�hardt """"
Now neurologist and scientist agree that the brain knowledge does not goes up to 27% of it and in the whole organism function not more than 38%.
Mijos, as you I'm and ovjective audiophile like true facts/measurements/sharts/diagrams and the like in the overall room/audio system but at the same time and as yiu I have common sense where subjectivity always is involve.
So and in this particular issue no scientist or mathematics or electrical theories or engineers can prove that you or me can't " listen " what for mathematics and the like is an inaudible sound for us or any audiophile, no one . I think and you can't prove I'm wrong that " inaudible " high frequencies puts its " color " to what any one of us can concious hear.
Regards and enjoy the MUSIC NOT DISTORTIONS,
Raul, all that is wonderful and very true, but bone conduction does not work through air. It works by physical contact. It is way less sensitive than air conduction with normal hearing. We use this characteristic to diagnose hearing problems with a tuning fork. The concept of masking is used in a fantastic number of ways to deal with pain and there is no reason it can not also be used for tinnitus. I always told people with tinnitus who had trouble sleeping to run a fan in there bedroom. The constant droning sound masks the tinnitus allowing them to sleep. A device that is implanted in contact with the mastoid process emitting a high frequency sound not audible by air conduction might indeed mask the tinnitus. Given that it is a very common problem I'm sure there is a lot of money being thrown at it.
I am still not convinced that airborne sound above 20 kHz can affect what we perceive through normal channels.
Dear @mijostyn : I'm sorry to read that coming from you with out any evidence that can support your " idea " when here is the support ( linked. )/evidence of what the whole body can listen ( bones are only a media in our body and I think that you read but not really read the brain preambule information:
"" X. Significance of the results
Given the existence of musical-instrument energy above 20 kilohertz, it is natural to ask whether the energy matters to human perception or music recording. The common view is that energy above 20 kHz does not matter, but AES preprint 3207 by Oohashi et al. claims that reproduced sound above 26 kHz "induces activation of alpha-EEG (electroencephalogram) rhythms that persist in the absence of high frequency stimulation, and can affect perception of sound quality."  Oohashi and his colleagues recorded gamelan to a bandwidth of 60 kHz, and played back the recording to listeners through a speaker system with an extra tweeter for the range above 26 kHz. This tweeter was driven by its own amplifier, and the 26 kHz electronic crossover before the amplifier used steep filters. The experimenters found that the listeners' EEGs and their subjective ratings of the sound quality were affected by whether this "ultra-tweeter" was on or off """"
Please you or any one else come here with true evidence/facts that proves that our wole organism can't listen over 20khz and why can't.
With all respect your opinion about means " nothing " in favor or against that issue with out " support ". Mijo, bone is only and example and not even you can prove that changes in the air SPL can't be detected by bones.
Raul, I am not arguing that other tissues besides ears can sense sound. There is a video of a fellow who is deaf as a door knob who listens to his system daily. He says he can "feel" the music. My only point of contention is at what frequency this occurs at. Most of us can easily sense bass below 250 Hz. But, our sensitivity would decline as frequency rises. People who have lost their hearing would be much more sensitive because when one sense is lost the others are heightened. As far as how high is concerned I do not know. The papers you reference are nowhere near substantial enough. We are not radio receivers or bats. 200 kHz even at insane volumes is highly unlikely. Our nervous systems are not fast enough to register that and our structures are too large to resonate at those that frequency. Electrical signals travel down neurons at 350 feet per second. That is a snails pace. The only way our brains can function the way they do is the distances are small and the number of transistors (synapses) is insanely high.
I am aware of rumours that we may be dreadfully susceptible to subsonic vibrations, but have not yet heard of military research into ultrasonic warfare (and I assume that the military would be the ones to wish to exploit this if it were possible).
@mijostyn Bernard Katz would be proud of you for pointing that out (he was a clever man but a wretched lecturer as I recall). It is surely correct that our neurons cannot support frequency modulated information that oscillates too fast for transmission along the average length neuron. And we haven't allowed for the refractory period whilst the neuron "re-adjusts its dress" or returns the sodium and potassium ions to their resting position. But if I ignore this, I run into a problem. A transmission speed of 350fps means 1Hz is the limit for a 350 foot long neuron, no? Probably, the longest neurons in auditory circuits are those in the VIIIth nerve itself. Let's say a generous 2" from cochlear to nucleus at the medullopontine junction. So, 350 x 6 = 2100Hz. But we can, when young, hear much higher frequencies. A moment's thought tells me it doesn't work that way at all. Only certain hair cells in the spiral of the cochlea respond to corresponding frequencies of sound. Likely they all send their notifications of having been stimulated along their connecting neurons at the same frequency. IF the cochlear was capable of sensing ultrasonic vibration, then that would be sent upstream at the same speed of 350fps. But we don't seem to hear those very high frequencies, even in the youngest and healthiest of specimens.
One could postulate that a general ultrahigh frequency effect might be exerted on the brain by other means (bone conduction, CSF conduction and ?glial physical vibration), but that wouldn't be anything other, I think, than a general degradation of brain function. I think that assuming we can in some way enjoy music that includes ultrasonic information, even as we have lost the intermediate high frequencies through aging, is hopeful, at best.
@mijostyn : You are trying to win and this is not the issue.
I never post or talk about 200khz, so what's all about.
Re-read and then post again or leave that way but please don't try to win, it's not the main subject:
""" Given the existence of musical-instrument energy above 20 kilohertz, it is natural to ask whether the energy matters to human perception or music recording. The common view is that energy above 20 kHz does not matter, but AES preprint 3207 by Oohashi et al. claims that reproduced sound above 26 kHz "induces activation of alpha-EEG (electroencephalogram) rhythms that persist in the absence of high frequency stimulation, and can affect perception of sound quality."  Oohashi and his colleagues recorded gamelan to a bandwidth of 60 kHz, and played back the recording to listeners through a speaker system with an extra tweeter for the range above 26 kHz. """
@mijostyn : What we can sense and what we need to know how measure, where measure, tools, etc. etc is extremely complex in a human being body where the brain knowledge by scientist/neurologist is only 27% and this 27% not inclusive in " deep " fashion . Your ears maybe can detect 18khz however you listen a way higher frequencies and even the brain sinthetized following harmonics by its incencious memory experiences during your life.
So not you or me or any one else could say: this is inaudible. Well you listen 24khz that is inaudible conciensous for you.
We all have to learn, I'm learning from this thread about because I have to make some searh on that issue.
Who win? everybody, not me or you but everybody.
Dear @dogberry : " is hopeful, at best ".
Well in the link posted ( the first one. ) those gentlemans came from CalTech, MIT and AES, so are not ametaurs but gentlemans with high knowledge levels and try to explain as better they can:
" From the fact that changes in subjects' EEGs "persist in the absence of high frequency stimulation," Oohashi and his colleagues infer that in audio comparisons, a substantial silent period is required between successive samples to avoid the second evaluation's being corrupted by "hangover" of reaction to the first. The preprint gives photos of EEG results for only three of sixteen subjects. I hope that more will be published ".
At the end is that exist lower than we can think knowledge levels by scientist of the overall human being TRUE " operation " whole body and specially this high frequency main subject because who cares about when it's enough that " somebody " says: " inaudible " and that's it. Rigth?
winning or losing has nothing to do with it Raul. This is a conversation trying to determine the way things work on a rational basis. We are forced into making assumptions about certain things. That humans can sense sound by mechanisms other than the normal auditory pathways is not in doubt. That it affects the way we listen is obvious. Some crazy fools like me surround themselves in subwoofers powered by huge amplifiers just so we can have that effect. Given the variability of human traits and associated issues like a hearing deficit. We vary in our ability to do this and at what frequency. Certainly the visceral sensation of music adds to our enjoyment. There is audible, by whatever means and inaudible. It is hard to know what you are missing.
Now stick the Pyxi in the Acrux box and send both the Pyxi and the Acrux Pyxi to a reviewer of high astute. 😈
And, will you please get on Christan and Donna. They are supposed to be designing a tonearm.