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SOTA Pyxi has arrived

franspambot said:
@wyn palmer have you considered sending a unit to Audio Science Review? I'm certain Amir would love to take look at it. Specs say it should make one of the best reviews, which would be great publicity for you all and help get the word out on no-nonsense, performant phono preamplifiers.
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I've considered that. However it's not my call. I believe that there are at least five reviews in process...
Besides, Amir and I have a bit of a difference of opinion as to what is important for phono stage reviews.
 
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wyn palmer said:
Besides, Amir and I have a bit of a difference of opinion as to what is important for phono stage reviews.
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That could make for a good thread. I don't find him combative and members there would welcome it. While not the most comprehensive reviews, the most scrutinized element is clipping. A lot of designers have engaged recently, see the Hagerman Bugle3 and ifi Zen reviews. It would be great to have that kind of dialogue continue.
 
franspambot said:
That could make for a good thread. I don't find him combative and members there would welcome it. While not the most comprehensive reviews, the most scrutinized element is clipping. A lot of designers have engaged recently, see the Hagerman Bugle3 and ifi Zen reviews. It would be great to have that kind of dialogue continue.
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I don't find him combative. Quite the opposite. He has simply shut down conversations when he finds it convenient- but that's a reasonable approach.
To be honest, I haven't visited ASR for years and I've no idea what the "clipping" issue is.
The WP architecture has the 75us in the first gain stage, and that is followed by an additional pole to compensate for the transition to unity gain prior to the 3180us/318us stage so overload is extremely well handled. I'll probably look it up on ASR, but if you can comment further, it would be appreciated.
 
wyn palmer said:
I don't find him combative. Quite the opposite. He has simply shut down conversations when he finds it convenient- but that's a reasonable approach.
To be honest, I haven't visited ASR for years and I've no idea what the "clipping" issue is.
The WP architecture has the 75us in the first gain stage, and that is followed by an additional pole to compensate for the transition to unity gain prior to the 3180us/318us stage so overload is extremely well handled. I'll probably look it up on ASR, but if you can comment further, it would be appreciated.
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It's nothing specific really, only that most of the phono preamps get a bit of criticism for potentially not handling clipping well. Considering the landscape, it's all likely fair. For example, "I would have wanted to see higher tolerance of input spikes as to lower the chances of clicks and pops clipping:"
https://www.audiosciencereview.com/forum/index.php?threads/hagerman-bugle3-phono-stage-review.43069/
I think the above is a good example of what his phono preamp reviews look like now. It's a positive review in the end and there is tougher criticism in the comments section from members. Example: https://www.audiosciencereview.com/...-phono-stage-review.43069/page-2#post-1525623

If you are interested, here is the start of one designer discussing the "low headroom" of his preamp: https://www.audiosciencereview.com/...ifi-zen-phono-review-phono-stage.35240/page-6
 
The max velocity ever encoded on an LP is c.70cm/sec and that is at about 5kHz, and about 35 cm/sec at 1kHz.
Stereo Lab - Maximum recorded velocities on gramophone records (pspatialaudio.com)
I've digitized thousands of LPs and the max amplitude I've seen is 14dB above the 1kHz 5cm/sec rms reference level for the cartridge- which would be 35cm/sec if it were at 1khz- so my experience and the paper agree.
The Pyxi, if I remember correctly, clips at c. +20dBv rms, or 23dBv peak at pretty well every frequency due to the architecture, so it follows the RIAA curve fairly well and is very resistant to HF overloads. With a gain of 65dB at 1kHz the overload margin for a 250uv RMS rated cartridge (-72dBv @ 1kHz, 5cm/sec) is 20-65+72= 27dB. Because the inverse RIAA curve is followed, this overload margin is about 37dB at 5kHz. Lots of margin exists for a real-world cartridge at the rated sensitivity, even in the presence of scratches or ticks that exceed the allowable modulation level on the disk. The chosen architecture has lots of benefits...
 
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Decibel_116 said:
Done
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Presumably that means that you have (had?) a unit. Alas, I can't perform a search on AK. Any comments on it?
Amir declined to evaluate the DIY version when asked, and also the pre-production version of the Pyxi, so I can't say that his evaluation is of personal significance.
What I have found is that ASRs influence on the members of the buying public that are interested in a phono stage is essentially zero.
Hifi "magazine" reviews are much, much more valuable.
The Pyxi is also mostly focused on being a low cost high performance MC phono stage and not a MM, and it's actually better as such.
Otherwise, it should be similar to the Mani 2 in a number of respects, and how Amir will assess it is anybody's guess.
 
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34dean said:
Another 3 hour session in the books.
Folks… this unit is superb. Period.
Hard to fathom it’s just $300.
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You really are a voice in the wilderness. I'm very glad that you're enjoying it.
I've not had any bad reports back (except for the ortofon/SUT noise issue, which is just how it is), and many reactions just like yours.
 
wyn palmer said:
Presumably that means that you have (had?) a unit. Alas, I can't perform a search on AK. Any comments on it?
Amir declined to evaluate the DIY version when asked, and also the pre-production version of the Pyxi, so I can't say that his evaluation is of personal significance.
What I have found is that ASRs influence on the members of the buying public that are interested in a phono stage is essentially zero.
Hifi "magazine" reviews are much, much more valuable.
The Pyxi is also mostly focused on being a low cost high performance MC phono stage and not a MM, and it's actually better as such.
Otherwise, it should be similar to the Mani 2 in a number of respects, and how Amir will assess it is anybody's guess.
Click to expand...

With all the hype on this forum about the Pyxi, I got on the wait list and received mine a while back. I am a little bit of an electronics nerd being an engineer and an audiophile. So, I pick up different gear from time to time to evaluate for myself. Lately, I have been on a phono preamp and MC cartridge kick. The latest phono preamps being the Pyxi and the BMC MCCI Signature. The BMC being of the transimpedance type. I did a quick comparison of the two and noticed some fairly significant "hiss" when the Pyxi when switched in. This was with the preamp volume at normal listening level. Other than that, I did not notice anything offensive about the Pyxi as far as distortion or other signal anomolies. The BMC MCCI was dead silent in comparison and had a particular sense of control on the signal that is very hard to describe. It had a sort of "ease" to the music that is very compelling. Now, these two preamps couldn't be more different and are certainly in different price and performance categories.

I compared the Pyxi to a couple other phono preamps I have, and the hiss continue to be of concern - at least in the configuration I was running. So, I had a thought and contacted Amir to see if he was interested in testing my Pyxi. He very graciously agreed to test it, so I sent it in. It may be a while before he is able to test it. He has quite a backlog. I sent it out of curiosity and to see how it compares to some of the units he has tested already. I have the utmost respect for Amir and the service he provides to this audio hobby.
 
Yes, it must be very reassuring knowing that Amir will just measure the preamp and not listen to it, and the received SINAD value will put it on the list of the preamps just where it belongs. His service to the audio hobby is truly immeasurable. Cut the BS and give us the SINAD. SINAD rules.
 
Decibel_116 said:
With all the hype on this forum about the Pyxi, I got on the wait list and received mine a while back. I am a little bit of an electronics nerd being an engineer and an audiophile. So, I pick up different gear from time to time to evaluate for myself. Lately, I have been on a phono preamp and MC cartridge kick. The latest phono preamps being the Pyxi and the BMC MCCI Signature. The BMC being of the transimpedance type. I did a quick comparison of the two and noticed some fairly significant "hiss" when the Pyxi when switched in. This was with the preamp volume at normal listening level. Other than that, I did not notice anything offensive about the Pyxi as far as distortion or other signal anomolies. The BMC MCCI was dead silent in comparison and had a particular sense of control on the signal that is very hard to describe. It had a sort of "ease" to the music that is very compelling. Now, these two preamps couldn't be more different and are certainly in different price and performance categories.

I compared the Pyxi to a couple other phono preamps I have, and the hiss continue to be of concern - at least in the configuration I was running. So, I had a thought and contacted Amir to see if he was interested in testing my Pyxi. He very graciously agreed to test it, so I sent it in. It may be a while before he is able to test it. He has quite a backlog. I sent it out of curiosity and to see how it compares to some of the units he has tested already. I have the utmost respect for Amir and the service he provides to this audio hobby.
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What was the configuration you used? I have performed extensive testing of the Pyxis etc. and I'm curious. By configuration I mean, gain, cartridge type etc.
Thanks!
 
wyn palmer said:
What was the configuration you used? I have performed extensive testing of the Pyxis etc. and I'm curious. By configuration I mean, gain, cartridge type etc.
Thanks!
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Me too, all my DIY units had no hiss at all with nothing connected just the outputs to the amp. Having said that , MM its super dead silent, and with MC I have a slight hum. However I attribute that to my cable choice and how its run in my system. When time permits and motivation follows I will revisit the cabling issue.

I wonder if his unit might not be up to par or something went south or damaged .

Athanasios
 
Nashou66 said:
Me too, all my DIY units had no hiss at all with nothing connected just the outputs to the amp. Having said that , MM its super dead silent, and with MC I have a slight hum. However I attribute that to my cable choice and how its run in my system. When time permits and motivation follows I will revisit the cabling issue.

I wonder if his unit might not be up to par or something went south or damaged .

Athanasios
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More likely it's something about the way it's being used- in MM mode with a high gain SUT, for example.
The Pyxi does not have FET inputs, and in MM mode the input current noise is very high. This is basically identical to the Mani2. It was one of those compromises needed to hit the price point.
The Acrux is most equivalent to the DIY design.
However, the Pyxi does work quite well in MC mode- better than in MM mode. That was its target market.
The absolute worst way to use the device is in MM mode with a high gain SUT attached.
There is a MM unit under consideration.
Still, I am always interested in user observations, and I have no issues with him sending the unit to Amir.
I also welcome the opportunity to exchange observations with @Decibel_116 as that is the main reason that I am doing the designs.
 
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CrSens said:
This makes it the perfect candidate for ASR review.....how come it is now suddenly accepted for review?
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I would be very interested in seeing how it measures on Amir's setup vs. my own. That is the main reason that I asked Amir to test a unit in the first place.
The correspondence between simulation and my measurements is remarkably good, and it would be very interesting to see what his APX555B reports, whatever concerns I might have concerning his methodology.
 
One other comment. I am fortunate enough to have three local Pyxi users (basically members of the local audio club) and I've had the chance to hear the unit versus other phono stages- all of which are at substantially higher price points. All three users use MC cartridges.
The noise was not noticeable. In fact the comment was made that the unit has very low hum, and comparable "hiss". These experiences are congruent with my own and with SoTA's, where comment has been made on how overall quiet it seems to be. The unit has also acquitted itself extremely well at various audio shows and demonstrations.
Contrary to what SoTA claims (I am not responsible for the inaccuracies in their advertising blurbs- they don't seem to act on my suggested changes) - the unit has OK noise performance, at least as far as the MC stage is concerned, but for MM it's entirely a function of the source impedance.
As for "a sense of ease". I'm not going to comment on that as I don't have the slightest idea what it means, and I'm not going to enter into a Hi-Fi verbal concept exchange.
 
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