Have to say the Purifi 1ET400A sounds fabulous very crudely set up on the test bench here 
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Review and Measurements of Purifi 1ET400A Amplifier
- Thread starter amirm
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maty
Major Contributor
I insisted on the CMRR because it is the only value that is not exceptional in your new amplifier. To understand us better, by measurements the 1ET400A would get a 9.5/10. Improving the CMRR, 10/10.
That the PSRR is so high is something that I value very much, as a sufferer of a very noisy electrical grid.
I strongly hope that the auditions are in accordance with technical excellence.
Have to say the Purifi !ET400A sounds fabulous very crudely set up on the test bench here
View attachment 29833
Have to say the Purifi !ET400A sounds fabulous very crudely set up on the test bench here
View attachment 29833
How does the Purifi setup sound compared to your P701 amps?
Nikke
Member
- Joined
- Jul 2, 2019
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- 20
Definitively half serious.
I hope living in a Stressless, listening to music all day and giving the thumbs up or down is still available.
Salud!
I haven't performed any serious comparisons yet so I will hold fire on commenting.
Ultimately they are different beasts, the 1200 should be better for driving those very difficult speaker loads, but the 1ET is lower distortion. How this translates into sound quality is another matter. I will give feedback when I have had a chance to do some extended listening comparisons.
@Bruno Putzeys
I have the outmost respect for Mr. Putzeys vast engineering know how. But sometimes the choice of business partners leaves me wishing for a different story.
"-Especially the high end audio market has successfully bamboozled customers into thinking value lies in esoteric materials and parts (which after all is easy to do, easy to communicate and easy to make a margin on) rather than in improving actual performance by engineering (which is hard to do, hard to get across and only turns a profit if enough people see the point)."
With the DIY engagement I see a great man contributing to a reasonable development in the HiFi market, but with the Mola Mola products not so much. Making an extremely expensive housing out of a billet of aluminum doesn’t contribute to expand our hobby to a wider and younger audience. Sadly too many companies follow the same path. You can see videos on line from manufacturer like CH Precision and darTZeel making beautiful but, in my opinion, insane luxurious case work. darTZeel are proud to make a very simple circuit design with few components for best sound. Why not put the excellent sounding electronics in a modest economical case so more people can enjoy the excellent sound?
Now to my question for Mr. @Bruno Putzeys :
Based on the new Purifi 1ET400A Amplifier how would you recommend a DIY project approach to maximize sound performance?
Building it as two mono blocks in separate cases or a dual mono build in one case?
Internal vs. external power supply?
Would a large beefy linear power supply give any sonic benefits over switched? Some claim better bass performance, lower noise etc. with traditional linear supply.
Any benefits with internal shielding walls inside the case between boards?
Grounding philosophies, e.g. star configuration?
Internal wiring, type (material, strands, insulation), routing?
Connectors?
Thoughts about quality of solder?
Quality or type of AC chassis inlet (plug, switch, fuse combined)?
Normal internal fuse or “HiFi fuse”?
Thank you for your contributions to the HiFi Community.
I have the outmost respect for Mr. Putzeys vast engineering know how. But sometimes the choice of business partners leaves me wishing for a different story.
"-Especially the high end audio market has successfully bamboozled customers into thinking value lies in esoteric materials and parts (which after all is easy to do, easy to communicate and easy to make a margin on) rather than in improving actual performance by engineering (which is hard to do, hard to get across and only turns a profit if enough people see the point)."
With the DIY engagement I see a great man contributing to a reasonable development in the HiFi market, but with the Mola Mola products not so much. Making an extremely expensive housing out of a billet of aluminum doesn’t contribute to expand our hobby to a wider and younger audience. Sadly too many companies follow the same path. You can see videos on line from manufacturer like CH Precision and darTZeel making beautiful but, in my opinion, insane luxurious case work. darTZeel are proud to make a very simple circuit design with few components for best sound. Why not put the excellent sounding electronics in a modest economical case so more people can enjoy the excellent sound?
Now to my question for Mr. @Bruno Putzeys :
Based on the new Purifi 1ET400A Amplifier how would you recommend a DIY project approach to maximize sound performance?
Building it as two mono blocks in separate cases or a dual mono build in one case?
Internal vs. external power supply?
Would a large beefy linear power supply give any sonic benefits over switched? Some claim better bass performance, lower noise etc. with traditional linear supply.
Any benefits with internal shielding walls inside the case between boards?
Grounding philosophies, e.g. star configuration?
Internal wiring, type (material, strands, insulation), routing?
Connectors?
Thoughts about quality of solder?
Quality or type of AC chassis inlet (plug, switch, fuse combined)?
Normal internal fuse or “HiFi fuse”?
Thank you for your contributions to the HiFi Community.
A few things I can answer
Grounding
https://www.google.com/url?sa=t&sou...FjAAegQIAxAB&usg=AOvVaw3fqIp-YT2Zj7GWzlaXoaZc
Hifi fuse - come on, this is Audio Science Review.
Mains inlet - Just think about the route of your house wiring and the feed to your house before you get excited about anything other than bog standard IEC inlets.
Solder - Do you think the modules are made with pure silver solder?
PSU - The modules have very high PSRR. Switched mode is not a dirty word.
Grounding
https://www.google.com/url?sa=t&sou...FjAAegQIAxAB&usg=AOvVaw3fqIp-YT2Zj7GWzlaXoaZc
Hifi fuse - come on, this is Audio Science Review.
Mains inlet - Just think about the route of your house wiring and the feed to your house before you get excited about anything other than bog standard IEC inlets.
Solder - Do you think the modules are made with pure silver solder?
PSU - The modules have very high PSRR. Switched mode is not a dirty word.
PCBs tend tend toward use of ground planes over single-point or star-earthing.
Internal vs external power supply is a design/cost choice rather than a performance issue.
Wire choice is based on current carrying capability rather than material. Routing can matter.
The type of well designed power supply is not particularly relevant to performance.
Same with good quality, inexpensive connectors, such as used in recording studios.
Beefy internal shielding if required at audio frequencies indicates poor design.
Anything else that can be laid to rest? I am a somewhat experienced hands-on hobbyist(and EE) FWIW.
Internal vs external power supply is a design/cost choice rather than a performance issue.
Wire choice is based on current carrying capability rather than material. Routing can matter.
The type of well designed power supply is not particularly relevant to performance.
Same with good quality, inexpensive connectors, such as used in recording studios.
Beefy internal shielding if required at audio frequencies indicates poor design.
Anything else that can be laid to rest? I am a somewhat experienced hands-on hobbyist(and EE) FWIW.
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Indeed. In the linked pdf from Bruno he points out how star doesn't work at high frequencies.
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There are too many audio enthusiasts overthinking long resolved science and engineering matters and lots of charlatans who feed them, fuelling drivel in a warped mutual admiration circle.
Thank goodness for ASR.
Thank goodness for ASR.
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Here here
restorer-john
Grand Contributor
Hear, hear...
I don’t care to start a big debate but I would like to add the following:
When I started out as an electronic engineer in my youth many things where black or white. As I grew older and got more experienced more shades of gray became evident and I was humbled that not everything is easily explained with our present measurement techniques. 40 years of measurements have taught me to be more open minded.
I do not believe we can hear everything we can measure, nor do I believe we can today measure everything we can hear, I hope we will get closer someday.
Allow me to end by quoting some insightful men:
“The less one knows about the universe, the easier it is to explain.”–Leon Brunschvicg;
“It is open to every man to choose the direction of his striving; and also every man may draw comfort from Lessing's fine saying, that the search for truth is more precious than its possession.” — Albert Einstein
“Theories crumble, but good observations never fade.”—Harlow Shapley.
As for the search for truth, I know from my own painful searching, with its many blind alleys, how hard it is to take a reliable step, be it ever so small, towards the understanding of that which is truly significant. — Albert Einstein
So many people today–and even professional scientists–seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is–in my opinion–the mark of distinction between a mere artisan or specialist and a real seeker after truth. — Albert Einstein
“It’s easy to be excited about facts when they support our own opinions. It’s nice to believe that uncomfortable facts are fake. Likewise, it’s comforting to believe that everyone who disagrees with us is ignorant. When the truth is so obvious, we say, “How could anyone but an uneducated bumpkin deny it?”
And yet, it seems that much of our knowledge is incomplete and that our deeply held beliefs may be more fragile than we imagine.” - Edwin Leap, MD
When I started out as an electronic engineer in my youth many things where black or white. As I grew older and got more experienced more shades of gray became evident and I was humbled that not everything is easily explained with our present measurement techniques. 40 years of measurements have taught me to be more open minded.
I do not believe we can hear everything we can measure, nor do I believe we can today measure everything we can hear, I hope we will get closer someday.
Allow me to end by quoting some insightful men:
“The less one knows about the universe, the easier it is to explain.”–Leon Brunschvicg;
“It is open to every man to choose the direction of his striving; and also every man may draw comfort from Lessing's fine saying, that the search for truth is more precious than its possession.” — Albert Einstein
“Theories crumble, but good observations never fade.”—Harlow Shapley.
As for the search for truth, I know from my own painful searching, with its many blind alleys, how hard it is to take a reliable step, be it ever so small, towards the understanding of that which is truly significant. — Albert Einstein
So many people today–and even professional scientists–seem to me like someone who has seen thousands of trees but has never seen a forest. A knowledge of the historic and philosophical background gives that kind of independence from prejudices of his generation from which most scientists are suffering. This independence created by philosophical insight is–in my opinion–the mark of distinction between a mere artisan or specialist and a real seeker after truth. — Albert Einstein
“It’s easy to be excited about facts when they support our own opinions. It’s nice to believe that uncomfortable facts are fake. Likewise, it’s comforting to believe that everyone who disagrees with us is ignorant. When the truth is so obvious, we say, “How could anyone but an uneducated bumpkin deny it?”
And yet, it seems that much of our knowledge is incomplete and that our deeply held beliefs may be more fragile than we imagine.” - Edwin Leap, MD
Hi, I do not know if Bruno will be able to see these questions before he leaves during August but these are a few matters that I have been wondering about regarding switching amplifiers for some time on a conceptual level.
- Since a Class-D amplifier switches on and off in a finite amount of time, there has to be a minimum pulse width. How does this affect the ability of the amplifier to render detail particularly at lower volume levels? This also leads me to ask why we do not get linearity plots for class D amplifiers both in independent or manufacturers' measurements in order to show how linear the amplifier is at low signal levels at various audio frequencies? I remember Lyngdorf audio used a design where volume level was varied by varying the power supply output voltage. Is there a change we can get this nice idea implemented in Purifi amplifiers in the future? Also, out of curiosity, what is the typical range of the minimum pulse width in commercial class-D amplifiers?
- In the Audiophilestyle interview, "unmeasured distortions" were discussed. For feedback to correct an error it has to switch the FETs on or off at certain points. For an audio amplifier with a finite switching frequency, the number of possible switching cycles per wavelength of the input signal decreases significantly as we go up in frequency. So for an amplifier with a maximum switching frequency of 500khz, the maximum number of pulses goes down from 25,000 during the period of a 20hz input signal to only 25 pulses during the period of a 20khz input signal . How do we make sure that those unmeasured distortions (or should we say distortions that manifest under dynamic conditions) do not leak more and more into the output as we go up in audio frequencies because feedback can not force the signal to change fast enough due to the maximum switching frequency limitation. I would be interested to know if Purifi had tested amplifiers with higher switching frequencies into a variety of speaker loads and if any noticeable improvement in sound quality was discerned and if there is a switching speed beyond which no improvement was found.
- I understand that self oscillating amplifiers rely on the phase shift between the output and input signals to switch on and off and that the phase shift depends on the values of passive components like the output filter. Is there a possibility for jitter-like effects to be exist in self oscillating amplifiers due to component tolerances or the presence of non-linearities which may affect the component tolerances dynamically like capacitor value sensitivity to frequency?
- BTL amplifier configuration has been looked at suspiciously in audiophile circles. Is there any particular advantage for BTL amplifier configuration in class D amplifiers other being a way to obtain more power? (The reason for this question is one of the comments in the FAQs of ncore fusion amps manual which implied better audio performance from 2 amps in BTL configuration than one with similar power.)
- Since a Class-D amplifier switches on and off in a finite amount of time, there has to be a minimum pulse width. How does this affect the ability of the amplifier to render detail particularly at lower volume levels? This also leads me to ask why we do not get linearity plots for class D amplifiers both in independent or manufacturers' measurements in order to show how linear the amplifier is at low signal levels at various audio frequencies? I remember Lyngdorf audio used a design where volume level was varied by varying the power supply output voltage. Is there a change we can get this nice idea implemented in Purifi amplifiers in the future? Also, out of curiosity, what is the typical range of the minimum pulse width in commercial class-D amplifiers?
- In the Audiophilestyle interview, "unmeasured distortions" were discussed. For feedback to correct an error it has to switch the FETs on or off at certain points. For an audio amplifier with a finite switching frequency, the number of possible switching cycles per wavelength of the input signal decreases significantly as we go up in frequency. So for an amplifier with a maximum switching frequency of 500khz, the maximum number of pulses goes down from 25,000 during the period of a 20hz input signal to only 25 pulses during the period of a 20khz input signal . How do we make sure that those unmeasured distortions (or should we say distortions that manifest under dynamic conditions) do not leak more and more into the output as we go up in audio frequencies because feedback can not force the signal to change fast enough due to the maximum switching frequency limitation. I would be interested to know if Purifi had tested amplifiers with higher switching frequencies into a variety of speaker loads and if any noticeable improvement in sound quality was discerned and if there is a switching speed beyond which no improvement was found.
- I understand that self oscillating amplifiers rely on the phase shift between the output and input signals to switch on and off and that the phase shift depends on the values of passive components like the output filter. Is there a possibility for jitter-like effects to be exist in self oscillating amplifiers due to component tolerances or the presence of non-linearities which may affect the component tolerances dynamically like capacitor value sensitivity to frequency?
- BTL amplifier configuration has been looked at suspiciously in audiophile circles. Is there any particular advantage for BTL amplifier configuration in class D amplifiers other being a way to obtain more power? (The reason for this question is one of the comments in the FAQs of ncore fusion amps manual which implied better audio performance from 2 amps in BTL configuration than one with similar power.)
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maty
Major Contributor
Michel Davis (bavmike, Mivera Audio) made a interesting picture of the new module, where I can see the Rubycon electrolytics and the bottom metal part.
https://i.pinimg.com/originals/b3/77/00/b37700d1f0a53de706583f50e1848547.jpg
Optimized and reduced.
And the rear side of the input buffer with the OPA1612.
With how tiny it is to desolder two SMD resistors and weld other equivalents of 0.1% or 0.01% tolerance to increase the CMRR must be a fine job. A good magnifying glass would help
https://i.pinimg.com/originals/b3/77/00/b37700d1f0a53de706583f50e1848547.jpg
Optimized and reduced.
And the rear side of the input buffer with the OPA1612.
With how tiny it is to desolder two SMD resistors and weld other equivalents of 0.1% or 0.01% tolerance to increase the CMRR must be a fine job. A good magnifying glass would help
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I think I actually have another question, it might have been answered by @Bruno Putzeys somewhere already:
Will Purifi handle the sales to DIY customers themselves, or are you planning to outsource that, as it really doesn't seem like a part of your core competences?
Maty, I am pretty sure the vertical PCB is not the Input Buffer. Two OPA1612s are located on the input board each in close proximity to the XLR connectors. As one would expect the input buffer to be located on the input board. After all the vertical PCB does not look like it is removable, so I don't know why you would think that is the input buffer, since OEMs are supposed to be able to adjust the buffer along their preferences. It seems to be just a measure of primarily saving space on the main PCB and it probably simplifies the PCB layout significantly. I don't know what the IC in that SOIC-8 package does or even what IC that is, but I am sure Bruno could tell you. I can't even read the part number.
About the resistors, just wait for your module and modify it?! I think very few here are planning to actually do that, so I don't know why you are still going on about this? If you care so much, just do it. No big deal, should take about a minute. Also I suspect like Bruno, that thin film precision resistors from the same reel, produced within fractions of a second of each other, on the same machine, using the same batches of raw material to manufacture the part, are likely to be matched better than spec.
Will Purifi handle the sales to DIY customers themselves, or are you planning to outsource that, as it really doesn't seem like a part of your core competences?
Maty, I am pretty sure the vertical PCB is not the Input Buffer. Two OPA1612s are located on the input board each in close proximity to the XLR connectors. As one would expect the input buffer to be located on the input board. After all the vertical PCB does not look like it is removable, so I don't know why you would think that is the input buffer, since OEMs are supposed to be able to adjust the buffer along their preferences. It seems to be just a measure of primarily saving space on the main PCB and it probably simplifies the PCB layout significantly. I don't know what the IC in that SOIC-8 package does or even what IC that is, but I am sure Bruno could tell you. I can't even read the part number.
About the resistors, just wait for your module and modify it?! I think very few here are planning to actually do that, so I don't know why you are still going on about this? If you care so much, just do it. No big deal, should take about a minute. Also I suspect like Bruno, that thin film precision resistors from the same reel, produced within fractions of a second of each other, on the same machine, using the same batches of raw material to manufacture the part, are likely to be matched better than spec.
maty
Major Contributor
I had in mind what xrk971 is doing with YARRA preamp on diyaudio.com, with PCB daughters to change the sound.
I do not think it is a matter of cost, since those of 0.1% are not so expensive, the kit will cost a lot and third parties are ignored in the commercialization, and it is supposed to still be on time for the first order but it is not my decision.
I do not think it is a matter of cost, since those of 0.1% are not so expensive, the kit will cost a lot and third parties are ignored in the commercialization, and it is supposed to still be on time for the first order but it is not my decision.
To be honest I do understand what you are trying to tell me/us? The Purifi supports custom input buffers, the input board supplied is mainly for evaluation and testing purposes (as one can tell by the layout and speaker connectors used). Literally everything except for the main amp pcb can be adjusted to the OEMs/DIYers preferences?!
If a third party supplier decides to offer a custom input buffer board for purchase (as I am sure someone will), they can go ahead and use 0,01% resistors where it matters and socketed OpAmps, although the ladder would radically limit their choices. Or they can even make the whole buffer circuit an interchangeable daughterboard, so I don't see how third parties are ignored? I must say I find their approach fairly reasonable. The upside of daughterboards compared to socketed ICs would be that you can actually optimise the circuitry around the OpAmp as well, and that most newer parts are only available in SMD packages.
If a third party supplier decides to offer a custom input buffer board for purchase (as I am sure someone will), they can go ahead and use 0,01% resistors where it matters and socketed OpAmps, although the ladder would radically limit their choices. Or they can even make the whole buffer circuit an interchangeable daughterboard, so I don't see how third parties are ignored? I must say I find their approach fairly reasonable. The upside of daughterboards compared to socketed ICs would be that you can actually optimise the circuitry around the OpAmp as well, and that most newer parts are only available in SMD packages.
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maty
Major Contributor
That I thought that OPA1612 and, therefore, the buffer, was the PCB daughter. What I focused on was the presumed improvement of the CMRR at a minimum cost if it was verified that the simple change of two resistances (SMD) with another 0.1% tolerance made it feasible, regardless of where they were. Now or later.
It is a business decision. No further comment on the CMRR is necessary I think.
It is a business decision. No further comment on the CMRR is necessary I think.
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