AudioCircle
Industry Circles => NuPrime Audio => Topic started by: mresseguie on 17 Jan 2022, 04:48 pm
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Evolution STA $4995.00
The NuPrime Evolution STA offers a breakthrough in distortion reduction. We called that Only Distortion Cancellation (ODC) design, continued advancing the state-of-the-art Class-D for the past decade.
A typical feedback error correction design inverts the output signal for summation with the original input signal to derive the negative error signal, which adds to the next cycle of the input signal to form a more accurate output signal. Nonprime’s ODC Class-D design derives the error signal from MOSFET devices and the output filter circuit directly, significantly reducing the negative feedback signal, which resulted in a substantial reduction in distortion THD+N of 0.002% @1kHz(5W), and less than 0.005% THD+N at 1KHZ (2W-100W). This breakthrough improvement in Class-D design resulted in a natural and pure sound characteristic.
https://nuprimeaudio.com/product/evolution-sta/?v=7516fd43adaa
https://nuprimeaudio.com/product/evolution-sta/?v=7516fd43adaa
Specifications:
Power Output (RMS): 230W @ 8 Ohms , 310W @ 4 Ohms
Power Output (peak): 270W @ 8 Ohms , 360W @ 4 Ohms
Gain: x21
Sensitivity (to rated power): 2Vrms
Input Impedance: 47K Ohms
EVO STA WATT / THD / S/N (typical) : @5W (0.0025% ,95db) , @50W (0.007% , 105db) , @100W (0.01% , 110db)
Frequency Response: 10Hz to 50kHz (-3dB)
Trigger IN and OUT
Standby Power : 1.5W @ 115V outlet, 1.7W @ 230V outlet
Idle Power : 24W @ 115V outlet, 26W @ 230V outlet
Worldwide AC voltage: (115VAC / 230VAC) with Voltage Select Switch
AC Fuse : Slow blow , 7A , 250VAC
Dimension : 430mm x 372mm x 66.5mm
Weight : 10.5Kg
Package Dimension: 642mm x 594mm x 254mm
Package Weight : 14Kg
Color : Black or Silver
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Jason,
Congratulations on your new baby! I'm guessing this amp must be pretty awesome sounding. Have you got anything more to say that's not already on the website?
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Due to covid travel restrictions throughout Asia, I haven't been able to listen to Evo STA out of Taiwan factory. But I don't need to listen to it for myself, I can rely on the chief engineer. HiFi Advice has been reviewing our amps and we come close to challenge the reference CH A1.5 ($39,500). I think Evo STA has a shot at matching any class A reference amp.
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Jason,
Congratulations on your new baby! I'm guessing this amp must be pretty awesome sounding. Have you got anything more to say that's not already on the website?
Hi Michael,
I think one is being built now, with your name on it. . . :thumb:
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Hi Michael,
I think one is being built now, with your name on it. . . :thumb:
Go ahead...surprise me. :thumb:
:popcorn:
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Well the surprise is the one with your name on it should be on its way next week. 8)
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Rusty, I saw this discussion, below, by Ralph Karsten over on Audiogon…. and I’m wondering if you guys generally agree with him about distortion and sound and how you would describe your new amps distortion profile? Thanks.
“IMO/IME the most important measurements are distortion vs frequency and a spectral presentation of what the distortion signature looks like. If the distortion does not rise with frequency anywhere in the audio band, and if the distortion signature allows the lower ordered harmonics to mask the presence of the higher ordered harmonics, then the amp has a very good chance of sounding quite good.
Quite often, such as in the pages of Stereophile, the distortion is only measured at 100Hz. In a nutshell that's simply inadequate- so even though the distortion might seem quite low, that's not enough to know if the amp 'measures well'.
The ear uses the higher ordered harmonics to sense sound pressure and so is keenly sensitive to them (it has over a 120dB range)! A slight amount of audible higher ordered harmonics will cause the amp to sound brighter and harsher because the ear also assigns tonality to all forms of distortion. If there is enough of the 2nd and 3rd harmonics present they can mask the higher orders. This is why an SET, which has more higher ordered harmonic distortion than any other kind of amp, can sound so smooth, whereas most solid state amps with 2 or 3 orders of magnitude lower distortion and still sound harsh and bright”.
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Well the surprise is the one with your name on it should be on its way next week. 8)
Hot damn! I wonder how that happened?
I’ll burn it in for a few days before I give it a good listen.
Thanks, John!
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Hot damn! I wonder how that happened?
I’ll burn it in for a few days before I give it a good listen.
Thanks, John!
I lied. I plugged it in and just had to listen right away.
It was delivered about 2 hours ago. Outside temperature was about 40 F. When I pulled the amp out of the <awesome> packaging, the case felt as though it had sat in a fridge overnight. I know better than to make judgemental comments at this point because the amp is cold and <presumeably> needs a good 100 hours to wake up. It's just a baby.
This baby's got BASS!
:popcorn:
Going on 8 hours....vanishingly low distortion....Last night, while I was listening to Natalie Merchant's Paradise is There, my wife commented on how loudly I was playing it. It hadn't seemed loud because there were no distortion cues to catch my attention.
I'll probably burn it in for another 4 or 5 hours on my main system before connecting it to my Omnia A300 for 'dedicated' burning in on my office system. I'll let it play for a couple days before bringing it back down for a listen.
:popcorn:
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Rusty, I saw this discussion, below, by Ralph Karsten over on Audiogon…. and I’m wondering if you guys generally agree with him about distortion and sound and how you would describe your new amps distortion profile? Thanks.
“IMO/IME the most important measurements are distortion vs frequency and a spectral presentation of what the distortion signature looks like. If the distortion does not rise with frequency anywhere in the audio band, and if the distortion signature allows the lower ordered harmonics to mask the presence of the higher ordered harmonics, then the amp has a very good chance of sounding quite good.
Quite often, such as in the pages of Stereophile, the distortion is only measured at 100Hz. In a nutshell that's simply inadequate- so even though the distortion might seem quite low, that's not enough to know if the amp 'measures well'.
The ear uses the higher ordered harmonics to sense sound pressure and so is keenly sensitive to them (it has over a 120dB range)! A slight amount of audible higher ordered harmonics will cause the amp to sound brighter and harsher because the ear also assigns tonality to all forms of distortion. If there is enough of the 2nd and 3rd harmonics present they can mask the higher orders. This is why an SET, which has more higher ordered harmonic distortion than any other kind of amp, can sound so smooth, whereas most solid state amps with 2 or 3 orders of magnitude lower distortion and still sound harsh and bright”.
That's true. But nowadays all the state of the art Class-D amps sounded very good with low distortion anyway, it wasn't like that 10 years ago. Nuprime amps across the board already have distortion that most people don't pay attention to the THD+N. Anything less than 0.1% is hardly noticeable. Some model such as STA-9 or AMG STA has Class A transistors circuit in the preamp stage with even-order harmonics not to mask off the harshness but to create more warmth. Fundamentally all existing Class-D amps use a certain way to do noise reduction:
A typical feedback error correction design inverts the output signal for summation with the original input signal to derive the negative error signal, which adds to the next cycle of the input signal to form a more accurate output signal.
The Evo STA uses a new design to perform error correction and noise reduction.
Nonprime’s ODC Class-D design derives the error signal from MOSFET devices and the output filter circuit directly, significantly reducing the negative feedback signal, which resulted in a substantial reduction in distortion THD+N of 0.002% @1kHz(5W), and less than 0.005% THD+N at 1KHZ (2W-100W). This breakthrough improvement in Class-D design resulted in a natural and pure sound characteristic.
I have stated earlier that any noise reduction with THD+N below 0.1 is hardly noticeable, so why does it matter for Evo STA to further reduce the noise? Apparently, the new design of deriving error signals from the devices directly is very hard to do (never heard of anyone else doing this), and it changes the perception of sound than we can quantify it (THD+N is the only measurable spec but there are other improvements going on here).
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Jason,
Approximately how many hours of burn in is needed before the Evolution STA amp is considered fully burned in?
Edit:
For crying out loud! Isn’t there some way to burn in an amp more quickly than 24 hrs/day? Just kidding. My Evo STA is only up to about 70 hours <though I’m not counting very closely> because it’s in my main system with my tube pre, and I won’t run it 24/7. [Ignore me. I’m just grumpy.]
When the amp had burned in for about 20 hours, it made acoustic guitar sound all goofy like it was being played in a big toilet. I’ve noticed this effect in two other pieces of audio gear during the early burn in phase. I assume it has something to do with capacitors, but I’m only guessing.
Carry on.
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I have owned TDSS-modded Ref 20 mono amps and also heard Evo mono amps (very similar). *Question- I'm interested in the the new Evo STA amp however unless I am missing something, it appears to have been designed as a STEREO amp- why were monoblocks not considered?? Pardon the pun, but it would seem the natural 'evolution' to the Evo monos to have Evo 'STA' monos, and not only a stereo offering... Confused. Thx
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It’s described on the website:
“It is a stereo amplifier with a dual-mono configuration.”
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I have owned TDSS-modded Ref 20 mono amps and also heard Evo mono amps (very similar). *Question- I'm interested in the the new Evo STA amp however unless I am missing something, it appears to have been designed as a STEREO amp- why were monoblocks not considered?? Pardon the pun, but it would seem the natural 'evolution' to the Evo monos to have Evo 'STA' monos, and not only a stereo offering... Confused. Thx
It was designed as two mono amp in a box, sharing the same power supply. It is possible that we can make pure mono version if there is sufficient demand.
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So then regular Evo mono amps (given the advantages of separate power supplies; etc.) will still operate at a higher performance level then the new STA stereo version?
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So then regular Evo mono amps (given the advantages of separate power supplies; etc.) will still operate at a higher performance level than the new STA stereo version?
Evo One mono amp has a slight advantage with more power and being a mono amp. The sound quality is similar but if the power requirement is the same, Evo STA has an advantage.
If you are stepping up from ST-10, STA-9, AMG STA etc, then Evo STA is a clear choice.
If you are looking for a super high-end system and since Evo One is not available, Evo STA is a clear choice.
We decided to discontinue Evo One when Evo STA is out because 2 x Evo One (MSRP almost $8000) is not going to offer a significant advantage over the new Evo STA (MSRP $4995). We didn't make the Evo STA mono because we are concerned that $9000 a pair will not have a significant advantage over Evo STA. Therefore Evo STA in a box offers the best price/performance for the super high-end series. In fact, we think that it will be able to match the CH Precision A1.5 (ST-10M and AMG STA were reviewed by HiFi Advice and compared to A1.5).
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Sutts,
If I may add...
I've never heard the Ref 20 amps nor the Evo One mono amps, so I cannot offer any sort of comparison. However, this Evolution STA dual-mono amplifer sounds excellent in my system. It has burned in for ~130 hours now, and I'm very happy with how it sounds. Hopefully, I'll be able to set time aside for critical listening in the next week or so. In the meantime, I'm really enjoying all the music I've thrown its way - no complaints.
Michael
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Michael- thank you- very positive endorsement indeed re: the Evo STA amp. However (and regardless of Jason's opinion) I have yet to hear a stereo amp from a high end manufacturer that beats the mono block version of that same amp. Would be fascinating to compare side by side my previous TDSS Ref 20 or Evo monos to the new Evo STA- 'the proof is in the pudding' as they say- if possible I will find some way to hear the new EVO STA and report my findings.
By the way- I have also found that a very good tube pre can elevate the Nuprime amps to amazing levels. My Absolare Passion (single-ended) preamp with the mono blocks was spooky good, so much so that if I acquire an Evo STA I will keep that same pairing (likely with an Evo dac, of which I have owned as well and am a big fan of). The amps I had after that I felt that eclipsed the TDSS Ref 20 monos were the GAN-based Class D Merrill Element 116's- should never have sold them :( Bass deeper then Nuprime, and low level detail superb. I will say thought that I am in full agreement with Jason that his Engineer has nailed the proper tonality with the Nuprime amps- superb in this area for Class D, or regardless of topology- hope this is maintained/furthered with the new STA version.
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Our chief engineer designed Ref 20. TDSS mod is a very minor improvement over the standard Ref 20.
Since then we have ST-10 and then Evo One was a big evolutionary design (could have called it revolution) change from the old Nuforce designs (Ref 20 was the last generation).
AMG was a baby Evo One with its own differences.
So we can confirm that Evo STA has a very noticeable improvement over Ref 20.
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Michael- thank you- very positive endorsement indeed re: the Evo STA amp. However (and regardless of Jason's opinion) I have yet to hear a stereo amp from a high end manufacturer that beats the mono block version of that same amp. Would be fascinating to compare side by side my previous TDSS Ref 20 or Evo monos to the new Evo STA- 'the proof is in the pudding' as they say- if possible I will find some way to hear the new EVO STA and report my findings.
By the way- I have also found that a very good tube pre can elevate the Nuprime amps to amazing levels. My Absolare Passion (single-ended) preamp with the mono blocks was spooky good, so much so that if I acquire an Evo STA I will keep that same pairing (likely with an Evo dac, of which I have owned as well and am a big fan of). The amps I had after that I felt that eclipsed the TDSS Ref 20 monos were the GAN-based Class D Merrill Element 116's- should never have sold them :( Bass deeper then Nuprime, and low level detail superb. I will say thought that I am in full agreement with Jason that his Engineer has nailed the proper tonality with the Nuprime amps- superb in this area for Class D, or regardless of topology- hope this is maintained/furthered with the new STA version.
I absolutely agree with you wrt tube preamps. While I have never heard an Absolare pre, I imagine it must be very nice. I’m using a Don Sachs 6SN7 Model 2 pre which I am very happy with.
I’m still debating whether I want to try the Evolution DAC.
Michael
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I’m still debating whether I want to try the Evolution DAC.
Michael
Of course you do. . . . :thumb:
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My wife and I left our home for a 4-day mini vacation. We returned this afternoon. After putting everything away, I powered up my DAC, Preamp, and the Evo STA amp, and put on some piano music to warm the components up.
About thirty minutes later....I'm listening to Eva Cassidy, and I'll be damned, but I keep hearing guitar plucks that I don't recall hearing before. The amp is now <after more than 150 hours of burn in> warm <tube> sounding yet there's incredible clarity, too. I'm impressed! Jason's engineer knows his stuff.
John, you'll just have to wait a bit before I decide on the DAC. I need to sell a couple components first cuz Melody's begun noticing all the gear I have. :nono:
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What happened to the input stage?
The new good sounding input stage of the Evolution one is out?
Description Evo One : " A new input stage with a 1MΩ input impedance. The high input impedance allows the pre-amplifier to see a much easier load and hence introduces less harmonic distortion and phase delay to the system."
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+1 Fenek
Why do I get the feeling there is subtle information we are not receiving here... I would love to hear from Jason's Chief Engineer (not Jason) about the changes to the new Evo STA, and why certain decisions were made in design. For example, I generally prefer monoblocks (if available), and I can't believe they would not carry on the tradition of their top model being monoblocks- why offer stereo only? I understand Jason's explanation, however there are going to be customers like myself that always enjoyed Nuforce/Nuprime's top offering being a mono version, not stereo.
Are they thinking that a mono version won't sell as well as a stereo version due to price point?? Of course we are not privy to their sales numbers, and maybe this is a big part of it- perhaps Nuprime's stereo offerings outsell the corresponding monoblock option like 99 to 1 or something and this was a Corporate costing/profit decision- maybe that's it. But don't tell me that they could not get even higher performance if they offered a monoblock version of the new Evo STA- I am sure the mono version of that would be even better. Look at Merrill Audio and even Atmasphere's new Class D offering- they are primarily monoblock offerings...
I appreciate any opinions on the above...
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+1 Fenek
Why do I get the feeling there is subtle information we are not receiving here... I would love to hear from Jason's Chief Engineer (not Jason) about the changes to the new Evo STA, and why certain decisions were made in design. For example, I generally prefer monoblocks (if available), and I can't believe they would not carry on the tradition of their top model being monoblocks- why offer stereo only? I understand Jason's explanation, however there are going to be customers like myself that always enjoyed Nuforce/Nuprime's top offering being a mono version, not stereo.
Are they thinking that a mono version won't sell as well as a stereo version due to price point?? Of course we are not privy to their sales numbers, and maybe this is a big part of it- perhaps Nuprime's stereo offerings outsell the corresponding monoblock option like 99 to 1 or something and this was a Corporate costing/profit decision- maybe that's it. But don't tell me that they could not get even higher performance if they offered a monoblock version of the new Evo STA- I am sure the mono version of that would be even better. Look at Merrill Audio and even Atmasphere's new Class D offering- they are primarily monoblock offerings...
I appreciate any opinions on the above...
I believe Jason already answered your question. Your input helps that.
It is possible that we can make pure mono version if there is sufficient demand.
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Two questions for Jason (or John):
My Evolution STA is connected to my preamp via single ended ICs. Is there a SQ benefit in switching to a balanced connection?
Second question is related to the first, but is specific to the Evolution DAC. If the Evo DAC is connected to the Evo STA, is there a sonic benefit to using the balanced connection over the single ended connection?
Twice I fooled myself into thinking my Evo STA had fully burned in only to discover further SQ improvements some 40 hours later. It's well past 200 hours now, and is superb sounding in my system. :popcorn:
Michael
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Two questions for Jason (or John):
My Evolution STA is connected to my preamp via single ended ICs. Is there a SQ benefit in switching to a balanced connection?
The benefit will depend on the preamp.
Second question is related to the first, but is specific to the Evolution DAC. If the Evo DAC is connected to the Evo STA, is there a sonic benefit to using the balanced connection over the single ended connection?
For a full balanced design, XLR simply has double the voltage over RCA for long distance cabling. For short distance, the difference should not be noticeable.
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Our New Zealand dealer, Totally Wired knows a lot about the entire range of Nuprime products and have written many good reviews. Here's the latest review of Evolution STA
https://totallywired.nz/nuprime-2/nuprime-evolution-sta/ (https://totallywired.nz/nuprime-2/nuprime-evolution-sta/)
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Our New Zealand dealer, Totally Wired knows a lot about the entire range of Nuprime products and have written many good reviews. Here's the latest review of Evolution STA
https://totallywired.nz/nuprime-2/nuprime-evolution-sta/ (https://totallywired.nz/nuprime-2/nuprime-evolution-sta/)
Thanks. I read this review, and I agree with what the fellow said. It really is a great amp. I'll eventually post my own very positive write up here on AC, but I have precious little spare time for the next couple weeks.
Michael
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A reviewer from Taiwan mentioned the difference between Evo One and Evo STA. So here's his subjective comment:
The difference is that EVO STA has a clearer outline, clearer sound and image, slightly smaller body, less warm and bright tone, and EVO One sounds more relaxed, stable and mellow. Simply put, EVO STA is like a young version of EVO One.
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… I agree with what the fellow said. It really is a great amp.
Michael
Did you happen to spend any time with it at low SPL, which for me is 65-ish dB avg @ 8’? If so I’d appreciate your thoughts on how well it performed.
This is one of few Class D amps that I find intriguing. For whatever ill informed reasons I seem to be biased against the many examples of amps that “simply” integrate modules. Thanks.
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Did you happen to spend any time with it at low SPL, which for me is 65-ish dB avg @ 8’? If so I’d appreciate your thoughts on how well it performed.
This is one of few Class D amps that I find intriguing. For whatever ill informed reasons I seem to be biased against the many examples of amps that “simply” integrate modules. Thanks.
Hello, Allan.
As it happens, I spend much of my time listening at low SPLs - because my wife can't concentrate on her tasks if the music is too loud, and because I suffer from hyperacusis in my right ear. [Encouraging my wife to go shopping every day results in fewer funds for my audio hobby :nono: Hyperacusis is <somewhat> treatable with pink noise therapy or a knowledgeable acupuncturist.] I haven't bothered to measure my listening position to my speakers in ages, but I think it's ~10'.
I still haven't posted my review of this amp, but I can tell you I really like it. I haven't switched back to my much loved KT88 amp since the Nuprime amp arrived. My sole complaint about it is that <unlike my KT88 amp> it doesn't heat up my listening room during the winter. :wink:
Michael
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Hello, Allan.
As it happens, I spend much of my time listening at low SPLs - because my wife can't concentrate on her tasks if the music is too loud, and because I suffer from hyperacusis in my right ear. [Encouraging my wife to go shopping every day results in fewer funds for my audio hobby :nono: Hyperacusis is <somewhat> treatable with pink noise therapy or a knowledgeable acupuncturist.] I haven't bothered to measure my listening position to my speakers in ages, but I think it's ~10'.
I still haven't posted my review of this amp, but I can tell you I really like it. I haven't switched back to my much loved KT88 amp since the Nuprime amp arrived. My sole complaint about it is that <unlike my KT88 amp> it doesn't heat up my listening room during the winter. :wink:
Michael
Greetings Michael. Many thanks for sharing your experience. I appreciate it. I returned to edit my post to characterize SPL preferences but was happy to find your response.
To SPL I should say I need to keep the volume down for reasons similar to yours but, for critical listening, absolute numbers are less important than life size SPL. Single, close mic’d front row acoustic guitar expectations are different than mid row concert hall symphony.
Besides a 60 year old back, the inefficiency of a full time 200W space heater is the primary reason I hesitate to jump on Class A. A west facing room in the middle of a NC summer is uncomfortable enough. I’m also both a cheap SOB and (more than) a bit irrational. I spend more on LED bulbs than we’re ever likely to save in electricity usage but I’m an engineer who’s obsessed (to a fault) with efficiency.
So the more I think seriously about amps the more I consider the value in finding that just right combination of performance, efficiency, and what I can only describe as topographical artistry.
In my limited experience I believe many Class A or A/B designs are owned end to end by the designer and reflect their values. Class D seems to be a relatively new art form with most designers choosing a paint by numbers approach. Constrained by the same picture, they’re left with primary color selection being their most significant differentiator. Perhaps this is an overly harsh and ill informed characterization and genuinely unfair to those who passionately labor in this art form. If you are one of those or one of their adherents please accept my humble apologies. I mean no disrespect.
Perhaps it’s premature for me to consider this, but what little I’ve learned about NuPrime in the past few hours suggests they are to Class D what someone like Nelson Pass is to Class A - at least in values. Bruno Putzeys and others will certainly come to mind but I’m thinking only of end to end design.
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I think your end-to-end remark is really true. But that is also where we are seeing some interesting evolution - we finally have more full-design class D amps instead of just module integrators.
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This is a slight cause of concern for me:
"...The difference is that EVO STA has a clearer outline, clearer sound and image, slightly smaller body, less warm and bright tone, and EVO One sounds more relaxed, stable and mellow. Simply put, EVO STA is like a young version of EVO One..."
I still want the body; large staging; and relaxed nature I had with my previous TDSS-modded Ref 20's and Evo monos, and was hoping this would be retained in the new Evo STA... I have yet to receive a response on this thread of what technically in the new design accounts for the sonic changes described above. Perhaps the only choice then is to go back to the original Evo monoblocks. Well, the dealer in my country (Canada) has yet to receive his Evo STA amp- hopefully soon and I will review it (likely with the superb Absolare preamp and Jeff Rowland Aeris dac with outboard SuperCap p/s and post my results here...
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In my limited experience I believe many Class A or A/B designs are owned end to end by the designer and reflect their values. Class D seems to be a relatively new art form with most designers choosing a paint by numbers approach. Constrained by the same picture, they’re left with primary color selection being their most significant differentiator. Perhaps this is an overly harsh and ill informed characterization and genuinely unfair to those who passionately labor in this art form. If you are one of those or one of their adherents please accept my humble apologies. I mean no disrespect.
Perhaps it’s premature for me to consider this, but what little I’ve learned about NuPrime in the past few hours suggests they are to Class D what someone like Nelson Pass is to Class A - at least in values. Bruno Putzeys and others will certainly come to mind but I’m thinking only of end to end design.
For those who are curious about how we design our amps since 2005 (Class-D is no longer a new art form) from the ground up (we don't use off-the-shelf modules), please read these two guides:
https://nuprimeaudio.com/guides/amp-design/ (https://nuprimeaudio.com/guides/amp-design/)
https://nuprimeaudio.com/guides/amp-comparison/ (https://nuprimeaudio.com/guides/amp-comparison/)
HiFi-Advice has been comparing our ST-10, ST-10M, and AMG STA with the $40,000 CH A1.5. Each amp has some characteristics that matched or surpassed the reference Class A amp. Our design goal for Evo STA was to combine the best of ST-10M and AMG STA. Let's see how we do this time :thumb:
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This is a slight cause of concern for me:
"...The difference is that EVO STA has a clearer outline, clearer sound and image, slightly smaller body, less warm and bright tone, and EVO One sounds more relaxed, stable and mellow. Simply put, EVO STA is like a young version of EVO One..."
I still want the body; large staging; and relaxed nature I had with my previous TDSS-modded Ref 20's and Evo monos, and was hoping this would be retained in the new Evo STA... I have yet to receive a response on this thread of what technically in the new design accounts for the sonic changes described above. Perhaps the only choice then is to go back to the original Evo monoblocks. Well, the dealer in my country (Canada) has yet to receive his Evo STA amp- hopefully soon and I will review it (likely with the superb Absolare preamp and Jeff Rowland Aeris dac with outboard SuperCap p/s and post my results here...
Keep in mind that we are comparing Evo STA and Evo One, not with other amps. So Evo STA having a slightly smaller body than Evo One is not a bad thing, we have to consider everything as a whole. The purpose is to present music more precisely.
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For those who are curious about how we design our amps since 2005 (Class-D is no longer a new art form) from the ground up (we don't use off-the-shelf modules), please read these two guides:
https://nuprimeaudio.com/guides/amp-design/ (https://nuprimeaudio.com/guides/amp-design/)
https://nuprimeaudio.com/guides/amp-comparison/ (https://nuprimeaudio.com/guides/amp-comparison/)
HiFi-Advice has been comparing our ST-10, ST-10M, and AMG STA with the $40,000 CH A1.5. Each amp has some characteristics that matched or surpassed the reference Class A amp. Our design goal for Evo STA was to combine the best of ST-10M and AMG STA. Let's see how we do this time :thumb:
Thank you for the references. They’re quite informative and part of the reason I got less sleep than usual last night.
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For those who are curious about how we design our amps…:
https://nuprimeaudio.com/guides/amp-comparison/ (https://nuprimeaudio.com/guides/amp-comparison/)
Thank you for the references. They’re quite informative and part of the reason I got less sleep than usual last night.
Rusty, The Evo STA isn’t listed in the Sonic Characteristic table. Would you please fill in the blanks? Thank you.
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Alan
I just looked and it's there.
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Alan
I just looked and it's there.
Jack,
If you scroll down to the bottom of the page, you'll see the separate 'Sonic Characteristics' graph (below the photograph of the Evolution One). The Evolution STA has not yet been added.
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I was referring to the big grid.
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Greetings Michael. Many thanks for sharing your experience. I appreciate it. I returned to edit my post to characterize SPL preferences but was happy to find your response.
You're welcome!
To SPL I should say I need to keep the volume down for reasons similar to yours but, for critical listening, absolute numbers are less important than life size SPL. Single, close mic’d front row acoustic guitar expectations are different than mid row concert hall symphony.
Agreed. I listen to a ton of 'simple' music - solo acoustic instruments, girl & a guitar, Jazz trio/quartets, etc. at low level SPL, but turn up the volume for orchestral music, Led Zeppelin, and similar music (but not as often as I did in my youth).
Besides a 60 year old back, the inefficiency of a full time 200W space heater is the primary reason I hesitate to jump on Class A. A west facing room in the middle of a NC summer is uncomfortable enough. I’m also both a cheap SOB and (more than) a bit irrational. I spend more on LED bulbs than we’re ever likely to save in electricity usage but I’m an engineer who’s obsessed (to a fault) with efficiency.
I see we have a lot in common - and I don't just mean LED bulbs. My back is about 1.5 years older than yours, but who's quibbling? :lol: My living room is east facing, so my KT88 comes in handy during winter mornings.
So the more I think seriously about amps the more I consider the value in finding that just right combination of performance, efficiency, and what I can only describe as topographical artistry.
In my limited experience I believe many Class A or A/B designs are owned end to end by the designer and reflect their values. Class D seems to be a relatively new art form with most designers choosing a paint by numbers approach. Constrained by the same picture, they’re left with primary color selection being their most significant differentiator. Perhaps this is an overly harsh and ill informed characterization and genuinely unfair to those who passionately labor in this art form. If you are one of those or one of their adherents please accept my humble apologies. I mean no disrespect.
Perhaps it’s premature for me to consider this, but what little I’ve learned about NuPrime in the past few hours suggests they are to Class D what someone like Nelson Pass is to Class A - at least in values. Bruno Putzeys and others will certainly come to mind but I’m thinking only of end to end design.
I suspect Jason will happily accept the compliment. I've followed Nuprime's Class D amp progression from the release of their 'cute' little IDA-8 all-in-one amp to their newest Evo STA, and have been impressed by most of their amps that I've gotten to try. I'd still have my IDA-8 if I hadn't gifted it to my son and daughter-in-law as a house warming gift. [I eased my pain by buying an Omnia A300. :) ]
Michael
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Alan
I just looked and it's there.
I see it in the first table “Relative Ranking of Power Amps” but not the second “Sonic Characteristic” table below the Evo One top view.
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Some may find our New Zealand Dealers evaluation valuable to the EVO STA
https://totallywired.nz/nuprime-2/nuprime-evolution-sta/
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I think he is referring to the bottom table. I forgot to update.
The bottom table is simply a summary from the product page.
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The bottom table is simply a summary from the product page.
Thank you Rusty.
With that in mind would you please help me understand one choice in particular? I’m coming from a place of technical ignorance and am really trying to understand the technology and implications.
I haven’t found a reference that helps me help understand the significance in choosing an op amp over a Class A Transistor Module.
From the Sonic Characteristic section I found this statement: Practically all the amp products on the market use Op Amp for preamp stage. Only a few very high end products use discrete transistors design.
From the Evo STA product page I found these statements:
- The Evolution STA offers a breakthrough in distortion reduction (Only Distortion Cancellation) and rivals the Evolution One in sound quality.
- Preamp stage and Class D oscillation circuit utilizing high-end NJR MUSES8820 op-amp.
- Hybrid Class-D technology that retains the merits of both Class-A and Class-D amplification.
I hope you understand that someone like me who isn’t as well informed as some could read into these statements that the STA rivals the One but uses a preamp stage is that is somehow inferior to that used in the One.
Does the STA rival the One in sound quality by trading the Class A Transistor Module for Only Distortion Cancellation?
From the descriptions I’ve found, op amps sound like the Class A Transistor Module packaged into a single device. Is that how or why the STA is considered a hybrid?
Thank you. I appreciate your help and patience.
Allan
Edit to add: If accurate, a reread of the NZ dealer review you posted before helped to understand the why of preamp choice - an evolution of the ST10. Still very interested in trade offs in preamp choice. Thanks again.
https://totallywired.nz/nuprime-2/nuprime-evolution-sta/
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Op Amp is a circuit that amplifies signal.
Op Amp modules are off-the-shelf parts that perform the above purpose. These modules are transistors packaged in a chip for commercial sales.
The Op Amp modules range in price and performance. Some like the MUSES8820 is expensive and very good.
Instead of using these off-the-shelf parts, an Op Amp circuit can be designed using transistors.
Very few high end audio companies in the world have engineer that can design custom Op Amp circuit that can create different sound characteristic. This is a very specialised skill. Some of you have heard about people swapping Op Amp to change the sound, that's the idea. But we are doing it at a whole different level and complexity.
I don't think our article implied that Op Amp modules are always inferior to custom Op Amp circuit. Obviously custom circuit is much more expensive and time consuming to design. The "Class D with a Soul" section of this article https://nuprimeaudio.com/guides/amp-design/ (https://nuprimeaudio.com/guides/amp-design/) talks about what I just said here. When our chief engineer design the op amp circuit, it is the preamp stage of the Class D topology, so he has to consider the entire design, so that he achieves the sound characteristic for the specific product. This is very complex. To design something like Evolution STA from the ground up, I think there are less than a handful of engineers in the world who can do that. The engineer must know analog design, Class D, and just happen to be an audiophile. :thumb:
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Op Amp is a circuit that amplifies signal.
Op Amp modules are off-the-shelf parts that perform the above purpose. These modules are transistors packaged in a chip for commercial sales.
The Op Amp modules range in price and performance. Some like the MUSES8820 is expensive and very good.
Instead of using these off-the-shelf parts, an Op Amp circuit can be designed using transistors.
Very few high end audio companies in the world have engineer that can design custom Op Amp circuit that can create different sound characteristic. This is a very specialised skill. Some of you have heard about people swapping Op Amp to change the sound, that's the idea. But we are doing it at a whole different level and complexity.
I don't think our article implied that Op Amp modules are always inferior to custom Op Amp circuit. Obviously custom circuit is much more expensive and time consuming to design. The "Class D with a Soul" section of this article https://nuprimeaudio.com/guides/amp-design/ (https://nuprimeaudio.com/guides/amp-design/) talks about what I just said here. When our chief engineer design the op amp circuit, it is the preamp stage of the Class D topology, so he has to consider the entire design, so that he achieves the sound characteristic for the specific product. This is very complex. To design something like Evolution STA from the ground up, I think there are less than a handful of engineers in the world who can do that. The engineer must know analog design, Class D, and just happen to be an audiophile. :thumb:
Many thanks Rusty. I appreciate the explanation. It’s starting to make sense.
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I found out more information about the linear power supply design in Evo STA.
There are two identical windings for two identical power outputs. Therefore Evo STA is really two mono amps in a box.
We design all our power supplies. Other features for EVO STA LPS:
- dual wires for each winding for low noise
- iron core is selected for low noise
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I found out more information about the linear power supply design in Evo STA.
There are two identical windings for two identical power outputs. Therefore Evo STA is really two mono amps in a box.
We design all our power supplies. Other features for EVO STA LPS:
- dual wires for each winding for low noise
- iron core is selected for low noise
Two mono amps in one box? Are there two power cords? 😉
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Between the CH and the NuPrime, certain key aspects have certainly noticeably shifted, but on the surface of it, and in an absolute sense, there is not very much to indicate that we just switched from a 31 K amplifier to one costing only 5 K. Honestly, it was more like switching from one high-end amplifier to another, invoking differences catering more to taste than to absolute quality. For instance, the Big Swiss amp remains the King of resolution and refinement. But to offset this, the NuPrime actually overshadows the CH in a couple of areas. Do read on to find out precisely how the two compare!
https://www.hifi-advice.com/blog/amplifier-reviews/power-amplifier-reviews/nuprime-evolution-sta-stereo-power-amplifier/
(https://www.hifi-advice.com/blog/amplifier-reviews/power-amplifier-reviews/nuprime-evolution-sta-stereo-power-amplifier/)
This review is very detailed. We are very appreciative of Christiaan's reviews because in each one, he precisely pointed out the best qualities and areas for improvement. So in Evolution STA, we set out to combine the best qualities of AMG STA and ST-10M and I think we did a good job. :thumb:
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Indeed. Very nice write up. Thanks much for posting. Thanks also for the power supply details, which I suppose supports the dual mono statement on the product page.
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So if the amp uses an op amp as the input section instead of a class A version as with some of the other Nuprime amp offerings, is it true to say that the amp never heats up at all? And if that's true, does it mean that the Evolution STA runs more efficiently than if it had a class A input section?
Thank you.
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So if the amp uses an op amp as the input section instead of a class A version as with some of the other Nuprime amp offerings, is it true to say that the amp never heats up at all? And if that's true, does it mean that the Evolution STA runs more efficiently than if it had a class A input section?
Thank you.
I can't answer the other question, but this is one cool running amp. A room heater it is not. The top case of mine barely feels warm.
Michael
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Thanks Michael. I am still interested in the efficiency value of this amplifier if anyone knows the answer. Thank you.
Edit: Removed a comment to Michael that was off topic.
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We started to use linear power supplies for most of our amps, so the efficiency is between a pure class D (i.e. Class D with switching power supply) and Class A amp. We don't measure efficiency anymore.
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Thank you.
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Due to covid travel restrictions throughout Asia, I haven't been able to listen to Evo STA out of Taiwan factory. But I don't need to listen to it for myself, I can rely on the chief engineer. HiFi Advice has been reviewing our amps and we come close to challenge the reference CH A1.5 ($39,500). I think Evo STA has a shot at matching any class A reference amp.
Hi Jason,
I am using a ST-10 to to drive a pair of Martin Logan ESL11A speakers.
Currently looking for an amp that sounds warmer and smoother.
Is the Evo STA warmer and smoother sounding than the ST10?
Is there a review of the Evo STA somewhere?
How can I get hold of a demonstration unit in Australia?
Thanks.
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Toward the top of this page, you'll discover this review:
https://www.hifi-advice.com/blog/amplifier-reviews/power-amplifier-reviews/nuprime-evolution-sta-stereo-power-amplifier/
(https://www.hifi-advice.com/blog/amplifier-reviews/power-amplifier-reviews/nuprime-evolution-sta-stereo-power-amplifier/)
This review is very detailed. We are very appreciative of Christiaan's reviews because in each one, he precisely pointed out the best qualities and areas for improvement. So in Evolution STA, we set out to combine the best qualities of AMG STA and ST-10M and I think we did a good job. :thumb:
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Also, this review:
Some may find our New Zealand Dealers evaluation valuable to the EVO STA
https://totallywired.nz/nuprime-2/nuprime-evolution-sta/
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Hi Jason,
I am using a ST-10 to to drive a pair of Martin Logan ESL11A speakers.
Currently looking for an amp that sounds warmer and smoother.
Is the Evo STA warmer and smoother sounding than the ST10?
Is there a review of the Evo STA somewhere?
How can I get hold of a demonstration unit in Australia?
Thanks.
Yes, Evo STA will give you warmer, smoother and yet more detailed sound than ST-10.
Besides Hifi-advice.com, The Absolute Sound September issue also has Evolution STA review.
Unfortunately we don't have an active dealer in Australia.
PM me, there is a like-new black Evo STA in the USA that you can purchase (and refund if you don't like it). You can also contact our New Zealand dealer Totallywired.nz.
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Jason- it would appear the Absolute Sound September review is of the AMG STA, not the Evolution STA- am I missing something? You indicated '
Evolution STA' as the review product- please correct me if in error and post a link to the Evo STA Absolute Sound review (if indeed there is one). Thanks
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I heard through the Canadian Distributor that indeed my wish may come true and Nuprime is bringing out monoblock versions if the new STA stereo amplifier. Can anyone confirm this and if so timing on the release? Thanks
John