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Bruno Putzeys - Darko interview


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5 hours ago, Stereophilus said:

We will continue to disagree regardless of my gear list.  Why? Because I trust people who listen to their designs, and I trust my own ears as well.

 

 

But that’s like saying “I trust my own eyes, and I’m telling you that space B is of a lighter shade than space A, science and measurements be damned”.

 

image.jpeg.3d70a05de205af9bacc41655fb35b5c5.jpeg

 

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I’m a regular reader/YouTube viewer/podcast listener of John Darko of Darko.Audio.  This is his most recent interview with Bruno Putzeys who doesn’t really need any introduction in this forum.  Be for

https://phys.org/news/2013-02-human-fourier-uncertainty-principle.html

😂   No. Shall we get started on what analogue media and playback suffer from (not least of all, analogue media and playback fans)? 🤣

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6 hours ago, frednork said:

Pass is on record as using blind tests in amp development, Would be very surprised if Putzeys does not.

 

Both do. 

 

@Grant Slack an overly simplistic and very incorrect view. Not least without subjective interpretations of performance we'd not have an industry.

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9 minutes ago, Steffen said:

 

But that’s like saying “I trust my own eyes, and I’m telling you that space B is of a lighter shade than space A, science and measurements be damned”.

 

image.jpeg.3d70a05de205af9bacc41655fb35b5c5.jpeg

 

There is a reason our brain sees B as a lighter shade than A.  Our brains are programmed to make sense not of B vs A, but of that picture as a whole.  I actually don’t care if they are the same shade or not, as long as the image makes sense.  The information from measurement is useful, but it tells me nothing of the image I see.  
 

Now, the question becomes is the deception beneficial, or harmful?  Not all deception is harmful.  If it gives a clearer picture of the whole, and leads to beneficial outcomes then we need to embrace it and broaden our collective perspectives.

 

Narrow-mindedly following the paradigm that our brains are wrong when there is objective evidence of a contrary truth can do a great deal of inadvertent damage, especially when the broader picture is lost.  I do think there is an important place for objective understanding, but sometimes I want to just enjoy a picture of a green cylinder on a checker board, rather than compare 2 grey squares.

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2 minutes ago, Stereophilus said:

I do think there is an important place for objective understanding, but sometimes I want to just enjoy a picture of a green cylinder on a checker board, rather than compare 2 grey squares.

 

I agree, but the point was that the science of human perception is a complex beast, and being human doesn’t make one an expert in it.

 

I fully concur that being fooled can be enjoyable, and an experience to seek out (everybody loves magic shows, or movies, for example). I also recognise that things outside the physical reality of music reproduction (a nicely designed front plate, pseudo-scientific lingo to describe the construction of a cable, or merely a high price tag) can alter the perception of music playback, and make it more enjoyable to certain listeners.

 

What I cannot go along with is when people insist that there are actual differences in the music reproduction, that some people with golden ears can hear, but instruments can’t measure.

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4 minutes ago, Steffen said:

 

I agree, but the point was that the science of human perception is a complex beast, and being human doesn’t make one an expert in it.

 

I fully concur that being fooled can be enjoyable, and an experience to seek out (everybody loves magic shows, or movies, for example). I also recognise that things outside the physical reality of music reproduction (a nicely designed front plate, pseudo-scientific lingo to describe the construction of a cable, or merely a high price tag) can alter the perception of music playback, and make it more enjoyable to certain listeners.

 

What I cannot go along with is when people insist that there are actual differences in the music reproduction, that some people with golden ears can hear, but instruments can’t measure.

Kind of my point too... Human perception is extremely complex and not well understood even to this day.  I keep coming back to the idea that only humans have perception of the whole.  When people do insist they hear differences that are not measurable, in my view, it is because we do not yet fully grasp human perception in all its complexity.  That is an issue of objective inadequacy, not subjective deception.

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2 hours ago, rmpfyf said:

 

Both do. 

 

@Grant Slack an overly simplistic and very incorrect view. Not least without subjective interpretations of performance we'd not have an industry.

 

I’m all in favour of subjective interpretations — validly conducted. You seem to have made an overly simplistic and very incorrect analysis of my view, if you think I am not. 

 

As for “both do”, well, it’s just too easy for them to say that, especiallly if they are saying that blind testing has shown audible improvements miles below the established limits of human sensory perception. If that is their claim, then they need to bring their findings into the harsh glare of independent verification. I’m guessing that hasn’t happened? Well then.

 

Why, for example, would Putzeys do blind testing, if he is also willing to make the statement quoted here. “...for those people who say they tried feedback and it didn’t sound good, they had real experiences -- they didn’t make it up...”, is literally saying that he thinks that casual, uncontrolled listening is all about the sound waves. If true, a blind test is completely unnecessary. Being a 100% disproven statement is another minor problem with it. Certainly, the quote above validates my original statement about electrical gurus not being human perception gurus.

 

cheers

Grant

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6 hours ago, Grant Slack said:

 

I’m all in favour of subjective interpretations — validly conducted. You seem to have made an overly simplistic and very incorrect analysis of my view, if you think I am not. 

 

As for “both do”, well, it’s just too easy for them to say that, especiallly if they are saying that blind testing has shown audible improvements miles below the established limits of human sensory perception. If that is their claim, then they need to bring their findings into the harsh glare of independent verification. I’m guessing that hasn’t happened? Well then.

 

Why, for example, would Putzeys do blind testing, if he is also willing to make the statement quoted here. “...for those people who say they tried feedback and it didn’t sound good, they had real experiences -- they didn’t make it up...”, is literally saying that he thinks that casual, uncontrolled listening is all about the sound waves. If true, a blind test is completely unnecessary. Being a 100% disproven statement is another minor problem with it. Certainly, the quote above validates my original statement about electrical gurus not being human perception gurus.

 

cheers

Grant

 

You've taken some quotes in a very specific context and make some sweeping and incorrect assessments on how others work and think.

 

For instance - didnt state anything regarding your support for subjective testing or otherwise. You seem to assume I have, and that I'm incorrect accordingly.

 

You've too many assumptions.

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16 hours ago, frednork said:

Pass is on record as using blind tests in amp development, Would be very surprised if Putzeys does not.

I’d be surprised if Pass can’t tell his amps apart in a blind test but I agree with one of the earlier posters  (@davewantsmoore )that it’s unlikely that the differences he’s hearing are from any special sauce coming from harmonic distortion. He’s almost certainly listening to the way his amps clip. 
 

 

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47 minutes ago, sir sanders zingmore said:

I’d be surprised if Pass can’t tell his amps apart in a blind test but I agree with one of the earlier posters  (@davewantsmoore )that it’s unlikely that the differences he’s hearing are from any special sauce coming from harmonic distortion. He’s almost certainly listening to the way his amps clip. 
 

 

 

Although I agree, NP amps would clip with certain "nice sounding" characteristics, I 'feel' as a F7 owner it would be quite easy to hear the difference between an F7/J2 and a low distortion Hypex/Purifi operating below clipping. These amplifiers couldn't sound more different from one another.

 

I.e. F7 smooth clipping:

image.png.d89af6f03678946fa8967b29b7ea4053.png

 

In any case I suspect most Firstwatt owners would be partnering their amplifiers with highly sensitive speakers, and therefore would spend very little time in clipping. For instance, with 94-95db sensitive speakers I probably spend most of my time in the 1-5watt window. 

 

In regards to harmonic distortion profiles, NP is on record discussing how he manipulates amplifier harmonic distortion profiles to shape amplifier sound. From memory he spoke about distortion and its impact on imaging, perceived smoothness, and listeners preferences for 2nd or 3rd harmonic distortion profiles.

 

There is a couple of good interviews on the Audiophilliac youtube channel where NP briefly discusses distortion, listeners preferences for distortion and his products. This is a great link written by NP. I have linked to page 3, but its worth a total read.  https://6moons.com/industryfeatures/distortion/distortion_3.html

 

If you have a moment look through the F7 product pdf.

NP explains his amplifier design and its distortion profile.

This makes it clear that NP is playing with the distortion profile, to shape his amplifier sound. 

https://www.firstwatt.com/pdf/prod_f7_man.pdf

image.png.06e68a2372ddc6021cd8333d4884e23b.png


 


 

 

 

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1 hour ago, sir sanders zingmore said:

He’s almost certainly listening to the way his amps clip.

As we've discussed before :) More time is spent clipping than people are willing to believe; hence why valves are still so popular.

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1 hour ago, Grizaudio said:

F7 owner it would be quite easy to hear the difference between an F7/J2 and a low distortion Hypex/Purifi operating below clipping

 

As @Ittaku states above, more time is spent in clipping than most people think. I don't know what speakers you have or how loud you listen but I imagine into most 'normal' speakers, even Purifi or Hypex amps are clipping.

 

To be clear, I have no issue with the idea that amps sound different, I just think that difference in sound is usually to do with clipping rather than anything else. I suspect that at ~ minus 65dB, that second harmonic in the F7 is less audible (in music) than most people think

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11 minutes ago, sir sanders zingmore said:

As @Ittaku states above, more time is spent in clipping than most people think. I don't know what speakers you have or how loud you listen but I imagine into most 'normal' speakers, even Purifi or Hypex amps are clipping.

I'll have both shortly to compare. I've had NC400 monoblocks for a while and will be getting Purifi ET1400 monoblocks in a week. Looking at the impedance profile of my speakers, they are actually very hard to drive and dipping to 2 ohms with phase angles to boot is going to stress just about any design. The NC400 is no contest for my valve monoblocks but then they cost 30x as much. It's hard to know if they really have decent current delivery despite being valve since they're so beefy, or just that they're always soft clipping (probably a combination of both). As SSZ said, if you actually measure amps into a real speaker load, you'll be surprised at how low the power output is before clipping shows up.

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5 minutes ago, Ittaku said:

I'll have both shortly to compare. I've had NC400 monoblocks for a while and will be getting Purifi ET1400 monoblocks in a week. Looking at the impedance profile of my speakers, they are actually very hard to drive and dipping to 2 ohms with phase angles to boot is going to stress just about any design. The NC400 is no contest for my valve monoblocks but then they cost 30x as much. It's hard to know if they really have decent current delivery despite being valve since they're so beefy, or just that they're always soft clipping (probably a combination of both). As SSZ said, if you actually measure amps into a real speaker load, you'll be surprised at how low the power output is before clipping shows up.

 

Fair enough. 

I sit about 2.5m from speakers in nearfield. 

I typically listen between 75-85db, speakers are 94db sensitive.    

 

I would be interested in your feedback on the Purifi amplifier modules.

Which brand did you go with? 

 

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3 minutes ago, Grizaudio said:

I would be interested in your feedback on the Purifi amplifier modules.

Which brand did you go with?

March. The barrier to entry for professionally built completed monoblocks with warranty and support is hard to beat, but I'm buying them on the reputation of the Purifi modules and my own experience with Hypex based amps previously.

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Out of interest I looked at some other Pass Labs amps and it seems the 30.5 has significantly more 3rd harmonic than second. I assume this is also a deliberate design choice

 

https://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements

 

image.png.00cfd063cedbd70ae674a59c95f21365.png

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49 minutes ago, sir sanders zingmore said:

Out of interest I looked at some other Pass Labs amps and it seems the 30.5 has significantly more 3rd harmonic than second. I assume this is also a deliberate design choice

 

https://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements

 

image.png.00cfd063cedbd70ae674a59c95f21365.png

Read this page from NP:

https://6moons.com/industryfeatures/distortion/distortion_3.html

 

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On 29/07/2020 at 7:07 PM, Stereophilus said:

For sure.  He is invested in what he designs and therefore biased.  I do like his openness in sharing his knowledge though.

At least his claims are based on facts. How an amp performs on the bench is not really a matter of opinions. Of course, some might prefer an amp that measures worse but weights 50 kg and has VU meters, just like some prefer overcooked pasta or cheese on oysters. Not saying you do of course. Just a joke to say that what people prefer often has not much to do with good engineering

:)

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On 29/07/2020 at 6:57 PM, RankStranger said:

 

 

Regarding the above, it helps to keep in mind that, although he’s an engineer, he’s selling his designs and he’ll get far more attention saying no amp will ever be audibly better than he will get by saying this is really great but I’m already designing a better one to replace it!

Purifi amps measure better than Hypex-based amps, but many think the difference is not audible. So the new design IS better, but probably not audibly better. Or if it can be heard (I doubt it), the difference would be extremely little.

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1 minute ago, o2so said:

Purifi amps measure better than Hypex-based amps, but many think the difference is not audible. So the new design IS better, but probably not audibly better. Or if it can be heard (I doubt it), the difference would be extremely little.

 

I suspect audible differences may exist between company input buffers. 

With Hypex and Purifi amplifiers measuring so cleanly, my suspicion is buffers will ultimately impact overall presentation.

 

The buffer also plays a very important role if you are feeding via unbalanced RCA.

 

The Neurochrome looks to provide a good grasp of what's required: 

https://neurochrome.com/products/purifi-1et400a-hypex-nc500-input-buffer

 

 

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6 hours ago, sir sanders zingmore said:

I’d be surprised if Pass can’t tell his amps apart in a blind test but I agree with one of the earlier posters  (@davewantsmoore )that it’s unlikely that the differences he’s hearing are from any special sauce coming from harmonic distortion. He’s almost certainly listening to the way his amps clip. 
 

 

 

I was about to direct you to an interesting podcast interview I had heard with Roger Sanders about amplifiers and clipping when I remembered which podcast and realised you were probably already aware 😂

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1 hour ago, o2so said:

Purifi amps measure better than Hypex-based amps, but many think the difference is not audible. So the new design IS better, but probably not audibly better. Or if it can be heard (I doubt it), the difference would be extremely little.

 

It’s been a while but I think my point was more about his motives as a marketer rather than whether he was right or wrong. I’ve heard neither amp :) 

 

Is that the general consensus, now that they have been around for a while?

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8 minutes ago, RankStranger said:

 

I was about to direct you to an interesting podcast interview I had heard with Roger Sanders about amplifiers and clipping when I remembered which podcast and realised you were probably already aware 😂

 

this one perhaps…..

 

Episode 7: For the Love of Sanders!:

Special Guest Edition! The 3 Sad Bastards are joined by Roger Sanders from Sanders Audio Systems in this first ever episode where someone has been brave enough to come on and engage in witty, respectful and engaging repartee! 

The 3 Sad Bastards are schooled by one of the audio industry great thinkers and innovators - listen in as Roger articulates his philosophy on amplifiers, speakers and hifi in general!

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7 minutes ago, RankStranger said:

 

Is that the general consensus, now that they have been around for a while?

 

You are asking about general consensus, in a Great Audio Debate thread? :) 

 

 

Regards

Grant

Edited by Grant Slack
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15 minutes ago, RankStranger said:

Is that the general consensus, now that they have been around for a while?

There are precious few comparisons out there, and certainly none that I can trust. For the most part it is Bruno's word that they sound better, and no doubt ASR measure them as being better (but they don't talk sound quality since $100 amps are allegedly not audibly different from $100,000 ones.)

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18 hours ago, Grant Slack said:

 

I’m all in favour of subjective interpretations — validly conducted. You seem to have made an overly simplistic and very incorrect analysis of my view, if you think I am not. 

 

As for “both do”, well, it’s just too easy for them to say that, especiallly if they are saying that blind testing has shown audible improvements miles below the established limits of human sensory perception. If that is their claim, then they need to bring their findings into the harsh glare of independent verification. I’m guessing that hasn’t happened? Well then.

 

Why, for example, would Putzeys do blind testing, if he is also willing to make the statement quoted here. “...for those people who say they tried feedback and it didn’t sound good, they had real experiences -- they didn’t make it up...”, is literally saying that he thinks that casual, uncontrolled listening is all about the sound waves. If true, a blind test is completely unnecessary. Being a 100% disproven statement is another minor problem with it. Certainly, the quote above validates my original statement about electrical gurus not being human perception gurus.

 

cheers

Grant

Interesting that you choose to paraphrase Bruno via a quote in ASR... The original and complete quote alludes to his desire to change peoples predjudices against negative feedback and class D generally.  Predjudices built on listening experiences.  As you well know an experience of percieved difference is a real (human) experience, even if there is no objective basis for that difference.  Bruno's comments there simply reflect his desire to change perceptions based on previous experience by giving them something new to consider.

 

You also talk as if audibility is a solved problem when it is far from that.  The studies on audibility of tonal variance, sound stage, and complex music are mired in their difficult methodology, inherent assumptions of human experience and very poor inter-subject reliability.  Thresholds of hearing test tones are one thing, but the complex effect of waveform distortions are a very different problem and one that is yet to be tackled with anything like the voracity needed to draw broad conclusions on audibility of distortions.  

 

I know many hold up the work of Toole as a beacon in this area, and yet as professional trained in critical appraisal of scientific methodology, his studies are rife with eroneous assumptions, bias and poor methodology.  The work he did has value, but the journey continues.

 

Now, im not saying NP or BP have the riddle solved any more than Toole does, but their experience, applied knowledge and training also have real value to the hifi community.  Value that provides impetus for growth and betterment.  Without that growth the industry stagnates.

 

There are hifi fora that in my view promote stagnation rather than growth, by promoting the concept that we have all the knowledge we need for hifi design, and the only thing left to do is engineer it to the lowest price point.  I do not agree with this view.

 

I posted BPs souncloud interview with JD here to promote growth, not stagnation.

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5 hours ago, Grant Slack said:

 

You are asking about general consensus, in a Great Audio Debate thread? :) 

 

 

Regards

Grant

Good one.

 

I would like to know if there is a general consensus on the meaning of 'clipping'? Surely it can be readily measured and verified on a scope. Alternately one could check if an amp's soft clipping mechanism has been triggered. 

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1 hour ago, Stereophilus said:

You also talk as if audibility is a solved problem when it is far from that.  The studies on audibility of tonal variance, sound stage, and complex music are mired in their difficult methodology,

 

For sure there is more to learn about audibility. There is more to learn about everything.

But saying that studies are mired, gives the impression that we know very little when in fact a lot of this stuff is actually very well understood.

 

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55 minutes ago, LHC said:

I would like to know if there is a general consensus on the meaning of 'clipping'? Surely it can be readily measured and verified on a scope. Alternately one could check if an amp's soft clipping mechanism has been triggered. 

Yes it is and it can be measured and verified. The issue is most measurements of amplifiers aren't done on real speakers with real world music, and even the 'simulated speaker load' in stereophile for example is out of date for how hard modern speakers are to drive. Some of us have connected up oscilloscopes to our amplifiers' outputs when connected to speakers just for grins and been horrified to see obvious clipping at not-very high volumes and have then shifted to completely different amplifier designs as a result, like SSZ did with his shift to Sanders.

Edited by Ittaku
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28 minutes ago, sir sanders zingmore said:

 

For sure there is more to learn about audibility. There is more to learn about everything.

But saying that studies are mired, gives the impression that we know very little when in fact a lot of this stuff is actually very well understood.

 

The statement was not intended to give the impression we know very little, rather that we need to not fall into the trap that we think we know it all.  Mired is used to convey my frustration when I see studies extrapolate their conclusions beyond their power, and in doing so holding back real progress.

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On 14/01/2021 at 2:24 AM, Ittaku said:

dipping to 2 ohms with phase angles to boot is going to stress just about any design. 

 

ups, you should have maybe instead of purifi amps look into NC1200 or NC2K...    25A from purifi (same as NC400)  vs.  38A from NC1200 or 48A from NC2K 

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5 hours ago, kukynas said:

 

ups, you should have maybe instead of purifi amps look into NC1200 or NC2K...    25A from purifi (same as NC400)  vs.  38A from NC1200 or 48A from NC2K 

That was actually unintentional and will be improved with my crossover redesign, so I'm not worried, but for the meantime it makes for a good challenge anyway.

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I cant remember if it was on this forum or on ASr, but March conducted a blind test between his Ncore and Purifi amps and all participants could pick a difference. 

Be interesting to see what @Ittaku finds.

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11 minutes ago, AudioGeek said:

I cant remember if it was on this forum or on ASr, but March conducted a blind test between his Ncore and Purifi amps and all participants could pick a difference. 

Be interesting to see what @Ittaku finds.

And that's very interesting considering both would allegedly be below the threshold of hearing difference according to ASR's own bullshit thresholds.

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40 minutes ago, Ittaku said:

That was actually unintentional and will be improved with my crossover redesign, so I'm not worried, but for the meantime it makes for a good challenge anyway.


yeah, I know, but it could have been interesting compar with your heavy heaters once you get them back 😀

 

btw, NAD C298 with purifi modules can be bridged, that woul be interesting comparison 👍

I think Kal Rubinson planning to test them

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4 minutes ago, kukynas said:


yeah, I know, but it could have been interesting compar with your heavy heaters once you get them back 😀

 

btw, NAD C298 with purifi modules can be bridged, that woul be interesting comparison 👍

I think Kal Rubinson planning to test them

I've compared my NC400s to my ARC power amps many times - no contest. Bridging amps makes them less able to tolerate low impedance, not the other way around - at least for class A/AB amps, not sure if there's something special about D.

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13 minutes ago, Ittaku said:

And that's very interesting considering both would allegedly be below the threshold of hearing difference according to ASR's own bullshit thresholds.

But not when they are clipping. (I know, I know, again with the clipping)

 

I  think the error that the ASR crowd makes is probably not about audibility thresholds for amps, it’s about how much power you need in order to avoid clipping. 

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5 minutes ago, Ittaku said:

I've compared my NC400s to my ARC power amps many times - no contest. Bridging amps makes them less able to tolerate low impedance, not the other way around.


you right especially in your case where each module would see 1 ohm load

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13 minutes ago, sir sanders zingmore said:

I  think the error that the ASR crowd makes is probably not about audibility thresholds for amps, it’s about how much power you need in order to avoid clipping. 

Fair call, but the NC400 and Purifi ET1400A should deliver identical current and virtually the same power.

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1 hour ago, AudioGeek said:

I cant remember if it was on this forum or on ASr, but March conducted a blind test between his Ncore and Purifi amps and all participants could pick a difference. 

Be interesting to see what @Ittaku finds.

Would be interested in a link to this if you have it

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5 hours ago, sir sanders zingmore said:

But not when they are clipping. (I know, I know, again with the clipping)

 

I  think the error that the ASR crowd makes is probably not about audibility thresholds for amps, it’s about how much power you need in order to avoid clipping. 

 

 

How much power one needs is dependant on so many factors.

 

I suspect I would rarely if ever hit clipping, with my 20watts.

Honestly, I'm not sure this is an issue everyone would have.

Too many assumptions.

 

For instance multiway amplifier setups reproducing small acoustic bandwidths would not suffer as much as full range amplifiers. High sensitivity setups also only require very few watts to operate optimally at very high SPL's.  Distance to speakers, required SPL, room size, easy to drive impedance profiles, personal hearing etc all mean this position is not necessarily valid or important.  

 

Edited by Grizaudio
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